THE LATEST NEWS FROM ROYAL HUISMAN AUTUMN / WINTER … · Pumula, Kamaxitha, Elfje,and both the...

THE LATEST NEWS FROM ROYAL HUISMAN AUTUMN / WINTER 2016 - 2017

techn ical des ign : power and sail

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While a well designedsail plan provides thehorsepower, it is the

underwaterappendagesthatdetermineperformance

in terms of resistance,stability, leeway and – ultimately –safety.

Generally speaking, the biggerthe sail plan the faster theboat. But beyond this rawpower, it is the hull formalong with the keel andrudder design that determineperformance at all points of

sail. For this reason, at the start of each newproject and together with the owner’s teamand chosen naval architect, Royal Huismanconducts in-depth analysis to develop acustomised operational profile that considers allthe requirements to build the ideal yachtfor the client.

A yacht under sail canbe compared to aswan: beautiful andserene above thewaterline, but paddlinglike hell beneath it.

What a

Stabilisers, although they can and have beenapplied on sailing superyachts, are essential forensuring comfort aboard motoryachts such asRoyal Huisman’s Arcadia and DART. Here againthere are multiple systems available on themarket, from fixed fins and hydraulic zero-speedstabilisers to gyroscopic and electric stabilisers, oreven the AntiRoll system proposed by DMSHolland inspired by the pectoral fins

of a whale.

The motoryachtArcadia was fittedwith conventionalzero-speedstabiliser fins, butstabiliser technologyhas developed since herlaunch in 2006 and forDART the shipyard researched other solutions.Offering good ‘at anchor’ stabilisation,

inboard gyro stabilisers are one optionthat offer the further advantage of not

being attached to the outside of thehull. But as they take up valuable

interior space, have somenoise issues, and requiretime to ‘warm up’, in thiscase they are not RoyalHuisman’s first choice.

External hydraulicfins require lessmaintenance, takeup less interiorspace for theactuators, andfunction as soon as

they are switched on.The problem is that zero-speed

fins like Arcadia’s necessarily create dragwhile underway, so for DART the Royal Huismanengineers opted for the latest-generation‘active’ retractable stabilisers that function atanchor and can fold away into pockets in theside of the hull when not in use to reduceresistance. Vessel speed and the angle of the finsin the water determine the degree of liftgenerated and the subsequent level of rollreduction. The ‘active’ control system sensesboat speed and the degree of movement andalters the fin angle to provide 80 - 90 per centroll reduction.

No MoreRockand Roll

Propellers do not immediately spring to mindwhen we think of sailing yachts, but togetherwith the propeller shaft they are a significantsource of drag when sailing. Most of the Royal Huisman fleet feature a singlecontrollable or variable pitch propellermounted on the centreline. The blades of acontrollable pitch propeller can rotate aroundtheir own axis to move the yachtforward or backwards. Asthe propeller rotates inonly onedirection,thisincreasesefficiency byreducing powerwastage and stress onthe propulsionmechanism. Acontrollable pitchpropeller can also bealigned or ‘feathered’to create the leastresistance when sailingwithout engine power.Ethereal, Athena and themotoryacht Arcadia are exceptionsinsofar as they have twin propellers. Inthe case of 90m / 295ft Athena, her sheersize dictated the use of twin screws to facilitatemanoeuvring and meant smaller engines couldbe installed that can be run more efficiently.

The latest development for reducing propellerdrag in performance-oriented sailing yachts is aretractable propulsion system: fixed orazimuthing thrusters that retract behind flushhull doors when sailing to gain valuable extraspeed. Such systems are clearly aimed at ownerswho take their superyacht racing very seriouslyindeed and Royal Huisman is ready to install thetechnology should a client request it.

One potential drawback worth taking intoaccount concerns the rating rules in Bucketregattas whereby a yacht with retractablepropulsion receives a rating penalty. To date thespeed advantage has outweighed that penalty,but the rules may well change next year, atwhich point performance gain will have to bemeasured against the likelihood of winning. Theyacht will be faster under sail, but then its ratingwill make it harder to win the race.

Arcadia (2006) isexecuted with zero-speed stabilisers

DART's propulsionpossibilities includeazimuthingthrusters or aconventional setupwith retractableAntiRoll stabilisers.


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While a well designedsail plan provides thehorsepower, it is the

underwaterappendagesthatdetermineperformance

in terms of resistance,stability, leeway and – ultimately –safety.

