Treating Rot in Wooden Boats.

[Casey]

Browsing through www.boatbuilding.com (a site dedicated to American Boatbuilding) I found an article headed 'Chemotherapy for Rot'. It advocates the use of antifreeze to proof wood against rot. It is worth a read although Cuprinol might take a knock!


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[Peterduck]

An American chap named Dave Carnell has esposed this treatment, but I personallly have my doubts about its effectiveness. It may work for some species but not for others. If there are any rot spores in the timber, it will not remove them, although I could imagine it killing those which are close to the surface where the treatment is applied. Rot spores do travel along the grain a considerable distance past where their effect is visible. I have successfully used antifreeze to prevent checking of the end of timber during seasoning. I applied it several times to the end of the log before conversion, and the resulting planks have seasoned well.
Peter.

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[mtb]

What would you use apart from glycol, creosote stinks .
The historic ships reg has some stuff including this which was from a seminar in the states
http://www.maritime.org/conf-sched.htm

I'm still undecided although as soon as I've repaired the deck I will start a regular pumping process to let the salt water do it's job, and help the timbers take up .
I cant see me getting the job done before winter and rain water wont do the hull any good.
cheers
Mick

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[Mirelle]

Not a good plan...

There is confusion between polyethylene glycol, used to stabilise ancient timbers in the VASA and the MARY ROSE, and ethylene glycol which is antifreeze, very sweet tasting, very poisonous and not much use at preventing rot!

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[OldGaffer]

I've used Cuprinol for years. Every autumn when the boat is lifted out we let the bigles dry out, then, while the seams are still tight, we slosh in a gallon or two of Cuprinol. We do the same again in March during the annual painting and decorating but are not quite so liberal with the Cuprinol because some of it seeps out through opening seams.

I can only assume this all works reasonably well because we have put in only three new bottom planks in about eight years. Topsides planks which do not get the same sort of treatment, do tend to rot more often and we have replaced 10-12 in the same time span. The boat is 93 years old. I have no idea how old each plank is though.

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[RCP]

For what it's worth, there is considerable support for ethylene glycol in Wooden Boat magazine. However, with a key ingredient added - Boric Acid. See "On the Waterfront" column in WB 123, 131, 160 and "Wood Technology" column in WB 110, 149, 152, and 159.

I don't have a link to post with this, but you can look up Pete Spectre's column, "On the Waterfront", WB 161, July/August 2001. Here, he references all the other mentions of this solution in WB, and gives a pretty good abstract to sum it up.

The key is combining Boric Acid with ethylene glycol into a solution. This is similar to the recipe in a number of commercial products that are used in building construction, agriculture, and ship building to combat wood destroying insects and fungi. Among them are Bora-Care and Timbor.

I have used the recipe that calls for combining ethylene glycol, boric acid, and borax into solution by boiling. It's quite easy, just be sure not to over cook. The gallon batches that I make keep indefinately (so far) without seperating.

The recipe I use is:
1 lb boric acid (available from thechemistrystore.com)
1 lb 4 oz borax (powder detergent)
2 lbs 4 oz ethylene glycol (anti freeze)
-Heat to a gentle boil
-bring to about 260 deg F (don't fight it. Mine tops out around 255)
(lot's of ventilation)

The concoction has worked for me, though I haven't clinically tested it. Most dramatically, it penetrates and kills rot quickly and thoroughly. I don't claim to be an expert, let alone an amatuer chemist. However, it is interesting to note the similarities of Carnell's concoctions to the commercial products. I would consider this a solid recommendation. It would be nice to see some testing data published. Maybe Practical Sailor could take it up.

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[john38]

If you look at the Wooden boat forums there's also a very large number of people who use a product called CPES. Clear Penetrating Epoxy Sealer buy Smiths in the US. It's not a traditional epoxy but a by-product from the timber industry. The theory is that it soaks into the wood (very deeply in areas where there might be some rot degradation - you've removed the really rotten stuff of course!!), and then forms a seal which allows wood to change it's moisture content very very slowly. If you apply it on dry timber then rot shouldn't be able to grow. It will also tend to reduce the movement of timbers so soaking up won't work - you'll need to have watertight joints before you launch your boat. Many people claim that CPES greatly increases the bond between the wood and your varnish or paint, so that you won't need to paint your boat as often.

