Pho

to c

ou

rtes

y o

f Pe

nd

enn

is

The arT of creaTing a really fasT superyachTtext by bransom bean

The Need for

SPEED

74 SHOWBOATS INTERNATIONAL SHOWBOATS INTERNATIONAL 75

The Need for Speed the need for sPeed

Pho

to b

y ch

ris

Mo

orh

ou

se (f

ort

un

a)

yacht to have reached 70 knots). “So we zero base everything,

looking to optimize power, weight and shape.”

Like everything else about a superyacht, it seems that there’s

a special art to creating a really fast superyacht.

“Owners won’t go to all this trouble if it doesn’t look and feel

like a luxury yacht,” reminds Blount.

KinD of a Drag The enemy of speed is drag or resistance. Sadly, in this battle for

speed, drag has many allies and sometimes defeating one only

reinforces another.

Drag increases with speed until the accelerating hull reaches

a sort of terminal velocity, called hull speed. Or, if there’s enough

power for the geometry of the hull, she lifts majestically up from

the water onto a graceful plane, shedding hydrodynamic drag

and gaining even more speed.

“And that’s when weight distribution gets really important,”

says Blount.

Drag can be visualized as things protruding from an otherwise

To own The floaTing work of arT ThaT is a superyachT

means being one of the very few who possess something very

special, a sophisticated confirmation of success and good taste.

But to own one that is really fast, well that raises the game to a

whole new level. Designing and building a high-performance

superyacht is not for the faint of heart or shallow of pocket.

“A high-speed yacht project is not easy,” observes Bill Blount

of Donald L. Blount and Associates, which has done the naval

architecture for some of the world’s fastest superyachts, includ-

ing the 136-foot, 68-knot Fortuna, the former Spanish royal yacht.

The problem is that the science of naval architecture is unques-

tionably one of the most challenging. Like predicting the weather,

the variables involved are almost endless, and achieving the

ambiance of a superyacht only makes it harder.

“It’s essential to find a compromise in naval architecture,”

says Luca Bassani, Wally’s founder and CEO, whose yachts look

like they’re doing 100 knots at anchor. The WallyPower 118

Galeocerdo is the fastest Wally ever built, with a 60-knot cruising

speed and 64-knot top speed.

Going faster on water is a sorcerer’s blend of calculations and

compromises within an envelope of physics’ implacable laws.

“As a yacht gets faster, it becomes more unforgiving, so the

process needs to get more technical and less artisanal; it becomes

a finely engineered product,” says Antonio Caviglia of custom

builder Otam. “We become very meticulous.”

So, in chats with yacht designers it’s much more common to

hear, “The trade-off is….” rather than Computational Fluid Dynam-

ics, Froude number or the Admiralty coefficient.

siMpLe, in TheoryUnfortunately it’s not just a question of adding more power.

That’s what Australian Ken Warby did in 1978 when he set the

(still standing) world unlimited water speed record at 511.11

kph (317.596 mph) in his Spirit of Australia. But the Spirit of

Australia is no superyacht. She is a 27-foot home-built boat

whose weight almost matches the thrust of the military surplus

Westinghouse J34 jet that powered her. The only concession to

comfort? A seat for Warby.

“Remember, we want to build a fast luxury yacht, not a stripped-

down race boat,” says Bas Mulder of Mulder Design, designers of

the world’s fastest superyacht, The World Is Not Enough (the only

designed by dutch naval architect frank Mulder, The World is Not enough was built by Millennium super yachts, John staluppi’s and John rosatti’s company. she is propelled by two Paxman diesel engines and two Lycoming gas turbines, producing a staggering 20,600 horsepower.

Builder: Millennium super yachtsLoa: 140'

propulsion: triple water jetsMaximum horsepower: 20,600 hp

Fortuna was built at izar for King Juan carlos of spain, who is renowned for his penchant for speed. she is propelled by three rolls-royce gas turbines and two Man diesel engines.

Builder: izar Loa: 136' propulsion: triple water jets

this yacht has been kept a closely guarded secret and she has undergone an extended development program. this unique propulsion system has no less than six gas turbines and three water jets.

