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11 September 2016 Updated Pictures

Transverse Stability - calculating BM and KB.

I've always known that boats turn over when they are top heavy, but never really understood the science behind it. Having a boat capsize is not my idea of a good day out. So this little corner of the site is Dr. Holt's attempt to understand model boat stability - without getting too scary or geeky.

Both BM and KB can be calculated and when added together these will give us the value KM.

For an intermediate hull form where the breadth is 0.2m and the draft is 0.07m:

Value
Formula
Result
BM (0.2 x 0.2) / (9 x 0.07) 0.063
KB 0.6 x 0.07 0.042
KM KB + BM 0.105

So in the diagram below we have now calculated BM and KB and KM.