Team M-SEC MULTI-HULL SURFACE EFFECT CRAFTmy.fit.edu/~swood/M-SEC Final Paper.pdf · M-SEC –...

08 Fall

F l o r i d a I n s t i t u t e o f T e c h n o l o g y

MFP 2010

Team M-SEC MULTI-HULL SURFACE EFFECT CRAFT

Brittany Burk Adam Harris

Michael Melita Cameron Roberts

Kait Trump

Department of Marine & Environmental Systems Senior Design Project – Final Report

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Letter of Transmittal

Florida Institute of Technology Department of Marine and Environmental Systems Marine Field Projects TO: Dr. Stephen Wood Department of Marine and Environmental Systems Florida Institute of Technology 150 W. University Blvd. Melbourne, FL 32901 FROM: Team M-SEC 150 W. University Blvd. Melbourne, FL 32901 RE: M-SEC Design Team Design Report Dr. Wood, The following Design Report on Team M-SEC’s senior design project is being submitted for your review. The report includes all concepts and design notes since the conception of the project. All of the sections have been written to the best of our ability, with all references and credits given or cited. We would like to thank the Faculty & Staff of the Department of Marine and Environmental Systems (DMES) for the guidance given, and the prospect of available funds for the project. Thank you and please contact us if you have any further questions. Sincerely,

Brittany Burk _____________________

Adam Harris _____________________

Michael Melita _____________________

Cameron Roberts _____________________

Kait Trump _____________________

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Acknowledgments

We would like to thank the following people and organizations for all the help they offered to the design group. This project would not be possible without their help. We would like to thank the Department of Marine & Systems (DMES) at the Florida Institute of Technology for their resources provided as well as the initial $1000 in capital to begin work on the project.

Dr. Stephen Wood PhD, PE, DMES

Dr. Stephen Jachec PhD, PE, DMES

Dr. Prasanta Sahoo PhD, DMES

Dr. Ron Reichard PhD, DMES

Mr. A.J. Finan B.S. ME, Cannibal Surfboard Co.

Mr. Brion Burk B.S. EE, General Scientific Corp.

Mr. Leo Melita B.S. EE/CSE, Consolidated Edison Corp.

Mr. Paul Bonenfant B.S. Chm., Lederle Laboratories

Mr. Travis Hunsucker B.S. OE, DMES

Mr. Brock Tucker B.S. B.A., Henegar Performing Arts Center

Mr. Larry Buist, ECE

ICCS (SW) Bill Battin, USN Ret., Research Technician, DMES

Mr. Bill Bailey, Machinist Florida Tech Machine Shop

Mr. Thomas Kehrer, CEO of KMB

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Table of Contents

Letter of Transmittal ................................................................................................................................................ 2

Acknowledgments ..................................................................................................................................................... 3

List of Figures .............................................................................................................................................................. 5

List of Abbreviations ................................................................................................................................................ 6

Executive Summary .................................................................................................................................................. 7

1.0 Introduction................................................................................................................................................. 8 1.1 Motivation & Objectives ..................................................................................................................... 8 1.2 Organization ........................................................................................................................................... 8

2.0 Background .................................................................................................................................................. 9 2.1 History of Surface Effect Craft .......................................................................................................... 9 2.2 Basic Theory ........................................................................................................................................ 11

3.0 Vessel Design ............................................................................................................................................ 15

4.0 Model Systems ......................................................................................................................................... 18 4.1 Propulsion System ............................................................................................................................ 18 4.2 Steering ................................................................................................................................................. 20 4.3 Batteries................................................................................................................................................ 21 4.4 Motor Control ...................................................................................................................................... 21 4.5 Lift ........................................................................................................................................................... 23 4.6 Cooling ................................................................................................................................................... 25 4.7 Radio Control ...................................................................................................................................... 25

5.0 Manufacturing.......................................................................................................................................... 26 5.1 Hull Fabrication ................................................................................................................................. 27 5.2 Internal Systems ................................................................................................................................ 33

5.2.1 Propulsion ......................................................................................................................................................... 34 5.2.2 Steering ............................................................................................................................................................... 36 5.2.3 Cooling ................................................................................................................................................................ 38 5.2.4 Lift ......................................................................................................................................................................... 39

6.0 Model Testing ........................................................................................................................................... 41 6.1 Static Thrust Test .............................................................................................................................. 41 6.2 Lift System Tests ................................................................................................................................ 42 6.3 Future Testing ............................................................................................................................................. 43

6.3.1 Software Testing............................................................................................................................................. 43 6.3.2 Speed Testing ................................................................................................................................................... 43 6.3.3 GPS Data Logging ........................................................................................................................................... 44 6.3.4 Lift Pressure Test ........................................................................................................................................... 44 6.3.4 Sea-keeping Test ............................................................................................................................................ 44

6.4 Testing Summary ............................................................................................................................... 45

7.0 Discussion & Recommendations ....................................................................................................... 45

8.0 Conclusion ................................................................................................................................................. 48

9.0 Appendix .................................................................................................................................................... 49 9.1 Budget .................................................................................................................................................... 49 9.2 MATLAB Code ...................................................................................................................................... 51 9.3 Time Sheet ........................................................................................................................................... 54

10.0 References ................................................................................................................................................. 56

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List of Figures

Figure 1: Speed vs. Resistance of Various Craft (Sklonick, 700) .............................................. 9Figure 2: The underside of a surface effect craft (Bertin, 749) ............................................. 12Figure 3: Various lift principles (Skolnick, 703) ......................................................................... 13Figure 4: Standard SES seal designs (Skolnick, 708) ................................................................ 14Figure 5: M-SEC 3-D Isometric View (Rhinoceros) .................................................................... 15Figure 6: M-SEC wireframe rendering (MaxSurf) ...................................................................... 16Figure 7: M-SEC Profile View (Rhinoceros) .................................................................................. 17Figure 8: M-SEC Plan View (Rhinoceros) ...................................................................................... 17Figure 9: M-SEC Beam Plan View (Rhinoceros) ......................................................................... 18Figure 10: 33mm Kehrer Jet (jet-drive.de) ................................................................................... 19Figure 11: Water-cooled Johnson 800 (jet-drive.de) ................................................................ 20Figure 12: Jet drive nozzle ................................................................................................................. 20Figure 13: Servo, motor, and drive configuration ..................................................................... 21Figure 14: Propulsion Wiring Schematic (jet-drive.de) ........................................................... 23Figure 15: Forward port skirt ........................................................................................................... 24Figure 16: Blower and ducting system .......................................................................................... 24Figure 17: Six-channel FM Radio Control System ...................................................................... 26Figure 18: One of the vessel’s six pieces on the CNC’s screen ................................................. 27Figure 19: The Dow foam being prepared for milling .............................................................. 28Figure 20: Center hull being milled ................................................................................................ 29Figure 21: Gluing and aligning the six pieces .............................................................................. 29Figure 22: The bulkhead being installed ....................................................................................... 30Figure 23: The layers of fiberglass cloth on the vessel ............................................................. 31Figure 24: The resin being applied to the vessel ........................................................................ 31Figure 25: Air is evacuated from the system, which forms a vacuum ................................. 32Figure 26: The vessel as it was tested in the Indian River ....................................................... 33Figure 27: Longitudinal Stringers & Electronics Deck ............................................................. 34Figure 28: Battery Wiring Configurations (Smart Draw) ...................................................... 36Figure 29: Jet Nozzle showing 3 pre-drilled holes at top (ProEngineer) ........................... 37Figure 30: DC Motor & Cooling Shell (ProEngineer) ................................................................ 38Figure 31: Blower Control Switch/Servo ...................................................................................... 40Figure 32: Fish Scale ............................................................................................................................ 41Figure 33: Static Thrust Test ............................................................................................................ 42Figure 34: Speed Trial Data Table .................................................................................................. 43

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List of Abbreviations ACV - Air Cushion Vehicle

ASW - Anti-Submarine Warfare

CNC – Computer Numerically Controlled

CSC – Cannibal Surfboard Company

DMES – Department of Marine & Environmental Systems

ESC – Electronic Speed Control

FIT – Florida Institute of Technology

M-SEC – Multi-hull Surface Effect Craft

SES – Surface Effect Ship

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Executive Summary

Surface Effect Ship, or SES, technology is still among the fields considered to be

‘experimental’ in many respects of naval architecture. They are extremely efficient

and also have superb sea keeping qualities. A ship classified as a surface effect craft,

uses an air pressure cushion created by forcing air into the space between the ships’

hulls. The air pressure is held between the hulls by skirts similar to those used by

hovercraft.

