Wood treatment - clinker boat

Christopher_B

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The previous owners of my Kestrel 22 had her for 40 years. They kept her ashore in the winter and treated the interior of the hull, which is unpainted, with a mix of wood preservative mixed with some sort of wood oil. All the timber is completely sound, so their method obviously works.

I want to keep the boat in the water all year round, antifouling and repainting on the scrubbing posts between tides. Wisdom has it that clinker boats are best kept wet. But there's always water in the bilge - a few pints get in between visits every couple of weeks. So the keel and lower ends of timbers are now well-soaked and likely to stay that way. Other wisdom has it that wood shouldn't be left completely soaked or it will certainly rot.

Obviously I can't treat the wet bits with preservative and oil. Is the only solution to go back to drying out for a few weeks each year?

Any ideas please!
 

trouville

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To late now but i would have used linseed oil diluted 50%,wood preservative is carcergenic,and having used it you will be inhaling it long after the smells gone.

A wooden boat takes up water,its a good idea to take it out from time to time,though the paint and under coat protect the wood,on mine i had just a small part of a plank that took up water and was clearly wet. i cut that out and now have no problem.

I heve left mine in for over two years when i wasent moving much nor fast and the then TBT antifouling worked well the weeds would fall off and apart from green weed about 3/4 cms around the waterline and about a 2 feet down she stayed clean. In the end i only took her out when the antifouling had been rubed away after 5 days she was quite dry again.

If planks are saturated you may have a problem as wood is made uo of what looklike long straws together, and the harder the wood the thiner,it also depends on how oily the wood is,its a combination of both and why teaks not the very best in terms of rot.Good though!!
 

Christopher_B

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Thanks for that. Yes, I know wood preservative is carcinogenic, but hopefully it won't be a threat now. She was last treated (not by me) two years ago and dried out thoroughly after that and before I bought her. Since pressure-treated construction timber is supposed to be OK so should the boat, though I'll have to be strict about using a mask if sanding or cutting.

I doubt anything is saturated at the moment - she's only been in the water a few months. I used to keep my first boat in the water two years at a time, but she was carvel, edge-glued mahogany and the bilges stayed dry.

I get the impression that clinker boats always take in some water, and have heard it said it's no bad thing, but how long before the wood does get saturated and is rot then inevitable? /forums/images/graemlins/confused.gif
 

Mirelle

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I don't think rot occurs much in saturated timber; timber that is rather wet, as opposed to saturated, would be more at risk I think, but in any case rot in timber that is in salt water is not very common, though in fairness bilge water is usually brackish rather than salt.

Rain water is the great destroyer of wooden boats!

Do you have a cockpit cover fitted?
 

Christopher_B

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[ QUOTE ]


Do you have a cockpit cover fitted?

[/ QUOTE ]

Yes, and there aren't any deck leaks to let rainwater in, so I'm fairly sure the bilge water is salt. The main or only source seems to be a slow weep from the joint between the centreboard case and the keel- no surprise there.
 

Christopher_B

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I just found this at

boatbuilding.com

[ QUOTE ]
I have a simple flat-bottomed skiff built of plywood and white pine, which has little resistance to rot. After ten years some rot developed in one of the  frames. It may have begun in the exposed end grain. It consumed the side frame, part of the bottom frame, and part of a seat brace fastened to the side frame.  The plywood gusset joining the side frame to the bottom frame was not attacked. I excised the rotted wood, saturated all with ethylene glycol antifreeze to kill all the rot organisms, and there has been no further deterioration in four more years afloat with wet bilges. I have not replaced any pieces, as I am building another boat that can replace it; that is more fun, anyway.

[/ QUOTE ]

Glycol is used I think for preserving saturated remains of wrecks such as the MAry Rose. Apparently glycol penetrates 40 mm into wood even through paint or varnish finishes and is non-toxic (unless ingested in large quantities). It is however very soluble in water and so would need replacing or protecting in aeas below the waterline.

It could be that treatment of the entire interior with glycol and then occasionally drying out the bilges and soaking them in fresh glycol would be the ultimate answer to rot prevention?

I wonder if anyone else has tried this and with what results?
 

