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West Wight Potter Mailing List maintainer
dfarrell@ridgecrest.ca.us
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Hi All:
I tried to send this to John directly but his Email kept bouncing back so I
posted it to the board. Sorry if this offends.
gretchen
>Hi John: This is a bit lengthy but this is what Judy sent me a couple of
months ago.
----- Original Message -----
From: <JBlumhorst@aol.com>
To: <wwpotter@tscnet.com>
Sent: Sunday, September 26, 1999 9:03 PM
Subject: Re: Tuning Shrouds
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> West Wight Potter Website at URL
> http://www.lesbois.com/wwpotter/
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> Hi Gretchen,
>
> Tuning shrouds is an art. There are two stages -- rough tune at the dock
or
> on the trailer, and fine tune while sailing.
>
> (BTW, I know just the basics about tuning shrouds, and right now I'm on a
> project to learn more. My rigger tuned my shrouds for me once and taught
me
> how, but I'm defintely no expert. So I may have some small mistakes in
this.
> Maybe sometime later this year, when I've learned more, I'll write up a
full
> tuning guide to the Potter 19)
>
> 1. On land: First, get the mast straight from side-to-side. You can
take
> the main halyard and pull it to the chainplate on one side, note the
length,
> and then take it over to the other chainplate. If the mast is straight
from
> side to side, the halyard should be the same length from side to side. If
> not, tighten the appropriate turnbuckle to pull it over.
>
> Shroud Tension -- This is the way my rigger showed me. The upper shrouds
> should be tighter than the lower ones. for the uppers, if you take two
> fingers and pull the shroud gently, sideways, at about 4 feet off the
deck,
> the shroud should move about 1.5 inches (two or three fingers width)
before
> you feel a marked increase in resistance. You've got to pull gently or
else
> you miss the point where the resistance increases markedly.
>
> The lower shrouds should be *much* looser than the upper ones. The purpose
of
> the lower shrouds on a fractional rig is to limit forward bending of the
mast
> at the middle when you vang (or tighten your backstay if you have an
> adjustable one). They aren't necessary for lateral stabilization of the
> mast; the uppers are suffiecient for lateral stabilization. If the lowers
> are too tight, they prevent the middle of the mast from bending forward,
> which "sucks" the draft out of your sail, flattening it and reducing power
in
> heavy winds.
>
> My lower shrouds are almost floppy when the vang and/or backstay are
loose.
> They are set to get real tight when there is about 2" of forward bend in
the
> mast. This keeps me from bending the mast too much. that 2" of forward
bend
> takes about 6" of draft out of the mainsail when I need to flatten it in
high
> winds.
> ~~~~~~~~~~~~~~~
>
> For front to back straightness (called mast rake), you can start by
> eyeballing the boat from 30 feet back. Or you can use a level to get the
> cockpit seats level (adjust the trailer) and then put the level on the
mast
> and adjust until the mast is perfectly upright. That's a starting point
for
> your tuning after sailing it.
>
> Forestay and backstay tension -- don't succumb to the temptation to make
your
> forestay loose, just so that you can attach it easier. The luff of your
jib
> (leading edge on the jib) will sag when you sail and you won't be able to
> point high and the boat will have a tendency to turn downwind (called "lee
> helm") and heel too much . It needs to be pretty tight. Get that
forestay
> tight !
> ~~~~~~~~~~~~~~~~~~
>
> 2. As for tuning on the water, there are two things you want to check
for.
>
> The first isn't too hard -- when you're sailing, look at the leeward
shrouds,
> They shouldn't be really, really flopping around. if they are, you've
got
> them too loose. A little slack is okay (unless you subscribe to the
> shock-loading school)I don't know how much is too much, wish I could give
you
> some better guidance, but.... I'll just do the best I can.
>
> When you're out sailing, the leeward (downwind) shrouds shouldn't be
sagging
> a great deal, but they will certainly be less tight than on land. There
are
> two schools of thought on this. some folks say a little loose is okay.
some
> say they should still have a little tension, or else it shock loads the
> rigging when you change tacks. I don't know which school is correct. Mine
> are defintely loose on the leeward (downwind) side, but they don't sag
with a
> curve (unless I've got WAY too much sail up , in which case I'm also
heeling
> too much and wrestling the tiller).
>
> The second part of tuning on the water is more complex. It has to do with
> weatherhelm. Weatherhelm is builit into a boat. It means that the boat
> should turn it's nose into the wind if you let go of the tiller. That's a
> good safe thing for a boat to do, right?