Team M-SEC has endeavored to mate the air skirt system to a trimaran hull design.

The concept is to further advance the sea keeping and efficiency/profitability of

trimaran vessel designs through the use of SES technology. The initial test is a proof

of concept; later tests will include sea-keeping analysis using an accelerometer and

an evaluation of the power requirements between a regular craft and a craft using

SES technology. Finally a peer review article will be submitted with the teams

findings.

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1.0 Introduction

1.1 Motivation & Objectives

Our group’s intent with this project was to advance our working knowledge of hull

design and naval architecture, model building, and testing as well the fundamental

theories of hydromechanics. We wanted also to gain experience in the field of group

dynamics and working in a team environment. The objective of our project was to

build a conceptual model of a trimaran type Surface Effect Ship. We designed our

initial hull model in MaxSurf and then transferred the geometry into Rhino, a 3-D

surface-modeling program. Our concept includes incorporating Surface Effect Ship

technology to lift the vessel’s hull out of the water to improve efficiency and sea

keeping characteristics. The design allows a ship of similar design to be made of

composites due to the latitudinal and longitudinal support of the air cushion.

Upon completion of the model, testing began. The concept was proven to work.

More study needs to be done and the model must be altered to gain more usable

data. Once this occurs, the team will produce a peer review journal article on their

findings.

1.2 Organization

Our team handles areas of the project that coincide best with their particular

interests and knowledge base. All team members were involved with all aspects of

the process but each member had specific responsibilities. The team was lead by

Cameron Roberts. He has handled the scheduling of tasks as well as specifying the

drives to be used in the propulsion system. Cameron also was instrumental in

assisting with the installation of the vessels onboard systems. Mike was the primary

Systems Engineer, responsible for making sure all of the mechanical and electrical

systems on the vessel worked correctly together. Throughout the project, Brittany

has conducted and complied vast amounts of research pertaining to our different

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proposed ideas. She was also responsible for the parts of the hull fabrication. Adam

was instrumental in aligning the team with local businesses for assistance. As the

primary Naval Architect, he was also mainly responsible for the design, construction

and fairing of the hulls. Kait has been the team’s scribe. She has assisted Brittany

with research, filed our weekly progress reports, and took notes at team meetings.

She also assisted with the hull construction process.

2.0 Background

2.1 History of Surface Effect Craft

Engineers must constantly adapt to advances in technology and the publics’ needs.

For centuries naval architects have been designing sea-going vessels to suit the

requirements of military and civilian organizations around the world. General

requirements include speed, efficiency, and cargo capacity. Many designs have been

created to fit these criteria and surface effect ships (SES) are one way professionals

have attained these goals. This design employs an air cushion, which is designed to

partially lift the hull form out of the water. If this is achieved, there is a reduction in

wetted area and therefore drag. A reduction in resistance allows the vessel to

achieve greater speed and mobility (Skolnick, 700). As shown in Fig. 1, the SES hull

form exhibits the lowest resistance characteristics in comparison to standard

planing and displacement hull forms.

Figure 1: Speed vs. Resistance of Various Craft (Sklonick, 700)

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Air cushion technology has come a long way from the 18th century when Emanuel

Swedenborg first developed the idea of riding on air. Swedenborg proposed a

“manually operated device” in which a person would thrust air under the vessel in

order to “raise the hull out of the water” (Fitzgerald, 2). However, his idea was soon

proved to be flawed because a human could not sustain the necessary air pressure

for extended periods.

The next great advancement came from Sir John Thornycroft in the mid 1870’s.

Thornycroft’s initial focus was on ground effect machines, but he later applied his

research to ships. His main goal was to design a hull that had “a concave bottom in

which air could be contained between the hull and the water” (Fitzgerald, 2). This

was a novel idea at the time. Around the same time period, a man named John B.

Ward recommended that ground effect machines should use “rotary fans to drive air

down and backwards” (Fitzgerald, 3).

Several other ideas were formed following this. The first man to suggest the

containment of air was James Walker in 1888 (Fitzgerald, 3). Many involved

different ways to push air under the vessel, including Gustaf de Laval’s idea for air

lubrication. However, a majority of these ideas failed because there was no method

to contain the air from escaping. The air lubrication method produced cavitation

beneath the hull, which reduced the efficiency of the vessel. To remedy this problem,

it was determined that “a consistent layer of air to isolate the hull surface” would be

required (Yun, 4). Chinese researchers performed testing in a tow tank to verify de

Laval’s theories. The researchers concluded that a “significant air gap” would be

more effective. Such an air capacity would require a different hull form (Yun, 4).

Research in this particular field continued for quite some time. The 1950’s saw a

major change in this field of study. Christopher Cockerell invented the first

hovercraft. Until this time, concepts such as these had been labeled “flying boats”

(Fitzgerald, 3). Cockerell’s invention marks the point where surface effect ships

diverge slightly from general air cushion vehicles (ACV).

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In the 1960’s, Britain, the United States, and the Soviet Union were at the forefront

of designing ACVs and SESs. These devices interested them mainly for military

purposes. Due to the vessel’s speed, it served as an excellent anti-submarine warfare

(ASW) craft. However, a vessel that was strictly a hovercraft would have difficulty

making transoceanic journeys. If such a voyage is necessary, an SES bridges the gap

nicely between a standard vessel and a hovercraft (Skolnick, 701).

Vessels such as these serve many practical purposes, which are not limited to

military usage. An SES would also be extremely useful as a high speed ferry and high

capacity cargo and freight transport. An SES could rapidly transport perishable

goods to distant lands and easily load and unload cargo and/or passengers

(Skolnick, 702).

The United States Navy created an SES with the most advanced technology available

in the 1960s. The vessel, termed XR-1, was equipped with state of the art SEAJETs,

designed by Donald E. Burg (Burg, 1). During testing XR-1 was fitted with fore and

aft seals to contain the air for the cushion. The XR-1 design was problematic. The

vessel capsized during high speed maneuverability testing (Steen, 9). M-SEC’s

trimaran hull form will in effect be more stable than a comparable catamaran hull

form and should be less prone to capsize.

Presently, trimaran hull form surface effect ships are uncommon. M-SEC hopes to

validate a concept not extensively explored previously. Such development of a novel

ship could have innumerable benefits to the military and commercial marine

industries.

2.2 Basic Theory

For years, ship builders have been searching for ways to build a faster and more

efficient vessel. Engineers have created a design that uses air to lift a ship out of the

water thus decrease its wetted area. Air cushion technology has been around for

decades and researchers are now trying to perfect the qualities that the air cushion

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has to offer. A surface effect ship is one of the most well known air cushion crafts.

Surface effect craft employ a self-regulating air cushion for lift support;

consequently, there is a reduction in wetted area and resistance.

A standard SES utilizes a catamaran hull form and two skirts, which are located at

the fore and aft of the ship. These skirts are made from a sturdy, but flexible

material that forms a seal with the water’s surface. The chamber that is created

under the ship is called the plenum.

Figure 2: The underside of a surface effect craft (Bertin, 749)

Air cushion vessels that have internal lift, which can be used at rest, are known as

“aerostatic” type craft. On these ships, deck mounted air fans force air into the

plenum and positive air pressure builds. When there is an excess of pressure in the

cushion, air leaks out beneath the edges of the fore and aft skirts (Skolnick, 703).

The principle behind this design allows the vessel to “sail along the top of the waves

instead of plowing through them” (Mechanical Engineering, 62). While in use, the air

cushion is able to support approximately 80% of a vessel’s weight, which greatly

decreases its draft (Dhanak, 3).

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SES hull and cushion designs are constantly evolving. Some designs involve an

entirely open and hard plenum chamber, while others include a flexible skirt. There

are also cushion designs where the air only exits along the outer edge of the craft.

The following picture illustrates only a few of the current lift designs (Skolnick,

703).