Generally speaking, the biggerthe sail plan the faster theboat. But beyond this rawpower, it is the hull formalong with the keel andrudder design that determineperformance at all points of

sail. For this reason, at the start of each newproject and together with the owner’s teamand chosen naval architect, Royal Huismanconducts in-depth analysis to develop acustomised operational profile that considers allthe requirements to build the ideal yachtfor the client.

A yacht under sail canbe compared to aswan: beautiful andserene above thewaterline, but paddlinglike hell beneath it.

The taller masts require a counter weight in theform of a lead filled keel (think of it as thependulum on a clock). Some would argue thatthis can limit cruising in shoal waters, anchoringin shallow bays or mooring in some harbours.But Royal Huisman’s Michael Koppstein believesthat owner focus on shallow draft is oftenmisplaced. As a former yacht captain, he sailed

the world withoutbeing overtly

restricted bydraft:

“What Ifound was

that the length ofthe yacht more than

draft defined where we could anchor or dock. Aberth for a 40m / 131ft yacht is generally foundat the seaward side of a marina. Thisautomatically puts the yacht in deeper water.The same for anchoring; to have sufficientswinging room in the event of a wind shift wefound ourselves in deeper than necessary partsof the bay. I wasn’t restricted by the draft asmuch as I was by the length. Of course, therewill always be exceptions, but these weencountered on only a few occasions.”

Historically, Royal Huisman has fitted fixed keelswith ballasted bulbs to its fleet designed by theworld’s premier naval architects. This trendcontinues with the more recent launches such asSea Eagle, Wisp, and the classic ketch (project399) currently in build.

By maintaining a moderate draft of around 4.5m / 15ft, all these yachts are able to visit theirfavourite destinations without difficulty, whilestill enjoying all-round performance under sail.

Fixed or lifting, telescopic or canting,centreboard or daggerboard, with or withouttrim tabs and winglets? The choice of keel findesign can be bewildering. Each type offersdistinct advantages and some disadvantagesdepending on the priorities of individual owners,who increasingly expect high performancecombined with shallow draft – two seeminglycontradictory attributes in a sailing yacht.

A deep fixed keel is the standard choice onyachts where modern performance rules out thelong or full keels of the past, which due to theirhigh wetted area and consequent drag wereinherently slow. The efficiency of a keel finimproves with increasing aspect ratio, soa deep narrow fin produces less dragthan a short, wide one for a givenamount of lift, resulting in afaster boat that can point closerinto the wind. As there are nomoving parts, it is also themost reliable solution,making it an ideal choicefor world cruisers.

“But a limiting factor isthe draft,” points outMartin Groen, RoyalHuisman’s concept designmanager. “No one wants aslow boat these days andthe bigger the rig, the deeperthe keel to maintain sufficientrighting moment.”

Ethereal’s hybrid propulsion system made her aground-breaking boat, but often overlooked isher fixed keel design with bulb winglets thatwas just as ingenious at the time of her launchin 2008. The winglets developed out of Pietervan Oosanen’s research for America’s Cupwinner Australia II. The small winglets on thebottom of Ethereal’s keel fin, optimised by VanOossanen Naval Architects, serve to increase liftand reduce drag. Principally of benefit whilesailing upwind when the yacht is heeled over,the winglets also provide additional side force,reducing leeway by improving ‘Velocity Made Good’.

Alternatively, a centreboard is a retractableblade that swings in a longitudinal slot in thehull or a short keel to reduce draft. DuboisNaval Architects designed 57.5m / 189ftTwizzle with a single engine and shallow stubkeel with a centreboard that varies draft from3.8m / 12ft and 10.8m / 35ft. The combinationallows her powerful ketch rig to perform at allpoints of sail. Other Royal Huisman yachts withcentreboards include 40m / 131ft Acharné,41m / 135ft Anakena and 41m / 135ft Surama(ex-William Tai).

The next step up in terms of complexity, costand performance is a fully ballasted liftingkeel that can reduce draft as it is retracted intoa keel box inside the yacht. Royal Huisman’sPumula, Kamaxitha, Elfje, and both the carboncomposite sloop (project 397) and the 58maluminium sloop (project 398) currently inbuild, all have lifting keels. Their designs areoptimised, but they are either up or down. The drawback of a lifting keel is that the keeltrunk generally consumes living space inside theyacht, requiring a compromise betweenperformance and amenity. A solution thatprovides the advantages of a lifting keel withoutthe loss of interior space is a telescopic keel,whereby a fin extension slides out of a keel stubto effectively double the draft. Daggerboardswork in a similar way. Commonly used on keel-less multihulls to counter leeway and convertforward motion into windward lift, 34m / 111ftSpiip (ex-Unfurled) designed by Germán Frersand built by Royal Huisman features a compositedaggerboard that protrudes from within thebulb, increasing draft from 3.9m / 13ft to5.8m / 19ft to maximise upwindperformance.Hyperionalsohas atelescopiccarbon composite daggerboard.

