Caulking

[Craigt]

I am about to re-caulk a 24' carvel planked Van de stadt with Sikaflef 291. She has been out of the water for about two years and some planks have opened up seams of 5-8mm. Do I need to try and introduce some moisture into the planking before caulking or half full the seam?
Thanks,

 

[miket]

I was told once by an experienced boatbuilder to cork as normal then launch boat and let the timber swell and push out surplus caulking. Then recover boat and remove surplus.

Seemed reasonably logical.

 

[Strathglass]

You certainly wont require to introduse some moisture as when you relaunch you will certainly heve to remove surples.
291 is a very good idea

 

[Guest]

5 to 8 mm!

The timbers must be bone dry or I hate be critical but she must have been very badly built in the first place! Assuming it that she wasn't built a buy a house chippy your best bet is not to caulk her immediately but to launch her and let a week's worth of tides flow through her for every year she has been out of the water. Then caulk her before repainting her topsides.

But then I'm a bit old fashioned in these things, there is probably a modern solution and long as it isn't too wet her down with a "Fresh" water

-{)>

 

[Craigt]

Re: 5 to 8 mm!

The 5-8mm are the few worst cases, mostly 2-3mm.
If putting in the tide first how long would you dry out for before caulking?
Thanks

 

[Guest]

This is where science meets art.

There is no rule of thumb on this. If you have a friendly would scientist he/she could probably calculate the absorb and rate off whatever natural reinforced plastic (wood) your vessel is constructed of and give a definitive answer.
The "classic" answer off course is you will know when you see it! (whatever that means)
The real answer is I don't know having spent my chart would pumping out vessels which had spent too long ashore fight got the feeling for the Formula I have already given you but.
But. But with everything to do with the boat's trial and error, especially error are the controlling factors.

If I was in your shoes I would be tempted to caulk with caulking cotton and white lead then put the technology into play and stray with SEA Water until the corking has stopped being expelled. A note of caution use the water in which she will be moored for the amount of mud/sand/(you won't mention it in polite company) will affect the expansion of the wood .

Beware the new inventions however good they seem in the short term the tried and tested method usually is in the long-term a far better bet. As long as off course you don't want a quick fix!

-{)>

 

[ccscott49]

Re: This is where science meets art.

It doesnt matter if you use salt or fresh water! Try putting sacks all over the planking, roughly sewn together, then get a pice of hose pipe, to go right round the gunwale/toe rail, make smal holes in the pipe, cnnect to a hose both ends and turn on the water supply, this will soak the sacks and the hull will absorb the water and the planks will then swell, you can then caulk, it is a technique used on hulls which have been out of the water for years in dry climates and extreme cold climates, both dry air! Try it. The salt fresh water thing is a falasy! Spores of rot will only grow between certain levels of dampness, wheter it is salt or fresh water it doesnt matter! They used to sink barges in fresh water, to preserve them when they had no work for them, why do hulls rot most at the waterline, in salt water, think about it! It is now a proven fact!

 

[Guest]

Sacking yes

Fresh water no under no circumstances freshwater will rot would 10 times faster than salt water salt keeps the boat fresh, ever tried to do the experiment of washing some of your bilges out with freshwater and some with salt water? Tthe fresh water once will smell of quicker than the salt water once. Fresh water should only be used for cleaning the salt of the bright work.

-{)>

 

[Mirelle]

Gosh, I\'m going to disagree!

L. F Herreshoff, in either "The Common Sense of Yacht Design" or "The Compleat Cruiser", recommends rinsing the whole of the inside of the boat with fresh water, using a hose, at laying up time, then lighting the coal stove to dry her through again. His point is that it is the tiny crystals of salt which are carried into the boat through the season which attract the damp and which keep her damp and smelly.

I used to have a mortal dread of fresh water, but some years ago I put the above advice into practice. Nearly everyone who comes aboard remarks on how fresh the boat seems, and I have no mildew, etc. problems.

The one thing that will make bilges smell really foul is soapy water; whatever you do, never leave soapy water standing anywhere!

 

[Guest]

Salt verses fresh.

As you say dried salt water will absorb water and keep damp encouraging mildew Etc
Freshwater when the left will go green and stagnant and Snell to high heaven.
For wetting down a conventionally built (carvel or clinker) boat Stanger and water line about will induce rot where a little salt will keep the clanks plimd up.
When you are washing out the interior of a vessel one assumes that and I am certain this is the case with Mirelle
that the pain work and Polish work are sound enough to not let the fresh water penetrate the wood, again when laying up his is a full body skipper who leads a boat with any damp in her. But when washing out the bilges on a regular basis during the season it is easily possible to leave a small puddle of freshwater lurking.
Again the same applies for soap wonderful staff at long as you can guarantee true remove all traces after it has then his work, otherwise the smell is, shall we say "interesting"

-{)>

 

[ccscott49]

Re: Salt verses fresh.

Are you trying to tell me fresh water rots wood and salt water doesnt, just to clarify this point, before going further?

 

[Skipjack]

Re: Salt verses fresh.

Strewth, Symbol, have you been at the sauce?

I'm clutching at straws a bit here, but a few years ago, in the Tell-Tales section of CB, there was a reference to the wonders of anti-freeze as a timber preservative. I recall that it was an interim announcement from someone who was conducting long term tests, and the editor of the time assured us he would stay on the case. There was a letter or two debunking (I think!) the use of glycolwhat'sitsname, but nothing since. The thrust of the piece was that if one squirts antifreeze onto bare timber inside the hull (possibly exterior, too), it wouldn't require further treatment, or it would stop the timbers drying out ashore. Something like that.

