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Drilling holes for the nesting bolts


Steve W

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The directions to my 11N say not to drill the holes after the epoxy has been poured. I have the two bulheads taped togther with the cardboard sawcut spacers. It seems like this would be a good time to drill the holes, put the bolts through and remve them and replace them one at a time when I'm sawing teh boat in half. If that isn't the way, what is it?

Take Care,

Steve

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I drilled the holes after the nesting bulkheads were fileted and glassed in but just prior to cutting the boat in half. This way it is assured that the holes align with each other and the soon to be halves of the hull are aligned at the same time. There is always a chance that something will move slightly at any time before this and the holes will then not be in line when the hull is cut.

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I drilled the initial pilot holes before sawing the boat in half.

I marked the hole locations with an oversize cross, then drilled all of the initial pilot holes while the boat was still in one piece. You need to make certain these holes are square to the bulkhead.

After "the big cut", half the holes were enlarged to 1/2" or 5/8" inch, then backfilled with thickened epoxy, which sealed the final hole to prevent rot, plus an epoxy bushing gives the washers under the bolt head and nut something substantial to compress against. After those cured and were sanded down, the boat was bolted together securely. The center of the epoxied holes were re-established from the "cross" mark and the final hole drilled through in one pass. (When you pour the epoxy plug, put the masking tape to plug the hole on the side with the cross, so that turns up as the smooth side and you won't sand your cross off).

Boat was separated and the remaining set of holes drilled oversized, backfilled, sanded smooth and after clamping boat back together a second time, remaining holes drilled.

It goes together perfect and all holes are backfilled and sealed with epoxy.

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Steve, I think you are missing a page of your plans. I have a 17" X 11" page devoted exclusively to the nesting bulkheads and it explains this whole process in detail and includes detail drawings. Here is a copy of both halves of that page:

scan0002.jpg

scan0001.jpg

Graham publishes very complete plans, but it is possible that a page is missing when the package goes out. I hope this clarifies things for you.

edit: The measurements on the drawings may not be accurate for the 11, but I am sure the directions themselves are good.

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Stick with the plans. My description was from memory and something I did over 5 years ago. Now that I think about it, I did drill and backfill the oversize holes before glueing up the boat. But do use the oversize cross to re-establish your hole centers on the tape side of the enlarged hole. That allows you to put the final hole right back in the center.

Get that right and the finished boat does join together perfectly. Two boats bolted together to make one may not seem strong enough, but it is. Remarkably so.

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