Builder: devonport (Pendennis Plus) Loa: 164' propulsion: triple water jets

Gentry eagle was built by the late tom Gentry, a speed fanatic. his passion to win the blue riband for the fastest atlantic passage drove him to build Gentry Eagle, in which he and a crew of five set a record time of 62 hours, seven minutes in 1989. she was relaunched as a yacht in 1992.

Builder: Vosper thornycroftLoa: 111' 11"

propulsion: single surface drive /twin water jets

Maximum horsepower: 11,560 hp

top 10

3

1 The World Is Not Enough | 70 knots

2 Fortuna | 68 knots

Alamshar | 65 knots

4 Gentry Eagle | 64 knots

these pagesThe World is Not enough (above) set a record as the world’s fastest

yacht but her 70 knots pales in comparison with the current standing water speed record established by Spirit of australia (left), essentially a rocket strapped to a hull. pershing made a name for itself with fast

production yachts using various propulsion options; the pershing 82 (previous page) is equipped with rolla surface piercing propellers but

pershing also has used turbines, most notably on the pershing 115.

76 SHOWBOATS INTERNATIONAL SHOWBOATS INTERNATIONAL 77

The Need for Speed the need for sPeed

Pho

to b

y KL

aus

Jord

an (s

Mer

aLd

a)

tion in the last twenty-five years,” observes Øino. To prove the point

he points to two yachts with similar volumes separated by two

decades. Smeralda at 925 gross tons was delivered in 2012 and

displaces 560 tonnes—a ratio of 61 percent; Eco (now Enigma)

delivered in 1991 at 1,030 gross tons displaces 1,000 tonnes or

almost double Smeralda’s displacement, with a 97-percent ratio.

“A higher budget is essential to reduce weight without sacrific-

ing comfort because it allows you to use the most advanced mate-

rials,” says Bassani. “But the fantasy of the client is infinite and it

can increase more and more the weight of the boat.”

poWer, JusT giVe Me More poWer“On the other hand there really hasn’t been a similar quantum

leap on the propulsion side,” observes Øino. So to go faster, as in

the Spirit of Australia, you can always add more and bigger engines.

“But as it relates to motor yachts, the power output options are

relatively fixed,” says Blount. “So the owner and naval architect

need to have a clear understanding of the project’s performance

expectations. The owner during the design or construction phase

may desire a change from the original design. The naval architect

needs to communicate the impact of that change, as it may require

an increase in the original power output to continue to meet the

owner’s performance expectations.”

smooth hull. So stabilizer manufacturers offer retractable versions

and “zero-drag” fins. Low-drag rotary stabilizers take advantage

of the Magnus effect—the reason for dimples in golf balls.

The other option is to just eliminate external stabilizers alto-

gether, replacing them with gyroscopic stabilizers, massive

flywheels spinning at very high speeds that work like a child’s

top. Those made by Seakeeper are aboard yachts built by Azimut,

Feadship, Wally, Gulfcraft and Sunseeker, to name a few.

It’s obvious that the hull’s shape or geometry affects drag, which

at its simplest is why the bow of a boat is narrower. Finding the

optimal shape for the entire hull was a hit-or-miss affair until it

became a measurable science in the last century with tank testing,

scale models pulled through a tank of water.

But a quantum leap forward with the development of hull

geometry is the use of computational fluid dynamics (CFD), where

the model and tank are replaced with software and computers

using complex algorithms to analyze simulated fluid flow. “CFD

helps us shave off drag elements including appendage design

throughout the boat’s shape,” says Blount.

You can also reduce drag by reducing friction between the

hull and the water; a clean, slippery bottom is the goal. The first

order of business is discouraging organisms like barnacles and

weed, something that is hard to do given environmental concerns

but not impossible. Akzo Nobel, makers of industry standard

coating AwlGrip, says customers using its just introduced Inter-

sleek Pro are reporting drag reduction of almost 10 percent

completely without biocides.

