My mainsheet block ripped off the CB trunk underway today.

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My mainsheet block ripped off the CB trunk underway today.

Postby zeroready » Sun Apr 25, 2021 4:42 pm

I replaced the original fiddle block with the Garhauer block from DR Marine. First time out with it, wife and kids on the boat. We were sailing along all of a sudden THUNK. Pulled right out. Lucky for me my wife is an outstanding crew member and started dousing the sails right away, while I held on to the wayward sheet and tried to keep us into the wind. We got it all under control and motored safely back to the harbor.

So when I installed the new one, I had to tap the new screw holes offset from the old ones because of the orientation of the base, and the bigger screws. The only thing I can figure is, and I really hope not, that when I took out the old screws out the metal plate on the under side of the CB trunk fell off, so my new screws were just threaded into the fiberglass. But I didn't hear anything fall when I was doing it so I don't know. The other thing is that the new screws that came with the new block seemed very short, like only about a quarter inch of screw coming out the base when the screws are in, maybe the metal plate is still there but the screws didn't reach it through the fiberglass. On the other hand when I tapped the new holes I didn't feel like I was going through metal, so I bet the metal plate fell off. No idea how I'm going to reattach it, probably have to careen the boat in my yard and go up through the CB slot, but I don't know I would get it back to where it goes.
zeroready
 
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Re: My mainsheet block ripped off the CB trunk underway toda

Postby GreenLake » Sun Apr 25, 2021 5:26 pm

That's why some have chosen instead to make an adapter plate which can be screwed into the existing holes and is tapped for the new hole pattern.

I don't think that the metal plate is loose on the inside of the CB trunk. Instead, it is my understanding that it would be firmly embedded in a fiberglass "pedestal" attached to the CB trunk. At least on my boat, the mainsheet block sits noticeably "behind" the CB.

With a small multimeter, it should be possible to probe whether any or all of your new holes reached metal. Just insert the probes, or some wire attached to the probes into adjacent holes and check whether the resistance drops as both wires touch the metal plate.

That should tell you whether you have a plate and how far down it is (and whether any or all of your new holes are reaching it).
~ green ~ lake ~ ~
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Re: My mainsheet block ripped off the CB trunk underway toda

Postby zeroready » Sun Apr 25, 2021 5:51 pm

That's a great idea with the multimeter, I'll give it a shot. I looked down into the holes as best I could, I believe I can see metal down there. I think I really just need longer screws and I bet it will be fine. The only thing once I get it reattached, I may not know if it's solid until I get it out again the either it holds or it pops off again.
zeroready
 
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Re: My mainsheet block ripped off the CB trunk underway toda

Postby zeroready » Sun Apr 25, 2021 7:42 pm

OK so I put my multimeter into the new holes, got no continuity. I figured the plate was gone, but then I put the probes into the old holes and got continuity! So the plate is indeed still there. The problem seems to be that the foot print for the new block base is bigger than the old one, and I'm guessing when I tapped the new holes I missed the plate, that would explain why it was so easy to tap, I was only going through fiberglass just outside the edge of the plate. In the picture you can see the square footprint of the old base and the older small holes, while my bigger holes are outside that area.

Image

So I think I have to make the adapter, I have some ideas but if anyone has done this or knows where a picture might be in the forum, I would appreciate it! As always thank you again GreenLake for the advice!
zeroready
 
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Re: My mainsheet block ripped off the CB trunk underway toda

Postby GreenLake » Sun Apr 25, 2021 7:51 pm

I think this is the link to the post I remembered reading: viewtopic.php?p=30924#p30924
~ green ~ lake ~ ~
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Re: My mainsheet block ripped off the CB trunk underway toda

Postby zeroready » Sun Apr 25, 2021 8:14 pm

Excellent thank you, it looks like I will have to use that pattern and get a piece of aluminum machined, I think the plate underneath is the exact size of the old base plate, too small for my new block. Thanks!
zeroready
 
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Re: My mainsheet block ripped off the CB trunk underway toda

Postby zeroready » Mon Apr 26, 2021 10:48 am

I called Rudy at DR marine, he's a genius. He said just drill new holes in the new base to match the holes on the old one. Then I can just use the old screws and I don't have to tap new holes in the boat or make an adapter.
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