Keel Warp

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Keel Warp

Postby Desert Jay on Fri Nov 12, 2010 5:47 pm

Both Dave and Bill, in their respective blogs, talked about warp in the aft part of the keel during its assembly. I'm almost ready to start that procedure and was hoping to avoid the same problem. Both spoke of the strip of blocking being an issue. Bill used scrap from the tapered keel strip to solve it and Dave redid something? Can you guys explain that again? I wasn't exactly clear what was causing the warp and how you remedied the problem.
Thanks,
Jay
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Re: Keel Warp

Postby decurtis on Sat Nov 13, 2010 10:13 am

Jay,
That's a tough question making me remember back that far :oops: I faintly recall the problem and went back in my blog to find the details. I have copied the information below. In my case I suspect it was a combination of some inaccurate cutting of the keel's timber supports and mostly the difficulty of finding well dried seasoned lumber that will not warp.

"I finished the keel assembly and was all set to get organized for pouring the lead when I noticed the keel was not straight from the centerboard back and curved left by almost an inch. Considering the entire hull is built around what should be a straight keel and keelson this was to say the least a little disappointing. I assumed that the keel blocking I had cut was not accurate and proceeded to cut it away from the keel sides. But there was still a curve. I then did some cutting at the butt joint of the keel sides and discovered that the vertical support for the butt joint was the culprit. I was now able to easily straighten the keel and block it with some lumber and clamps. I am now ready to replace the the keel blocking and crossing my fingers when the epoxy cures that the problem will be solved. A dry fit of the keelson now shows a nice straight keel so if my repair work is successful I can get back on schedule."

At the original post
http://pocketshipadventure.blogspot.com/2009/03/crooked-keel-and-whats-in-name.html
John C. Harris has an interesting comment that the keel being out by an inch probably wouldn't affect the boat's performance.

P.S. I just read Bill's blog after posting this and read about the blocking needed at the tapered end when laying up the keel. I honestly don't remember if I used that blocking when clamping everything together; if it was in the manual I am sure I would have seen it since I read very, very carefully on my first boat build of any kind. If I did miss it, it seems probable that without the blocking you could easily introduce a warp on the keel.
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Re: Keel Warp

Postby Shudoman on Mon Nov 15, 2010 10:03 am

That blocking is only mentioned in one place in the manual but you can see it in one of the pictures. I don't have my manual here with me now but I'll post the pg # when I get home. When I created the bottom rear frame I kept the wedge shaped sections that I cut off and used them to create the proper angle for the blocking later. I was still off by about 1/4" but I was able to warp it back the other way by steaming it out. I attribute that 1/4" to the tables that I used to clamp the keel to during glue-up. They were the folding type and don't open up true and flat.

After the little corrections and all the work everything aligns perfectly. A real relief since the keel determines the rest of the boat.

Bill
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Re: Keel Warp

Postby Desert Jay on Mon Nov 15, 2010 12:42 pm

Something occurred to me as I was gluing up the 1st side of the keel. The whole assembly was lying flat on the table (my table is solid) but the aft part of the keel is, obviously, not flat (or parallel to the table top) since it tapers from the mid point. In the manual I then noticed a wedge of wood propping the aft end of the keel to raise the aft section as the assembly lays on its side. This seems to be an important detail, which probably is worth a mention in future manual edits, to allow for that offset as the epoxy cures. I will be sure that I lift the end adequately when I fasten the other keel side piece so that the aft aligns with the center of the mid point behind the trunk.
Jay
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Re: Keel Warp

Postby Shudoman on Mon Nov 15, 2010 4:17 pm

Exactly Jay!

It's would be VERY easy to miss in the manual and I think that it's where a lot of people are left scratching their heads.

Bill
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