REPORT

SuperyachtTheT R U T H • O P I N I O N K N O W L E D G E • I D E A S A N D E X P E R T I N D U S T R Y A N A L Y S I S

ISSUE 172AUGUST/

SEPTEMBER 2016

GALACTICA SUPER NOVATSR is granted exclusive access on board the 70m motoryacht during her final day of sea trials.

LIGHTINGThe current state of lighting technology and where it might be heading in the future.

HULL FORMSIn an exclusive with TSR, Van Oossanen discuss their three new hull concepts.

AV/ITA look at what is behind some of the most innovative AV/IT installations on board recent launches.

The Superyacht REPORT

68 ISSUE 172

Van Oossanen hull forms

As the inventors of the Fast Displacement Hull Form and Hull Vane, Van Oossanen Naval Architects are regarded as a forward-thinking team looking to accelerate the pace of innovation. Co-directors Perry van Oossanen and Niels Moerke recently spoke exclusively with TSR about three new hull concepts that promise to consolidate that reputation.

Who said hulls are dull?

The ongoing quest for more eco-friendly yachts with reduced fuel consumption

roughly covers four areas of research: engine efficiency, alternative or sustainable energy sources, propulsion efficiency, and lowering the resistance of the hull. Van Oossanen has mainly focused on the latter and patented two solutions that do just that: the Fast Displacement Hull Form and the Hull Vane.

“We were taught at university that the fast displacement concept wasn’t possible,” says Perry van Oossanen. “We learned that if you want to go slow you need a round-bilge displacement hull; if you want to go fast you need a semi-displacement or planing hull with hard chines. There was no compromise.”

Perry begged to differ. Taking into account the typical operational profile of a large motoryacht, he wanted to combine fast top speeds for rapid transfers with the efficiency of a displacement hull at slower cruising speeds. The result was the Fast Displacement Hull Form or FDHF.

TSR attended the sea trials of 65m Heesen Galactica Star, the first superyacht to incorporate the FDHF, in 2013 (in this issue we also report on the commissioning of 70m Galactica Super Nova with FDHF, see page 46). The trials proved conclusively that the

FDHF performs better than conventional displacement hulls with resistance values at semi-displacement speeds that are 15-20 per cent less than those of hard chine hull forms. Better sea-keeping and wave reduction also meant improved on-board comfort.

The Hull Vane, which last year won the Dutch Maritime Innovation Award, constitutes a separate business unit for Van Oossanen. It basically comprises a fixed foil under the stern section of the hull behind the rudders that optimises the flow around the aft body to reduce resistance. The result is less power and less fuel to reach a given speed.

Taking into account the typical operational profile of a large

motoryacht, Perry wanted to combine fast top speeds for rapid transfers

with the efficiency of a displacement hull at slower cruising speeds.

ISSUE 172 69

The Superyacht REPORT Van Oossanen hull forms

CO-DIRECTORS NIELS MOERKE (LEFT)AND PERRY VAN OOSSANEN.PHOTO: JUSTIN RATCLIFFE

Moreover, the foil provides additional passive stability by reducing pitching. Heesen was (again) the first to adopt the concept on a yacht with 42m Alive launched in 2014. Alive combined the Hull Vane with a FHDF to harness the power-to-speed benefits of both, resulting in fuel savings of up to 30 per cent compared with conventional yachts of equivalent size and gross tonnage.

With 10 FDHFs up to 70m already launched and at least 15 under construction or in design, the working principles are well proven. But not content to rest on its laurels, over the last 18 months Van Oossanen has been finessing the concept still further by examining alternative volume-length ratios to find new unique selling points aimed at providing the market with more choice, particularly with regard to available living space.

“Our approach has been to develop the naval architecture around the perceived needs of the market, rather than the other way round,” says Perry. “Most designers are locked into the

existing layout solutions provided by conventional hull forms, but we don’t believe these always meet the evolving expectations of the market.”