Perhaps, if the editor looks in here, he could check the mag's database, and possibly do a follow up. Always one for a conspiracy theory, when nothing was forthcoming, I conjured up images of Marine Paints R Us PLC nobbling the editor before we realise that all we need for a maintenance free century is a couple of coats of Liebfraumilch!

 

[Stemar]

Re: antifreeze

Have a look at http://boatbuilding.com/content/rot.html.

The timber treatment seems OK, but it's highly toxic, so think long and hard before applying his treatment for rotten toes!

 

[Mirelle]

Re: Salt water versus fresh.

Well, in a way, yes. The higher osmotic pressure of salt water as compared to fresh certainly seems to discourage some types of rot. One does not find many boats with rot in the actual bilge sump. The skeletons of old boats laid aside in creeks seem to rot from the top down, leaving the keel and the checked in timbers like a giant fish bone.

The more concentrated the solution, the better, it would seem (which is why some wooden fishing boats had handfuls of salt chucked into their nether regions and some US built wooden trading ships even had salt stops and salt boxes).

Now, having got that off my chest, I actually agree with your earlier posting; it is the critical level of dampness that does the trick and from that point of view it does not really matter whether the source of damp is salt or fresh. <P ID="edit"><FONT SIZE=-1>Edited by mirelle on Wed Nov 28 17:43:03 2001 (server time).</FONT></P>

 

[Mirelle]

Sauce and polyethylene glycol

Symbol's owner uses voice recognition software when posting; sometimes you need to interpolate.

Polyethylene glycol is the very expensive stuff that the "Vasa" and the "Mary Rose" are preserved with. This leads to occasional speculations that ethylene glycol, ordinary antifreexe, would have some preservative qualities.

There are two serious snags to this; firstly it is toxic but sweet tasting, so children and pets kill themselves by licking it. Secondly it dissolves in water (otherwise why put it in your car radiator!)

 

[ccscott49]

Re: Salt water versus fresh.

Now, then bilge sumps are often full of water, so relative humidity too high! Salt thrown into the nether regions, is a fallacy as I said before, they used to pack salt behind linings in old ships, did that stop them rotting? No it didnt. The ships you see with just the ribs sticking up etc, are one of two things, in the splash zone, ideal rot conditions, or more often, eaten by wood borers etc, weakened then pounded by waves, until they disapear. This is not speculation, but actual fact. I will get hold of the thesis done on this phenomonen and let you know how to get it or get it to you! Think it was done by/for Mystic Seaport museum.

 

[Guest]

My voice dictation apologises

I don't know why but boats kept ashore in a rainy climate tend to rot far quicker than those kept in salt water. those that are kept under cover or ashore in a dry climate do not qualify.
The obvious conclusion is that salt water helps reduce the tendency to rot although no truth is probably that depending on the material, (type of wood) and the rate of rot depends sum woods prefer to be kept wet in fresh something salt and some not wet at all. As far as I know nobody has done a study on woods verses for rot rate verses conditions as experienced by yacht hulls. Or perhaps they have?

-{)>

 

[Mirelle]

Durability

I don't know of any definitive study. The Royal Navy did a great deal of work on the longevity of wooden hulls when it was a matter of National Defence - in 1815 the RN was reduced to its "peace time establishment" and the number of men in the service dropped from over 100,000 to about 15,000. Most ships were laid up. But experience in the 18th century showed that laid up ships rotted - could something be done? The solution was to build ships in India out of teak, sail them home, usually with a "kit of parts" for a sister ship aboard as cargo, then lay them up under a full length roof to keep the rain out. HMS Unicorn (Chatham, 1826) in Dundee is still under her roof and HMS Trincomalee (Bombay 1817) in British West Hartlepool was teak built - both are "Leda" class frigates.

You are certainly right, boats laid ashore and exposed to rain fall apart fast. Boats stored under cover fare much better, and we can conclude that the commonest cause of rot in yachts is rain water. Keep that out and you are probably OK.

 

[ccscott49]

Re: My voice dictation apologises

Please read what I said again, if the humidity allows (rain etc.) the wood will rot, most boatbuilding timbers. Wood that is kept wet ie. submerged, will not "rot" in fresh or salt. In rainy climates the wood is in ideal rot conditios, if it were salt water rain, impossible I know, but have you seen what happens to wood constantly in salt spray? ie, docks, yes it rots, I'm still looking for the study, I will have to wait until my brother returns from offshore, he has it. Timbers are tested for their durabilty by doing just this, they are put in the ground, ideal rot conditions and then it is seen how long the timber lasts. ie, teak, extremely durable, etc. In the meantime I think I will keep quiet.

 

[Guest]

I wonder whether we are barking up the wrong tree!

Granted wood kept constantly under water does not rot, nor does metal corrode when kept dry metal has not corrode nor wood rot, the constituents which gets metal to corrode is the right humidity with the right amount of oxygen, I wonder whether wood requires oxygen and damp to induce rot like metals oily would tends not to succumb as easily as a un-oiled material. Salt of course will attract damp and may keep would just damp enough to stop rot starting where the lack of salt allows you would drive out just enough to start rotting?


-{)>