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Subject: Re: [world-cruising] Filler for Keels - about keelage
From: Russ Swan (ruswan@XXX.XXX)
Date: Tue Mar 11 2003 - 18:29:49 EST
Jim and Doug,
----- Original Message -----
From: "Jim Townsend" <jt_lotus@XXX.XXX>
> The fluid that comes to mind would be one of the newer anti-freeze
solutions. They gererally inhibit rust and are claimed to not be an
environmental hazzard. Neutral bouyancy, fairly cheap.
> Another thought might be a light weight concrete mix made up of cement and
styrofoam beads which would result in a net weight about the same an most
any fluid.
Thanks Jim. I'll check it out.
----- Original Message -----
From: "Doug Barnard" <dbarnard@XXX.XXX>
> Brent Swain, designer of the origami-style welded steel sailboat, likes
> to use the spare room in the bilge keels as diesel tanks. He builds up
> an area inside, in the bilges, to increase the capacity. You might want
> to think about something like this, and then remove your existing tanks
> to increase interior or storage space. You just can't beat that weight
> down low!
Doug,
My first thought was "Great idea"! Unfortunately, water will
inevitably condense inside there and settle in awkward spots where I won't
be able to drain (or pump it out). But thanks anyway.
> Though this begs the question: what is your boat, and why does it need
> all that keelage?
Lowana is a 30ft steel, flat-chined, cutter-rigged cruising yacht and
originally a bilge keeler with a full centre length keel. The bilge keel
fins were part of the original design. I think the fins were basically
there to hold the boat upright in the shallows when the tide goes out. They
also
helped a little in keeping a good track into headwinds and probably added a
little stiffness against the pressure of the wind on sails.
Although her hull suggests a coastal cruising yacht, she's a well travelled
boat having come originally from New Zealand. She's spent time in New
Guinea and the South Pacific with previous owners. I've taken her over to
Indonesia a couple of times as well and we've survived some nasty weather
together.
A refit of the boat took over two years, during which time the port fin bent
out of shape by 30mm on the trailing edge. Caused me all sorts of vibration
and humming-noise problems. I was in a rush to leave for Indonesia at one
time, so cut the fins off. Unfortunately the loss of this weight amidships
caused me all sorts of hull-trim problems during that trip including very
bad lee-helm going to weather.
All attempts to trim the hull again by placing lead around the boat only led
to a higher centre of gravity and tenderness. Anything over 30 kts was just
blowing me too far over. Lowana doesn't travel well past about 15 degrees
heel. I eventually hired a designer who measured it all up to look for
another solution e.g. add extra depth to the keel, extend the stern a bit
etc. The best solution in the long run was to just put the fins back on,
plus add 70 kg of lead to each side.
By changing a flat plate to a symetrical shaped tank, I've managed to get
around the problem of the bent fin, and I can now take all that extra lead
off the hull floor around the midships and bow areas (there was no more room
in the centre keel). With the weight now repositioned below the boat, I
hope to be able to sit upright and keep a bit more sail up for longer. I'm
also hopeful that the shape of the foil will assist in keeping her nose to
windward.
Cheers,
and thanks for your interest..
Russ Swan
Lowana IV, Darwin Australia
Adventure Yarns
True stories of unusual travels by adventurous people
http://www.adventureyarns.com.au
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