PDA

View Full Version : cpes & keel bolts



Stan Derelian
08-02-2001, 10:06 PM
If cpes was poured into keel bolt holes that go thru floors into a wooden keel, would its water barrier properties isolate the bolts electrically after it was absorbed into the wool and cured? Just wondering.

RGM
08-03-2001, 09:30 AM
I've been looking at your question, pondering it for awhile. Here's what I've come up with. NO. First of all, what exactly are you trying to do? Is this new construction or repair? Does the boat in question have an electrolysis problem now? Or are you planning on having one? What are the keel bolts made of? What material are the rest of the fasteners (plank to frame, frame to floor timber, etc.) made of? Are you thinking that this is a good preventative maintenance step? CPES'ing or flat out epoxying keel bolt holes won't do anything for electrically isolating your keel bolts. It will interfer with the ability of the wood to tighten up around the keel bolts if and when water reaches the bolt holes, thereby giving you leaks that wont want to go away as the boat takes up. Not a happy ending to a repair story. If there is an electrolysis problem try to identify the source and cure it. Spend less time and money attemting to cure/fix the resulting symptoms. Good luck.
Hey Chemist, where have you been? You all right?

paladin
08-03-2001, 12:21 PM
I attacked the "problem" slightly differently, although my boat was new construction about 8 years ago and before I had heard of CPES. I drilled the bolt holes about 1/4th inch oversized to start with. then purchased some glass epoxy "pipe", fire retardent, with the same inside diameter as the keel bolts. My keel was laminated up using a low viscosity epoxy before buttering up the glue stuff. Then....I saturated the bolt holes with low viscosity resin....and after it was pretty much set I inserted the fiberglass pipe in the hole. The pipe had been scored and well coated with resin before the insertion. After the resin set, I cleaned everything off flush. The outside of the hull had 4 layers of e-glass on the bottom. I then attached the keel using bedding compounds and used bedding compound under the backing plates inside the boat. After eight years it still seems solid as a rock and no leaks. I do intend to use CPES in a similar manner on the next boat.

thechemist
08-03-2001, 05:15 PM
Here I am...I just now noticed the Bat-Light shining on the clouds. I have not been gone recently, I've actually be not-quite-lurking...there have been a few attractively amusing threads over in miscellaneous......and not much in the way of chemical problems here, and, well, you know how it is...

There was something a while ago about CPES and wood and electrical resistance and electrolysis...lemme see if I can find it.

Ah, yes. this: http://media5.hypernet.com/~dick/ubb/Forum1/HTML/000658.html

Naturally, it follows that you would not want to try this in waterlogged wood......it would have to be something dried out enough that there was open porosity in the wood, but it looks like this would work. Remember, ther are no absolute elctrical barriers. It's all relative. Paladinsfo has certainly got the right solution for new construction, but it is often difficult to rebore old holes for sleeves in old boats.

Bob Cleek
08-03-2001, 08:39 PM
From reading Smith's product literature, and from first hand experience, CPES is permeable and not waterPROOF. Wood soaked in CPES does swell up the same as wood that isn't, but it takes longer because of the CPES barrier, which is waterRESISTANT. (Remember the water resistant watches they used to have?) It's really the relative humidity thing more than getting wet and waterlogged. CPES breathes, but doesn't swallow. Actually, I'd think that it might be a good idea on new construction to stick a cork in the bottom of the keel bolt hole and pour CPES in until it won't hold no more. Let it sit for an hour or so and then drain the excess out. Sure would take care of all that exposed end grain. I'd let it dry real good before trying to drive a bolt, though. And, if you had a tight fit, the friction heat could gum up the whole shebang and well... can you tell this is a stream of consciousness post? LOL Call Steve Smith and ask him. Inquiring minds want to know!

Concordia41
08-04-2001, 04:29 AM
Thanks Chemist - that prior post perfectly answered a question I hadn't had time to research.
-M

Thad
08-04-2001, 06:18 AM
What do you do if you later want to replace your keel bolts?

thechemist
08-04-2001, 01:54 PM
I would think a loose enough fit to let a bolt drop in would let it come out. There are flap wheels with quarter-inch shafts, and shaft extensions for electric drills, and one should be able to make an extension for a small 60-grit flap wheel and sand off any bumps on the inside of the hole to where the keel bolt that came out would go back in, or a new one anyhow.

Naturally, one would sand the holes clear before toughening up the wood with that CPES impregnation, rather than after.

None of this wil glue a keel bolt in, so it can come out when you want it to.

If you assume the inevitability of an empty space below the waterline filling with water, due to diffusion and condensation if nothing else, then hang a small piece of teflon tubing down in the 1/16 inch radial gap on each one, and use a syringe and 14 gauge needle every once in a while to suck out any condensation that accumulates.

Paint the keel-bolts with a corrosion-inhibiting epoxy primer/topcoat system, and they will not rust.

If that isn't bulletproof enough, you could continuously flush the void spaces with dry nitrogen, made from a pressure-swing-absorption system and a refrigeration unit to give you bone-dry nitrogen for the purge gas, but that might be a bit much for some.

On the third hand, Monel keel-bolts wouldn't rust.....

Incidentally, Acme threads [the square ones] are much stronger than conventional threads, so if you have to have custom keel-bolts made at your local machine shop ask them to cut Acme threads and make you matching nuts.

steve sparhawk
08-04-2001, 10:09 PM
Funny you should mention that about the nitrogen, Chemist.
Folks around here in South Dakota have been using that very same method in their prairie schooners for years with not one single recorded failure. (of course they may have actually picked up that tip from one of your older posts)

NormMessinger
08-05-2001, 11:15 AM
http://media5.hypernet.com/~dick/ubb/smile.gif http://media5.hypernet.com/~dick/ubb/smile.gif http://media5.hypernet.com/~dick/ubb/smile.gif http://media5.hypernet.com/~dick/ubb/smile.gif http://media5.hypernet.com/~dick/ubb/smile.gif http://media5.hypernet.com/~dick/ubb/smile.gif http://media5.hypernet.com/~dick/ubb/smile.gif http://media5.hypernet.com/~dick/ubb/smile.gif

Stan Derelian
08-05-2001, 05:17 PM
Thanks for all the replies. Even the smart-ass ones.
It is an old boat that has had all the frames replaced using silicon bronze screws. Lots of sealing with red lead and cpes where appropriate---just about every surface. However, the big expense of s/b lag bolts for the floors and keels made me think about other possibilities. Based on the chemist's and other's replies I might experiment and try this, checking the bolts next year, and replacing if there are bad signs.

Thanks again, and don't feel that you can't add more here if anyone has good reasons to not try this.