Figure 3: Various lift principles (Skolnick, 703)

As in most machines, the SES comes with its share of drawbacks. One of the

designers’ main goals is to maintain the stability and ride quality of the SES while

decreasing the drag caused by the fore and aft skirts. Air cushion technology is

perfect for riding waves with a long wavelength and low frequency. The following

formula characterizes a vessel traveling through waves. V is the vessels speed, T is

the period, λ is the wavelength:

𝑓 =𝑉 + 𝑐𝜆

=𝑉𝜆

+1𝑇

At low frequencies the heave and pitch of the vessel are nearly independent of wave

height. However, as the wavelength shortens and the frequency increases, the ship’s

dynamic stability becomes dependent upon wave height, speed, and the design of

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the air cushion (Dhanak, 1). In order to maintain the highest level of efficiency, the

air cushion must react to and contour with the water’s surface. Restoring forces

produced by the hulls are another large concern that the engineers face. Yet, these

restoring forces are much less for a surface effect ship than for a displacement ship.

The main reason is because the high fineness ratio and the decreased wetted area

produce less drag (Skolnick, 708).

There have been many different ideas concerning the skirts method of sealing and

air escape rates. The following illustration shows a few main skirt sealing ideas.

Figure 4: Standard SES seal designs (Skolnick, 708)

Throughout the design and testing of our vessel we will be using numerous

equations. The following is the equation that characterizes the vertical displacement

forces on a craft:

𝑀𝑑2𝜂3

𝑑𝑡2 = (𝑝𝑐 − 𝑝𝑎)𝐴𝑏 −𝑀𝑔

When using the above equation hydrodynamic forces on the vessel’s hull may be

neglected. In this equation η3 represents vertical displacement, M is the mass of the

vessel, pc is the cushion pressure, pa is the atmospheric pressure, and Ab is the

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cushion’s base area (Dhanak, 3). The following equation describes the dynamic

pressure within the air cushion:

𝑝𝑐 = 𝑝0 + 𝑝𝑎 + 𝜇(𝑡)𝑝0

The equilibrium pressure, which supports the mass of the ship, is described by po +

pa. The final term of the previous equation characterizes the excess pressure created

by the lift fans.

𝜌𝑐 = 𝜌𝑎(1 +𝜇(𝑡)𝑝0

𝑝0 + 𝑝𝑎)

1𝛾

The above equation demonstrates the density within the air cushion when there is

no gain or loss of heat. To ensure that the correct data has been calculated we will

be comparing our findings to another SES’s results (Dhanak, 4).

3.0 Vessel Design

To construct an accurate model, the first step in M-SEC’s design process was to

create a model in specialized hull design software. Two different software packages,

ProSurf and MaxSurf, are available through Florida Tech. Maxsurf was chosen for its

superior capabilities and power. MaxSurf is also much easier to use with minimal

training. A final hull shape was decided and implemented into Rhinoceros, modeling

software that is compatible with the software needed to construct a usable model

for a computer-numerical-controlled machine (Shown in Fig1.1).

Figure 5: M-SEC 3-D Isometric View (Rhinoceros)

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Figure 6: M-SEC wireframe rendering (MaxSurf)

An important facet of the chosen design is the single continuous air chamber. Dual

air chambers in a trimaran surface effect vessel would take two separate air systems

working together under a computer control system to regulate a uniform pressure

throughout the craft. It was decided that creating a hull form with a single air

chamber would be far more practical in a full size vessel. Furthermore, dual air

chambers would defeat the purpose of a single self-regulating air chamber.

A continuous air chamber was attained by shifting forward the central hull by ten

inches, or 1/6.6 of the model’s length overall (Shown in Fig1.2). This ultimately

creates a U-shaped air chamber where the air cushion can regulate pressure

throughout the entire underside of the vessel (Shown in Fig1.3). Scaling the

trimaran model based on a chosen propulsion system gave a required dimension of

66 inches long and 33 inches wide. The actual size of the model is ultimately

irrelevant to real life scenarios in the case that any size vessel can incorporate a

surface effect system.

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Figure 7: M-SEC Profile View (Rhinoceros)

The main purpose of a surface effect ship is to reduce drag as the vessel moves

through the water. The hulls were designed to be narrow, but still wide enough to

fit the jet drives and other components. As shown in (Fig1.3) one may notice the

steepness and sharp entry of M-SEC’s bows. This not only improves the vessel’s

ability to slice through rough water, but also allows the skirt systems to be vertically

flush with the walls of the hulls ensuring a seal for the air chamber. The aft sections

of the outer hulls are nearly flat over their bilges to accommodate the jet drive

intakes and to provide a solid planing surface. One aspect of the design that was

investigated is the slip introduced by lifting the hulls from the water. Surface effect

ships use their underwater propulsion systems and hulls to ensure steady tracking.

The central hull is designed with a slightly greater draft to improve vessel steerage

(Shown in Fig1.4). Without this additional section of hull in the water, the vessel

might be forced sideways in strong wind or currents.

Figure 8: M-SEC Plan View (Rhinoceros)

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Figure 9: M-SEC Beam Plan View (Rhinoceros)

4.0 Model Systems

Team M-SEC has elected to build a remote-controlled model boat to test our trimaran

surface effect ship concept. With an accurate model, we can easily and practically test

sea-keeping ability, hull drag, air cushion effects, and hull efficiency. Early in the project

design stages, we investigated building a simple hull model designed to be tested in a

large tow tank. However, given our limited experience in hull testing and the difficulties

of getting access to a suitable tow tank, we have decided to keep our model testable

locally. Local testing requires that the model be capable of its own power and lift. It must

be easily controlled and easy to operate. To attain these goals, the following systems have

been designed.

4.1 Propulsion System

M-SEC is propelled by dual water jet drives. These drives, produced by Kehrer

Modellbau (KMB), provide an economical and durable source of propulsion. Made

from machined plastic, these drives are easy to install, easy to maintain, and will not

corrode. They are approximately 11.8 centimeters long, 4.4 centimeters wide and

5.0 centimeters high, each weighing 150 grams. Composite propellers spin at

approximately 23,000 revolutions per minute within each housing; water is forced

from the large intakes on the bottom of the vessel to the outlets. In static testing,

each motor produced approximately 30 Newtons of thrust. The drives installed in

M-SEC feature forward thrust only, directed by a truncated cone nozzle. Reverse

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capability is possible with the installation of a different nozzle and an additional

control servo. Shown below is a schematic from KMB of the 33 millimeter drive

fitted with reversing capability.

Figure 10: 33mm Kehrer Jet (jet-drive.de)

The KMB drives are matched with Johnson 800 DC brushed electric motors. These

motors are each fitted with aluminum water cooling jackets to prevent overheating

and to increase longevity. These motors are optimally run at 16 volts. At peak

operating efficiency, each motor draws approximately 22 amps. The maximum stall

current is approximately 160 amps. Under no load, each motor draws

approximately four amps. Across the positive and negative terminals of each motor

are wired three ceramic capacitors. These capacitors act to reduce electrical noise

and to ensure reliable radio and speed control operation.

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Figure 11: Water-cooled Johnson 800 (jet-drive.de)

The motors are mounted securely to each jet drive with a plastic mounting bracket.

Threaded rods align and secure the motors and drives. This bracket allows spacing

for a composite rubber and aluminum shaft coupler. This couples the four

millimeter motor shaft to the five millimeter jet drive shaft while reducing vibration.

4.2 Steering

M-SEC is steered by thrust vectoring. In each outer hull, a high-torque servo controls

the nozzles of each drive. Servo linkages consist of stiff steel wire sheathed in

greased tubing. The servos and nozzles are connected by two control wires to utilize

push and pull for continuous positive control. The steering servos are wired

together to provide simultaneous control. Trim adjustments can be made remotely

via trim levers on the remote control unit and physically by adjusting the linkages.

Figure 12: Jet drive nozzle

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Figure 13: Servo, motor, and drive configuration

4.3 Batteries

M-SEC is powered by four sealed lead-acid batteries. Each battery has a nominal

voltage rating of four volts and a capacity of eight amp-hours. The four batteries

were initially wired in series to create a 16 volt battery pack with an eight amp-hour

capacity. As will be further explained in section 6.4 (motor control), the batteries

were finally configured in two eight volt battery packs, each with an eight amp-hour

capacity. Lead-acid batteries were chosen for their low cost, ease of charging,

reliability, and lack of charge memory. Nickel cadmium (NiCad), nickel metal

hydride (NiMH), lithium ion (Li-Ion), and lithium polymer (Li-Po) battery systems

were thoroughly investigated but none offered the ease of use and cost efficiency of

lead-acid batteries. Further power systems will be discussed in section 7.0

(Discussion & Recommendations).

