On board the amazing SeaCart 30

Thedailysail take a tour on the hot new Swedish trimaran

Having had very little to report on the new production racing multihull front up until about 12 months ago, so suddenly there have been a spate of them, from the Decision 35 and M28 cats on the Swiss lakes, to the Latvian-built Catri 24 trimaran and most recently the Volvo Extreme 40. But of all the new multihulls the one we feel will gain the most commercial succcess is the Marc Lombard-designed, Marstrom-built SeaCart 30 trimaran.

The SeaCart 30 is the brainchild of Swede Calle Hennix and perhaps what is most interesting about Hennix, is that like many of those who sail on the Nokia Oops Cup, he has a hardcore background in offshore monohull racing, having sailed around the world in the Whitbread on board Roger Nilson's maxi ketch, The Card. He was also part of Gunnar Krantz's short-lived Tre Kronor Swedish America's Cup campaign in 1992, before making a concerted effort to knuckle down, in his words, "to be a normal person with a normal life and a normal job," while still spending a considerable amount of time sailing.

After two years sailing Formula 18s, in 2001 he began sailing extensively in the Nokia Oops Cup on the Sony trimaran. This set the cogs turning: "I thought this is amazing fun, but it should be a little bit smaller, it should be trailerable and you can open up a completely new arena for sailing. It should be very easy to handle and you can bring lots of guests out and you can also do very serious grand prix and one important thing for me was offshore racing."

Hennix says he had a look around the marketplace and could find nothing that suited his purposes. "Everything was cruising boats, if you wanted something hotter for racing you put a carbon mast on. But all the ORMA stuff wasn’t there. If you want to fly a hull, if you want to go offshore seriously, and you want to crank on really hard and go for it…I scanned the market and there was nothing."

Hennix got a team together including himself, a representative from Marstrom and Anders Lewander, with whom he would subsequently win the gruelling Archipelago Raid in 2003. Between them they drafted a 28 page long brief for what they wanted. To help them in their preparations they took a long look at their Formula 28 trimaran Exocet, concluding that this was close to what they were looking for but lacked offshore ability. They took their brief around the best known multihull designers, eventually choosing Marc Lombard on the basis that aside from his ability with the French ORMA 60 trimarans, he had experience of production building.

Design work was complete in the spring of 2004 and Marstrom went full steam ahead into full female tooling for the SeaCart's all-carbon fibre autoclaved production.

As Hennix anticipates building the boat in volume, much work was carried out to simply the production tooling and the build process, so, for example, the main hull and deck are made in a single one piece mould. "It is super strong and super light," says Hennix. "You crack it off the moulds with two guys lifting it and then you put everything in and it ends up at around 300kg, so it is pretty cool. And the same with the floats with the beams on them. They are 65kg." Marstrom went straight into a production run of 10 boats with the first boat launched in April this year.

Compared to other performance multihulls of this size, the design of the SeaCart 30 is unique in many ways. Although it started at 28ft long, 2ft was subsequently added to the transom. The result is a narrow trimaran for length, compared to the effectively square ORMA trimarans. On a 9.15m LOA, she has a beam of 6.6m (21.8ft) and Hennix says this is the same length:beam ration as Ellen's B&Q Castorama trimaran and also presumably similar to Olivier de Kersauson's Geronimo. The ORMA trmarans are square because with overall length and mast height limited, gaining beam (and thereby increasing righting moment) is a fundamental way to up their power.

"It is easier to work the waves if you have a narrow boat," reasons Hennix. "It is easier to fly a hull. And it is more spectacular - what we need during Grand Prix close in to cities and so on. That is why we have a mast 1m taller than what Marc Lombard said."

Most noticable about the SeaCart is her large volume floats. These are capable of supporting 350% of her 1,100kg all-up weight, the same buoyancy percentage as the ORMA trimarans Lombard has designed. It is possible to add ORMA 60-style curved retractible foils in the floats, and the internal structure is in place to do this, but no one has actually gone ahead with this yet. These are likely to be offered as an option extra as soon as a buyer shows interest in them, but Hennix is in two minds about their effectiveness on the SeaCart as his smaller 30 footer pitches more than an ORMA 60 - while curved foils are designed to give lift, if inclined wrongly then they can actually contribute to the boat going down the mine... "With foils in flat conditions, you might be able to do 24 knots on a reach. It is an option and we can start to build those and sell them as a kit - that could be a future development," says Hennix.

However putting a trim tab on the daggerboard, as many of the 60ft trimarans have to help their windward performance (as well as to balance the helm under pilot) is a step to far feels Callix. Already she is complex enough.

The SeaCart is demountable for trailing, the conical beam ends pulling out of sockets in the main hull, once the substantial 'water stays' have been undone. These rods extend up from just above the chine in the mainhull to the underside of each beam close to its termination at the float and are integral to the bracing of the SeaCart. Once the beams/floats are off they stack on their side on the trailer alongside the main hull. Hennix says it takes around 8 manhours to assemble or disassemble the boat, although he has done it in 1.5 hours with four.

While she may have three hulls, the SeaCart only has two rudders - one in each float. This, says Hennix, is because the boat is not wide and the rudders are big, which although draggy ensures manoeuvrability in light airs. A side benefit of this is that with the aft end of the main hull is not designed so that it must contain a rudder, new possibilities have opened up. There is a sugar scoop at the back and while this can be used as a bathing platform, it also has a set of rails on it, allowing the outboard motor to be pulled 'inside' the boat while racing.



Above Calle Hennix on the traveller, while Paul Larsen steers

When we went on board the SeaCart with Hennix, as well as Helena Darvelid and Paul Larsen last week during Weymouth Speed Week what particularly struck us was how stiff the whole boat feels compared to other demountable trimarans around this size.

