Re: How does a boat sink in 15 minutes?
Back in the 90s I had a 19 foot jet boat with through transom exhaust. A short section of rubber hose connected the exhaust manifolds to the transom fittings and had rotted from the inside.
Launched the boat and sped off across a lake. Within five minutes we had water up to the seats and coming in faster than the bilge pump could handle it. Immediately turned for shore and beached the boat.
Any further out, or if the engine had stalled the boat would have been lost well within 15 minutes. Don't know the exact volume, but the cooling system moves a lot of water.