An Even Keel 8.1m5.3m

<

<

1 Portland, Maine - 8m / 26ft

2 Boston, Massachusetts - 10m / 33ft

3 Nantucket Boat Basin - 4m / 13ft

4 West Palm Beach, Florida - 5.2m / 17ft

5 Bahia Mar, Florida - 4m / 13ft

6 Island Gardens Deep Harbour, Miami - 5.5m / 18ft

7 Albany Marina, Bahamas - 4.8m / 16ft

8 Emerald Bay, Bahamas - 4.2m / 14ft

9 Atlantis, Bahamas - 3.9m / 13ft

10 Falmouth Harbour, Antigua - 6.1m / 20ft

11 Gustavia, St Barth - 4.6m / 15ft

12 Simpson Bay, St Maarten - 5.5m / 18ft

13 Town Quay, St Tropez - 4m / 13ft

14 Cannes - 5m / 16ft

15 Golfe Juan - 5m / 16ft

16 Antibes - 7m / 23ft

17 Portofino - 4.5m / 15ft

18 Porto Cervo - 5m / 16ft

19 Montenegro - 12m / 40ft

Dubois NavalArchitects designed57.5m / 189ft Twizzlewith a centreboardthat varies draft from3.8m / 12ft and10.8m / 35ft.

The fully ballasted keel of Ngoni(project 398) has a draft of 8.1m / 26ft,but can be lifted to 5.3m / 17ft.

Hyperion (1998)designed by GermánFrers features acomposite daggerboardthat protrudes fromwithin the bulb

*Data supplied by the Superyacht Intelligence Agency

*

Typical drafts in55m berths insome of our

favourite locations

123

4

56

789

1011

12

1314151617

1819

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For monohull sailors who want the ultimate inperformance, a canting keel is the obviouschoice. By swinging the keel to windward tocounteract the heeling force of the sails,canting keels are now almost standard issue onmaxi racers such as 42m / 139ft SAMURAI (exMari-Cha IV) before her arrival in Vollenhove,where she was refitted with a retractable keel.The technology has been around for decades,but ongoing mechanical and structural issueson race boats has so far restricted their use onsuperyachts. The structure needs to be strongenough to resist the very high forces generatedby slamming or possible grounding, rigidenough not to overload the hydraulics, and yetlight enough not to counteract the advantagesof moving the ballast in the first place. Ascanting systems becomes more reliable andaffordable, no doubt they will become morecommon on superyachts. Royal Huisman hasreceived enquiries, for example, for a cantingkeel to reduce the heeling angle rather thanincrease performance (at the risk of stating theobvious, a canting keel is not designed toreduce draft – if used at anchor it would simplymake the boat list to one side).

Always looking to encourage research intosustainable energy along with Dutchingenuity and synergy, Royal Huisman is theproud sponsor of the TU Delft Solar BoatTeam, which designs and develops hydrofoilboats powered purely by solar energy.

The Solar Boat Team was founded by students ofHolland’s Delft University of Technology with theintention of winning the first Frisian SolarChallenge in 2006. Although they started fromscratch and faced unexplored design challenges,a boat was conceived and built, winning therace. This success continued with the next teamin 2008, which managed to win with an entirelynew boat design.

The Dutch Solar Challenge, the World Cup forsolar powered boats that takes place every twoyears, has grown into a major international eventwith around 50 teams taking part. Theperformance of the boats has also increaseddramatically: in 2006 the fastest took 17 hoursto complete the 200 km / 108nm course; by2014 that time had been cut to just over 7hours. The TU Delft team also participates in theDutch Championships, the Amsterdam SolarBoat Race and the Monaco Solar Challengeorganised by the Yacht Club de Monaco.

Royal Huisman’s Advanced Composite division,with sister company Rondal, supported the Delftteam by supplying engineering know-how,materials and facilities to build the advancedcomposite hull at the shipyard’s facility inVollenhove. Using solar energy alone to power aboat presents a number of challenges: thepower output of even the most advanced solarcells is limited, so a light and highly efficienthydrodynamic hull is crucial to minimiseresistance.