"When you have it and you stretch up the rig and everything and you go offshore - it won’t move. It is one piece," confirms Hennix. "So it is really amazing and you can sail on one hull in big seas no problem. If you are going to have guys like Paul Larsen sail it - it has got to stay in one piece."

While this is partly due to the massive 'water stays' it is also due to the construction. The laminate spec for the boat, Hennix says is not far short of a modern 60ft trimaran and has the additional advantage of the carbon fibre laminate (relatively high modulus T600 is used) not only being cooked at 135degC, but also being squeezed within an inch of its life within an autoclave. Despite the streamlined product the trimaran is still a complex beast to put together, incorporating some 64 main parts including the mast.

Above decks the mast is the now standard multihull carbon fibre wing section, supported by a single set of spreaders/one diamond, forestay and shrouds. The rig and sail wardrobe, developed by North Sweden was trialled on their F28 trimaran before it was finalised for the Sea Cart. The standard package includes three sails - main, jib, genniker while a Code Zero and smaller ORC jib flown off an inner forestay is offered as an offshore package. Hennix says that for offshore use he might like a few more sails, for example one to drive the boat in very light winds.

The SeaCart we sailed had a nylon genniker - Cuben fibre is banned - and a 3DL Kevlar mainsail. Carbon 3DL could be used says Hennix.

While the boat is sold as an inshore racer, Hennix is planning to add an offshore package to take the boat all the way up to Category 1 spec if required.

Under sail the performance is blistering as you would except. While we were on board we did a few runs during Weymouth Speed Week and managed a 500m run averaging 17.7 knots in around 12-15 knots of breeze - the top boat of the day.

As the photos demonstrate flying her main hull happens readily - although in fact having the mainhull kissing the surface of the water, as you would a Tornado's weather hull, is the most efficient way to sail her. "That is a good way of going upwind. 13.5 knots upwind in big waves you don’t have the main hull in. It just touches the tops - smooth, quiet, fast, fun," says Hennix.

Another great aspect of the SeaCart is her manoeuvrability - she tacks more readily than most other multihulls with minor easing of headsail and traveller depending upon the conditions. This Hennix attributes to her big rudders, rounded mainhulls and the daggerboard position. But significantly this was another feature of her design aimed at enticing monohull sailors across to her. "Most of the people who sail monohulls they have a tactical mind, they are going to tack on every shift and everything you see, and on normal multihulls you go all the way to the end and you tack once and you go to the mark. With this one you can sail tactically."

As ever she is sensitive to trim and crew position and it is likely that in light conditions you'd put at least one of the crew down to leeward up forward.



A very nice feature is the semi-circular mainsheet track. None of your metal here - it is built entirely in carbon fibre. "We have 2-3 times less weight with this carbon track. It is a much neater solution. That is one thing we’ve done which is not normal. It is one piece. The 60ft guys are really impressed and they want it for their boats," says Hennix.

The sail controls Hennix and his team have thought about at length. While there are winches on the cabintop for halyards, reefing lines, mast rotation, etc all the sheets are handled manually without winches from the weather float, where all the action happens. The four/five crew typically hold the tiller, main sheet, main traveller, main sheet fine tune and the sheet for the self tacking jib. "It is very functional, standard stuff. The layout of the boat is very one design. If you can sail a Melges, or whatever, you can step over to this and have the same stuff. There are some furler ropes, but the rest of the sail controls are there. So it is also designed to be a good cross-platform to go from monohulls to multihulls," he says.

While the set-up seemed to work extreme well for crewed racing, it doesn't take a leap of imagination to see a market for this boat in short handed racing such as the OSTAR or the two handed round Britain and Ireland and in this configuration, sail handling might benefit from a winch and some jammers in the floats and a little more depth in what is at present a very shallow cockpit.

At present six of the ten SeaCart built so far have been sold and four more are immediately ready for buying - three in white, one in blue! The price of the boat with its basic inshore spec is at present Euros 138,004 ex VAT and sails, which at today's exchange rate amounts to around £94,000.

Hennix plans to set the SeaCart up as a one design class and the rules are in the process of being finalised. Already he has been sailing the boat far and wide, campaigning her relentlessly around Scandinavia, including the Gotland Rund and a trip to Malmo during the America's Cup Acts, where several Alinghi crewman including known multihull enthusiast Mike Drummond went sailing on her. He has also taken the boat to France and most recently the UK.

This year one SeaCart only event has been held in Sandhamn, where they had four boats on the start line and this included a Pro-Am event.

Next year Hennix is in the process of setting up a series of five events are planned around Scandinavia. One will be the Gotland Runt, the others are likely to be in port racing in Oslo, Gothenberg, Malmo and Stockholm. "The concept could easily be in England or France. It is not that hard. We are talking a lot with television. Eurosport, everyone has been chasing me around – how is it going with your boats?" he says.

At present he has some sponsors for the boats, such as Audi, but it currently looking for a circuit sponsor. Campaign cost Hennix estimate would be around 150,000 Kronor (£10,000ish) but this depends on a wide variety of issues like crew costs. "Another thing we want to do with the SeaCart series is also provide money for traveling, with the boats, moving them around. There you should have help with money and I hope the organization will take care of it. Then there’s prize money, etc."

Wouldn't it be nice and a great development for our sport if a boat like this could become as popular internationally as for example the Mumm 30? "This is definitely more fun," says Hennix. "A Mumm 30 is extremely good fun when it blows a lot downwind. With this you start to have fun in 10 knots of breeze. Or less. You also come back with a smile on your face. It is like when the snowboard came out when you used to ski and it got so long. It is like a refreshment..."