Then there’s air. Once any vessel gets to 50-knot speeds, aero-

dynamics becomes important; remember the stall speed of the

Douglas DC3 is 58 knots; the Piper J-3 Cub stops flying at 33 knots.

“Classically, yacht exterior designers are interested in aesthet-

ics,” says Blount. “But yachts using gas turbines need wind tunnel

tests just to make sure enough air will get to the engines, and

the ducting of exhaust avoids having a low pressure area that

collects exhaust gases where the owner wants to stand and watch

the shoreline fly by.”

sheDDing Those eXcess pounDs“But enemy number one of going fast is weight; you must focus

on weight and weight distribution,” says Espen Øino, designer

of legendary yachts 509-foot Al Said and 414-foot Octopus as

well as some very fast ones like 115-foot Moon Goddess, capable

of 45 knots, and all-carbon fiber 125-foot Shooting Star with a

top speed of 48 knots.

Reducing weight also reduces the boat’s draft, which as a

bonus allows the boat to go more places where the water is

shallower, like The Bahamas. Less weight also means less lift is

needed to get the boat up onto that all-important plane, when

the physics changes again.

Obvious ways to reduce weight are lighter batteries and using

lighter materials in the hull and superstructure, traditionally alumi-

num but more commonly now carbon fiber, Kevlar or ARAMAT,

a combination of Kevlar and fiberglass with a weight reduction of

six to 12 percent over conventional fiberglass, aluminum and steel.

(Titanium has been mooted. During the Cold War the Soviets built

seven Alfa class submarines with titanium hulls, but titanium is

expensive, even by superyacht standards.)

The holy grail of greater strength and lighter weight is possible

using finite element analysis (FEA) software early in the devel-

opment of the structural design.

Luxurious materials are often heavy. There’s a lot of weight

in marble and hardwood, but natural stone and wood veneers

reinforced with aluminum honeycomb transform that beauti-

ful finish to feather-light. It can reduce the weight of marble by

up to 75 percent.

Some very curious things have been done in the unending

quest for lightness, like replacing ceramic toilet bowls in the crew

accommodations with lighter stainless steel.

“There has been some tremendous progress in weight reduc-

the WallyPower 118 Galeocerdo’s sleek design is the result of an extensive r&d program. she is driven by three Vericor tf50 gas turbines, each driving a rolls-royce Kamewa water jet.

Builder: Wally/intermarineLoa: 118'

propulsion: triple water jets Maximum horsepower: 16,800 hp

initially called Mercury, this yacht was designed by Peter du cane for the Greek shipping tycoon stavros niarchos. she has three gas turbines combined with surface drives as well as two conventional engines for low-speed maneuverability.

Builder: Vosper thornycraftLoa: 103'

propulsion: triple water jets / twin screwsMaximum horsepower: 13,620 hp

designed by rob humphreys, this high-speed yacht was constructed in carbon fiber with every component analyzed to save weight. she is powered by three Mtu 16V 4000 M90 engines, each rated at 3,650 horsepower and Kamewa jet units.

Builder: McMullen & WingLoa: 123' 3"

propulsion: triple water jets Maximum horsepower: 11,000 hp

a Mangusta 108, Nobody’s engines set her apart from others in the series: two Lycoming gas turbines combined with water jets.

Builder: overmarineLoa: 110'

propulsion: triple water jetsMaximum horsepower: 8,770 hp

top 10

5 Galeocerdo | 64 knots

6 Brave Challenger | 60 knots

7 Ermis2 | 57 knots

8 Nobody | 55 knots

(cont.)

these pagesa computational fluid dynamics study

by naval architects BMT nigel gee for an oceanco project simulates how water will

interact with the hull (left). espen Øino has several fast yachts to his credit, including

(above, clockwise from left) Moon Goddess, Smeralda and Shooting Star.

78 SHOWBOATS INTERNATIONAL78 SHOWBOATS INTERNATIONAL

The Need for Speed

LosT in TransLaTion“Traditional fixed pitch, fully submerged propellers reach a

natural tip speed/blade load limit, after which cavitation occurs

with resultant loss of performance and physical erosion of the

blades,” says California-based designer Doug Sharp.

