caulking/painting/launching

[Woodpile]

Hello all,

I would appreciate some advice about caulking and painting my new acquistion. It's 26ft of carvel mahogany on oak, that's been out of the water for a couple of years so the seams have opened - on average enough to poke a matchstick into.

Repairs to a few rotten planks are underway, and I'm hoping to have her floating by the New Year - but I haven't quite grasped the essentials regarding caulking and painting.

Before I leave her in a mud berth to take-up, should I rake out and renew all the caulking? And should I paint an 'undercoat' or antifoul? Or do I wait until after the planks have swelled again? Or do it twice!

All the 'old hands' in my yard recommend 'bunging in a load of Sikaflex' on top of my caulking, but do I really want my seams all gunked with this stuff? It seems like a bodge...

Any thoughts much appreciated!

Donny

 

[Strathglass]

What your yard sugests is correct. Irrespective of what you caulk it with, when the wood expands it will squirt the caulking out the seams. Before repainting you will have to remove the excess to get the hull smooth again. If you use Sikaflex this will be much easier to do.
Also, Sikaflex is easier on the planking than other materials as the wood expands and there will be less tendancy to pull out any suspect rivits. Something has to give.

Iain

 

[Woodpile]

Thanks very much Iain,

If I understand you correctly, it's a one-off job with the cotton and then sikaflex on top before she goes in the water for the first time. Apart from having to 'shave off' the extruded extra sikaflex when the planks swell, the job's (hopefully!) done and she should be ready for paint. Is that right?

One more thing, if you're still in the mood for indulging naive questions! The hull is very thinly coated with old rubbed down paint at the moment, almost bare wood in places. How much fresh paint should go on the hull before she goes in again for the first time? Or should I wait till she's fully taken-up before putting any fresh paint on at all?

Thanks again!
Donny

 

[EASLOOP]

Hi,
I am no expert but have quite a bit of experience in caulking etc. I am in the process of rebuilding a early 60's East Anglain Sloop. She is built of mahogony on oak with a laid teak deck.
I stripped the hull completely and after looking at the cauling decided to re-do that completely. I raked out all of the old stuff (it was putty) which was a VERY long and tough job - testament to putty as it had been there for 40 years. I completely recaulked with cotton and a mix of red-lead powder and linseed oil putty below the waterline, and linseed oil putty and white lead paste above the line.
Prior to starting I sought advice, and it was varied. However one bit of advice told me that Sikaflex type products do not always adhere well to old wood, even when primed at £30 per 250 ml. Also, when the planks take up the rubber is squeezed out cracking the paint. This is then trimmed off and repainted. Then during a spell of hot weather the above the waterline planks dry out and the rubber gets sucked in to the seam, cracking the paint again. The only solution now is to refill the seams with sikaflex, but then the planks get wet during the winter and the rubber gets squeezed out again - reminds me of a joke with a bucket of bricks? I had some sikaflex seams in my hull and I discovered that as she dried out so the rubber 'let go'. I could grab one end of the rubber in the seam and pull it out in a long strip. You try doing that with putty. Another point - stick some rubber on a blanket. When it sets you can rip it off in a single lump (might damage the blanket of course) however, put some putty on the blanket and see if you can pull it off in one lump - case of s*** sticking to blankets etc.
I hope to launch in the spring after 9 years of re-building, so she is really dry. Going to put lots of paint on her and see what happens. I'll let you know
Regards
John

 

[Mirelle]

I agree

My advice would be to rake out the seams. I learned, by watching a professional, years after I had done the job myself the hard way, that one can often get the hardened putty out quite easily with tool consisting of a handle and a small block of steel, about 1" x 3/4" x the typical width of the seam, welded onto a rod joining it to the handle. Place the block on the seam, pull with the handle, and tap it with a small hammer to start it each time it gets stuck. Quick and easy, far better than a bent file tang!

This leaves the cotton in place. If it is still good, harden it down and re-putty; if not, rake it out with a bent file tang (easy with no putty! and renew.

I share your unease about Sikaflex, after 12 years of trying to keep teak decks tight. 90% of it works - 10% loses adhesion and leaks - so what use is the 90%, which is holding on like a limpet?

After the first season the planking will have swelled up a bit and squeezed the putty out a bit. This (unlike Sikaflex!) is dead easy to scrape back to level with the planking, after which, assuming the boat's structure is OK, there will be no further developments for another 20-30 years or so.

