Design number: Year: 2007
The result of exceptionally close collaboration between HYD and her owner, the award-winning Ermis² is the result of a lengthy research and development process designed to ensure that she met a series of challenging goals. Intended as a family boat, outwardly she exhibits a deliberately workmanlike appearance that hints at her seakeeping capabilities, but that deceptive exterior hides one of the most technologically advanced and fastest superyachts afloat today.
To attain speeds in excess of 55 knots her construction used significant amounts of carbon fibre and Kevlar to enable her to minimise weight while maximising strength, and an extended period of tank-testing of scale models was required before the designs were finalised to ensure that she would be stable and efficient at high speed through a variety of sea states. In order to achieve a raceboat-like trim a rapid-transfer fuel system and a 7-tonne water ballast tank were incorporated to ensure the optimal trim at all times.
Inside, Ermis2 surprises with an interior décor that is reminiscent of a Caribbean beach house. Expanses of white painted timber panelling have been used to reinforce the ambience of easy comfort, rather than dramatic opulence. This is a boat intended for gentle relaxation with family and friends. Yet close examination reveals an attention to detail that could escape the casual observer, with the wood grain in the panels treated to emphasise the vitality of the underlying grain, rather than covered with a heavier finish that while striking to the eye would detract from the attractiveness of the underlying material.
Other features that contribute to the family atmosphere include the galley, which can be opened up to the dining area when the owner and his friends choose to take over the cooking themselves, or closed off when the family opts for a little more privacy.
The following text by Rob Humphreys offers some more technical insight into the thinking behind this unusual vessel: Ermis2 has been a technical challenge from day one, and all the more interesting and enjoyable for that. The owner had specific characteristics in mind when he commissioned us to design the boat, and in general these requirements were less concerned with personal indulgence than with an appreciation of real seagoing capability, and a high speed capability at that. Accommodation volume was always secondary, and there was always an implied desire for real honesty in the design – a preference to show rather than hide the workings of the vessel, to compromise as little as possible and to resist dressing over the technical solutions as they arose. I have always viewed boats as animate beings – with all the temperamental variation of any living, thinking creature – and clearly this boat was really going to have a soul.
From a naval architecture point of view the interesting immediate issues were displacement, deadrise angle, beam:length ratio and the longitudinal distribution of buoyancy. Starting with a reasonable assumption of what weight the boat could be built to, the question was how to distribute this displaced volume to meet the requirements of speed and seakindliness, two characteristics that do not always walk hand in hand. A wide hull with relatively shallow deadrise angle offers more lift but usually at the cost of a much more uncomfortable ride, whereas an extreme deadrise will soften any wave encounter but can generate insufficient lift to reach the higher speeds. This choice was also complicated by the fact that there was no real preconception as to what the final length needed to be, so the decision resolved itself largely around the range of power units available and the need to strike an optimum balance. Unlike a sailing yacht, where sail area is infinitely variable at the design stage, with a power boat horse-power tends to scale in a series of steps, and by definition some combinations of boat and power units will work better than others. Of course, there was the gas turbine option to think of as well, but we considered from the beginning that this would be a rarefied choice with a string of technical impediments that did not live comfortably with the requirement that the boat needed to be a working vessel with day-to-day cruising requirements, rather than a potential record-breaker. General maintenance and an easy running of the boat are vital considerations for a happy ship.
From first conceptual thoughts we carried out a series of tank test sessions, working with the Wolfson Unit of Southampton University, an organisation with which I have had a close relationship over the years. Much of the most interesting work we carried out was in the wave tank, running hulls in both a Mediterranean and Caribbean wave spectrum, at a variety of Significant Wave Heights and of course across a range of boatspeeds. Armed with the validation we achieved, I was then able to establish the final parameters of length, beam, deadrise angle, etc., and progress to the final lines, while at the same time starting to assemble the associated building blocks of the design.
One of the biggest challenges was to be able to build the boat to a demanding weight schedule, and here the Owner himself set a real challenge by being demonstrably happy to sacrifice some of the trappings that are generally meat-and-drink in the superyacht arena. In terms of the yacht’s systems it was always a case of try-simple-first and resort to complications if the basics would not suffice. He also encouraged a construction approach more in keeping with the grand prix sailing world with which we are very familiar, flagging the widespread use of carbon composites and titanium hardware. Here High Modulus rose to the technical challenge, while McMullen and Wing displayed a typical Kiwi enthusiasm to embrace a challenging objective and brought their engineering aptitude to the fore.
In all the tank testing we had done we were able to measure the vertical accelerations in different speed/seastate combinations and were able to assess what sort of g-forces we were likely to be dealing with. Germanischer Lloyd, given the task of vetting all aspects of the design and build, normally apply a 1g threshold on commercial vessels of this kind, and thus also for private yachts, but we foresaw that this was low of the mark and self-imposed an engineering threshold of 2.2g through the Centre of Gravity, requiring GL to use this as their base. So for High Modulus it was an even more substantial challenge than it might have been – in their words ‘…the structural design brief was simple: to develop a structure to withstand twice the load at half the weight of a conventional high speed motoryacht’.
