VCG = vertical centre of gravity
"Going down the mine" is digging your bows in down wind. Surviving means this doesn't become a pitchpole.

At the risk of oversimplifying (or being patronising) any moving body can be considered to carry its momentum (momentum = mass x velocity and is what keeps a moving body in motion) at its centre of gravity. When you stuff the bows going down wind, this momentum is what causes you to capsize. If the centre of gravity is high the momentum will have a larger lever arm than had it been lower, so if the boat's total VCG is kept as low as possible you're less likely to cartwheel.