The Benefits of Trailing & Sailing Trimarans
I interviewed Stephen Walker from Ahoy Boats, which serves as the UK’s Astus & Magnum trimarans distributor, for the first Small Trimarans book. And in the years since I’ve spoken to him, it appears his promotion of small tris is stronger than ever.
Stephen is an avid sailor and wealth of specialized knowledge. It’s hard to be bored when listening to him talk about trimarans.
So when fellow sailor Adrian Ezard sent me the link to Stephen’s YouTube Channel recently, it was impossible to not post a couple of the videos found there. The first one features some great benefits of trailing and sailing these boats. And the 2nd one shows off just a little bit of the fun offered by a Magnum in ideal conditions.
Thanks Adrian ;-)
The Benefits of Sailing & Trailing trimarans …
Trapezing on Magnum 18 trimaran …
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February 19th, 2013 at 2:48 pm
Another example in the tradition of fat trimarans. Their “Virus Proas” were more interesting.
February 19th, 2013 at 7:44 pm
“wide” seems a better term than “fat” when describing this type of main hull…when viewed in section, the total frontal area and girth of this type of flat but shallow hull can be identical to that of a longer/skinnier/deeper one, possibly even less depending on overall dimensions.
As you scale sizes down, the long skinny displacement hull thing requires more draft to meet minimum static displacement requirements, as well as more freeboard to deal with wave action underway…compared to a wide flat hull a long/skinny vee’d or rounded one is slower to develop maximum flotation and resistance to further sinking both due to volume and the greater ability of a flat hull to generate dynamic lift, and in smaller boats that will encounter any kind of sea conditions this might actually require a shape that is “fatter” in the sense of having more girth, wetted surface, etc. to get some margin of safety and stay within the long/skinny format.
The main trade off is pounding, but there are ways to minimize that both in the design and operation of the boat…speed alone can do a lot to even it out, and I think in many cases when people are looking at flatter bottom hull and ama designs they are envisioning the kind of pounding that happens to heavier monohulls going into head-on seas, much of which is caused by the *weight* of the boat and inertia as it falls off the tops of waves/swells and that wave action is met and collides or combines with the pivoting forces of the rig and ballast keel when the boat reconnects with the water.
Combined with flat bottomed forward hull sections that kind of energy can literally tear boats and even ships apart, but when weight is minimal and the design/engineering is right you can drive a wide hull very quickly and even out the ride considerably in surprisingly large seas, with any truly dangerous situations being almost entirely attributable to operator error from just driving things too hard.