New Keelbolts

Dear All
My issue is how can I get a really tight fit on my replacement keelbolts. To explain: my keel stub is mostly mahogany, the floors and skins(s) kauri (good pine): there is a layer of teak below the mahogany, on top of the lead keel. The keelbolts are bronze and show just the beginning of corrosion in the area which was in the mahogany - but I have been advised to change them as (the argument goes) once corrosion has started it will continue. The boat was built (launched 1983) with epoxy glues and was covered with glass down past the top of the lead - in theory water-proof but the wood was indeed damp (I drilled down outside the keelbolts with an extended holesaw and therefore was able to smell and taste the sawdust). Now, when I find good stock for my new bolts (and am being told Stainless 2205 is the stuff to go for as no current bronzes contain enough nickel - at least whats available here in New Zealand) I want to seal them so that water will not pass up from the pockets (which I am not confident can be made waterproof except by somehow filling them with molten lead).

My original bolts were 19 mm or 7/8ths...what about buying 20mm stock and hammering that stock thru the lead, making a good "interference" fit (is that possible?) -or should I ream out to 20mm and use some goop along the bolts? The easiest way to fill the pockets is to use some epoxy and filler powder - any comments on the best?
One bolt was tilted somewhat so that the washer and the nut had to be ground down to make them flush to the lead - again I want to make it truly waterproof.


Comments please!!

 

dewatering the keel stub

This is to add to my original post....
I have drilled down thru the keel stub with an extended holesaw, which cut timber about 3/8ths wider then the keel bolts. Quite a bit of the timber I cut thru was damp (I think from timber leaking up the keel bolts but I don't know for sure), but apparently not yet in a state of decay.

Before I refit new keel bolts, I want to dry out the timber. When I pour epoxy down around the new keel bolts (using a so-called penetrating epoxy), I want to be sure I am sealing timber but not sealing in rot and even sealing in solvents etc.
So - I think I need to remove salt, as if there is any there it will stop wood drying out at all and will sit there waiting to suck in and hold water molecules (even if they are just from water vapour). I intend to wash the holes (by filling them with fresh water for say 30 minutes - by plugging the bottom of the keel bolt hole)....then?? what about filling the hole with meths to somehow extract the water which will have soaked into the wood ??? or using acetone?? I don't want to lock in such solvents (which I guess I will do when I pour in epoxy unless I have waited for days or weeks) unless I can be sure the stuff left in is benign as far as both the wood and the metal of the keel bolts are concerned.

Or should I just leave the holes as they are - -freshly-drilled - -and trust the epoxy to penetrate and to prevent future rotting and decay?

 

Random thoughts to get thread going, there are more than one ways to skin the cat.

Q. My original bolts were 19 mm or 7/8ths...what about buying 20mm stock and hammering that stock thru the lead, making a good "interference" fit (is that possible?)
-A. No

Q. -or should I ream out to 20mm and use some goop along the bolts? The easiest way to fill the pockets is to use some epoxy and filler powder - any comments on the best?
-?. pockets? I don’t think this would solve any other than the hydrodynamics, you should use sealant between the keel and the keelson, Epoxy or Sika come to mind

Q. One bolt was tilted somewhat so that the washer and the nut had to be ground down to make them flush to the lead
-?. I understand the washer being ground but the nut?

O. The boat was built (launched 1983) with epoxy glues and was covered with glass down past the top of the lead - in theory water-proof but the wood was indeed damp
-A. In theory yes in practice no, if the glass went round the hull and keelson and then the keel was bolted on, in theory this would be a bit better.

Q. I think I need to remove salt
-Opinion. You might try adding some salt it could be better to keep the wood moist all the time.

 

Hi Richard - -thanks for the input.
Maybe my reference to "pockets" was misleading - -I meant the pockets in the keel for the washer and nut on the bottom of the keelbolt (more or less halfway down the keel).
Your reaction to grinding the nut is a wake-up call - -I hadn't properly thought about the consequences before. I was just assuming there was enough strength all round to cover that. But filling and re-drilling maybe not be feasible - at least the additional strength from doing it properly might not be significant enough to justify dropping the keel. Am pondering that.

Your point about salt might be a pointer to the difference between true wooden boats and epoxy-wooden boats: I want to get the moisture content of the wood down to what is best for re-encapsulating it in epoxy. Maybe I have to get a moisture meter onto the job (ie, do it properly!) - -tho as the keel stub is maybe 8 inches wide I guess such a meter won't measure deep enough in to indicate the moisture level around the keelbolt holes, which is what I am concerned about.

In fact, it this encapsulating angle which worries me about using meths or acetone down the holes - I don't know whether remnant chemicals will be left and what action thay might have on the keelbolts over the next 20 years.

Amazing how much there is to all this!

 

Try http://nautarch.tamu.edu/class/anth605/File6.htm
It wasn’t the one i had in mind but with the key words you’ll find the info on was it a Hawaiian uni site, but the above is ok 2-->

Waterlogged Wood Conservation

Polyethylene Glycol (PEG) Method
Sucrose Method
Acetone-Rosin Method
Alcohol-Ether Method
Camphor-Alcohol Method
Freeze Drying of Waterlogged Wood
Silicone Oil Treatment

In the ACETONE-ROSIN METHOD you might forget the rosin and just let it be or acetone diluted epoxy instead?

What about puling the keel of and cutting of the glass that comes down it somewhat to the edge of the teak, drying it and glassing it over with epoxy way into the hull or wood keel, that should give you a dry bilge, at the same time it would make it easier to bore the holes in the keel to fit your new keel bolts.

If you use SIKA in between use a SIKA primer!
Epoxy with a hard filler might work better, have the bog whet when you lay the boat on the keel.

Are you sure your bronze bolts are corroded? they sound too new for that but anything is possible.

 

Good stuff - -thanks. Will work my way thru that stuff. I am getting more uncertain about whether my old bolts are a problem: they are just somewhat pink where they were in the mahogany part of the stub, and there are two or three hair-depth corrosion areas of less than a square inch each. I may have to get one cut in two to find out what it's like inside - shame if it turns out ot be OK!