One-design trimaran

Here is a little rocketship of a folding trimaran built in Sweden. The promotional material that came with this design stresses performance and race potential. Clearly this design is not about comfort. The design work was done by Marc Lombard with engineering done by Kare Ljung of Windexair.

To start with, the D/L for this boat without crew is 35.58. That's low enough for me to have double checked my math. But, if we consider that the crew is an essential part of the tri's stability profile and add four 175-pounders to the "all up racing weight" of 2,046 pounds, we get a total displacement of 2,746 and this brings the D/L up to 47.75. Any way you might choose to look at the displacement you can be certain that this is a very light boat.

The maximum beam is 21 feet, 10 inches. The main hull has a full-length chine just above the DWL where the topsides flare out to provide some room below for seating. The sectional shape of the main hull shows no deadrise. The amas are splayed out at about 4.5 degrees. Depending upon which drawing you look at, the bows of the amas are pretty much in line with the stem of the main hull. The SeaCart is very capable of sailing on one ama and flying the main hull.
There is a very deep, high aspect ratio centerboard in the main hull that draws 6 feet, 7 inches when down. Draft with the board up is 1 foot, 2 inches.

The SeaCart is a good-looking boat. The cabintrunk is short and shapely and is visually lost in the bulk of all that beam. The rig is big. The carbon mast is a pivoting wing type that aligns with the mainsail to make a seamless foil on either tack. There is 53.8 square feet of area in the wing mast alone. So, let's add that to the upwind listed sail area of 667 square feet, which I assume includes the roach of the fat-head main. This gives us 720 square feet of sail area and an SA/D of 58.75 if I use the crew-included displacement.

Wow! So what we have here is a boat with an SA/D higher than its D/L. I think that is a first for these reviews. This is really a clear indication of the stability gained in those amas with that beam. Of course you are going to have to be diligent with sail reduction if you want to avoid doing the breaststroke. There are three reefs in the mainsail. Twelve knots of breeze is enough to get you up on one ama, so things could get interesting fast in the SeaCart. The top speed recorded so far is 27.4 knots. If this is not enough for you the company does offer a souped-up version for those in need of more speed. If you do get carried away with your quest for speed there is an escape hatch in the side of the main hull.

There is not much interior volume in this all-carbon hull. The standard boat comes with an all black, raw carbon fiber interior finish with berth flats fore and aft but nothing you would really call "furniture." Life below will be spartan. But on a long race there is room for the off watch to get a few hours of sleep as you zoom along at 25 knots plus. What did you expect below in 2,046 pounds? A Baba 30?

You can fold up your SeaCart and tow it behind a small car. Under power with a six-horsepower outboard you can do 9.5 knots. I'm not certain this boat is everyone's cup of tea, but it's fun to consider the excitement of sailing a boat with this speed potential.