shock and aww

Shock, horror perhaps but I, Shanghai Sailor, have to compliment anarchist David on his latest couple of pieces. The keel first.

I remember notable keel failures all the way back to Cheeki Raffiki. Notable perhaps only because they resulted in fatalities and were very publicly reported.

Back in the “good old days” keels ran pretty much the whole length of the yacht. A modern view of this can be found by watching some of the earlier videos from Leo and the Tally Ho team which would suggest that a well found yacht would bounce off the hard stuff when the draft equaled a little bit more than the available water, and then just carry on.

Over the years however keel roots have become shorter and shorter especially on race boats to put the weight as low as possible the bulb is at the end of a long, thin foil. Sometimes this is made of carbon which, while known for its overall strength-to-weight ratio, is not fond of sudden shock loads.

Then of course there are the keel bolts and the laminate layup they are stuck through.

Some builders include a steel grid inside the boat to spread the keel loads and link them all the way to the rig, while other designers underestimate loads in this area. One notable case was the Clipper fleet which had to stop in the Philippines to deal with their wobbly keels even though the actual builders had added 12-14 layers of laminate beyond the specification they had been provided to the hull in the keel area…

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