Re: Lateen rigged Potter

From: hlg@pacbell.net
Date: Wed Feb 02 2000 - 21:02:59 PST


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Ken Preston wrote:

>I think I've almost got it now. The tube/socket for the mast is aluminum I
>take it and the bolt to support the mast is just to put the boom height at
>the correct elevation.

Yep. I actually have several holes so the depth is adjustable, but I've
always used the lowest hole, about 18 inches down. I bought a tool from
Sears that enabled me to drill holes perpendicularly through the center of
the tube. I was afraid the mast would bind if the bolt wasn't perpendicular
and centered.

.(I'm thinking that if I can't find Sunfish parts I
>might just use off shelf tubing for a mast, or maybe even wood spars. . .
>and cut the mast full length to the bunk deck elevation) or are you trying
>to isolate the mast heel from the spider or whatever secures the lower end
>of the tube?

You could use off-the shelf tubing from a metal supply source if it is a
similar grade so it won't bend or break. There are Sunfish (now part of
Vanguard) dealers all over the country and also many used boats and parts
around. Somebody in Texas gave me the mast, but I bought the rest of the
spars new from a dealer. You would also need the Sunfish endcaps, but they
are not expensive.

I used the trailer roller bracket as an easy, secure, and adjustable way to
attach the foot of the tube to the sole. The bracket is wider than the
tube, and I have a long fully threaded bolt through the bracket and tube,
with nuts on each side to fix the position of the mast from left to right.
That provides verticality adjustment from side to side, but I got it right
the first time so never had to diddle with it. The bracket is slotted where
it bolts to the sole, so I can also adjust rake, but I haven't had need to
do that either. It's still a good idea to build in adjustments like that
when you have an experimental rig, I think. (This was strictly eyeball
engineering.)

Incidentally, you will want a Sunfish gooseneck. It's $40 but is
beautifully wrought out of bronze, and it wouldn't be worth while to try to
find or build a substitute. It's a tried and true design. The only
improvement I made was the addition of a quick adjust lever like the ones
used on bicycle seats, so I don't need a wrench to loosen the gooseneck to
adjust its position along the boom.

I hadn't thought about using a mast that went all the way down. It would
need some kind of socket at the bottom that would allow it to turn. It
would be slightly longer than the standard 10 ft Sunfish mast so would be a
little heavier to step, compounded by the extra leverage, but might not be
a problem. I have stepped my 10-footer while holding it out at arms length
while standing on the ground.

With no tube inside restraining the buried part of the mast, any bowing of
the mast would continue inside the cabin, I can imagine. That might reduce
the mast bending stress concentration at the cabintop, but it might
increase the load on the sole attachment. Both Lars and Steve used the
socket tube all the way to the sole.

My original gunter mast went through the cabintop and stepped in a slot on
the bunk deck in the cabin. The mast was stayed so the cabintop did not
have to carry the load. I modified it by sawing off the (wooden) mast,
using the lower stub as a compression post, and stepping the upper portion
of the mast on the cabintop, butting the two mast pieces together. That
made it easier to rig because the shorter mast was lighter and I could
leave the stays attached when trailering It also eliminated the problem of
sealing around the removable mast. I have lever type attachments on the
side stays, so I could ease one stay enough to unstep or step the mast. It
was still a lot of trouble to tie up the mast and all the dangling lines
and stays, so I then tried the lateen rig after reading the glowing reports
from Lars Mulford and Larry Brown.

Steve Barnes converted his P14, Popeye, at the same time I did mine, and we
compared notes as we went. He was very pleased with Popeye at first but
later decided he needed more sail area for his location. There's usually
too much wind in my area, but even in light air my Sunfish sail seems
adequate for me.

>The penetration through the stiffened cabin top sounds fine
>to me, maybe a pair of hanging knees down the coachroof side would help. .
>.just epoxy them in perhaps. . .I'll keep that in mind.

I like my shelf idea better because it would transfer load to the decks
instead of the cabin, and it would also provide useful storage for bulky
lightweight items.

>Is the mast socket
>tube a full time fixture or do you remove it if you're using the gunter. .
>.though I guess you don't use the gunter that much any more do you? Only if
>getting reef points installed on the lateen. . .h'mm.

The gunter rig mast steps in its normal location; the lateen mast is 11
inches forward, at the front edge of the coachroof. The gunter mast stub
and the lateen mast socket both remain in place, and both are securely
attached to the roof and the sole. It's important that the lateen mast be
positioned forward to put the center of effort in the right place, over the
centerboard. It would have an impossible weather helm if you put the
lateen mast in the same location as the original Potter mast.

I haven't wanted to use the original rig since I installed the lateen, but
it still has some appeal, and I might buy a new main for it someday. As a
first generation US Potter, it is something of a classic, and the wooden
spars look salty. It's also easy to heave to with a sloop rig, and I don't
know if there is a practical way to do so with the lateen. I don't know how
durable the reefed lateen rig would be in a blow, since there is a length
of line between mast and yard when reefed. I need to test it in more severe
conditions. Dave Kautz and I were sailing together on Lake Anderson one
afternoon when Dave decided it was reef time for his P15 (with the standard
quadrilateral main). I was still fairly comfortable, but I put one reef in
the lateen anyway. We found the two boats performed identically under those
conditions (upwind, as I recall) as we sailed along at the same speed and
pointing angle.

 . . .and does the tube project above the coachroof? I probably could
>have improvised but it sure is nice to know how other peoples' experiments
>have worked out!

Mine does not extend above the roof, but Steve's does. It looks like a
little smokestack. I suppose that would add a little stiffness, but I don't
think it is necessary. The mast socket on a Sunfish is only about 10 inches
deep. All the spars visibly bow, including the mast, but that seems to help
absorb the shock of a gust as well as depowering the sail at the right
time. I can sail comfortably in higher winds with the unreefed lateen rig
(80 sq ft) than I can with the original gunter main and jib (72 sq ft).

I've told this stuff before, so if I'm annoying people by putting it on the
list again, let me know and I'll go off list. I thought there might be
someone new who would be interested.

Harry Gordon
P14 #234, Manatee
Mountain View, CA



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