“Given the twin requirements of lightness andhydrodynamic efficiency, we were able to advisethe TU Delft team on the best carbon compositematerials and processes,” says Adri Wolf,Manager of the Advanced Composite Division.“The actual construction was then carried out atour sister company Rondal and we weredelighted when the bare hull came in under theoriginal design weight of 33kg / 73lbs”.

In 2010 the TU Delft team was the first tointroduce hydrofoils reducing resistance bylifting the hull out of the water. The 2014team took another leap forward with adouble-T-wing configuration, minimising drageven further to achieve their best top speed of28kn / 51km/h. The 2016 edition saw theintroduction of further technologicaldevelopments and refinements.

Foils on sailing boats have proved their worthwith the fast and highly manoeuvrable Mothclass (a 3.35m / 11ft sailing dinghy) andlatterly with the spectacular America’s Cupcatamarans. But it is one thing to harness thewind and quite another to drive a boat usingonly the sun’s rays and solar panels, whichprovide the equivalent energy required topower a couple of household water boilers.Foil technology is constantly advancing andone of the America’s Cup Teams evencontacted the TU Delft teamrecently to enquire abouttheir solutions for theautomatic control of theheight of the foils.

The current solar team consists of 25 studentsfrom different university faculties. Around halfof them put their degree on hold for a year towork on the solar boat full time. Althoughwinning is important for the team, theultimate goal is to educate the nextgeneration of engineers and naval architects,while also exploring the potential ofsustainable energy and solar technology in the marine and superyacht industry.

BRING ON THE

SUNSHINE

Under the watchful eyeof Athena at theAmerica’s Cup, the foilson the catamaransenable speeds in excessof 48kn / 88 km/h

Ethereal (Ron Holland,Pieter Beeldsnijder, 2009):the small winglets on thekeel, optimised by VanOossanen Naval Architects,serve to increase lift andreduce drag.

inhuis2016


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Like keels, rudder efficiency improves withincreasing aspect ratio, so the modern standardon large sailing yachts is for high aspect ratiorudders, usually made of carbon composite, thatare long and thin (when Tony Castro designedthe motoryacht Arcadia, he reverted to hissailing background by specifying efficient tall andslim rudders whilst fitting them with breakawaytips).

Royal Huisman routinely fits single centrelinerudders as the less wetted surface area thebetter, but there are circumstances where twinrudders are preferable. On a hull with a verywide aft section like the Volvo Open 60s and70s, a centreline rudder will lose traction whenheeling hard, but with two rudders one may liftcompletely out of the water while the other isburied still deeper. Twin rudders were consideredfor 58m / 190ft Ngoni, but tank testing andcomputer studies showed that a centrelinerudder would perform better.

Again like keels, rudders that are long and thinraise the question of draft: you don’t want yourvulnerable steering to draw more than your keel,especially on yachts with a lifting keel. So on theadvanced composite sloop in build (project 397),Royal Huisman has introduced a shorter rudderthat is fitted with an extension blade that can beraised or lowered together with the keel fin.

Spade rudders hang down beneath the hulland are self-supported by the stock. By movingthe stock aft from the leading edge, a spaderudder becomes a balanced rudder. It is said tobe ‘balanced’ because the axis of rotationbehind the front edge means the pressure ofwater caused by movement through the wateracts on the forward part to exert a force thatcounteracts the pressure on the aft part, whichreduces the angle of deflection. However, adegree of semi-balance is normal to avoidrudder instability (i.e. the area in front of thepivot is less than that behind) so that the ruddercan be moved with less effort than anunbalanced rudder.

Wisp, Athena and the motoryacht Arcadia haveskeg rudders, which look like spade ruddersexcept they have a metal protrusion or skegfixed to the hull to protect the leading edge. Itcombines the swiftness of a spade rudder withsome of the protection that is offered by a fullkeel rudder.

Anchor systems are not appendages as such, but they spend much of their life underwater.Beyond their weight they don’t dramaticallyaffect performance, but they certainly influencethe way a yacht looks and is operated. A provensystem on yachts with a flared bow like Athenaand Arcadia are pool anchors housed inpockets built into the hull in the bow. Analternative solution that appears on Hyperion,Twizzle, project 399, and several other RoyalHuisman yachts are plow anchors that sit inshallow cheeks on the bow. The advantage ofsuch systems are that the anchors work bysimple gravity, which never fails: all you need todo is release the brake.

