Subject: Re: [harryproa] Re: mast bouyancy
From: Dave Howorth
Date: 2/7/2006, 2:36 PM

On Tue, 2006-02-07 at 02:02 +0000, Robert wrote:
> Hi Carlos,
> My own experience with lots of capsizes in small boats and
> windsurfers is that the sail damps the initial rotation and then if
> you don't uncleat you have a hard time of it getting it back as it
> tends to hold onto the water pretty hard. I have seen bouyant panels
> sewn into the tops of dinghy sails and they seem to work to avoid
> turning over completely.

Brian Phipps does it successfully with Darts, AFAIK. But a standard Dart
will not normally turtle immediately anyway.

>  Theoretically it should work on a bigger
> boat but scaling up often brings suprises. I am assuming a capsize
> from carrying too much sail in pretty strong winds such as one does
> when racing. On the other hand a racing boat would have a taller mast
> and therefore more mast bouyancy set higher, while a cruising boat is
> extremely unlikely to go over.  I have seen the bouys on the top of 
> masts but have no idea of the cons.

Don't forget that in strong winds the sail is likely to be reefed, so
the righting arm will be decreased and the heel angle at which it has an
effect will increase. All of which means you may need a lot more
buoyancy if it's mounted in the sail. Consider the strength of the sail
and fittings required to withstand the impact as well. Mounting a float
at the top of the mast overcomes this; designing the mast to incorporate
the buoyancy does even better.

>  Is the extra windage that much of a problem or not?.

As well as the windage, it also seriously affects the shape of the top
of the sail (aka ruins it). Again, mast-based buoyancy is better.

Regards, Dave

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