Keel Bolt Anchor Repair

[Ben Steinberg]

A #10 fastener tapped into g10 will hold better than a wood screw into a few layers of fiberglass. Correct though.  it would raise the plate by the thickness of the g10. Run it through a tablesaw on edge to thin it down more easily than planing.
Alternatively you could riddle the plastic with additional holes in between the ones that are stripped or go for a few strips of g10 and the blind insertion method.

[Jeff Jones]

just do this and be done with it already. 

I think cutting the thing out was the hardest part.   

So there i was, just finished a red bull when i ran out of epoxy.  No more work on the fordeck cap.  Hmm....  i've aways wondered what's under there.  And then the saw came out.

It's your fault steinberg

[Jeff Jones]

Oh and if you have a Bennett that's leaking i'd bet money that some of it is coming from the joint in the keel trunk.   The top part of the trunk is glued over the bottom part (socket fit) with what looks like west / microspheres.   After 15 years of banging around that stuff can micro-crack.   You'd be surprised how much water pressure there is in your keep trunk when your sailing along at 14 knot's.   

[Thomas Leith]

KVT Koenig's minimum order quantity is 100 pieces and he says he doesn't have a "sub distributor". Maybe I'll have to go with t-nuts after all, but I don't think they're 316 stainless.

[Jay Harrell]

You'll be glad you did. (Eventually)  Ben's keel boxes DO NOT LEAK.

just do this and be done with it already. 

I think cutting the thing out was the hardest part.   

So there i was, just finished a red bull when i ran out of epoxy.  No more work on the fordeck cap.  Hmm....  i've aways wondered what's under there.  And then the saw came out.

It's your fault steinberg

[Darren Gilbert]

Jeff...wow...more pictures please!  That's #31 right?

[Jeff Jones]

I'll take a bunch of detailed pictures through the process.   

Ya, that's 31.  She's getting an new foredeck cap so i figured while i'm at it.

[Thomas Leith]

Since I haven't found an economical way to obtain BigHeads, what about a 316 SS or bronze or titanium (saves weight!) thread repair coil like HeliCoils installed directly into the plastic keel guide plate? Will they grip the plastic tightly enough to withstand repeated tighten/loosen cycles? Will red locktite stick to that plastic?

Does anyone know the technical name of that material so I can talk to an engineer at the HeliCoil company?

I have an idea for how it might work:

1) Drill the "oversize" hole from the bottom of the plate just deep enough for a coil
2) Use a bottoming tap to cut the oversize thread to accept the coil
3) Install the coil from the bottom of the plate
4) Make sure the hole from the top of the plate is just large enough for the bolt

Voila! A metal thread installed directly into the keel guide plate.

The coil can't move upwards in the plate because there's plastic in the way. If it wants to move downwards at all, it can't go far because it'll hit the deck of the boat. But it might not want to move.

      t

http://www.noblefix.com/PDF/Helicoil/HeliCoil%20Catalogue.pdf

[Thomas Leith]

I talked to a sales support engineer at HeliCoil (Robin) who told me that there should be no problem whatever installing a HeliCoil in the plastic keel guide plate (I take it to be some kind of nylon). If you look on pages 18 - 19 of the catalog (link in earlier post) you'll see that the recommended DRILL size in plastic is different from the size recommended for steel. The size of the TAP is the same for any material. She says as long as you're confident you can cut a clean, sharp thread in the plastic, the HeliCoil will not move under the conditions we need for the keel bolts without any need for an adhesive (finger tight wing nut torque) . They have three highly corrosion-resistant materials to choose from.

So, I think I have found a solution that avoids the need to buy 100 BigHeads. I plan to install an M-8 HeliCoil with a 1.5 diameter thread length. I can see putting HeliCoils in G-10 and carbon masts too: these things would be good for any part you might want to disassemble from time to time on the Viper.

[Ben Steinberg]

Heli coils work well but typically threads get burnt out in applications where the bolt is frequently threaded and unthreaded like the keel bolts. I'd rock the t nut or make my own big head.

[Steve LeMay]

We used to heli coil ski bindings all the time. That coupled with some bad ass epoxy, good to go.

[Dan Tucker]

I put a Helicoil in the foward hole on #50. Ben is right, it won't like the repeated screwing & unscrewing. Lasted > 1 season for me. YMMV.

Sent from my Tab or phone => brevity & Swypos

[Ben Steinberg]

make your own big head.  Get some 5/16 id stainless tube and run a 3/8 tap through it.  Bring it to your local welder and have them weld it to a fender washer.  good to go. 

[Chris Shaughnessy]

As Paul Y. to grab a handful from the shop before he heads over for Sarnia, figure 2 bigheads = 1 beer ? 

[Thomas Leith]

I thought about making my own out of bronze because it'd be easier to cut a thread in and I could braze instead of having to weld. There is one guy I know of who I'd trust to weld a 316 part and maintain its corrosion resistance. He could do it over the winter. But this is a last resort. I'd probably go with whatever grade of SS t-nut

If there is an economical way for me to get four Big Head female sockets in an appropriate size, I'll take it. I haven't tried offering Paul beer for boat bits, only money. My bet is 1 Big Head = 2 pints at least. I'm sure those parts cost quite a bit, and then there's the "remember to ship" charge and the "transportation charge".