On Meteor the twin anchors had to be mountedbelow her bowsprit, but on Kamaxitha, whichalso has a bowsprit, her vertical bow meant asubmarine anchor system was introduced.When fully retracted in its underwater pocket, aplate welded to the bottom of the anchorbecomes a flush part of the hull. To ensureproper alignment while weighing the anchor, atransverse pin on the anchor stock is forcedthrough a corkscrew guide in the hawse pipe onthe way in. A snubbing line can be attached tothe anchor chain to bring the tension pointfurther forward.

Tank testing confirmeda single centrelinerudder would be the optimum forperformance

KeepingonCourse Anchors

Aweigh

On Ngoni the submarinesystem has been furtherrefined with two anchorsplaced one in front of theother along the centreline

Champagne christens Athena’s pool anchor (left)which is housed into a pocket in the hull. The Germán Frers Spiip features a swing-overanchor system: where the snubbing line attachesto the chain.

GOOD LOOKS, HIGH PERFORMANCE

Taking into account the ever-increasingsize of rigs with matching loads, sparmaker Rondal – Royal Huisman’s sistercompany – has invested heavily inresearch to enhance the performance ofsuperyacht masts and booms. Real-timedata provided by load sensors meansthe Rondal engineers can develop veryreliable models, allowing rigs to betuned to a high degree of accuracy.

Rondal developed its first performanceboom two decades ago in response to thegrowing loads on rigs. The ingeniousfurling system uses an outhaul car toprovide foot tensioning at both full andreefed mainsail positions. The latest version,which will appear on Royal Huisman’sNgoni (project 398) and the classic ketch(project 399), introduces new and improvedfeatures, including a very sleek, low-profiledesign for the compact outhaul system thatcan cope with even higher loads anddeeper reefs while still remaining wellwithin the weight budget.

“In the case of Ngoni that carries a square-top mainsail, the objective was not toexpose the crew to having to go up themast to detach the batten,” says Rondal’sCommercial Director, Paul Dielemans.“Together with industry professionals wedesigned an innovative solution wherebythe locking system is integrated into theheadboard and batten car assembly, so thesail can be lowered and folded on theboom from the deck. A one-to-one scalemodel was built to test the concept upfront. We were very proud to haveovercome the challenge created with thisproject.”

Another recent development is Rondal’sinternal connection for diagonal stays: theminimalist design eliminates exteriorturnbuckles to provide a clean, flush lookthat still facilitates length adjustment.

Not forgetting the unique design freedomprovided by the ‘Style to Order’ service,whereby Rondal determines the technicaldimensions and allows the designer toshape the outer shell in harmony with theoverall design aesthetic. The ‘Best-in-Class’Rondal spars of Sybaris, the latest PeriniNavi ketch, showcases recent examples ofthese stylised spars. Moreover, the 74m /242ft main mast by Rondal is the tallestcarbon one-piece spar ever built.

Besides building two more 70m / 230ft-plusmasts, Rondal is applying its advancedcomposite knowledge and expertise toother sail and motoryacht components suchas superstructures, rudders, radar masts,large hatches and other specials. In eachcase, the goal is to combine good lookswith impressive weight savings and efficient performance.

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inhuis2016

On Ngoni (project 398) the submarine systemhas been further refined with two anchorsplaced one in front of the other along thecentreline. The carbon sloop (project 397) is alsounusual insofar as it will have a submarine plowanchor instead of the customary pool anchor,which presents a simpler shape for ensuring thatthe bottom plate fits flush with the hull.

Swing-over anchors are anothersystem employed by Royal Huismanon yachts such as Unfurled, Gliss,Blue Papillon and Sea Eagle. Theanchors, which lie upside and out ofsight in the anchor locker, can be‘flipped over’ and deployed at thetouch of a button. The advantage is aclean, uncluttered deck for offshoresailing and flush good looks, butclearly a degree of bow flare isrequired for the anchors to dropcleanly without touching the hull. Incase of total blackout, such anchorscan also be deployed using a simplemanual or battery-powered tool.

In Sight

Hidden on the bow, Twizzle’s plowanchors are simply deployed, releasethe brake and leave it to gravity.

The masts and booms on Sybarishave been selected by her owneras ‘Best-in-Class’. The 74m / 242ftRondal main mast is the tallestcarbon one-piece spar ever built.

THE LATEST NEWS FROM ROYAL HUISMAN AUTUMN / WINTER … · Pumula, Kamaxitha, Elfje,and both the...

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