Join Date: Jul 2000
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Jeff's discertation is quite comprehensive.
I'd like to add 'simplicity' to the mix.
A boat designed for 'offshore / Blue Water is usually TWICE as strong than a boat designed for 'coastal'.
Typically when you analyse (back calculate) the structural components on a 'coastal' boat you typically realize that the designer has an in-built "factor of safety" of 3; meaning the boat is built three times as strong as it needs to be for 'maximum normal' conditions. For a Blue Water boat, the structural "factor of safety" is usually in the range of 5 or 6 times as strong.
It seems that many designers first conceptually design the boat .... and then mathematically (imaginarily) derive the maximum loading by calculating what load applied horizontally at the top of the mast will result in the boat to be heeled over at 45 degrees ... and then structurally design just about everything in reference to or based on this 'number' AND applying (multiplyng) the appropriate "safety factors" to the structure components. Such 'factors of safety' in design take care of the unknown or unforseen loads that such a boat will encounter ... the historical 'insurance claim' scantlings (actuarial data) of what survived maximum conditions or not has probably led to the 'customary' choice of 'safety factors'.
Obviously it probably gets more complicated than this ... but my back-calculations always seem to arrive at these 'factor of safety' numbers for coastal vs. 'blue water' design.