Or in other words, once you’ve settled on the power plant, the

objective is to save as much of the power created by your choice

of diesel engines or gas turbines and to minimize the power lost

as it’s delivered to the water, usually via screws/propellers or

water jets. “The objective is to try to optimize for two ideal speeds,

cruising and top speed,” says Øino.

Propeller shafts and brackets create drag, and as propellers get

larger in diameter they give the yacht a greater draft.

“A traditional propeller is efficient up to twenty-five knots or

so,” observes Johan Huber of Voith, “and water jets really come

into their own at forty knots; our Linear Jet bridges that gap.”

Voith has become synonymous with marine propulsion. The

company’s entry into superyachts has been its ultra-quiet thrust-

ers now specified by top yacht designers like Øino. Reputed to be

the propulsion of John Staluppi’s latest James Bond yacht, Project

Skyfall, Voith’s latest innovation is the Linear Jet with a double

walled nozzle nestled again the hull for reduced noise and vibra-

tion and a shallower draft.

“Water jet technology improvement, depending the manufac-

turer and their respective series of water jets, has increased their

efficiency by ten percent over the last decade,” says Blount.

Another option, surface drive units reduce underwater drag by

50 percent in a setup that moves the propellers to the stern and

raises them halfway out of the water. A “free” aesthetic accessory

is the spectacular rooster tail of white water thrown up astern of

the yacht, letting everyone know you have them.

WhoLe LoTTa shaKin’ goin’ on“Naval vessels can’t hide in port when it gets rough,” says Blount.

“Owners of well-designed high-performance yachts shouldn’t need

to either.” High speeds at sea can mean miserable pounding when

the seas begin to build and that can literally destroy an interior

designer’s creation. “Accelerations are a killer for human comfort

and put heavy loads on a lighter structure so the light weight

necessary for performance means problems with comfort and

structure,” says Sharp. “So the balance of weight to comfort and

speed is the primary focus for top-end performance.”

Sharpening the bottom into a deep-V improves rough weather

performance. “Our designs quite comfortably take two- to three-

meter seas at forty knots, using twenty-one degrees of deadrise,”

says Otam’s Caviglia. “But we know our yachts are subject to more

stress at these speeds.”

To strengthen their hulls, Otam makes all bulkheads structural,

joining hull and deck. All tanks are integral parts of the hull. And

a final structural touch is that all furniture is custom built into the

yacht. “Like a tailor-made suit,” says Caviglia.

a sign of The TiMesSo what happened to sedate, slow and stately lifestyle that was

classic gin-and-tonic yachting?

“Our typical owner does like to sit in one place quietly and enjoy

all the delights of the sea, but they also happen to be people who

want to get there fast,” says Caviglia.

“Life in general has become faster,” says Øino. “In the past you

carefully drafted a letter, sent it off regular post or airmail if you

were in a hurry; once it got to the other end, the recipient might

have it in the in-tray for a day or so before posting back your

answer. Now, we fire off an email, and if we don’t get a response

the next day we worry that something’s wrong.”

Baglietto is a builder of yachts synonymous with speed. Its sales

manager, Giulio Bertani, observes, “Owners no longer have to

compromise comfort to achieve speed. ‘Yacht-addicted’ owners

who are also committed to doing business all over the world need

to fit their cruises in a limited timeframe. Yachts able to reach

distant places at a high speed are essential to them.” •

Daloli (ex-AA Absolute) was designed by frank Mulder and was built by heesen yachts in 1995 for the sultan of brunei.

Builder: heesen yachtsLoa: 120'

propulsion: triple water jetsMaximum horsepower: 9,520 hp

Launched in 1995, Sun ark is another performance yacht designed by frank Mulder and built by heesen.

Builder: heesen yachtsLoa: 120' 3"

propulsion: triple water jets Maximum horsepower: 9,520 hp

for more fast yachts, visit boat international online at: www.boatinternational.com/yachts/the-register/top-20-fastest-yachts/.

top 10

9 Daloli | 54 knots

10 Sun Ark | 54 knots

(cont.)

Voith Linear Jet