 

[ianwright]

Re: I agree

Another vote for putty, with or without red/white lead ,it's better than sikkaflex on real plank on frame hulls.

IanW

Vertue 203, Patience

 

[nordic_ranger]

In the past I have used Putty on top of Cotton caulking and have found it to be successful. More recently I used a black material manufactured by Boatlife for use underwater on a friends boat this is a sikaflex type material for this purpose and desinged not to harden like Putty which you can paint or antifoul over. The boats been in and out of the water for the past three years and the boatlife material is looking good. In bygone days Tallow was used a lot when relaunching a boat rubbed into the seams from the inside if you had a leak to allow time for the wood to sweal and stop the leak. I don't know of any current sources for this material. Another old trick was to put fine sawdust along the seams inside the boat while it was still out of the water and wet it, this helped to swell the wood similarly old jute sacks were used for this purpose you could however use old sheets to do this.


I would rather be afloat than ashore.

 

[Strathglass]

Yes Donny what you are assuming is correct. I would tend to paint any primer and undercoat on first. You could also put a top coat on as you will only be touching up over the seams.
It really depends on whether you are cleaning the joins and painting it between tides or not.

Iain

 

[mtb]

Do International Paints do a paint suitable for painting in these cold temp's.
I think the putty has to be the way for seams .
I will be doing plenty of it shortly , can any one tell me where to get caulking from oh and just to confirm which type of putty is preferable to use .
This is for oak planking.
Cheers
Mick

http://homepage.ntlworld.com/boats
I need a couple of oak tree's .. for me trawler

 

[Woodpile]

www.tradboats.com seem to have most of what's required. Never used them myself, but I will unless anyone has any better suggestions?

Donny

 

[Woodpile]

THANKS!

Thanks to everyone all the advice. Very useful indeed - I think it's got to be putty!

Donny

 

[EASLOOP]

Above the waterline I used bog standard linseed oil putty mixed with white lead paste - 1 part white lead to 3 parts putty. If it is too stiff mix in some RAW linseed oil to loosen it up. Keep it stiff though or you will end up with very thick paint. Below the waterline I used the mix above plus a healthy amount of red lead powder so the mix turns a nice rich pink colour. I used cotton caulking, 6 strand stuff stripping off enough strands to fill the seam in question. Twist the strands together to the point when it just starts to coil up on itself. This can be a job as the cotton keeps getting into knots ?! Then hammer the stuff into the seam so it is firmly in place. Follow this with trowelled putty mix making sure it goes all the say to the cotton. Remember that when the planks take up they will exert a lot of pressure on the caulking and you do not want the plank lands to split. Wait 24 hours then prime the filled seams so as to keep the weather off - unless you have her under cover of course. In any event prime within 30 days of applying the putty. I get my stuff from Starbuck Chandlery in Gravesend, or from Coventry boats in , yes, you guessed it - Coventry. Numbers in the book.
Good luck and happy hammering.

John

 

[Mirelle]

a fussy detail....

Prime the seams before caulking and let it dry; prime the caulking before puttying and let it dry, prime the putty soon after applying (i.e. put a coat of primer on the whole hull!).

 

[mtb]

Owe you a mug of tea for that one and priming before must be a good idea to .
Cheers
Mick

http://homepage.ntlworld.com/boats
I need a couple of oak tree's .. for me trawler

 

[EASLOOP]

Re: a fussy detail....

Excellent point. I overlooked the fact that I primed the seams but I did so after driving the cotton. Also, my primer was made up by myself consisting of Red Lead Powder in BOILED linseed oil. Mixed up to a paint like consistency. After a respectable length of time I primed over the whole lot with a proprietery paint. Another point; I used two caulking irons, No 0 and No 00 although a curved one would have been a good investment as well. I used a regular wooden mallet to drive the cotton; this required some muscle as the mallet is quite light. The 'proper' mallet would have made life easier as it weighs 1 Kg. I know this sounds contradictory but a heavier mallet does its own work.

Rgds
John

 

[Guest]

Re: I agree

I share your views concerning the Sikaflex on teakdecks. Have you considered the Coelan? A sort of coating supposedly allowing the wood to breathe, but hopefully eliminating leaks. I consider coating my deck with Coelan after recaulking, but need to find people with experience when it comes to this product. Anyone?