Van Oossanen’s ongoing research into both the FDHF and Hull Vane has led to the development of three new hull designs, each offering different advantages in terms of efficiency, interior volume and exterior space with exterior styling that can be customised to suit individual clients.

“Our approach has been to develop the naval architecture around the

perceived needs of the market, rather than the other way round.”

– Perry van Oossanen, co-director, Van Oossanen

The Superyacht REPORT

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Van Oossanen hull forms

One is good, three is betterThe Be-Tri is a radical 50m trimaran concept that combines a central FDHF with two outriggers fi tted with one Hull Vane spanning across all three hulls. In a research paper presented at a RINA conference in Genoa in 2015, Van Oossanen compared the concept with an LY3-compliant, sub-500gt, 50m FDHF in terms of costs (including maintenance over a 20-year cycle), energy effi ciency, luxury and comfort. Based on extensive CFD analysis, the trimaran outperforms the equivalent monohull in all four criteria. In fact, it is up to 30 per cent more effi cient with the same installed power, providing excellent speed potential, range and comfort in waves.

The same research paper analysed typical user profi les to determine which kind of client would be attracted to the concept. Theoretical comparisons of the four user categories – Economist, Environmentalist, Family Man and Retiree – revealed a preference across the board for the trimaran over the monohull (especially the Environmentalist and Retiree, because their appreciation is based mainly on the energy effi ciency and comfort of the vessels). But arguably the main attraction from a user perspective is the extra deck space. With a 12.5m beam across the three hulls, Van Oossanen calculates the Be-Tri offers up to 75 per cent more deck area for the same gross tonnage, length and interior volume.

A PRELIMINARY SKETCH OF THE BE-TRI CONCEPT BY FRANK LAUPMAN OF OMEGA ARCHITECTS.

Van Oossanen calculates the

Be-Tri offers up to 75 per cent

more deck area for the same

gross tonnage, length and

interior volume.

The Superyacht REPORT Van Oossanen hull forms

enwa.com

Keep your system clean without chemicalsEnwaMatic® for maritime applications

2x MTU 16V4000 M93L 36.0

2x MTU 16V4000 M73L 33.1

2x MTU 12V4000 M73L 28.6

2x MTU 16V2000 M93 26.2

2x MTU 12V2000 M93 23.1

2x MTU 12V2000 M72 20.1

6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 366 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36

Speed, knots

Total installed power, kW

7,000

6,000

5,000

4,000

3,000

2,000

1,000

0

Be-Tri power-speed curve

“Other recent multihull motoryachts fail to utilise the extra beam provided by the outriggers, because they are often attached as separate bodies amidships,” says Perry. “By moving the outriggers aft, made possible by the Hull Vane, the main deck can be extended over the full beam to open up a range of wide-body deck layouts.”

Placing two or more slender hulls next to each other effectively separates stability from other hydrostatic hull functions, increasing the non-planing performance of the hulls in the process. Freed from the need to provide stability by their width, the slender hulls produce minimal wave-making resistance. A critical evaluation, however, is the distance or air gap between the hulls – too little and the stability advantage is diminished and the wave interference reduces performance; too much and the beam exceeds most marina berths and the yacht is more diffi cult to manoeuvre.

High-speed multihull ferries with hydrofoils are common enough, but trimaran superyachts with lifting foils are rare. The best known example is 61m White Rabbit Echo built by Echo Yachts in Australia, which is fi tted with four active foils that span the gap fore and aft between the central hull and the sponsons. The owner is apparently so happy with the confi guration that he is in the process of building an 83m version.

“The difference is that the foils on White Rabbit Echo are purely for controlling pitch and roll to improve ride comfort,” explains Perry. “The Hull Vane on the Be-Tri concept also increases the overall effi ciency by reducing resistance, resulting in higher speeds.”

THE BE-TRI CONCEPT WITH HULL VANE.

