pivot hole

[DanaDCole]

It's me again. I'm emailing a copy of this to CLC also--I think it's critical.

First let me say the CLC manuals are very, very good, but they're not perfect--nothing is. I've worked on committees writing step-by-step manuals and even with subject-matter experts who have done a particular job a thousand times it's nearly impossible to get it right. Every time you edit a step, it could throw something off somewhere else.

My concern is about the pivot holes in the centerboard trunk. On page 26 of the manual it says, "Notice the epoxy-filled hole in the lower left corner: Leave it so until much later." First, I think that hole should be filled with thickened epoxy, but I can't find where it says to do that--did it anyway.

On page 223 I found this: "You've located and drilled out the pivot hole already. Like other holes in the hull, this hole will have been filled with epoxy, allowed to cure, and then drilled out with a smaller hole." I've searched and searched and am unable to find the instructions on drilling the hole(s). It's not that simple because the trunk holes are inside the keel, so you've got four pieces of plywood to drill through. You can't see to line them up because they are filled with epoxy.

My thinking on this is that the holes should be drilled in the trunk sides and keel sides before they are assembled. Before that is done, the holes in the keel sides should be filled with thickened epoxy. The unblocked trunk sides and keel sides should be very carefully aligned and clamped together, then all drilled at the same time, making absolutely sure they are drilled in the center of the epoxy fill, or that at least no wood is exposed. Then, when the parts are assembled, a peg can be used to make sure all the holes are aligned. If water should get to the wood here, it would be next to impossible to repair.

This would best be done on a drill press (with helpers), or with one of those brackets that are supposed to hold a hand drill exactly aligned (not sure how well those work). Perhaps all this is to be done after the keel is assembled, but it seems to me it would be a lot harder to keep everything in alignment. Or I suppose each hole could be drilled independently before assembly, but I find it next to impossible to get the hole in the exact center of the epoxy fill. How do you accurately mark the center? It's pretty hard to see the edges after the holes have been filled, and even then it's too small to draw geometric lines accurately. Is there a tool for this I don't know about? If they are drilled individually, they still have to be perfectly straight, as noted above.

At any rate, that's a lot of steps and it would be hard to miss them in the manual, but if I did please let me know.

[truenorth]

I guess I'll try -- all holes should be filled with thickened epoxy, so there shouldn't be any confusion about that. An earlier post here also mentions (correctly) that fillets use mostly wood flour (dark) and glue ups, laminations, and holes use silica (white).

I'm not there yet, but it's definitely true that the pivot hole on page 223 was indeed drilled and filled earlier in the process. Paging back, at least to page 220 when the hull isn't even painted, there's a clearly visible hole. When you do this is up to you, which is why the manual isn't specific. But if you put the kit together right, you won't need to worry about too much. If you don't trust the line up, you can dry fit the components on the bench as I did and see where the pivot should be.

The first post shows the hole about 2/3 down lined up with the keel on the bench. The second post shows the full keel assembly upright. I inserted the centerboard shortly after this photo and confirmed everything lined up. Believe me, I was as surprised as anyone.

http://sunmonkeypocketship.blogspot.com ... round.html
http://sunmonkeypocketship.blogspot.com ... -news.html

I suppose if you really wanted to, you could drill your pivot hole right now, but you never know if there's some shifting either way once you pull the hull together. When I was screwing down the keelson and the floors, there was definitely some tussling that may have pulled things out of alignment. If that happens, you'll just need to drill another set of holes. It's actually not that big a deal.

The only recommendation I'd make is to be sure you locate and drill the hole before you paint over the epoxy. I made this mistake with the centerboard trunk and had to find the hole again. Hope this helps...

[DanaDCole]

Thanks for the advice. Has me kind of worried, though. If things shift and I have to drill new holes it's going to be a little hard to make sure there is not exposed wood. Also, it would be impossible to use the holes to line everything up if they are filled with opaque epoxy. At any rate, I'll make it work.

The manual says to use the holes to get everything lined up, so I think I will drill small holes (not the full 3/8") so I can see the alignment.

My plan is to drill the full-size holes immediately after the keel sides are firmly glued to the CB trunk. That way I can get the assembly into the drill press (with helpers) and if I have to re-seal the wood I can see what I'm doing a lot better.

[DanaDCole]

OK, here's my solution: I used a circle template that has tick marks every 90 degrees to draw accurate diameter lines across the thickened epoxy filler. Where they cross I was able to punch a pretty darn accurate center on each of the four fillers. This afternoon when it's a little warmer and I can gather a helper or two, I will clamp the two halves of the CB trunk together and the two keel halves together, making sure the two halves of each are very, very carefully aligned along their edges. Then, with helpers holding the parts horizontal, I will use a drill press to drill through the two CB trunk halves and the two keel halves.

I plan to go ahead and drill the full 3/8" hole, perhaps starting with a 1/4" or 1/8" hole. I have found that bits smaller than that have a tendency to bend and follow any inconsistencies in the epoxy mix (although there shouldn't be any--I mixed it forever!) By having the final 3/8" hole, I can use the 3/8" rod to align the CB trunk halves when I assemble them and then all four pieces when I assemble the CB trunk to the keel. This should ensure that I will be able to install the CB pivot OK and not expose any bare wood.

Does that sound like a plan? If anyone has any burning issues, please let me know before I start--perhaps around 2:00 or 2:30 Central. (Sorry if I am obsessing too much about this, but if anything goes wrong down there it will be extremely hard to get at and and fix in the future.)