Re: boom outhaul -- Every inch lost adds 3 inches of draft to your
Sat, 22 May 1999 10:26:05 EDT

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West Wight Potter Website at URL
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In a message dated 5/21/99 5:19:31 AM Pacific Daylight Time, writes:

> I think someone might have solved a problem with the wooden thingy. By
> extending
> the boom he/she can pull the out haul more and flatten the main sail.
> Just the thing
> in heavy air. I keep looking at my boom wishing that I could flatten the
> main
> more. The loose footed main just looks like it is to loose. I think you
> have
> given me an idea. Will have to work on it some.
> What do you think, Judy?

HI John,

I did some asking around about your question and thought about the problem.
I think I might have an explanation of what's going on and why you're having
trouble getting your sail outhauled enough. I'm not sure since I don't have
a small Potter.

The boom is long enoung for main sail with a bolt rope in the luff and just
exactly the right length to fit in the cabin. Installing slugs on the main
adds about an inch and a half to the length of the foot of the sail (and of
course the rest of the sail, but that's not relevant to the problem).

When the sailmaker adds slugs to the sail, s/he should measure the boom
length first. That would identify a potential problem -- the foot of the
sail gets about 1.0 to 1.5 inches too long to be properly outhauled on the
stock boom.

An inch and a half is a LOT of outhaul to lose. If you take a 10' piece of
PVC pipe and bend it so the ends are 1.5 inches closer together it bows out
about 5". (I just happen to have a 10' piece of PVC lying around and I
thought I'd better check my math).

If the foot of your sail is is 1.5 inches too long, the DRAFT gets 5"
(approx) deeper!!! For every inch of outhaul you lose, the draft gets about
3 inches deeper (circumference = pi * diameter). That's going to make a HUGE
difference in how your sail handles.

Your observation that "the foot of the sail looks way too loose" is
absolutely correct!!!

There are two solutions: trim the luff/front of the sail before adding slugs,
(I'd guess in the $100 range for the whole job at a sailmaker) or add an
extension onto the end of the boom (get an $8-10 part from Dwyer mast).

I went to the sailmake yesterday to have a new luff, grommets, batten pockets
resewn/repaired/reinforced and a window put into a used sail I bought for one
of my other boats. It cost me about $100 total. But there was no headboard
at the top and no long batten that came right to the luff; that would be
extra work.