Sorry that answer is incorrect.

Both boats are symmetical relative to their centerline and as such the centre of gravity lies at the same point with both designs and as they are equally heavy and equally wide both design will have exactly the same righting moment.


The reasons why tris are build and use have nothing to do with any differences in righting moment.

The real reasons are that a tri (of equal specs) has less wetted surface area in light winds then a catamaran. In the really light stuff the tri can be balanced on its centre hull only while keeping its rig straight up. This is the most effective sail power to wetted surface such a boat can attain. A catamaran can not in any way achieve this. It either heels to sail on only one hull but also heels the rig or the rig is straight up but both hulls are in the water.

The other reason for building tri's is that the largest portions of the rig loads (which are fore-aft) are taking up by the centre hull instead of a beam structure. The first is much easier to build strong and stiff. Building cats at the same size requires more engineering and more use of exceptional material like carbon. In effect LARGE tris could be build cheaper and with less exotic materials. When done right they could also be lighter overall, but with the new material the building of large cats in now really held back by this anymore.

So now we are seeing much more large catamarans build. In the past it used to be trimarans.

For small sailboats there is no advantage is building a tri over a catamaran; here is will be both more expensive and heavier because of the third hull. The advantage of better light wind performance is too rare to really compensate for the drawbacks.

The only reasons to still build racing tri's is that they can be build wider then a catamaran with less effort and stiffness problems. So in the French ORMA we still see tri's as the class rules allow these boats to be as wide as they are long.

Wouter