Sounds to me like the Big Wave Rider encountered a williwaw (a sudden violent squall blowing offshore
from a mountainous coast). I've never sailed the Derwent, but I remember seeing williwaws one day as I rounded Bream Head
headed for Whangerei. What impressed me was relatively light (15-20k) conditions, punctuated by short duration gusts of over 50k. You could tell the gusts were coming because they picked up the surface water
into a cloud of moving spray. I feathered up into the first few blasts in my ultralight mono (4.5 tons, 40 ft), then said no sense in damaging the sails
, so I furled them and fired up the motor
It was similar or even more extreme conditions in the lee of the Pitons in St Lucia
which lead to the capsize
of a Lagoon
. The cat was motoring with the main up and sheeted in light air when the williwaw hit, and went over on its side just like BWR.
I think the lesson to be learned for all sailors is to be wary when the wind
is blowing off tall mountains, especially at night when you can't see the williwaws coming.
Regardless of what some moderators might think, I think that this has been a pretty good thread, with a minimum of personal attacks.
I was particularly interested in the post which gave flat water capsize wind
strengths for various cats. It really emphasizes the point others have made that there are huge tradeoffs in stability for performance. I'm curious how those numbers were derived, especially what lift
coefficient they assumed for the sails.