Keel Bolt Shear pin Idea
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billstevens_1999
- Posts: 5
- Joined: Sat Feb 27, 2010 6:10 pm
- Sailboat: MacGregor 25
Re: Keel Bolt Shear pin Idea
I have had the worst happen on my V-25. At dock, the keel cable breaking. Sailed out to shallow water, dive and reconnect the cable and assume no other damage as no apparent leaks. Sail on, then weeks later hit a rock with the keel partly down and the cable breaks again. I used a large rope between the wenches to support the keel. I then trailer the boat home for inspection and repair. I ended up dropping the keel, cleaned and refinished it. Repaired the pivot hole as it was oval going forward and down. I replaced the pivot bolt. The lock down pin was imbedded in the trunk with the hole elongated as described. Repaired and reinforced that area too. While I was repairing things. I had some old sheets of solid fiberglass about 1/4 in thick which I cut into strips about 3" wide to fit inside the trunk in front of the pivot bolt to the front of the keel tunnel on both sides to shim the keel so that to stop the keel slop. I also used some behind the pivot bolt too. I used 3M-4200 adhesive in case I needed to remove it.
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heinzir
- Engineer
- Posts: 101
- Joined: Wed Oct 29, 2008 9:01 pm
- Sailboat: Venture 23
- Location: Lake Minnetonka, MN
Re: Keel Bolt Shear pin Idea
There was a thread in the Venture 23 forum a while back about using nylon bolts for the lock down pin. The point was made that the nylon would probably not break cleanly but would bend and/or elongate before breaking, possibly jamming in the keel well and causing more problems than it solves.
IMHO, damage to the keel lock down bolt and surrounding trunk area is rarely caused by an unintentional grounding. It is usually caused by something like the keel cable breaking (ask me how I know) or the keel bouncing up and down in heavy seas if it is not locked down but resting against the bolt.
A steel shear pin would probably work to protect the fiberglass in the case of grounding with the keel locked down but could be dangerous for those of us that sail with the top of the keel resting against the bolt. Shallow waters and an invasive weed problem require us to be able to raise the keel quickly without having to go below to remove the bolt. I would be afraid of the shear pin shearing at the wrong time, allowing the keel to swing down too far too quickly, possibly breaking the cable.
My solution was to fix the damaged trunk with epoxy and fiberglass and to reinforce the area with 1/4" thick metal plates glassed to each side.
IMHO, damage to the keel lock down bolt and surrounding trunk area is rarely caused by an unintentional grounding. It is usually caused by something like the keel cable breaking (ask me how I know) or the keel bouncing up and down in heavy seas if it is not locked down but resting against the bolt.
A steel shear pin would probably work to protect the fiberglass in the case of grounding with the keel locked down but could be dangerous for those of us that sail with the top of the keel resting against the bolt. Shallow waters and an invasive weed problem require us to be able to raise the keel quickly without having to go below to remove the bolt. I would be afraid of the shear pin shearing at the wrong time, allowing the keel to swing down too far too quickly, possibly breaking the cable.
My solution was to fix the damaged trunk with epoxy and fiberglass and to reinforce the area with 1/4" thick metal plates glassed to each side.