Algodoo

Build your boat and test it... Or just copy another guys boat and scale it to fit in the red box.

The "endless" seas get rougher and rougher if you turn on air, Put on wind for an extra testing.
This tests the stability of your boat; if it hits the bottom or gets turned upsidedown, your boat is unsafe at that roughness of seas
Also, PLEASE make it fit in the red box. Its not designed to be acurite any bigger.

Have fun messing with the air, and axel values along with the amount of water! This particular boat is rather stable.