>
> So while you're sailing, you should have to lightly (and I do mean
lightly)
> pull on the tiller to keep the boat from rounding up into the wind. The
> basic idea here is that if the mast is raked aft too much, you'll have too
> much weather helm. you'll have to pull too hard on the tiller to go
straight
> and the rudder will be acting like a brake. To reduce weatherhelm, you
> loosen the backstay and tighten the forestay. If the mast is raked too
far
> foward, you might have a "leehelm" --which is dangerous because if you let
go
> of the tiller, the boat will run away downwind!
>
> There are other things that can increase weatherhelm too -- too much sail
> area, too much heeling, too much mainsail compared to jib, too much weight
in
> the front of the boat (not likely on a P19, with two people in the
cockpit).
>
> Rousmaniere's book "Annapolis Book of Seamanship" has a couple of nice
pages
> on tuning for weatherhelm on pages 85-87. He also gives a method of
> measuring weatherhelm to know if you've got the right amount. (Your tiller
> should be at about 2-3 degrees off center when you've got the right amount
of
> weatherhelm, assuming you hae your boat loaded correctly and you are
heeling
> appropriately, which for a Potter is 12-15 degrees or so)
>
> ~~~~~~~~~~~~~~~~~~~~~
> As for fastening the turnbuckles -- do you have closed body turnbuckles
with
> two nuts on the top or do you have open body turnbuckles (where you can
see
> the threaded part of the toggles)? Somebody else will have to advise you
on
> the specifices of the closed-body ones, cuz I have open body turnbuckles.
>
> If you have a CDI on your jib, you have at least one open body turnbuckle,
> inside the furling drum. don't forget to put a cotter pin in that,
because,
> for sure, it will unsrew itself loose when you furl and unfurl the jib!
That
> will bring your mast down.
>
> The general idea is that once you have the length set and tuned, you need
to
> fix them at that length. On my open-body turnbuckles, I put cotter pins
> through tiny holes in the threaded part. A cotter pin is like a bobby pin
of
> stainless steel. you put the pronged end through the hole and then
separate
> them about 30 degrees. I cut off one prong and bend the very tip of the
end
> 60 degrees, leaving just enough length to catch on the side of the
turnbuckle
> body. I cut the other prong a little shorter and leave it straight. Then
> wrap about 3 or 4 layers of self-sticking riggers tape around the
turnbuckle
> body and cotter pin. Don't bend the cotter pin prongs way out, you won't
be
> able to pull them out in an emergency. (My rigger taught me that)
>
> On the closed body turnbuckes, I guess you just put tape around the
locking
> nuts, but i really don't know what I'm talking about here... :^)
Somebody
> else chime in here, please???
>
> You also need to put riggers tape around the circular clips that hold the
> turnbuckles to the chainplates and shrouds. You don't want to have a jib
> sheet (line that you use to trim the jib) or your pantleg pull out that
clip
> by mistake!
> ~~~~~~~~~~~~~~~
>
> Hope that helps. When in doubt, spend a few bucks and get your local
rigger
> to show you how. Read Rousemaniere's chapter 1,2, 3 (on sail trim) and
15
> (on heavy weather sailing) so you understand what you're doing to your
boat.
> That's better than all the words I could possibly write.
>
> Best,
> Judy B
>
> In a message dated 9/26/99 8:53:44 PM Pacific Daylight Time,
> gpotter@calinet.com writes:
>
> >
> > The only thing that happened that I have to figure out is the turn
buckles
> > on the shrouds kept coming loose. I have to "tune" the rigging this
week.
> > Back out to the parking lot I guess. But now I know how to raise the
mast
> > the mast raising system so I know I could get the mast up by myself
and
> > tune the rigging. I think I'm supposed to tape them or something once
> > everything's tuned. Any ideas?
> >
> > I remember reading on this board how to tune the shrouds but now I
can't
> > find it. Can someone point me to it again. Sorry.
> >
> > gretchen
> > <><
> > P19 #1121 "Sparrow"
> >
>
>
gretchen
"Sparrow" P19 #1121
<><
----- Original Message -----
From: "John spooner" <ocean@verinet.com>
To: "Potter" <wwpotter@tscnet.com>
Sent: Wednesday, February 09, 2000 10:23 PM
Subject: A'hoy Judy!
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> West Wight Potter Mailing List maintainer
> dfarrell@ridgecrest.ca.us
> List hosted by www.tscnet.com
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> Judy,
> Sometime ago you posted info on tuning a P-19's rigging, I can't find it
> now.
> Can you direct me to it??
> Thanks...John Spooner Ft Collins, CO
>
>
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