Another stupid question...
Why are some boats V bottomed instead of flat?
If you cut a paddle through the water, it sort of hardens up the water on both sides, making pulling it at the same time very hard.
The same thing happens when a boat slides through the water. The moved water hardens, and although the boat slides through it, it sort of resists the boat dependant upon it hull shape.
If the boat has a flat bottom, it pushes the water downwards and the pressure sort of builds up under the middle of the hull - much the same way as the sugar formed a round shape in front of the square fronted raft. This does nothing to stop the boat rocking from side to side....
If the bottom of the boat is round, it pushes most of the water downwards, and a little sideways, hardening the water to the sides as well as the bottom. This side pressure helps keep the boat stable..
The third shape is the V bottomed hull. This pushes all the water out to the sides. The downward force of gravity works against the water pushing sideways and up and resists any rocking forces. You see this with powerboats that will rock from end to end as they power over waves, but little or no sideways rocking. This makes the moving hull as stable as a much wider stationary hull...
Canoes usually start V bottomed, pushing the water sideways, before flattening out and pushing the water downwards in the middle part of its length. This supplies stability and a better cut through the water with a shallow draft or depth, which is very useful in shallow water.
Some of the angled side is usually in the displacement area in canoes to give more dynamic stability.