4.4 Motor Control

M-SEC features a single variable electronic speed control powering each motor

simultaneously. This allows for precise fine-tuning of vessel speed for testing and

operation and can preserve battery life when high speed operation is unnecessary.

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The first speed control fitted to M-SEC, an AS-32 150 Opto, was manufactured by

Modellbau Regler. It had a continuous current rating of 150 amps, a spike current

rating of 200 amps, water cooling, and was wired directly to M-SEC’s 16 volt battery

pack. This speed control allowed for a significant factor of safety due to its high-

capacity and water cooling. Programming of this speed control was made difficult by

the lack of clear instructions written in English. Regardless, programming was

eventually successful and the speed control functioned well. After several hours of

motor operation, this speed control stopped working. Troubleshooting and

professional advice failed to remedy the broken speed control. This necessitated the

purchase of an alternative speed control since a direct replacement from Germany

was unattainable. After consultation with Hobby Town USA, a Traxxas® EVX-2

Marine speed control was purchased. This speed control featured similar

specifications to the initial speed control, but was designed for dual battery inputs.

Further consultation with Hobby Town USA staff advised that the dual battery

inputs from the speed control could be re-wired in series then connected to the

single 16 volt battery pack. This advice was incorrect and ultimately led to a

dangerous situation by shorting out the 16 volt battery pack and destroying the

speed control. The current speed control, Traxxas® EVX-2, is only different from the

previously destroyed speed control in that water cooling capabilities are replaced

with an aluminum heat sink. The single 16 volt battery pack was reconfigured to

dual eight volt battery packs to allow for dual battery input into the speed control.

After testing, this speed control and dual battery configuration worked properly.

An example wiring schematic is shown below. The sole difference in this schematic

and that of the system installed in M-SEC is the wiring of the dual battery packs

(Akku in German). The series wiring occurs within the speed control and thus

separate battery packs are necessary. The noise suppression capacitors are also

shown connected to the motors. The ESC and the power unit will be located in the

central hull and the wiring will be directed to each outer hull.

One advantage of the current EVX-2 speed control is its battery eliminator circuitry.

This eliminates the need for a separate battery to power the servos, speed control,

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and radio receiver. Since all of these components are reasonably efficient, it is

convenient for them to draw power directly from the main battery bank. This

eliminates the need to consider charging and locating an additional battery.

Figure 14: Propulsion Wiring Schematic (jet-drive.de)

4.5 Lift

In preliminary planning, squirrel cage fans were chosen to provide lift beneath M-

SEC’s hulls. After further investigation, it was determined that these fans lack the

requisite static pressure ratings to supply continuous air pressure without

overheating or being overrun. After much consideration, a standard battery-

powered leaf blower was selected to provide lift. A Worx blower featuring an 18 volt

NiCad rechargeable battery, simple operation, and compact size was chosen. The

blower was reconfigured to fit the requirements of M-SEC with the use of PVC

ductwork. The blower was also re-wired for remote operation.

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Another integral part of the lift system is the skirt structure at the forward and aft

ends of the vessel. Spanning the breadth of the aft quarters of the outer hulls is a

heavy neoprene “mud flap” skirt. Constructed from numerous layers of two

millimeter neoprene, this skirt allows for low drag and sufficient air retention. Each

side of the forward sections of the vessel is fitted with removable neoprene skirts.

These skirts are made removable by mounting them to acrylic plates. These plates

are securely screwed to the underside of M-SEC. This unique design, as further

explained in section 5.2.4 (Lift), allows for water to pass easily through the skirts

while still retaining air pressure within. When the lift system is activated, air

sputters out from underneath the skirts as designed and not from the sides or

between individual skirt sections.

Figure 15: Forward port skirt

Figure 16: Blower and ducting system

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4.6 Cooling

The motors installed in M-SEC require water cooling to operate safely and

efficiently. Several options for cooling were evaluated. Traditionally, a simple water

pickup would be fitted in the bilge to provide forced water pressure while the vessel

is underway. This system is adequate for most vessels but is not so with M-SEC.

Continuous cooling while M-SEC is underway and stationary was deemed necessary.

To ensure continuous cooling, a waterproof, battery-powered fountain pump was

installed. This pump features compact size, low power consumption, and simple

on/off operation. The pump is mounted to a through-hull intake towards the

forward section of the central hull. This ensures constant submersion and will not

be affected by wave action. Plumbing consists of brass hardware and vinyl tubing.

The pump delivers water from the central intake, into each motor’s water cooling

jacket, then out through exit ports on each outer transom.

4.7 Radio Control

M-SEC will is remotely controlled by a Tower Hobbies six-channel System 3000 FM

aviation radio control package. The model requires four channels for operation

(throttle, steering, and lift system on/off, cooling system on/off). The handset is

powered by a rechargeable NiCad battery while the on board servos, radio receiver,

and speed control utilize power from the main battery bank. This battery eliminator

circuit, as previously mentioned in section 4.4 (Motor Control), eliminates the need

for an additional servo battery on board the vessel. The servos, batteries, radio

transceiver unit, and antenna are all easily connected through the use of special

adapters. The expected range of radio reception is 500 yards over ground. The radio

system is shown below.

26

Figure 17: Six-channel FM Radio Control System

The radio system is properly tuned to ensure straight vessel tracking. Professional

assistance from Hobby Town USA ensured that proper End Point Adjustments were

made to each radio channel and that the full range of motion of the servos and

throttle were being used. It was also learned that the radio transmitter must be

turned on before turning on the speed control and on board radios. An errant signal

could lead to a runaway boat. By transmitting before turning on the speed control, a

signal is already present.

5.0 Manufacturing

The manufacturing process of model began in May and is still in progress as the

team moves toward completion of a solid test platform. M-SEC's manufacturing

process was divided into two distinct periods. The first was hull fabrication and the

second was interior system installation.

27

5.1 Hull Fabrication

This vessel’s fabrication process provided invaluable experience to the team. The

process began with research once the topic was chosen. Several hours were

dedicated to locating technical papers and journal articles that pertained to surface

effect crafts. Due to this research the team had the knowledge required to begin the

design of the model. The original design was created in the engineering software,

MaxSurf, which was provided by the Florida Institute of Technology. Once the basic

concept was created the design was imported into Rhinoceros, which is a more

versatile engineering software. The design was modified several times throughout

the planning process.

When design and planning were completed, fabrication began. The first step in

fabrication was milling. This process took more time than expected. Many problems

were encountered, but eventually overcome. The 66”x33”x7” vessel was too large

for the Computer Numeric Control (CNC) machine to mill in one piece. Therefore,

the design had to be split up into six separate sections and then imported into

Mastercam, the CNC’s controlling software. The following picture, portrayed on the

CNC’s screen, shows one of the six pieces the final design was divided into.

Figure 18: One of the vessel’s six pieces on the CNC’s screen

28

The milling settings were then established and ready for operation. However,

another problem arose. The Machine Shop did not have a long enough bit to mill our

vessel. The advice of Bill Bailey, the head machinist, was sought for this problem. He

used his knowledge of the hardware to help overcome the dilemma. The final

problem was that Bill Bailey believed the original low density surfboard foam that

we purchased from Cannibal Surfboards, was inappropriate for the CNC machine.

Upon the advice of Stephanie Hopper, 2 sheets of 4’x8’x3” blue Dow insulation foam

was purchased as a replacement. The figure below shows an example of the Dow

foam and measuring process.

Figure 19: The Dow foam being prepared for milling

The Dow foam was cut into several pieces and appropriate sized blocks were

created for each hull section. The blocks were attached to wood sheets for the CNC

machine to attach to and milled over the next several hours. The following picture

shows part of the vessel being milled.

29

Figure 20: Center hull being milled

Following the milling process, the six hull pieces were transported to Cannibal

Surfboards. AJ Finan, the owner of Cannibal Surfboards, was invaluable throughout

the fabrication of the vessel. AJ has been professionally designing and

manufacturing surfboards for over 18 years. He also has an engineering degree

specializing in aerospace composite materials. His goal when designing surfboards

is to create something lightweight and fast, yet can withstand heavy surf.

