Hi,

First - stability can be affected by various elements of the hull. Turning a design somehow to V-hull or flat bottom can create more or less stability depending the case.

Freeship shows only the righting force, in reality you should take the change in CG to considerations too. In flat bottom kayak paddler will (or can) sit lower thus lowering the CG.

For example, if I lower the CG height for two flat bottomed kayak's (East Greenland, kog #86 and #87) by just 1cm (3/8") righting arm increases by 15-40% at 10 to 20 degree heel. That is significant change.

Toni.

: Bored last night and decided to try something on my Kayak design. A couple of
: people had suggested I needed to flatten out the V in the bottom of the
: boat. So I thought I would try it just to see what difference it made.

: I had roughly 2" of rise at the chine. I lowered it to 1" and I
: carried this further forward and aft than was in the existing design. When
: I ran the cross curves in FreeShip there was just barely any difference.
: Unless I don't understand the numbers that is.

: 15 degrees heel was .228 KN sin(Ø) and is now .235 KN sin(Ø) (3% increase)
: 20 degrees heel was .301 KN sin(Ø) and is now .305 KN sin(Ø) (1% increase)

: Granted I don't really have anything to compare KN sin(Ø) too. But this seems
: like a mighty small increase to me. Resistance did increase but the wetted
: surface also increased so I expected that.

: Looks to me in practical terms, that you can feel it made no difference.