A huge amount of research and testing was carried out, including Finite Element computation, and as part of the package High Modulus favoured a sandwich bottom panel as opposed to a solid carbon bottom panel. ‘The most heavily loaded area of any high speed motoryacht structure is the bottom shell, and … the need for extreme long-term toughness in this area. Backed-up with substantial experience and specialist research, High Modulus recommended the use of high elongation Airex R63 linear foam cores, coupled with carbon fibre and Kevlar®-reinforced epoxy skins. The resulting shell and structure were not only substantially lighter than the equivalent solid carbon fibre laminate: they were also substantially tougher.’ This was of course substantiated by destructive panel testing, because nothing could be left to chance.
Nothing delights me more than the opportunity to start a project with a clean sheet of paper, and in the same way as we came at this challenge with a fairly fresh pair of eyes, builder McMullen and Wing were able to look at advanced composite construction without prejudice or vested interest, and were at the forefront in expressing their preference for a female-moulded, vacuum-infused approach. Though potentially troublesome to set up, this produces a highly reliable laminate consolidation and with the female mould dramatically reduces the need for surface filling and fairing, giving us the lightest and most durable hull shell that we could have wished for.
Not only was the hull built this way, the deck, superstructure and internal structure were also built with the same rigorous attention to weight and the final total for the entire composite package of 17 tonnes is impressive indeed for a 37-metre high speed motor yacht, especially given the demanding engineering threshold that we super-imposed over the engineering calculations. Even the interior panelling, furniture and other components were subject to a ruthless weight audit, with much energy expended by interior designer Jo Humphreys in the search for light solutions. In High Modulus’ words, ‘The result is a boat that truly represents the current state of the art – one of the highest technology luxury motoryachts ever built. The structure achieves excellent stiffness, strength and toughness, with considerable weight savings: the structural weight being approximately half that of a wet lay-up glass, epoxy and foam core structure.’
Of course, one of the benefits of being towards the right end of a weight struggle is that it gives one a range of options. Our general understanding, backed up by the high speed testing we did, was that an aftward-LCG was a very desirable feature for high speed efficiency. However, while fine in a Class One racing powerboat this bow-up attitude does not suit the all-round user-friendliness of what is at the end of the day a cruising yacht. For reasons of slow-speed trans-Oceanic range we were already budgeting for immense fuel capacity (we have a 56,000 litre fuel capacity), but through use of a rapid-transfer system we established that we could make significant alteration to the longitudinal trim of the boat in the time it took to leave or return to dock. And with an additional 7-tonne sea water ballast tank forward, again with a swift deployment system, we gained an ability to get the boat into quasi-race mode as required, or alternatively drop her down to level trim for optimum forward visibility and slow speed manoeuvrability, with the bow thruster properly immersed and the wine dead level in the glass. This longitudinal trimming facility meant that at the design stage we were able to lay out the machinery and other heavy components to give us a base longitudinal centre of gravity position that is much further aft than would be considered appropriate for a run-of-the-mill large motor yacht.
Rounding up, we have thoroughly enjoyed our work on Ermis2 and are geared up to attract more work in the large motor yacht sector, not just at the high speed end. Ermis2 is not so much a showboat as a comfortable working vessel, and from the very beginning she did seem to work. Second time out with a 30 tonne fuel payload, the throttles were opened out for the first time to a speed of nearly 53 knots. That number, though academic in the general scheme of things, has been steadily climbing throughout the trials and should continue to do so as fine tuning proceeds and the boat gets close to her optimum high speed displacement and trim. But speed, of course, is not all that the boat is about – she is extremely comfortable, surprisingly quiet and conversation-friendly even at speed; she does not rattle and shake and she can go through the night in dead silent mode. It was satisfying indeed to hear the owner’s measured assessment on completion of his acceptance trials, ‘All our objectives have been exceeded’.
We do, of course, understand that many will see Ermis2 as a boat out of its time in this greener climate, but the truth is that she is a sprint boat with a speed capability that will be used only on occasion. And that sprint capability is as much about low resistance design as it is about brute power, a characteristic that serves the boat well throughout the speed range. The fact of the matter is that Ermis will be more fuel-efficient at modest speeds than many standard production motor yachts. This thinking is in line with a powerboat philosophy I developed and designed to fifteen years ago for a low-energy carbon/Kevlar RIB that is now resurgent as the Ribling 555 and an Olympic coaching vessel used by David Howlett in support of Ian Percy’s Beijing Star campaign. To quote Howlett, “We have been using the boat for the last four months to support the GBR Star Percy/Simpson team in Hayling, Medemblik, Cascais & Lake Garda. The boat has worked fantastically well and exceeded many of the design criteria. We have transported the hull on the roof of a car, the engine in the trailer box and the rest of the Ribling 555 in the car. This has saved us having a second tow vehicle as other RIBs would have needed. We can tow the Star on the plane at 14kts and have reached 31kts when not towing. The fuel economy (using the two 25ltr removable plastic fuel tanks) enables me to use the boat at regattas for about 5 days between re-fills and … it has been heartening to hear the praise for the boat from the other professionals on the water who can clearly see the boat’s advantages.”
Ermis2 comes out of this same philosophy.