At Cannibal Surfboards, the six pieces were glued together using Gorilla glue and

aligned using a laser level, as shown below.

Figure 21: Gluing and aligning the six pieces

30

The machining marks left by the CNC machine were then sanded smooth and small

imperfections were covered by spackle. Larger cracks or holes were filled with

Great Stuff, large portions of excess foam were hot knifed off, and once again the

entire vessel was sanded smooth. The following picture During the milling process

the bows of the outer hulls were damaged. Small portions of fiberglass were used to

reshape and reinforce the hulls.

The team overestimated the time required to complete each step of the following

steps. For instance, there was not enough time budgeted to allow for resin to harden

and to sand the vessel multiple times. Once the foam hulls were faired to the criteria

we supplied, fiberglass bulkheads were installed. These bulkheads were for extra

rigidity and to create a separate cavity for the jet drives and motors.

Figure 22: The bulkhead being installed

The top and the bottom of the model needed to be fiberglassed separately,

beginning with the bottom. Several different ounce cloths were spray tacked in

layers to the vessel. This step was very tedious. It was necessary to get each layer of

fiberglass as smooth as possible. The picture below shows the many layers of

fiberglass on the vessel.

31

Figure 23: The layers of fiberglass cloth on the vessel

Small imperfections, wrinkles or creases, would become exponentially worse with

each added layer. Extra fiberglass was added to the tips of each bow to prevent

fracture in the event of a collision. Once all of the layers were laid the body of the

vessel had 5 layers. Epoxy resin was applied and allowed to penetrate each layer as

seen in the following picture.

Figure 24: The resin being applied to the vessel

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The vacuum bagging system was then set up. A layer of peel ply was laid on top of

the epoxy-coated fiberglass. To form the vacuum bag, sealant tape was used to

fasten a thick piece of plastic to a thinner, more flexible piece of plastic. Once

completely sealed the air was evacuated from inside the bag using an air

compressor. The vacuum bagging system can be seen easier in the following picture.

Figure 25: Air is evacuated from the system, which forms a vacuum

This method created the vacuum that was needed to pull the resin through all 5

layers of cloth. The vessel was allowed to remain in the vacuum for approximately

24 hours. After this period the model was removed from the vacuum bag and the

newly hardened fiberglass was sanded smooth. The vacuum bagging process was

repeated for the top of the vessel. However, this time the team encountered a

problem. The air was not being evacuated from the bag properly. This meant that

somewhere in the system there was a leak. When the leak could not be found via

visual inspection, a sonic leak detector was used. Once fixed, the resin was allowed

several hours to properly harden.

When the sanding was finished, the vessel was taken out for its initial buoyancy test.

While in the water, the vessel was initially loaded with approximately 120 pounds of

weight. This provided a general idea of the amount of load the hull form could carry

33

and while remaining afloat. The picture below displays the vessel while it was being

tested.

Figure 26: The vessel as it was tested in the Indian River

The model performed exceedingly well and in the end was proven to hold in excess

of 185 pounds, which is well beyond the necessary specifications of the project.

With the buoyancy test complete, work began on the separation of the top hatch.

Measurements were made to ensure the lid was cut in the proper location. With the

lid removed, as much foam as possible was removed with the router. Most of the

remaining foam was dissolved with acetone. The foam in the bows, however,

remains for added rigidity.

5.2 Internal Systems

With the hull fabrication finished, the model was brought back to the team’s

workspace. There, the many internal systems that would power, steer and lift the

vessel were installed. Before installation began, wooden stringers were installed

along the top edge of the hull. This was to provide rigidity along the length of the

hull as well as create rails for our top deck to be mounted on in the future. Then a

34

plywood deck was laid in the center hull and fixed with epoxy resin. This deck

provided a place to secure the batteries, speed control and remote control

components, as well as strengthen the center hull.

Figure 27: Longitudinal Stringers & Electronics Deck

The wooden stringers and decks greatly improved the strength of the hull once the

foam plug was removed. Fiberglass is characteristically very strong in a radius, or

curve, but lacks strength and stiffness in long flat sections.

5.2.1 Propulsion

The first of the vessels systems to be installed was the propulsion. This consisted of

the water jet/impeller assembly, the vector nozzles and the DC electric motors.

Installation began by measuring out the location of the jet exit ports and marking

them on the transom of each of the two side hulls. The boat was then taken to the

Florida Institute of Technology machine shop to drill the holes. A hole saw bit was

used to drill to appropriate size holes. To mark out the hole for the induction port

we put the jet housing in position and traced the perimeter. Then a Dremel® was

used to cut the pattern. A grinding wheel attachment was used to adjust the opening

to fit the housing. This whole process proved to be very tedious and took a lot more

35

time than was originally anticipated. After the port side drive was fit, the team

moved on to the starboard side. The second side was much less difficult to complete

with lessons learned from the first.

Pictures of cutting out holes

Once the holes were both cut and the drives were in place, epoxy resin was

thickened with colloidal silica and laid around drives to permanently fix then in

place. After the epoxy hardened the boat was tested to ensure that the hulls were

still watertight. Both drives leaked so epoxy resin was poured into the hulls around

the drive housings and allowed to fill the holes and harden. The boat was again

tested and no leaks were found. With the hulls sealed, the vector cones were

attached and the DC motors were connected.

Next work began on the battery pack. The Johnson 800 series DC motors run on 16v,

which is an uncommon voltage. Much research was done and finally, 4 cells

individually rated at 4 volts and 8 amp hours were chosen. These cells were

connected in series using a custom made wiring harness. This battery pack was then

connected to the wiring harness and the ESC. The boat was then taken to a pool and

tested. This was the first operational test of the jet drives in water. While the drives

were running the motors were monitored to evaluate heat build-up. It was found

that under normal operation, the motors remained relatively cool.

A battery retainer strap was fabricated from a strip of 1”x1/8” aluminum. The strip

was bent into shape using a vice. Holes were then drilled in the strap to bolt on the

batteries. The strap is designed to be modular, allowing all the battery cells to be

removed from the boat together.

Battery pack

As mentioned earlier, the original speed controller failed in the midst of our

assembly phase. A new ESC was obtained and installed in the boat so assembly and

testing could resume. The new Traxxas® EVX-2 unit required dual battery input.

This meant that the battery wiring harness had to be redesigned. Because the two

36

battery inputs were connected in series inside the ESC, the 4-cell 16v pack had to be

split in two. The new configuration, shown below consisted of dual 8v, 2-cell packs.

Figure 28: Battery Wiring Configurations (Smart Draw)

5.2.2 Steering

The next system to be installed was the steering. Due to the lack of experience with

RC systems, the team consulted the staff at Hobby Town USA. They were

instrumental in the design and implementation of the servo control system. With

their advice, the control rods and the proper servo wiring harness were purchased.

Installation began by drilling the holes in the transom of the outer hulls to allow the

control rods to pass through. The jet nozzles had pre-drilled holes as shown below.

37

Figure 29: Jet Nozzle showing 3 pre-drilled holes at top (ProEngineer)

Once the holes were drilled, the guide tubes were cut to length and glued in place

with quick set, two-part epoxy. While the epoxy was setting, work began on the

mounting plates for the servos. For the plates, 4”X5” luan was cut and glued in place

in the side hulls. The servos were then mounted using rubber washers to reduce

harmful vibrations that could shorten their lifespan. When all of the epoxy had

hardened the control rods were slid in place and the ball joint connectors were

attached using Loctite® Super Glue. The rods were threaded into the servo arms

and adjusted so that the jet nozzle straight. Since the RC receiver unit was mounted

forward of the battery pack on the electronics deck, the power and control wires

had to be extended. To accomplish this, 22-gauge wire was spliced in-line with the

servos and connectors. Finally, the two servo leads were plugged into the y-harness,

then into the RC receiver unit. The y-harness allowed both servos to be controlled

using one channel on the RC transmitter. All electrical connections were made using

crimp-type connections and waterproof heat shrink tubing.

After, the system was installed it was powered on and tested. The boat was then,

once again taken to a pool for a practical trial. When the boat was placed in the

38

water it was noted that water was forcing its way into the hulls through the guide

tubes for the servo control rods. To stop this leak, DOW Corning® High Vacuum

Silicone grease was applied to the rods to create a seal with the tubes. This solution

proved to be very effective.

