Keel Bolt Shear pin Idea

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Tsatzsue
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Keel Bolt Shear pin Idea

Post by Tsatzsue » Wed May 04, 2011 6:06 am

I just bought a 1977 Venture 25 in mint condition. After spending the weekend rebeding all of the deck harware I noticed a cover on the interior keel locker area where the hold down bolt is. After opening it low and behold the dreaded damage. Looks like the keel hit something and tore a slot about 4 inches long in the locker. It was repaired but I can still see the damage from the keel side. Not a big deal no stress cracks and a pretty clean cut ...Miracle. I live in new Engalnd and use a snow blower a lot. Without a shear pin I would have gone throug a butt load of snow blowers. Has anyone thought about that type of application here? Maybe a coulple of stainess spacers on the sides for a sharp shearing surface and a pin that is grooved (shear pin) so that it will fail before the fibergass when an object is struck. Maybe even a hard wood dowel. Seems pretty simple. Sure beats fibergalss damage. Carry a half dozen on board and away you go. Thoughts anyone?

PS: I am a new member as of yesterday. Can't wait to get it in the water!!!!

Tsatzsue
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Re: Keel Bolt Shear pin Idea

Post by Tsatzsue » Wed May 04, 2011 10:03 am

Come on someone must have thought of this?? Maybe everyone is running to the patent office.....ha ha. :?: :D

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mastreb
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Re: Keel Bolt Shear pin Idea

Post by mastreb » Wed May 04, 2011 12:09 pm

If I understand the configuration, you'd lose the keel to the deep when the shear pin broke. Perhaps that's preferable to hull damage, but it would be harder to replace these days than a fiberglass repair in my opinion. I might not understand the problem though.

Matt

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restless
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Re: Keel Bolt Shear pin Idea

Post by restless » Wed May 04, 2011 12:32 pm

I agree with the above. Doesn't your keel contain a load of iron too?

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Re: Keel Bolt Shear pin Idea

Post by Hamin' X » Wed May 04, 2011 12:50 pm

The hold-down bolt is separate from the pivot bolt. My understanding of the main purpose of the hold down bolt, is to keep the keel in the full down position. The main reason for this is during a knock down, it will keep the keel in the extended position, thereby maintaining the righting moment to bring the boat back up. If the the keel were allowed to swing free, it could fold up into the hull during a knock down and allow the boat to turn turtle. With your shear pin design, you might get into serious trouble in shoaling conditions, should the pin shear and suddenly heel the boat at the same time.

JMHO.

~Rich

Tsatzsue
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Re: Keel Bolt Shear pin Idea

Post by Tsatzsue » Wed May 04, 2011 1:46 pm

I see the confusion...I am not talking about the main bolt. I am talking about the hold down pin. From what I have read this pin is to be put in during heavy weather or to insure self righting in a knock down. It is also supposed to eliminate the banging around of the ceterboard. Seems that the idea is to keep the keel from moving but the force needed to do that does not even come close to the force exerted when an object is struck at 5 knots with a full load on.

Tsatzsue
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Re: Keel Bolt Shear pin Idea

Post by Tsatzsue » Wed May 04, 2011 1:53 pm

I think we crossed posts. HaminX... I see what you are saying but I think that if you hit the shoal with enough force the keel locker would have already yielded and be damaged thus producing the same chance of an unexpected heel.

thomasgoodmaniii
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Re: Keel Bolt Shear pin Idea

Post by thomasgoodmaniii » Wed May 04, 2011 5:30 pm

i have read posts on other forums that mention the use of wooden dowls and such for preventing keel trunk damage. i also saw the sugestion of a nylon or composite bolt. that idea seems to be the best as it gives you a way to mantain tension on sealing washers. i personally like the idea of a shear pin because if you are healed over and hit a shoal the water is shallow so you arn't in great danger if you can get the sheets let out. the main thing is to not have the keel come back into the trunk with great force in the event of a rollover and smash through the boat.

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Re: Keel Bolt Shear pin Idea

Post by tubeydude » Wed May 04, 2011 6:37 pm

Seems like a good idea to me.

Here's a bag of 25 3/8-16 x 3 Nylon bolts for about 9 bucks from http://www.mcmaster.com part # 91244A638

If you still have the rubber seals, washers and nut you are good.

