Why does my boat tip over?

@Boredplanet there is no once centre of buoyancy. It likes to move around, for the submerged volume changes size and shape constantly. The best thing to do is to guesstimate where it might lie, then test it in the Bay.

@LeMagicBaguette thanks. Man i wish there was a green center of buoyancy button

You likely have a high centre of gravity.

When working with boats, it's best to keep the CoG close to the centre of buoyancy, so that, in the event of a tipping force, the CoB moves to correct the now offset CoG. If the latter is too high out of the water, the CoB will never be able to move beyond it, leading to a capsize. The simplest solution is to place the CoB above the CoG, but this usually is not possible without an enormous draft, which is rather inefficient for anything that isn't a submarine.