5.2.3 Cooling

The model’s DC motors have built in cooling ports to pump water through while in

operation. In the original design, water would be forced through the system while

the vessel was in motion using a scoop fitted into the bottom of the central hull. The

team decided to redesign the system to feature “active cooling.” This included a

water pump that would force water through the tubing to cool the components even

when the boat was stationary.

Figure 30: DC Motor & Cooling Shell (ProEngineer)

To accomplish this, a battery operated fountain pump was used. The inlet hose was

mounted through a hole in the central hull. Care was taken to place the pumps

impeller below the waterline. This ensured that through Archimedes’ principle,

water would be forced up the tube, thus priming the pump. It was then sealed with

silicone adhesive caulk. A custom outlet adapter was created using various brass

39

hose fittings. Nylon tubing was used to connect the pump to the motor cooling shell

and then to the outlet ports on the stern of the vessel. The system was tested with

excellent results.

5.2.4 Lift

The final system to be installed was the lift system. It was the most important

portion of the project, and great attention was give to its design and construction.

The system can be broken into two major components; the fan that creates the

positive pressure beneath the hulls, and the flexible fore and aft skirts that contain

the air. Both are absolutely critical to the successful operation of the vessel.

First to be installed was the lifting fan. For this application, a battery-operated

blower was chosen. PVC piping was used to direct the airflow from the outlet on the

blower down into the air plenum below the deck. Neoprene was used to seal the

PVC piping in the blower outlet tube.

Blower

To mount the blower, the PVC piping was positioned on the deck and traced using a

permanent marker. A hole saw drill bit was then used to drill through the wooden

decking and fiberglass. Once this was complete, the pipes were test fit and adjusted

until a proper fitment was achieved.

With the blower in place, wiring the power switch began. The RC receiver’s “landing

gear” channel was selected to operate the blower because of its “on-off”

functionality. First a servo was mounted on the electronics deck. Then a monetary

switch was attached to the servo. When the servo is activated, the arm rotates and

operates the switch.

40

Figure 31: Blower Control Switch/Servo

Following the blower installation, construction began on the fore and aft skirts. The

skirts were constructed of 2mm Neoprene fabric. Each skirt section was mounted to

an acrylic sheet. This made the sections removable and adjustable for testing

purposes.

The front skirts were constructed first. Neoprene sections were cut into a diamond

shape and then folded over. They were then glued with Loctite® Super Glue along

pre-marked lines on the acrylic sheets. When all of the pieces were attached, they

were glued together for strength.

The rear skirt’s initial design was that of a “U-shaped” trough extending between the

two side hulls. The neoprene’s shape was maintained by using an internal wire

frame. This whole assembly was also mounted on an acrylic sheet. To fix the skirt

assemblies to the hull, threaded inserts were drilled into the hull and sealed with

epoxy. Each acrylic sheet also had weather stripping put on it to create a seal when

it was screwed to the hull.

After the initial lift test, it was discovered that the rear skirt design caused quite a

bit of drag. To correct this, a second design was created employing a “mud flap” like

section of neoprene between the hulls. A wooden dowel was later added across the

41

top of the flap to create a better seal with the water. Testing showed that this new

rear flap design had solved the drag issue.

6.0 Model Testing

Team M-SEC is currently planning and conducting a battery of tests that will allow

the collection of meaningful data. This data will give solid conclusions in terms of lift

effectiveness, hull efficiency, hull performance, and sea-keeping ability. All of the

following tests have been and will be performed in calm waters such as the Indian

River Lagoon, Crane Creek, and swimming pools.

6.1 Static Thrust Test

The static thrust test was conducted in a swimming pool. An accurate fish scale was

used to determine the thrust output by the jet drives. (Shown in Fig. 32)The test was

conducted with the batteries fully charged and the throttle engaged fully. The drives

produced approximately 30 Newtons of thrust. In conclusion this test was a

resounding success. The thrust output exceeded expectations.

Figure 32: Fish Scale

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Figure 33: Static Thrust Test

6.2 Lift System Tests

The life system test consisted of only vertical movement rather horizontal

movement. As further explained in the GPS Data Logging section, GPS data will be

used to gauge the comparative effectiveness of the hull’s operation with the lift

system off and on. This comparison will be made in a variety of sea conditions

ranging from flat calm to heavy chop. Performing static testing of the lift system will

include accurate measurement of hull draft change with the lift system on and off, as

well as the change in air cushion volume within the hull. Preliminary lift system

testing showed that the hull lifts approximately 1.5 to 2 inches from the standard

waterline with the lift system activated. A measuring stick was temporarily affixed

to the sides of the stern and bow of the outer hulls to give a reference datum. The

test was a success in that the bow of the model lifted approximately two inches from

waterline. The stern lifted slightly less; this was determined to be a factor of the aft

placement of heavy batteries. Further testing of the lift system showed increased

maneuverability and speed while underway with the lift system activated. Future

testing with a GPS device in open water will prove that the model moves much more

effectively with the lift system turned on.

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6.3 Future Testing

6.3.1 Software Testing

The final hull design, produced in MaxSurf, can be exported to various other

software packages for further analysis. MaxSurf will give useful data regarding hull

particulars, such as wetted area and size specifications. HydroMax will be used to

determine theoretical hull strength and stability data as well as hydrostatic

information. These software packages will be further investigated during the fall of

2010.

Other simple preliminary tests will be performed. These will include an accurate

weighing of our complete model, hull length, breadth, and draft measurements, hull

displacement with the lift system on and off, and a calculation of the volume

contained within the interior hull walls and the lift skirts. These factors will be

beneficial in determining the performance of our model and for model similitude

comparison to a possible full-size vessel.

6.3.2 Speed Testing

Preliminary speed runs have been conducted in the Indian River Lagoon. Markers

were spaced 75 feet apart in calm water. M-SEC was run at full velocity with the lift

system active. Several speed runs were performed, alternating directions to reduce

error from current, wind, and steerage. The average top speed for M-SEC with the

lift system active is 9.995 ft/sec. or 5.92 knots. Further testing of M-SEC’s

capabilities will be performed.

Trial Distance (ft.) Time (sec.) Speed (ft./sec.)

1 75 7 10.71

2 75 7.5 10

3 75 9.1 8.24

4 75 6.8 11.03

Average 75 7.6 9.995

Figure 34: Speed Trial Data Table

44

6.3.3 GPS Data Logging

M-SEC is currently equipped with a GiSTEQ DL-500 high-speed GPS data logger to

record accurate time, position, and velocity data at a rate of 5Hz. The unit is self-

sufficient and relies on battery power and contains enough internal memory to

store weeks of testing data. With these data, hull speed and comparative efficiency

with the lift system turned on and off can be analyzed. MATLAB has been used to

analyze the data exported from the GPS (See Appendix 8.2).

Preliminary testing with the GPS data logging system has been unsuccessful. Team

M-SEC has encountered errors in the values exported in NMEA strings from the DL-

500’s included software package. Speed over ground values (measured in knots)

have been truncated to single digits. This reduction in accuracy renders the planned

GPS testing unreliable. Further testing will ensue with the GPS and additional

MATLAB code development will occur.

6.3.4 Lift Pressure Test

It is important to know the actual pressures generated in the plenum during M-SEC

operation. To evaluate such performance, M-SEC will be fitted with a precise, low-

range pressure gauge and a data logging system. This gauge will measure the static

pressure held beneath the hulls and will provide insight into the effectiveness of the

lift system. This data could also be coupled with sea-state and sea-keeping data to

study how the pressure is affected by wave action and vessel motion.

6.3.4 Sea-keeping Test

M-SEC will be fitted with a simple, multi-axis accelerometer. This will enable the

collection of accurate motion data for the operation of M-SEC. Testing the hull in

various sea states will also provide quantifiable conclusions as to the effectiveness

of the lift system and the trimaran hull form.

45

The sea-keeping tests are in the early stages of development and will be further

investigated and researched as the project progresses. Guidance and insight will be

sought from several Florida Tech professors to ensure that this test will be reliable

and easy to perform.

6.4 Testing Summary

It is important to note that M-SEC is an ongoing project and that testing is currently

being conducted and will be conducted in the future. Guidance and professional

insight will be sought from professors and industry professionals. Team M-SEC hope

to develop solid, data-supported conclusions as to the effectiveness of the trimaran

surface effect ship concept.

