An experiment on the difference between planing and displacement hulls.
http://www.2imagine.net/blogger2004/spoon.html
Gotta Love The Guy…
I really get a kick out of him. Informative too. 
sing
Afrikaners Think They Invented Water
Those Afrikaners think they invented water, but you have to admit they are prety good…
I don’t get it
The guy uses a spoon and a knife to demonstrate bernouli and says that’s the difference between a planing hull and a displacement hull? I might buy it if the planing hull had no rocker. Or if the knife had chines. Or…
So which should I paddle a knife or a spoon?
Thought You Had…
a knife.
sing
Good point about rocker NM
Yes, Rocker…
– Last Updated: Dec-21-04 5:31 AM EST –
the thing is that a displacement hull with a rocker is so much more like that spoon. A planing hull will have that curvature front to back, but the sides are very flat and abrupt.
If you see the dedicated surf boats, which are extremely fast on the waves, the only rocker is up front. The stern only kicks up 1" or so. Furthermore, it seems to take Corran's demonstration to the other end. It's not uncommon to see surf boats with a slight concavity down the middle of the hull bottom. My Venom actually has a concavity up front and then just behind the seat, a double concavity, sort of like channels, each running from my butt cheeks back. It's a wicked fast boat compared to anything I have surfed so far. I am making wave sections and carving up and down the steep face like I never imagined possible before.
The tripping in the surf boat is as he describes. When I hit the trough, and I'm not careful of keeping the shore side edge up a bit, it cuts into the water and creates a tripping situation. This doesn't happen that much these days as I get more and more used to the boat and the speed. In other words, I have learned to make quicker edge to edge transitions.
sing