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Old 26-04-2018, 08:50   #16
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Re: Insufficient threads on keel bolt. Double nut?

Only one bolt? I see you're in Oregon so, freshwater boat? I think you'll be ok with that solution.
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Old 26-04-2018, 09:00   #17
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Re: Insufficient threads on keel bolt. Double nut?

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Originally Posted by chris95040 View Post
I think I see cracks, too. I'd want to really know what was going on there.

Hey, for folks with J-bolts, couldn't you just get off cheap by drilling and tapping new bolt holes from inside the bilge?
Trilling and tapping into a lead keel isn’t going to help.
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Old 26-04-2018, 09:14   #18
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Re: Insufficient threads on keel bolt. Double nut?

I think a coupler nut will serve your purpose. Go to: mcmaster-carr web, search: "coupler nut". Enter the diameter & threads per inch (or if metric, they may have that as well) and select the steel alloy: 304 stainless steel (or, if available, 316 stainless steel for better corrosion resistance). For detailed drawing with dimensions, click on the SKU number.
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Old 26-04-2018, 09:17   #19
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Re: Insufficient threads on keel bolt. Double nut?

Have a machine shop make a stainless nut, 2-3 inches long. This will give more thread contact to withstand the torque. Use plenty of anti-seize compound.
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Old 26-04-2018, 09:26   #20
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Re: Insufficient threads on keel bolt. Double nut?

I may be seeing things but it looks like the bolt is actually threaded into something from the photo. If that is really the case, then it may unscrew and allow you to replace it without huge cost & labour.
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Old 26-04-2018, 09:31   #21
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Re: Insufficient threads on keel bolt. Double nut?

Good thinking! However, it’s not necessary to use a machine shop to obtain a nut of extra length. This is an off the shelf item. See my previous comment for purchase of a “coupler nut”.
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Old 26-04-2018, 09:47   #22
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Re: Insufficient threads on keel bolt. Double nut?

Use a deep sock such that both nuts are gripped to preclude the bottom one having enough grip to throw off your torque reading, if that makes any sense. Don't use washers because the bottom nut will have thread to bite on and aligning flats might be a problem.
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Old 26-04-2018, 10:47   #23
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Re: Insufficient threads on keel bolt. Double nut?

I'm basically a simpleton, but if you are confident in all other aspects, why not just load it up with stainless washers, and add 2 nuts on top of it, where the good threads start?

Torque the bottom nut to spec, and add an extra nut on top?
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Old 26-04-2018, 11:01   #24
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Re: Insufficient threads on keel bolt. Double nut?

I would remove the bottom washer, and fabricate a spacer in same type of steel but much larger(2x3 in) that the bolt nut. This 'pad' shall be of a thikness of the nut(with a hole to pass over the bolt ). It would spead the load of the bolt and increase the contact area, wiich in my opinion, would add to the strength of the keel attachment.
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Old 26-04-2018, 11:11   #25
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Re: Insufficient threads on keel bolt. Double nut?

Have you contacted Catalina? They'll be able to tell you exactly what's in your keel, and what's necessary for a 'factory repair'. Then you can decide what you want to do. The coupler nut and over sized washer appeals to me. And lots of anti-sieze such as Tufgel.
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Old 26-04-2018, 11:13   #26
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Re: Insufficient threads on keel bolt. Double nut?

Quote:
Originally Posted by Hardhead View Post
I'm basically a simpleton, but if you are confident in all other aspects, why not just load it up with stainless washers, and add 2 nuts on top of it, where the good threads start?

Torque the bottom nut to spec, and add an extra nut on top?
My concern would the washers to bolt/threaded rod distance would allow for lateral movement. JMHO
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Old 26-04-2018, 11:20   #27
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Re: Insufficient threads on keel bolt. Double nut?

I agree, although if you had close fitting ID on the washers, or a backing plate, it might not be too bad. Still a factor though.

I think the best idea, first, would be to call Catalina, as has been mentioned. Or possibly Catalina Direct, who are unusually helpful when I have called in the past.
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Old 26-04-2018, 14:55   #28
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Re: Insufficient threads on keel bolt. Double nut?

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Trilling and tapping into a lead keel isn’t going to help.


I agree.
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Old 26-04-2018, 15:44   #29
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Re: Insufficient threads on keel bolt. Double nut?

I believe your plan to use a second nut as a spacer is a good solution. FWIW, I'm a mechanical engineer (and a sailor).

I would suggest you keep an eye on it in the future though. If there is some mystery stress causing the problem, then the second nut will fail too. My guess would be the threads were stripped during installation when the boat was built. It would take a massive force to strip those threads.

Obviously, dropping the keel to replace the bolt would be a ridiculous cost, and totally unnecessary.
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Old 26-04-2018, 15:48   #30
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Re: Insufficient threads on keel bolt. Double nut?

Looks to me like someone simply over-torqued it. Stainless is really soft...it's soft enough that you can snap a 5/16" bolt with a 3/8" socket on a 12" handle. It's why torquing your keel bolts to the proper spec is important. Go to far and you've ruined the bolt.

I agree if this is the trailing bolt and you've got good threads to just put a coupler nut on it. That said, I would probably put a proper backing plate on it, if only because it will make torquing to spec easier. I'd clean off all the crap under the existing washer, level it, and probably put a small plate of G10 there. While it's structurally not important given it's location, it's not a bad idea.
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