7.0 Resources

Team M-SEC took advantage of every possible resource available. Florida Institute

of Technology offers students a wide variety of resources. These resources include

professors, staff, and graduate students from the varying academic departments and

physical resources such as a fully stocked machine shop. Many resources outside of

Florida Institute of Technology were also employed.

Professors and staff within the Department of Marine and Environmental Systems

(DMES) have monumentally helped team M-SEC. Dr. Stephen Wood has guided the

project over the past seven months. Dr. Stephen Jachec was instrumental in

developing MATLAB coding for GPS testing. Dr. Prasanta Sahoo offered insight into

naval architecture and Maxsurf hull design software. Dr. Ronnal Reichard aided in

the development of the idea of a surface effect ship concept. Mr. Travis Hunsucker

was helpful in formulating ideas pertaining to his hydrofoil research. Mr. Bill Battin

was invaluable for systems and electrical advice.

Faculty and staff outside of the DMES also aided team M-SEC. Mr. Larry Buist offered

assistance in designing and engineering an alternative battery system. Mr. Bill

46

Bailey and the Florida Institute of Technology machine shop staff worked with the

team for countless hours to produce the M-SEC model.

Resources that Florida Institute of Technology could not offer were also sought. The

fabrication of team M-SEC’s model could not have been accomplished without the

experience and expertise of Mr. AJ Finan of Cannibal Surfboards. Mr. Thomas

Kehrer, of KMB, provided his knowledge of the propulsion systems purchased. Mr.

Brion Burk, Mr Leo Melita, Mr. Paul Bonenfant, and Mr. Brock Tucker also used their

previous education and experience to help team M-SEC.

8.0 Discussion & Recommendations

In preliminary testing M-SEC has performed very well. As intended, M-SEC’s

maneuverability and speed are greatly improved by operating the lift system. With

the lift system off and the skirts attached, the vessel is sluggish and has very high

drag. With the system activated, air pressure bleeds out from under the forward and

aft skirts such that they are not submerged. The vessel skims across the water. M-

SEC’s performance is promising. Exciting possibilities are ahead for this model and

for the design implications in full-size vessels of numerous types.

There are numerous tasks yet to be completed in finishing M-SEC. Chief among

these tasks is the aesthetic and cosmetic improvement of the model. Throughout the

summer of 2010, priorities shifted from an overall complete model to a functioning

model. Over the course of fall 2010, M-SEC will undergo additional fairing, fiberglass

work, and painting. The top deck structure will be installed as will a blower system

intake cowling. By the spring 2011 Senior Design Showcase at Florida Tech, M-SEC

will be a professionally finished model.

At present M-SEC functions well. All components were specifically chosen to work

with one another and to work well. In the course of building M-SEC and consulting

with professionals, advice has been given on alternative power sources and other

47

improvements that can be made to the systems and to the hull design. These

include, but are not limited to, addition reverse thrust capability, separate speed

controls for differential thrust control, implementation of a common 24 volt power

system fitted with a voltage regulation circuit, re-design of the stern of the central

hull, and the addition of a second lift blower.

Team M-SEC has been collaborating with Mr. Larry Buist of Florida Tech’s electrical

engineering department to develop a more capable 24 volt power system. The

aforementioned nominal voltage for M-SEC’s motors is 16 volts. This voltage is not

common and as such charging becomes a challenge with conventional 12 and 24

volt battery chargers. A 24 volt system would be simple to charge, would provide a

significantly increased range of operation and longevity, and would be relatively

inexpensive to implement. One drawback of the current 16 volt power system is the

limited run time. With eight amp-hour batteries, the motors are only able to operate

at full speed for approximately eight minutes. This short duration makes testing and

use more difficult and inconvenient. A 24 volt battery would be able to deliver the

requisite nominal 16 volts for a greater length of time.

As M-SEC is currently configured, steerage is effective only while moving briskly

forward. Jet drives, in vessels of all sizes, are fairly ineffective at low speeds. There

are several changes that could be made to improve maneuverability. The addition of

another speed control to power each motor separately would allow differential

thrust. This would enhance turning ability with such a wide beam vessel. The

addition of reverse scoop nozzles would be very simple to accomplish and would

provide a means of stopping the vessel. Reverse travel would not be the primary

reason for adding reverse capability. A brief shock of reverse thrust would bring the

vessel to an instant halt instead of having the vessel coast for several yards before

settling. This can improve control and safety. Another added benefit of reverse

scoops would be operating each jet drive with opposing thrust. With a wide beam

vessel, complete turns would be simple. Such additions would vastly improve the

operating characteristics of M-SEC.

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In preliminary run tests of M-SEC, it has been noted that the stern of the central hull

creates an area of low pressure and thus creates drag. An efficient re-design would

slope the aft portion of the central hull to a sleeker and more streamlined double-

ended central hull form. This would reduce drag and improve the sailing

characteristics of M-SEC. Further analysis will be performed by modifying computer

models of M-SEC and utilizing hull analysis software packages to predict vessel

characteristics and drag. A decision on modifying the hull will occur at a later date in

fall 2010.

9.0 Conclusion

In conclusion, project M-SEC was a success. The team gained learned valuable skills

throughout the course of this project. These skills include: time management,

organization, communication, professional, and practical. The practical skills

include: machining, composite work, coding, hull design, electrical, and technical

writing. Team M-SEC looks forward to further research and continued development

of the trimaran surface effect ship concept.

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10.0 Appendix

10.1 Budget

M-SEC Budget

Income

Donations Grants

COE MFP

$ -

$ -

$ 400.00

$ 1,000.00

Itemized Donations

Date

Item Description

Value Donated by

5 Hz GPS Data Logger

80.00 Cameron Roberts

Total: $ 80.00

Purchases

Item Details Qnty. Cost (Each) Total Team Cost From

Foam Modeling Foam 2 $ 30.00 $ 60.00

$ 60.00 Cannibal Surfboards

Glass Matte All weights (4oz, 6oz) 1 $ 216.00 $ 216.00


Vacuum Bag Materials for Vac Bagging 1 $ 76.00 $ 76.00


Resin Gallon container 1 $ 47.00 $ 47.00


Water Jet 33mm Jet Drive w/steering 2 $ 105.17 $ 210.34

$ 210.34 Kehrer Modellbau

Motor 800w 16v motor w/cooling 2 $ 68.64 $ 137.28


Motor Kit Noise Supressor 2 $ 2.21 $ 4.42


Adapter Motor adapter flange 2 $ 13.83 $ 27.66


Couplers 5-4mm shaft coupler 2 $ 7.64 $ 15.28


Water Pickup Cooling water intake 2 $ 4.20 $ 8.40


Hose Silicone Cooling hose 2 $ 3.21 $ 6.42


ESC 150A Electronic Speed Control 1 $ 105.12

$ 105.12


Shipping Shipping from KMB 1 $ 49.53 $ 49.53


DOW Foam 4'x8'x3" Blue Foam 1 $ 46.00 $ 46.00

$ - White Cap

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Batteries 4V 8 Ah Lead Acid Cells 4 $ 19.99 $ 79.96

