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• ## Re: [junkrig] weight aloft and stability?

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• Hi. As far as we talk about static stability, it is just a simple lever arm. Remember also that a mast that floats will add to static stability when it becomes
Message 1 of 41 , Nov 1, 2004
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Hi.

As far as we talk about static stability, it is just a simple lever arm. Remember also that a mast that floats will add to static stability when it becomes immersed.
When it comes to dynamic stability, a heawy mast is positive, as it raise the moment of inertia, and that help to withstand sudden impact from waves.
It was usual to hoist weights high up in the masts to ease the ships motions, in the glorious days of sail.
My boat have a displasement of 1400 kg. The weight of my mast is 70kg. She is very ease in a seaway.

An easy way to do a inclining test is described in a book by Brion Toss, named "The Rigging Handbook".
Look for page 136.

Victor
----- Original Message -----
From: De Clarke
To: junkrig@yahoogroups.com
Sent: Sunday, October 31, 2004 1:57 AM
Subject: [junkrig] weight aloft and stability?

This is probably an eejit question, but asking eejit questions is how
to become less of an eejit I guess :-)

Here's the question. Is there a nice neat formula for figuring out
weight-aloft trade-offs, i.e. the relationship between height above
deck and weight? Is this just a simple lever arm? Or do we have to
know all kinds of stuff about hull form and marine-architect arcana
to figure it out?

If I shorten a 20 ft mast by 25 pct, i.e. to 15 feet, but I then hang
a rig on it that is 25 pct heavier than the old rig, is it a zero sum
game?

If I mount a 10 pound gizmo 10 feet above deck, does it contribute
twice as much instability as it would if mounted 5 feet above deck?
Is it that neat and linear?

Also, if anyone has come up with a simplified version of the Navy's
"inclination experiment" for determining vessel stability, let me know!
I'm about to try to work out such a simplified version for small hulls,
starting with the naval instruction/procedure manual for the I.E. on
monster hulls. "Using a fork lift, move 5000 lbs worth of fuel drums
to the starboard side" -- not quite :-)

de (contemplating radar arches, boom gallows and other such "weight

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:De Clarke, Software Engineer UCO/Lick Observatory, UCSC:
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• Hi all, For what its worth - I used two 8 garden bamboo poles that are about half inch at the thick end, overlap the thin ends to make battens of 10 for my
Message 41 of 41 , Oct 6, 2012
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Hi all,
For what its worth - I used two 8' garden bamboo poles that are about half inch at the thick end, overlap the thin ends to make battens of 10' for my latten sail, I just use Gaffer tape to fasten them together in the middle. I have used this for the last ten years with no problems, mainly on lakes in England & France, did some sea sailing but not much! A pack of 10 costs about �4 here in England
I hope this helps
Best regards
Stuart Keane
Yorkshire, England

Sent from my BlackBerry� smartphone

-----Original Message-----
From: Rod Symington <rodsymington@...>
Sender: junkrig@yahoogroups.com
Date: Fri, 5 Oct 2012 20:56:28
To: <junkrig@yahoogroups.com>
Subject: Re: [junkrig] Re: Battens

Hi Peter:

I omitted to include bamboo (the obvious choice) for my battens, as I cannot find any length greater than 8 feet. (Even they are expensive: \$20 for 2-inch diameter, \$10 for 1-inch diameter: I bought 5 of the latter for my mizzen.)

Thus I was looking for a feasible alternative. I suppose the solution is to rig temporary battens and sail to somewhere where cheap (or free) bamboo is available... :)

Rod

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