Re: Potter 19 keel lock down - a sorry tale

JBlumhorst@aol.com
Wed, 20 Oct 1999 11:37:24 EDT


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West Wight Potter Website at URL
http://www.lesbois.com/wwpotter/
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Hi Webgang,

I have a sorry tale to tell. My 1985 P19 #266 originally came with a keel
lockdown that consisted of a bolt thru the keel trunk and keel about 3" down
from the top, and about 6 or 8" aft of the front edge of the keel trunk. For
the first 6 months I owned Redwing, I used the bolt to lock down the keel.
It worked well, and she rarely took on any water thru the keel trunk. On
really rough occasions, she'd take on a half cup or so of water.

For those of you not familiary with the 1985 P19 built by Joe Edwards, the
keel trunk is not as strong or thick-walled as most other years. The glass
is only 3/8" thick -- it's the worst keel trunk ever put in a P19. There are
a few other odd details about my weird keel trunk that contributed to the
damage. The aft edge is slanted almost twenty degrees off vertical, and the
hole at the hull is about 4 inches longer at the aft edge, so it permits the
keel to rotate back at the bottom edge when you hit something. That sounds
like a good idea in theory, but it practice it causes all the force from the
collision to point load right on the front top corner of the keel trunk.

I have wondered more than once if my keel trunk was original, or if it had
been repaired sometime in the past, because it's the only one I've ever seen
quite like it. Everyother P19 keel trunk I've ever seen fits the keel
differently from mine. The new keel trunks from IM are quite different from
mine, as are the old HMS 18 keel trunks.

So, last Spring, I put several layers of glass around the trunk, to reinforce
it. Unfortunately, I glassed over the hole in the trunk for the bolt, so I
sailed her for about 6 months using bungees to hold the keel down. As it
turns out, that's probably a good thing.

Three weeks ago, I finally got aaround to re-drilling the hole and put the
bolt through. It was great, no more water in the cabin as the keel moved in
chop.

Now the bad news -- Two Sunday's agol we hit a huge square rock that used to
be part of the retaining sea wall next to the slip in the Ayala Marina on
Angel Island at a very low speed.

The keel, unable to ride up, rotated back at the bottom, forward at the top
-- and did some damage. It put a small crack in the top 1.5" forward corner
of the keel trunk, and pushed up the front third of the keel cap, snapping
off a 1/4" SS bolt in the process and cracking the fiberglass keel cap.

What irony! Tthe boat has made it through 15 years with that mechanism for
locking down the keel, and the first day that I sailed with it fixed, I
busted up the keel trunk a bit. If the bolt had not been there, or had it
been a nylon bolt that could have sheared off, there would have been no
damage.

Let me tell you about how most P19's handle hitting rocks. My husband was
sailing one day with Jerry B when they hit a huge submerged rock at nearly 6
knots. Kapow! Dead stop in under one second! And there was no damage to
the keel trunk, not a bit. Now that's the way a keel trunk ought to be
built! Jerry's keel trunk on HMS 18 #48 has side walls 2.5 inches thick, a
front edge even thicker, and his keel ties down with a simple piece of line
to a jamming horn cleat on the aft wall of the trunk. Jerry can leave a few
inches of slack in the line to permit the keel to ride up, but it can't go
too far in the event of a knockdown or capsize. The front and back edges of
Jerry's keel trunk are vertical, so when he hits a rock, the force is
distributed all along the aft edge, not point loaded like mine was when it
rotated on the locking bolt.

I could fix the crack and leave the original design alone -- after all, it
made it though 15 years. But, since I KNOW I'll hit more rocks and I was
going to beef up the trunk anyway with more glass.... soooo... I'm going to
cutt out the keel trunk and glass in a new one designed like the one on
Jerry's boat. Last weekend I went over to Jerry's and measured all the
dimensions. The work will start right after our last PY cruise of the season
on Nov 6-7 in Alameda.

I'd recommend NOT using a SS bolt through the keel and trunk to lock down the
keel. When you hit something, the keel rotates back and up at the bottom,
while the top rotates forward and down. That's what caused the keel trunk
and cap to be damaged.

The P19 is NOT a swing keel and putting a bolt through the keel makes no
sense whatsoever -- you'll cause point loading on the top front edge of the
keel trunk.

For now, I'm still sailing the boat with the 1" crack in the front corner of
the keel trunk, but I'm going to use a NYLON bolt through the trunk and
keel, or the bungee cords. If the keel hits something, the nylon bolt will
shear, permitting the keel to rise up like it used to.

Sadder (because my beautiful boat Redwing has a boo-boo) but wiser,
Judy B

In a message dated 10/20/99 6:15:37 AM Pacific Daylight Time, lks@ll.mit.edu
writes:

>
> Keith,
> I have a P-19 made the same year that I acquired recently.
> It has a hole in the keel trunk so I can put a pin through the whole
> thing (trunk and keel) when the keel is down and lined up fore and aft.
> Sounds like you will have to drill the hole yourself.
>
> Since the pin also holds the keel in the
> correct fore and aft position it also stops water sloshing through
> the gap at the front of the keel which you will probably have if
> you don't put a pin in.
>
>
>
>
>
> Regards,
> Keith Sisterson
> P-19 #460 <TBN