Enjoy,

Erik

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mastreb
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Re: Keel Bolt Shear pin Idea

Post by mastreb » Wed May 04, 2011 7:53 pm

Yep, I'm on board with a shear pin for the hold down boat--I don't see a circumstance where damaging the hull is better than shearing a pin.

Matt

Tsatzsue
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Re: Keel Bolt Shear pin Idea

Post by Tsatzsue » Thu May 05, 2011 6:25 am

I appreciate all the feedback. I like the nylon bolt idea. I am hoping that the 3" is long enough. I will scope it out after work. This forum is great!! I'm glad I joined. Some day my boat will see water...I hope. :)

Tsatzsue
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Re: Keel Bolt Shear pin Idea

Post by Tsatzsue » Thu May 05, 2011 7:06 am

Even better....Mcmaster carr nylon threaded rod pn#98831A031. 24"x3/8" $7.22. Cut to the corrct size, make extras, and use sealing washers #94709A516 $6.47 (10) and nylon wing nuts #94924A031 $8.93 (50). Limited to large quantities but in my book you can never have enough hardware. With this configuration I may not need to install the shearing surface on the locker and just add a few more layers of fiberglass. I'll be pulling the keel next week to resurface. I'll repair the inside of the locker then and keep you guys posted on the outcome. I'll post some pics.

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Re: Keel Bolt Shear pin Idea

Post by flynfol » Thu May 05, 2011 1:00 pm

There are a couple trains of thought with the lock bolt. I'm curious, which direction is your"arc" in the trunk? I would venture a guess that many keel trunks have been damaged from the keel falling and contacting the bolt or upper back side of the trunk than damage from grounding. My trunk had been previously repaired, but was due to not having the keel locked in large seas. The keel unlocked can swing fore and aft and damage the cable or the trunk. I have grounded in the unpredictable waters of the north channel, and have bent the bolt with no damage to the reinforced repaired trunk. For what it is worth, I think the lock bolt is an integral part of keeping the keel where it is supposed to be ......literally......and plastic or wood will not do it.

Tsatzsue
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Re: Keel Bolt Shear pin Idea

Post by Tsatzsue » Thu May 05, 2011 1:54 pm

The groove is on an arch forward following the path as if the keel had been driven backward at the bottom. The original trunk construction might hold if something was struck without so much force but I am not so sure now that there is a patch. I need to sure the patch up with more glass. The original manual states...

" If you are sailing in shallow water, where you can reasonable expect to hit bottom, install the lock bolt in the top keel trunk hole before lowering the keel. Then lower the keel until it comes to rest against the bolt. Since the lock bolt now does not pass through the keel, it will swing back if you hit bottom." The drawing does a poor job of showing where this top hole is. I do have an upper hole visible from the cabin side. Is that it? It doesn't appear to go through the other side. hard to see from my office desk.

I have seen a lot of posts that state they sail, depending on the depth condition with the keel part way cranked up. I would assume the winch and cable should be able to handle this. Any thoughts?

SJK1962
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Re: Keel Bolt Shear pin Idea

Post by SJK1962 » Fri Jun 17, 2011 5:46 pm

I FOR ONE AM VERY NEW TO THIS FORM , BUT NOT TO SAILING. I TOO MAVE BEEN TRYING OT FIGURE OUT THE SAME THING. MY VENTURE 21 KEEL HAS HIT THE RUBBER BUMPER IN THE LOCKER AND DID SOME DAMMAGE. I AM REPAIRING IT TODAY AND LIKE THE NYLON PIN IDEA ALOT. THE PIN COULD BE LARGER AND THEREFOR STRONG ENOUGH TO HOLD IN A KNOCK DOWN EVENT ,BUT ALOT SOFTER THAN STAINLESS. I DONT LIKE THE IDEA OF A SOLID PIN AND I WILL TRY IT AND POST RESULTS. STAINLESS WASHERS ATTACHED TO THE OUTSIDE OF THE LOCKER SHOULD AID IN THE SHEAR FACTOR
THE CABLE IS ENOUGH TO HOLD THE KEEL IN ANY POSSITION HOWEVER THE HUMMING NOISE IS ENOUGH TO DRIVE ME OVERBOARD

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