$ 79.96 Batteries Plus

Shrink Tube Wiring Acc. 2 $ 3.49 $ 6.98

$ 6.98 Radio Shack

Fountain Pump Cooling System 1 $ 35.00 $ 35.00

$ 35.00

Creations of a Craftsman

Neoprene 29 sq. ft. 1 $ 130.00 $ 130.00

$ 130.00 Seattle Fabrics

Leaf Blower Worx 18v Blower 1 $ 112.00 $ 112.00

$ 130.00 Sears

Silicone Adhesive Silicone Sealant 1 $ 3.89 $ 3.89

$ 3.89 Home Depot

Battery Connectors 14ga. Power Connectors 1 $ 3.98 $ 3.98

$ 3.98 Radio Shack

PVC Pipe 2"x2' PVC Pipe 1 $ 3.36

$ 3.36

$ 3.36 Home Depot

Brass Tee 1/4" Brass Threaded Tee 1 $ 5.09 $ 5.09

$ 5.09 Lowes

Brass Barb 1/8" x 1/4" Threaded Barb 4 $ 2.77 $ 11.08

$ 11.08 Lowes

Vinyl Hose .17" Black Vinyl Hose (.ft) 6 $ 0.16 $ 0.96

$ 0.96 Lowes

Acrylic Sheet 18"x24" Acrylic Sheet 1 $ 7.98 $ 7.98

$ 7.98 Lowes

Servo Arm Futaba Splined Servo Horn 1 $ 3.49 $ 3.49

$ 3.49 Hobby Town USA

Servo Arm Package Tower Hobbies Servo Arms 1 $ 9.45 $ 9.45


Y-Harness 2-to-1 Servo Control Harness 1 $ 5.50 $ 5.50


Servo Rods 4-40 Connecting Rods 4 $ 1.29 $ 5.16


Rod Housing 30" Push-rod Housing 1 $ 1.05 $ 1.05


Snap Connector Con-snap 14ga. Connectors 2 $ 2.50 $ 5.00

$ 5.00 West Marine

Brass Connector 1/8"x1-1/2" 1 $ 2.26 $ 2.26

$ 2.26 West Marine

Brass Bushing 1/4"x1/8" 1 $ 3.40 $ 3.40

$ 3.40 West Marine

Silicone Hose Silicone Water Hose (ft.) 1 $ 0.91 $ 0.91

$ 0.91 West Marine

Mounting Hardware Treaded Screws/Nuts 7 $ 0.98 $ 6.86

$ 6.86 Home Depot

Acrylic Sheet 18"x24" Acrylic Sheet 1 $ 9.77 $ 9.77

$ 9.77 Home Depot

Speed Control EVX-2 Traxxas ESC 1 $ 114.99 $ 114.99

$ 114.99 Graves Hobby

Misc

$ 48.95

$ -

$ 48.95

$ -

$ -

Total:

$ 1,599.06

Operating Budget

Total: $ 1,400.00 Remaining:

$ (199.06)

51

Salaries

Project Totals

Team Hours: 1697 Project Value (Materials):

$ 3,278.12

Cost ($10.00/hr):

$ 16,970.00 Project Value (Hours):

$ 17,470.00

Consulting Cost:

$ 1500.00 Project Total:

$ 20,748.12

10.2 MATLAB Code % M-SEC

% GPS DATA ANALYZER

% Cameron Roberts

% with assistance from

% Dr. Stephen Jachec

% 6/29/2010

close all

clear all

clc

filename = input('Enter name of GPS data file: ', 's');

fid=fopen(filename);

counter = 0;

kk = 0;

while(~feof(fid))

kk = kk + 1;

S = fscanf(fid,'%s',1);

if (isempty(S))

break

end

line_header = S(1:6);

TF = strcmp(line_header, '$GPRMC');

52

if TF == 1;

counter = counter + 1; %track imported data

hour_str = S(8:9); %import hours then convert

hour(counter) = str2num(hour_str);

min_str = S(10:11); %import minutes then convert

minute(counter) = str2num(min_str);

sec_str = S(13:17); %import dec. seconds then convert

second(counter) = str2num(sec_str);

lat_deg_str = S(21:22); %import lat degrees (always N)

lat_deg(counter) = str2num(lat_deg_str);

lat_min_str = S(23:29); %import lat dec. min (always N)

lat_min(counter) = str2num(lat_min_str);

lon_deg_str = S(33:35); %import lon degrees (always W)

lon_deg(counter) = str2num(lon_deg_str);

lon_min_str = S(36:42); %import lon dec. min (always W)

lon_min(counter) = str2num(lon_min_str);

sog_str = S(46:49); %import speed over ground in knots

sog(counter) = str2num(sog_str);

crs_str = S(51:54); %import course in degrees

crs(counter) = str2num(crs_str);

day_str = S(56:57); %import date, ddmmyy

day(counter) = str2num(day_str);

month_str = S(58:59); %import date, ddmmyy

month(counter) = str2num(month_str);

year_str = S(60:61); %import date, ddmmyy

year(counter) = str2num(year_str);

end

53

end

time = datenum(year,month,day,hour,minute,second);

time_elapsed = (0:0.2:counter);

lat = lat_deg + lat_min/60; %convert ddmm.mmmm to dd.dddd

lon = lon_deg + lon_min/60;

%m_proj('set','mercator');

%convert dd.dddd to x and y coord, lon (-) for W, lat (+) for N

%[x,y] = m_ll2xy(-(lon),lat);

% figure

% hold on

% for j = 1:counter

% plot(time(j),sog,'--r','LineWidth',10)

% end

% datetick('x',13)

% xlabel('Elapsed Time (s)');

% ylabel('Speed (knots)');

% title('Vessel Speed vs. Elapsed Time');

%figure

%hold on

% for k = 1:counter

% plot(X(k),Y(k),'.')

% title(['Time is ',num2str(time(k))]);

% pause(0.1)

% M = getframe;

% end

%plot(time(counter), sog(counter))

fclose(fid);

54

10.3 Time Sheet

Person Hours Worked Brittany Burk 373 Adam Harris 302 Mike Melita 376

Cameron Roberts 371 Kait Trump 275

TOTAL 1697

** For complete daily personnel time log, please see DVD included with M-SEC Design Notebook. **

10.4 MSDS

** For full Material Safety Data Sheets, please see DVD included with M-SEC Design Notebook. **

Relevant MSDS:

• 3M Bondo® • 3M Super 77Multi-purpose Adhesive® • Acetone • Acrylic sheet • DOW© Foam Insulation • Gorilla Glue® • GREATSTUFF® Foam • Loctite© Super Glue Ultra Gel Contol • Neoprene • PVC • PVC Pipe & Fittings • Rust-oleum© Satin Grey • Scotch© Tape 622 • Silicone Elastomer • Vinyl Spackling • West Systems© 105 Epoxy Resin • West Systems© 205 Fast Hardener • West Systems© 406 Colloidal Silica • Woven Fiberglass Fabric • Vacuum Bag Materials

56

11.0 References

"Airtech - Products." AIRTECH International, INC. Web. 21 July 2010. <http://airtechonline.com/products/index.htm>.

"A.J. Finan In A Vacuum." Transworld Surf. Web. 21 July 2010. <http://surf.transworld.net/1000100766/gear-guide-articles/aj-finan-in-a-vacuum/>.

Bertin, D.; Bittanti, S.; Savaresi, S.M.; , "Control of the wave induced vibrations in Air Cushion Catamarans," Control Applications, 1997., Proceedings of the 1997 IEEE International Conference on , vol., no., pp.749-754, 5-7 Oct. 1997.

Burg, Donald E. "AIR RIDE CRAFT, INC." Sea Coaster. Web. 22 July 2010. <http://www.seacoaster.com/Resume.htm>.

"Cannibal Surfboards." The Surfboard Warehouse. Web. 22 July 2010. <http://www.thesurfboardwarehouse.com/cannibal.asp>.

Dhanak, M.; , "Air cushion vehicle response to waves in the surf zone," OCEANS 2009, MTS/IEEE Biloxi - Marine Technology for Our Future: Global and Local Challenges , vol., no., pp.1-8, 26-29 Oct. 2009.

JPS Composite Materials. Web. 22 July 2010. <http://www.jpsglass.com/construction.html>.

"Hovercraft of Saunders-Roe, Westland Aircraft, British Hovercraft Corporation." Bartie's World of Isle of Wight Postcards and Hovercraft. Web. 03 May 2010. <http://www.bartiesworld.co.uk/hovercraft/saunders.htm>.

Kehrer, Thomas. Kehrer Modellbau. Web. 1 May 2010. <http://www.jet-drive.de/>. "Making full speed: Remanufacturing gives an old vessel a new mission." Mechanical Engineering-CIME 123.12 (2001): 62+. Military and Intelligence Database. Web. 3 May 2010.

Skolnick, A.; , "Transoceanic surface effect ships," Proceedings of the IEEE , vol.56, no.4, pp. 700- 712, April 1968. "Surface Effect Ship at AllExperts." Expert Archive Questions. Web. 03 May 2010. <http://en.allexperts.com/e/s/su/surface_effect_ship.htm>.

Steen, Sverre. (2004) "Experiences with Seakeeping Abilities of SES Ships", MARINTEK Report RTO-MP-AVT-110

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"WWW.RESININFUSION.COM." RESIN INFUSION. Web. 21 July 2010.<http://www.resininfusion.com/vacuumbag.html>.

Yun, Liang, and Alan Bliault. Theory and Design of Air Cushion Craft. London: Arnold, 2000. Print.

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