Really nice looking boat. I've always wanted to try a greenland type.
The closest I came was a Nordkapp, way too tippy for my at 19". ha ha

I think reducing the rocker some isn't a bad idea for lakes, but I would be careful what it does to stability. Hmmm. Let me think about that a bit.


All else being equal reducing the rocker should...
1. Increase the prismatic coefficient some, and possibly the surface areas also, which usually means slightly better high end speed but somewhat higher cruising drag, which you sort of had already by virtue of long and skinny.
2. Better tracking.
3. Essentially, less rocker will make it seem even longer and skinnier.
4. I'm not sure about the effect on stability. You gain some waterplane beam in the ends but lose some waterplane beam in the middle. What's even less clear is the effect on secondary stability. I think initial stability might stay about the same and secondary stability might go down.
5. Your center of gravity will be slightly higher also, this will reduce stability for sure. Maybe not much.

The other thing you really have to watch for is your total weight, and your center of gravity. As you probably know, heavier guys need wider boats. That's all there is too it. Just 1/2" can make alot of difference though. Keep in mind reducing the rocker will raise your center of gravity also.

Remember your basic theory, at least for initial stability...

Height of metacenter = I/V
I = Area Moment of Inertia of Waterplane, a function of beam^3 x length
V = ( weight of you + your boat + your gear ) / density of water

You are in fresh water also, I think. This also means more volume, and thus a lower area moment of inertia, so less stability again even though your center of gravity drops a little also, just not as much. I think that's right anyway. Not sure.

Anyhow, I think you have the software for all this. If you don't Jim does. Also you pretty much have to do eskimo rolls with this type, though they are easier, as long as you have the energy. Alot depends on how hard you want to work to stay upright, how long your trips are. That nordkapp was lots of fun, but I didn't go too far from the dock that day. ha ha

p.s. 17.1' seems rather short for 19" beam. Maybe not. Depends on your size. I prefer a shorter boat myself, but mine is 16.5' long and 23.5" wide, single chine. That is actually wide enough for me to wet exit and re-enter. I add some foam on the inside sides of the cockpit, too reduce free surface effect when swamped. Works for me and makes it a great boat for the Bay. If I went skinnier, like more towards a Greenland type, working with a total displacement of 220#+60#+40# = 320 pounds, I might go to 20' x 21". If I got my weight down to say 170+40#+20# = 230#, I might go to 19'x 19.5". With some more skill, maybe 19' x 19". Maybe. Depends again how hard I want to work. ha ha

Definitely try out a boat close to what you think you want to build. Cheers.