The bad news is that it's expensive and it's not available in the UK - you've got to order it from the US, or from Scandinavia, and since it's got a high VOC content it will cost you a fortune in shipping - since it's ususally treated as hazardous.

The mahogany runabout fraternity in the US - seem to be very keen advocates of this product, and some of their boats have had thousands of hours of effort devoted to restoration and finishing.

John

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[Richard_Blake]

Ten years ago (just after purchase!), our surveyor found that our remaining original 1911 pitch pine planks (bottom three each side) were overly water-softened, with some wet rot. He recommended impregnation with something called Immac clear penetrating epoxy resin - which was apparently originally developed to impregnate concrete!

We had it done, and it has been very successful. It is NOT a complete moisture barrier, as a normal epoxy would be. There is still slow but sure moisture take-up and loss (just-visible shrinking at the moment after 4 weeks out of the water in our recent heat-wave). So everything has turned out more stable, and stronger. The planks are still traditionally caulked and stopped with red-lead putty. The wood behind the impregnation depth (grit your teeth and push the moisture meter prongs further in) has let go of moisture over the 4 weeks.

Unfortunately the only Immac I can find now on the internet is a brand of cosmetic. Anyone know if the stuff still exists under another name? or is it (was it) the same kind of animal as the CPES just mentioned?

In those days, we were naive but lucky. We were sometimes too quick to accept advice. With what we know now (agreeing with epoxy doubts earlier posted) we would probably not make the same decision, but go with drying out, Cuprinol, and impregnation with linseed oil, which on other bits we've treated hardens things up considerably. Immac worked, though, and extended the life of our garboards by ten years, and I reckon at least another five to come!

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[john38]

Richard,
This sounds very much like the Smiths CPES product. This has been used extensively for concrete impregnation. There is only one (finnish) distributor in Europe who sells it under the name LIGNU
Here are web references to this product
http://www.lignu.com/lignu/tech_info/concrete.php
http://www.star-distributing.com/smith/cpeswhy.html
if you want more detail go to the Smiths Web or the Rot Doctors web site.site
http://www.smithandcompany.org/

I'd be interested if you thought that these were the same product as you used.

Isn't cuprinol going to be banned soon - I've got a feeling it already is in the USA?.

Regards
John



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[Richard_Blake]

Thanks, John, I'll check out the sites. Not that I'm going to be needing it again, having had it ten years ago, as it were.....

Would be good to know if it's useful to others, though. Let's find some builders with left-over stuff, treat lots of off-cuts and soak them (not the builders of course).

Cuprinol banned? I'll have to find a way of getting back to the UK and buying up all available old stocks!
They'll be banning Clearasil next! Have a secret weapon, though. Ssh! A large tub of red lead powder I bought when it was still just legal here. I shall henceforth mix it with everything!
By the way, I know one should use red lead below the waterline and white lead above - but why...? Anyone enlighten me?

What's your poison, bottoms up and rot the regs!
Richard

('shcuse the flippancy - am alone in the house recovering a little alcoholically from a day's boat restoring....)

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[Gordonmc]

Red lead is cheap... but paste for caulking will leach through topside paint... so white lead is used instead.

One thing I don't know is why neat white lead paste is specified for the sterntube/deadwood void when you will never see it...

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[Mirelle]

At a guess, because it never goes off, out of contact with air? I removed a deck fitting bedded in it 48 years after it was screwed on and the white lead paste was still soft!

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[fishermantwo]

I have to agree with the use of the old style concentrated glycol antifreeze. I have a 57 year old commercial fishing vessel, still working. Hardwood frames with all the original oregon planking still. The only rot has treated very effectively with glycol, I just poured it into the damaged area and it was "sucked up". I then followed up with the recipe for a sealer off the wooden boat site.

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