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Van Oossanen hull forms

More volume, less lengthThe idea behind the Gran Displacement concept was to create maximum interior volume within a relatively short hull of 35m-40m, without sacrifi cing the performance characteristics of the FDHF. This is achieved by extending the width of the hull along its length above the waterline with a fl ange to create a maximum beam of 12m, while maintaining a modest waterline beam for comfort and effi ciency.

The same fl ange, which looks rather like a pronounced spray rail, serves as an attachment point for a Hull Vane and a secondary foil – the Hull Vane Assist. Positioned under the forward section of the hull, this second foil is designed to partially lift the hull out of the water at higher speeds,

reducing the amount of water that is displaced and thus resistance. It also helps to dampen vertical accelerations by as much as 40 per cent.

Van Oossanen calculate that for a design that is maximised under the 500gt threshold, the Gran Displacement wide-body design

provides at least 30 per cent more interior space than a conventional monohull – a solution that may well appeal to the Asian or Middle Eastern markets, where potential owners are likely to spend more time inside their yachts than other nationalities.

THE GRAN DISPLACEMENT CONCEPT WITH HULL VANE ASSIST.

2x MTU 16V4000 M93L 30.0

2x MTU 16V4000 M73L 26.9

2x MTU 12V4000 M73L 22.8

2x MTU 16V2000 M93 20.9

2x MTU 12V2000 M93 18.8

2x MTU 12V2000 M72 16.6

0

1000

2000

3000

4000

5000

6000

7000

6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36

Tota

l Ins

talle

d Po

wer

, kW

Speed knots6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36

Speed, knots

Total installed power, kW

7,000

6,000

5,000

4,000

3,000

2,000

1,000

0

Gran Displacement power-speed curve

A RENDER OF THE GRAN DISPLACEMENT CONCEPT BY BARBARA DE ANGELIS.

ISSUE 172 73

The Superyacht REPORT Van Oossanen hull forms

Maximum length, optimum comfortThe Fast Displacement XL basically takes an opposite approach to the Gran Displacement concept, but with similar overall objectives. Instead of prioritising volume over length, it aims to maximise length within a FDHF platform for optimal speed, range and comfort. In fact, Van Oossanen has stretched the Fast Displacement XL to 62.5m with a beam of 9m, while remaining below 500gt. Uniquely for a 60m hull with high-speed potential, it has a draught of 2m or less while offering interior volume equal to a conventional 500gt yacht. The hull length could go shorter or longer, assuming a three-deck layout with 2.2m headroom or if a client wanted a sleek-looking sportsboat with a raised pilothouse confi guration. “We’ve carefully examined the existing 500gt designs and realised that a lot of volume is wasted on these yachts,” says Perry. “On the Fast Displacement XL we’ve redistributed this volume

into the length of the vessel, creating a more comfortable and more effi cient hull with a lot more exterior space. This comes without major compromises for the interior layout.”

Developed for a private client, and with a shipyard also interested, of the

three proposals the Fast Displacement XL is likely the closest to being built (the modest gross tonnage compared with most 60m hulls means the yacht would also be cheaper to build) and a patent is pending on the concept.

A RENDER OF THE FAST DISPLACEMENT

2x MTU 16V4000 M93L 34.0

2x MTU 16V4000 M73L 31.5

2x MTU 12V4000 M73L 27.8

2x MTU 16V2000 M93 25.7

2x MTU 12V2000 M93 23.2

2x MTU 12V2000 M72 20.5

6 8 10 12 14 16 18 20 22 24 26 28 30 32 34Speed, knots

The modest gross tonnage compared with most 60m hulls means the yacht would also be cheaper to build.

