sideslip, round and vee

[sigurd]

My tornado hulls are slightly vee'd all the way aft, even though most of the sections are "rather" semicercular; in other words only the bows are sharp vee. I think some multis are actually round all the way to the bow, even if it is fine: there is no "kink" in the section at the keel at all. Is this right? Does it matter at all? Maybe it has an effect when there is slight leeway? Are there vortices flowing to windward of the keel kink?

[catsketcher]

When the Tornado was being built Rodney Marsh had to design it in a way that could be built by materials of the 60's so used ply. Good Tornados have been built by double diagonal and compunded plywood. These are built in two halves and can't get a round on the bottom up the front - the radius required is too tight.

More modern cats are built from foam and such which is more amenable to any shape a designer wishes to draw so the sharp keel may be gone in many hulls. All the strip plank cats (from 6 to 11.6m) I have built have no keel line becuase it is harder to make than making it round. I don't know if there is much difference either way but a sharp line shows the sections forward are fine down low. Certainly the Tornado is a great boat - sailed one for a while - Marstrom nomex boat good fun.

cheers

Phil Thompson

[sigurd]

Interesting. This one appears to be built by "sail craft". The core is some red foam. Any idea what foam that could be and how old the boat might be?