Mirelle

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Not the best plan

There is an extensive discussion of both ethylene glycol (antifreeze) and polyethylene glycol (PEG, as in Mary Rose, Vasa, etc, not same stuff!) in the archives of the Woodenboat Forum. Hope no-one objects to my mentioning AN Other Magazine here, but the subject is too big to cover adequately here.

Basically, it would not work and you might poison a pet or a child in the process.

Ethylene glycol is highly poisonous but tastes sweet so childen and pets will lick it - and die. But aside from that it will leach out instantly.
 

Christopher_B

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Re: Not the best plan

Thanks for the tip about the Wooden Boat Forum. HAving read much of that debate as well as some other literature on EG, I agree with you that it's probably not the best plan. However, IMHO the reasons are not quite as you state them.

EG, with or without additives, is a very effective preservative and is retained in wood for substantial periods. Even in wet bilges it is thought that it would have 'half life' of tens to hundreds of days.

Although toxic, it requires ingestion in quite large quantities - spoonfuls or cupfuls- to be lethal. I suppose if children or pets were allowed to lick the boat long enough they could be at risk.

EG/borate combinations are in fact marketed as 'green, safe' alternatives to conventional wood preservatives. Like many products used on boats, if you drink them enough of them they'll kill you (make mine a triple!/forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif) but once applied they <u>should</u> be safe.

HOWEVER - what now seriously worries me (and it's only briefly addressed on the Forum) is evaporation. EG doesn't evaporate quickly, but some scientifically endowed correspondents calculated that in an enclosed and poorly ventilated cabin it would be possible to get more than the safe maximum exposure in only a couple of weeks sleeping on board.

We're not talking lethal doses here, just safe limits. All the same, prolonged exposure by inhalation is very dangerous because you're unaware of it. I can resist licking the boat but I can't help wanting to breathe sometimes.

I suppose in the end the question is whether treatment is necessary at all. I only raised the question because of the obsessive care the previous owners of 'Leda' took to soak her in preserative every year, with apparently great results. But maybe she'd have been just as sound with just a good dousing in linseed oil from time to time.
 

Mirelle

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Thanks. I stand corrected.

I reckon that linseed oil, perhaps cut with paraffin, does just as well, and has the added benefit of dimensionally stabilising the wood.

The poster girl for this treatment is "Fanny of Cowes" which was saturated with linseed oil when she was built in the 1850's.
 

Christopher_B

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And many thanks to you too

A very helpful exchange - much appreciated and I learnt a lot.

So it's linseed oil and paraffin, then. Linseed oil has a clean bill of health. Paraffin also seems pretty safe though a good airing wil be needed. Still leaves me with the question of when and whether to dry her out to do the bilges but perhaps I'm being too anxious about this. Leda was the centre of the life of Thelma and Alec (who fitted her out from a bare hull) and was sold to me reluctantly only because of Alec's death last year, so I'm feeling more than ordinarily obliged to do right by her and them. Perhaps a lift out every couple of years is the best compromise.
 

Casey

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Re: And many thanks to you too

One thing that I had to do on Kala Sona was to clean all the limber holes out. The previous owners had taken a dog with them on their travels and the resultant hairs dropping into the bilges making a fine filter in the waterways which soon blocked up resulting in pools of water where the channels were blocked. It took me a week of having to strip off in the garage before my dearly beloved would let me into the house the stench was so bad. All holes now clear and the bilges are well painted. I still spray cuprinol into all of the places I cannot easily reach and, most important thing of all, ensure a through draught of air.
 

Christopher_B

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Re: And many thanks to you too

Reminds me of a Tupperware boat I joined that had been left for some months in a very hot place. Below smelled like something had died there. A detailed search eventually located a poly bag with something dark and slimy in it, leaking evil fluid into the bilge. Contents were identified (just) as potatoes. Despite vigorous cleaning, the smell never left the boat for the five weeks we were aboard. The juices seemed to have been absorbed into the hull material.

Well, Leda's limber holes are OK and there's always a through current of air, so I hope that will be enough. There's not much else I can do really to keep the bilges drier when I'm not on board, except perhaps try to tackle the classic centerboard case leak next time she's out of the water.
 
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