6 8 10 12 14 16 18 20 22 24 26 28 30 32 34

Speed, knots

Total installed power, kW

7,000

6,000

5,000

4,000

3,000

2,000

1,000

0

Gran Displacement power-speed curve

The Superyacht REPORT

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Van Oossanen hull forms

ASSISTING INNOVATIONAn integral part of Van Oossanen’s mission to improve hull effi ciency has been further development of the Hull Vane in combination with a second foil called the Hull Vane Assist. The two foils working together signifi cantly reduce vertical motions and as these accelerations induce seasickness more than roll angle, Perry argues that this comfort factor is the innovation’s principal advantage:

“There is an increase in performance in most sea conditions, but reduction in resistance resulting from the increased lift is mostly cancelled out by the drag of the forward foil.”

Earlier this year Van Oossanen spent nearly three weeks at the Marine Research Institute Netherlands (MARIN) institute tank testing the Hull Vane and Hull Vane Assist on a FHDF model. Unusually, the tank testing preceded in-depth CFD analysis, but the initial results confi rmed their predictions.

“In this kind of research project it’s better to test the basic concept fi rst before getting too involved in the details,” explains co-managing director Niels Moerke. “We can now go away and use the optimised settings and foil positions from the tank testing for the CFD studies.”

At higher speeds the Hull Vane creates a larger lift force that tends to trim the vessel bow down, affecting both performance and manoeuvrability. The idea behind the Hull Vane Assist, therefore, is to balance the trim by adding a second foil forward. The tank testing served to calculate the optimal

longitudinal and vertical position of both foils and their angle of attack.

The unmodifi ed FDHF model was tested fi rst to establish a baseline for the resistance values and sea keeping characteristics. Next, the model was fi tted with a Hull Vane. For these runs, the position of the foil was determined by CFD and extreme confi gurations were also tested to check the robustness of the extrapolation method.

Lastly, the forward foil was added to fi nd the best balance between the forces generated by the Hull Vane and the assisting

foil. The resistance curve and sea keeping performance of the optimised confi guration showed signifi cant stability gains in terms of heave and pitch when compared with the previous tests (bare hull and bare hull with Hull Vane). Van Oossanen Fluid Dynamics is now at work crunching the numbers, but Perry admits there are potential drawbacks still to be resolved:

“Unlike the Hull Vane, which is tucked under the buttocks in the stern and does not increase the draught, the Hull Vane Assist extends below the keel, so we’re looking into the feasibility of a retractable strut attaching the foil to the hull. There is also the question of the strength and rigidity of the structure itself, which is required to support the weight of half the vessel at speeds in excess of 16 knots.”

PERRY AND NIELS WITH HULL VANE COLLEAGUES BRUNO AND KASPER AT MARIN.

THE HULL VANE ASSIST IS CLEARLY VISIBLE UNDER THE FOREBODY OF THE FDHF MODEL DURING TANK TESTING.

PERRY VAN OOSSANEN AND NIELS MOERKE TANK TESTING THE HULL VANE ASSIST EARLIER THIS YEAR.

The Superyacht REPORT Van Oossanen hull forms

More speed v less fuelBy focusing on reducing resistance to increase hull effi ciency, Van Oossanen attempts to reconcile the seemingly opposing trends in modern yacht design for higher speeds and lower fuel consumption. The FDHF, Hull Vane, and now the Hull Vane Assist, go some way to resolving the riddle. Adapted to the user profi les of the Be-Tri, Gran Displacement and Fast Displacement XL concepts, they are examples of how innovative naval architecture can deliver more fuel-effi cient yachts and cater to the increasingly diverse needs of today’s owners at the same time.

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EMAIL: ISSUE172@SUPERYACHTREPORT.COM

WITH SUBJECT: WHO SAID HULLS ARE DULL?

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New hull developments

FDFH BE-TRI GRAN DISPLACEMENT FDHF XL

Comparative dimensions for a 500gt platform

LENGTH 45-50M 45-50M 35-40M 55-62M

BEAM 8-9M 12-15M 10-12M 8-9M

DRAUGHT 2-2.8M 2-2.8M 2.5-3.2M 1.8-2.2M

31.6

18.9

34.0

19.2

31.0

16.7

32.6

19.9

high power option (2 x 3,440kW) low power option (2 x 900kW)