RE: P19 keel trunks - one more time [long]

Judith Blumhorst, DC (
Fri, 17 Dec 1999 16:32:30 -0800

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West Wight Potter Website at URL
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Thanks Mac, for your description of what happened whne you it an oyster bar with your keel. I've hit rocks in my P19, and the keel always popped up when the breakaway bolt snapped, rather than translating aft.

If you look at your keel trunk, I think you'll find that it's about 21" from front to back at the top, and 25" at the bottom where it joins the hull. There's 3 or 4 inches extra room at the bottom between the keel and hull. I have drawings of the keel trunk "plug" used when they lay up the hulls, and I believe all the IM-built boats have that extra space at the back and bottom of the keel trunk. (maybe not the very early IM boats, I'm not sure)

When I was talking to the guys at my local boat yard about repairing my keel trunk, I asked about that extra 3 or four inches. They said that designing it like that gives you a safey margin so youre not likely to split the hull if you hit something hard.

I'm sorry to hear that you did some minor "crush" damage, but happy to hear that it was easily and strongly (if not elegantly) repaired with Marine Tex. It's reassuring to me to hear that they seem to know what they're talking about on this issue of keel trunk design.

Fair winds,
Judy B
1985 WWP-19 #266 Redwing
SF Bay, CA

From: Mac Davis[]
Sent: Friday, December 17, 1999 5:16 PM
To: Judith Blumhorst, DC; 'Potter List'
Subject: Re: P19 keel trunks - one more time [long]

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Hi Judy,
You said inter alia,
"I'm curious about how your keel locks down. I think that, with *any* keel design, it's possible to run hard aground and damage it somehow. Even a swing keel. It all depends on how you hit the obstruction. I've heard of pivot bolts getting bent on swing-keel boats in a grounding so it wouldn't go up or down, and/or developing leaks around the pivot bolt after running hard aground. So I'm curious about the design of your keel trunk, Mac. How does the keel lock down, and where did the damage occur?"

Both times, I was sailing with the keel full down in 5 to 6 feet of water in the Gulf after storms had roiled the normally clear water. Impact with the oyster bar was unexpected and abrupt. Kelpie stopped completely, pinned against the bar by wind pressure on the sails. Letting the sheets run free allowed her to pivot and free herself. In both incidents, the keel did not ride up noticeably, but rather moved aft in translation rather than rotation.

Neither time was the keel locked down. Since a lot of the water I traverse on a day sail is really thin, this is SOP for me.
No damage occurred to the forward edge of the trunk in either incident. All damage was concentrated at the rear of the trunk, and consisted of crush damage to the rounded profile of the trunk where the square profile of the keel impacted. Severest damage was at the exterior aft end of the trunk opening. Easily accessible and strongly if not elegantly repaired with Marine-Tex.

My keel trunk (1995 model) is free-standing, about 15 inches tall, and 25 inches inside opening. It appears to be bonded to the hull, but not the liner. Where the trunk penetrates the liner, a heavy application of (non-structural) sealer is visible. The leading edge and sides of the trunk are slightly over a half inch thick, increasing to maybe three quarter inch on the aft end.
Looking down from above you can see that the trunk lay-up is solid, is made of multiple layers of cloth and mat.
Hope this is what you're looking for,
Mac Davis
Kelpie, WWP19 #804, Aripeka, FL