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 Post subject: Re: T37 Centerboard is only 140 lbs ???
PostPosted: 13 Dec 2019 17:08 
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Skipper

Joined: 09 Aug 2017 15:35
Posts: 307
Location: Maine/USVI
Because of the distance from the aft end of the centerboard to those bolts, you want to be absolutely certain you've got that plate system in the exactly the right spot. For some reason, my board binds to port and the board is perfectly straight. I also started ruminating on a board-down passage to wind. Those bolts working and working, up the mountain, down the mountain, against nothing but epoxy filler. Would receivers bedded in appropriate West System spooge be an improvement? I don't know. But I can't picture how you'd "pin" those. Laterally?


 
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 Post subject: Re: T37 Centerboard is only 140 lbs ???
PostPosted: 14 Dec 2019 08:39 
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Skipper

Joined: 04 Aug 2013 13:33
Posts: 250
Yes, athwartship, a pin for each threaded sleeve. (Just did a MS Paint sketch that might describe it better). Regarding alignment, if the existing holes line up then they can be used when drilling out for the larger size for the threaded sleeve.

If they don't line up, a simple model of the centerboard (which only weights a few pounds and is easy to handle) can be used to position the pivot pin bracket and the bracket used as a drill guide (up to 3/8") and then the holes drilled out for the sleeve. Something like two 2x4 or 2x6 cut so their total width is half the centerboard thickness (at the bracket pin hole) less the 3/16" for that quarter sheet of acrylic panel leftover from an old project years ago. The panel is long enough to reach to the aft end of the opening in the trunk.

In your case though, the first thing I'd check is the hole in the centerboard. if it isn't true to the center-plane of the board, the end could contact the inside of the well in the up position, but if this is the case, it should not look aligned from all angles when down either.

By the way, 316 stainless may be better than titanium. Looking at McMaster-Carr, there is grade 2 which is more pure and has the best corrosion resistance in saltwater, but the properties are not quite as strong as steel. Grade 5 titanium alloy is much stronger than steel, but may not be as corrosive-resistant as 316 stainless. Also, bolts are available so there would be no need to tap rod material. I'm still shopping...


Attachments:
File comment: This may give a better idea of the bolt hole fix
Sketch of centerboard bolt hole repair.png
Sketch of centerboard bolt hole repair.png [ 23.95 KB | Viewed 0 times ]

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Dave Lorick
Lunacy #198
Tampa, FL
 
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 Post subject: Re: T37 Centerboard is only 140 lbs ???
PostPosted: 14 Dec 2019 16:33 
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Skipper

Joined: 09 Aug 2017 15:35
Posts: 307
Location: Maine/USVI
I like it, but being a shed (not even barn) carpenter, actually hitting that insert correctly with a bit drilling from the side just doesn't seem like a happening thing. If I was going to try to set six of those pins, I might step back and think about just doing a new hinge pin assembly all the way through, countersunk rings on the outside of the keel and pinned. A single piece of stainless or bronze bar or heavy tube. A way to remove it if desired. No need for the angle iron, six bolts into laminate, six pins, etc. It would make me feel better on a long passage to wind, to be sure.

And you might as well put those pins all the way through the bolt receivers in the laminate.

You may be right. My centerboard is straight and in excellent condition. But if that hole is off at all (apparently from manufacture if true), it would cause the board to pull one way or the other. After I gave the aft end of the board (pissed off) a couple of yanks, it dropped and retrieved and dropped again reasonably smoothly. Not a big confidence builder, though.


 
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 Post subject: Re: T37 Centerboard is only 140 lbs ???
PostPosted: 27 Dec 2019 17:25 
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Skipper

Joined: 09 Aug 2017 15:35
Posts: 307
Location: Maine/USVI
See the post about "WOW." The original pivot assembly was lag bolted into lead.


 
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 Post subject: Re: T37 Centerboard is only 140 lbs ???
PostPosted: 27 Dec 2019 20:15 
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Skipper

Joined: 04 Aug 2013 13:33
Posts: 250
When I first looked at the T37 I bought, the board was laying on the bottom (still with pennant run through to the clutch). I contacted Tartan regarding repair and they said to put bigger lag bolts in there.

When I repowered my old boat, I had a lag bolt in one of the motor mounts of the old diesel. How could anybody expect a lag bolt in laminate to be something sound..?

Regarding the pin to retain the bolt (that was tapped so it serves as a thread insert in the keel), it doesn't have to hit square; a nick in the side would serve the purpose to retain it.

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Dave Lorick
Lunacy #198
Tampa, FL


 
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