Design and Construction of Floating

Breakwaters for the Port of Bremerton using

Physical and Computer Modeling

Robert F. Henry, P.E. Art Anderson Associates

Panchy Arumugasaamy, PhD, P.E. Art Anderson Associates

Woosuk Ahn, PhD, PE Reid Middleton

C.J. Garrison, PhD, P.E. Consultant in Marine Hydrodynamics

Vladimir Shepsis, PhD, P.E. Coast and Harbor Engineering

Site Location

Seattle

Bremerton

Old (Existing) Bremerton Marina

Ferry Terminal

Old (Existing) Bremerton Marina

Ferry Terminal

Old (Existing) Bremerton Marina

Ferry Terminal

New Bremerton Marina

Challenges of the New Marina

Existing marina was constructed in 1990s

Shallow draft floating breakwater attenuate

waves generated by wind

A limited existing body of knowledge regarding A limited existing body of knowledge regarding

wake waves

The large scale of harbor protection

requirements

A need to quantify the wake problem and its

effects

Data Collection and Modeling

Field Data

Collection

Physical

Modeling

Computer

Modeling

Data Collection Locations

Surface Displacement

10/4/02 03:44:32 - Burst 629 Data

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OUTSIDE INSIDE

AvgHeight = 0.08m

MaxHeight = 0.42m

AvgPeriod = 3.5

SigPeriod = 5.14

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Time (hrs:min:sec)

Surface Displacement

9/29/02 01:01:36 - Burst 807 Data

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Time (hrs:min:sec)

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OUTSIDE INSIDE

AvgHeight = 0.08m

MaxHeight = 0.45m

AvgPeriod = 3.7

SigPeriod = 4.55

Field Data and Engineering

Analysis Conclusions

The performance of the breakwater is expressed through a transmission coefficient Kt.

It was estimated for the existing breakwater is approximately Kt=0.65. approximately Kt=0.65.

To satisfy standard criteria for marina performance, Kt should be less than 0.40

To meet Kt=0.4, Beam (width) = 22.5 ft and Draft (depth)= 7.5 ft.

Physical Model Setup

101ft 147.6ft

17.4ft 24ft

13.1ft

14.1ft

WAVE

cL

2.3ftEXISTING

BREAKWATER

36ft36ft

13.1ft

WG2

WAVE

MAKER

CLUMP

WEIGHTS

FLOATING

BREAKWATER

FLUME BOTTOM

WG1 WG3 WG410ftWIRE

MOORING

LINE

1.6ftBREAKWATER

MODIFIED

BREAKWATER

1

12CHAIN

MOORING

Model Breakwater Installation

Model of Existing

Breakwater

Mooring Chains and

Clump Weights

Mooring Line

Wave Tank in Motion

Physical Modeling Summary

To satisfy the requirement of Kt=0.4, the

breakwater beam and draft should be

24.5 ft and 8.0 ft, respectively

2-D Computer Modeling

(Transects 1-4)

210800

211000

211200

211400

80

90

100

Depth(feet, MLLW)

4

1198000 1198400 1198800 1199200 1199600 1200000

209200

209400

209600

209800

210000

210200

210400

210600

0

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704

3

21

2D Computer Model in Action

(Existing Marina)

Wave Heights for Existing

Marina Conditions

3.0

4.0

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Transect 1 (South)

Transect 2

Transect 3

Transect 4 (North)

Breakwater

ShorelineIncident Waves

0.0

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Distance (feet)

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2D Computer Model in Action

(New Marina)

Wave Heights for New

Marina Conditions

3.0

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Transect 1 (South)

Transect 2

Transect 3

Transect 4 (North)

Breakwater (locationvaries in transects)

Shoreline

Incident

Waves

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Distance (feet)

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Breakwater and Mooring

Lines Layout

Elastic Connection for

Modeling

Tension in Catenary Moorings

120,000

CATENARY LINE TENSIONHs=2.9', T0 = 2.9s

246

0 100 200 300 400 500TIME, (s)

0

40,000

80,000

T

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Line 6

Line 4

Line 2

Mooring Analysis and

Structural Design

Mooring Analysis

Iterations of mooring and hydrodynamic

analyses

Level of pretension, length, and size of mooring

lines were determined

Typical Mooring Line

Mooring Analysis and

Structural Design

Consideration of various facilities and float

launching methods

Maximum length of individual body = 150 ft

Four different concrete mix designs (ready mixed)

Lightweight fine aggregate (imported from

Colorado State) blending with normal weight

aggregates.

Concrete Mixture Details

Typical Breakwater Section

Breakwater Connection Plan

A1 C4126 ft

112 ft

A1A2

A3A4 B4B3B2B1

C4C3

C2C1

Construction of Breakwater

Breakwater Side wall

Foam Filler for Breakwater

Breakwater Top Deck Being Poured

Work is Underway!

Breakwater Launch

Breakwater Launch Floating

Breakwater Launch

Breakwater Launch Floating

Assembled Breakwater Being Towed

Assembled Breakwater

Public Access to Marina

Access Ramp from Marina to

Breakwater

Completed Marina with Breakwater

Summary

Not only breakwater but also over-water

park

Innovative construction applicable to many

different manufacturing and launching different manufacturing and launching

methods.

Make an impact on other local governments,

A/E firms and contractors to develop future

durable and cost-effective breakwaters.

Environmental & public-friendly breakwater

We will Happy to Answer any

Questions?

Thank You