Re: Turtling
Mon, 30 Aug 1999 02:12:13 EDT

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West Wight Potter Website at URL
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I must be missing something - While the bumper may slide up and provide some
useful buoyancy (and righting moment) when the mast is horizontal, it seems
to me that as you rotate the boat further towards a turtle, the bumpers will
climb back up toward the hull and work against you.

The Hobie Wave catamaran (13') comes from the factory equipped with a mast
head float to prevent them from turtling. The rental/lesson fleet of Capri
14.2s at a local sailing lake have been retrofitted with these floats to
prevent mast and rigging damage due to turtling in the relatively shallow
lake. They (the rental people) tell me that the floats are very effective on
the Capris - since the Capri 14.2 is similar in size and weight to the Potter
15 it may be safe to assume that the Hobie float would work well on a P-15.

Since a P-15 on it's side is unlikely to take water into the cabin,
preventing a turtle with a masthead float should allow one to consider their
Potter to be self-rescuing, since the water in the cockpit will drain out
(albeit slowly with the std. 3/4" drain)on it's own.

I've done a couple calculations which may be of interest:

The centerboard in my boat weighs about 75 lbs., and being approx.
rectangular, I'm assuming the center of mass is about half way down the
board. The boat draws 3' with the board down so let's say the center of mass
of the board is about 1.5' away from the center of buoyancy. So, with the
boat on it's side the centerboard is providing a righting moment of approx.
112.5 ft*lbs.

Hobie advertises the "Baby Bob" masthead float (mentioned above) as having a
buoyancy of 32 lbs. I estimate the top of the mast to be about 16' away from
the center of buoyancy (15' of mast and a foot or so of cabin and freeboard).
This means, if I've got all this right, that as soon as that masthead float
hits the water it adds a righting moment of 512 ft*lbs. If you combine the
two you find yourself with a grand total of 624 ft*lbs of righting moment in
a knockdown with may be even more than what the keel provides in a P-19! The
obvious disadvantage is that the float doesn't do you a bit of good UNTIL it
hits the water. But, as disaster prevention, it might be worth looking into.

I have to say that I'm not quite so cavalier as some as regards the stability
of the P-15. I've sailed ours in some fairly windy condition and have
observed the same confidence inspiring behavior as others - you'd really have
to make an effort to get knocked down. But I don't think that it's the wind
that's going to get you - I've read a number of accounts of voyages in boats
small and large and it's seldom the wind that brings disaster to experienced
sailers either, it's waves. And this is where the relatively small size of
the Potter makes it vulnerable. What is a small wave to a large boat can be a
big problem for a small boat. A following wave can push you into a broach
situation and the boat's own momentum will cause it to "trip" over it's own
centerboard and gunwale into a capsize. That same wave may try to roll the
boat on over.

For those of us who sail on protected waters where there isn't enough fetch
to develop good size waves this is less of a concern. But the folks who, once
they have left the protection of the harbor, sail on the open ocean have to
consider the behavior of the water as much or more than that of the wind.
Wind is compressible and that gives it some compliance. Water is
incompressible and less tolerant of our intrusion.

'nuf rambling, time for bed.

Dave Kautz
P-15 #1632 Tilly Lucy
Palo Alto, CA

In a message dated 8/29/99 9:40:56 PM Pacific Daylight Time,

<< Friends:

I have a suggestion for those that fear turtling a WWP-15. Note I said
The technique's main virtue is to give the user a little peace of mind as
gains confidence in his ability to sail boat in a variety of conditions.
This confidence eradicates the fear. Since it is a passive safety measure,
it has little downside.

I use two round (12") orange fenders when I dock my boat. When sailing I
sometimes tie one around each shroud with a loose loop. This loop holds the
fender as close to the shroud as possible. The loop is loose enough that
fender can move unimpeded up and down the shroud and associated hardware.

If the boat suffers a knocked down, the fender should slide up the shroud
until it hits the mast a couple of feet off the deck. At this location, the
fender and mast provides a large lever with significant effort to keep the
mast near the surface of the water preventing the boat from turtling.
Considering the loop in the line might hang up on the shroud rigging,
attaching them to the shroud with a carabiner (metal ring) would help ensure
the floatation would move up the mast to achieve significant leverage. The
fender should return to its original position when the boat rights.