Wood under stanchion base plates

guydickinson

guydickinson

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On my quite old GRP sailing boat I have stainless stanchions and stanchion holders. These are bolted through a wooden plate and then through the deck. That's fine but a lot of the wooden 'under plates' (for want of a better word) are soft and green and need replacing. I'm not sure what wood they are but can anyone suggest what is a good wood for this? (Their thickness is tapered - thicker on the outer side, incidentally). Many thanks.
 
I would use plywood, less risk of it splitting when you drill holes through it. Seal up with epoxy and it'll last years.
 
Mahogany would be a good choice I think, resistant to rot and not as soft as teak.
 
Thanks a lot. The problem with plastic might be that its a bit difficult to plane? (It has to be thicker one end than other). I guess I will probably go the plywood route with epoxy.
 
Tufnol. Perfect material for the job. Will never degrade, can be machined as well as any timber, no grain, looks OK, can be varnished if you want, in keeping with the style of boat, stronger than any plywood or timber.
 
I have an inkling that polyethylene can creep under compression. Certainly it does under tension. I am considering buying the Poundland chopping boars as backing plates for small deck fittings, and also for use as "feed" for the techy heat gun for welding e.g. tanks on tractors.


EDIT a paper on creep details.

http://link.springer.com/article/10.1007/BF00738628#page-1


It might go some way to explain why polypropylene ropes can sometimes heat up under strain, and weld themselves into the original solid material. Happened to me when I was pulling a large oar tree up a medium steep incline when I had forgotten the wire rope; a small length about 150mm, wrapped round a circular winch bar just went solid.
 
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Presumably these bases have a tapered thickness so that the stanchions are not made to lean out, by the camber of the deck. That would seem to rule out the chopping board route. For the same reason, I wouldn't use plywood.
A good dense hardwood, such as teak or iroko would seem a good choice.
 
Can tufnol be bought easily enough? I did find a place online selling it but the prices were eyewatering, probably because it was in huge industrial sizes.
 
It's a while (decades!) since I fitted out a couple of grp boats.

In line with the advice at the time, I used use backing pads of thick marine ply, tapered as per your opening post, with a metal plate or large washers to spread the load from the nuts into the ply. The ply isn't going to break and it will tend to mould to any imperfections in the under-deck surface. If you use hardwood or metal you'll get stresses in the deck and spreader plate.

For the bolt holes you could consider drilling them oversize, filling them with epoxy and re-drilling. Any water getting in through the bolt hole won't get into the deck core.

Hope it helps.

Cheers
 
Teak, and if the deck camber is constant you can machine a long strip to the required thickness and angle and then mark out and drill the holes and (presumably triangular) shapes before cutting. That is how I did mine 20 years ago and they are still there!
 
PGC said:
It's a while (decades!) since I fitted out a couple of grp boats.

In line with the advice at the time, I used use backing pads of thick marine ply, tapered as per your opening post, with a metal plate or large washers to spread the load from the nuts into the ply. The ply isn't going to break and it will tend to mould to any imperfections in the under-deck surface. If you use hardwood or metal you'll get stresses in the deck and spreader plate.

For the bolt holes you could consider drilling them oversize, filling them with epoxy and re-drilling. Any water getting in through the bolt hole won't get into the deck core.

Hope it helps.

Cheers
Click to expand...

Yes, but the OP is concerned with the pads located between the stanchion feet, and the deck. Backing pads are different animals.
 
Kelpie said:
Can tufnol be bought easily enough? I did find a place online selling it but the prices were eyewatering, probably because it was in huge industrial sizes.
Click to expand...

I last looked for some on Ebay a few months ago. At that time there was a good selection of smaller pieces in a range of thicknesses. Just checked, many suppliers of small bits.
 
I used a bit of old close grained hardwood from the junk pile, coated in epoxy.
Two layers to make the thickness.
I think it was once a cupboard drawer side or something.

Tufnol is quite dear and not always great when kept wet. Also some sealants don't like it much.
It is machinable though, and wears OK for pulleys, bushes etc.

For similar jobs, I've used wedges made of GRP offcuts epoxied together.
(the bits of GRP I cut out to put in extra portlights have been incredibly useful....)
 
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