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painting a hull
Posted: Sun August 5th, 2007, 12:04 am
I have just finished stripping the hull of my boat down to bare wood. It's looking really good but I am a little bewildered about the array of paints. Can anyone please advise? Also, the boat is clinker built about 25 years ago but has never been in the water should I use some sort of sealent on the seams before painting?
Posted: Fri August 31st, 2007, 11:27 pm
I suspect you mean Carvel, that is planks joined edge to edge, rather than the over lapping of Clinker.
First off chose a paint manufacturer whose paints you can buy locally, Blakes or International etc and stick with one company.... Get their booklet, normally given away freely, giving painting guidelines, and abide by it.
Undercoats are much more important than topcoats! not unusual to have 10 layers under 1 layer of topcoat, if you count filler and sanding in between coats as well. I did 14 on Bluenose, back in 1980, the finish was staggering on the last coat.
A little trick is to mix topcoat and undercoat together 50:50 for one last coat before you topcoat. You will have to use conventional enamel too, not epoxy and 2 pot paint, as the wood will doubtless move, with moisture and drying in the sun...
Filling the seams.... Either you could use a flexible sealant/glue like Sikaflex, or you could glue thin splines of timber in between each plank using epoxy, and then overcoat with epoxy.. Difficult and time consuming, but if you get it 100% you could go on to have a very stable base for 2 pot paint... however, I would advise against. Go for Sikaflex or similar and a conventional system...
If after a year afloat the boat moves and the seams show, at least you can sand them off and repaint without losing much sleep, if you epoxy and it goes like that you will have spent a lot of money for little gain.
Looks like a visit to the chandlery coming on!
hope this helps,
Posted: Tue October 23rd, 2007, 6:23 am
And just as a belated postscript to John's comments, if the boat is indeed clinker rather than carvel, then you should not use any sealant at the laps at all. Whatever you put in there, once the wood gets wet and swells, will cause permanent damage to the timber.
Posted: Wed March 5th, 2008, 10:40 pm
Thank you for the very sound advice and sorry for not replying for so long. Mike's foot notes to John's comments make a lot of sense to me now after I read all about the renovation of a boat called Fair Rover. The restorer of this boat put the vessel in the water and let the tide go in and out of her until the planking took up. At which time, with the aid of some very good bilge pumps it refloated. .
Posted: Fri March 7th, 2008, 5:28 pm
Just a brief note regarding your planking seams. If they are completely open, you must first fill the gap with caulking cotton, taking strands of the cotton (available at most good chandlers) and twisting them together to make a "rope" that is slightly thicker than the gap in your seams. If you cant get hold of suitable caulking irons, Take a small wood chisel and shape the end on a grinder so it is no longer sharp and of a suitable profile to fit into your seams. press the cotton "rope" firmly into the seam at your starting point (usually at the stem) for around 3/4" along the length. work along the seam leaving small loops around 1 1/2" in length, roughly 1/2" proud of the hull. once again, if you struggle to get "irons", next profile a broad brick bolster to the correct thickness for the thinest of your seams and take the sharp edge off the blade. A slightly convex surface is ideal but flat will do. Using a good joiners mallet and the bolster, work along each seam (starting at the garboards and working upwards), gently hammering your loops of cotton into the seams until they are at least 1/8" below the surface but not hammered thru to the point where you can see the cotton inside the bilges! If you struggle to obtain caulking cotton, hanks of hemp (from most plumbers merchant's) can be used in a similar manner (at a push) as it is quite similar to oakum, which was used as caulking for centuries! plumbers hemp will swell in water (as will caulking cotton) and is treated with an addative to prevent it rotting when wet. When you have completed this, take some boiled linseed oil and thin it down with paraffin until it is very runny and paint liberally over your exposed planking, paying extra attention to the inner lands of the seams. This will feed the wood well, especially if your boat has never seen water and will stabilize the timber for "paying" the seams. I am not a fan of sikafex or any other "modern" sealants for this job. On "Zanzibar", I am mixing the following by weight: 3 parts linseed oil putty to 1 part red lead (if you cant obtain red lead, use a good quality OIL based primer/ undercoat), 1/2 a measure of linseed oil (boiled or raw is fine) to make a fine paste. If it is still a little "stiff", thin it further with a touch of white spirit until it has the consistency of soft(ish) butter. Use a broad, flexible scraper of putty knife to work the mix well into the gaps of your seams until it is slightly proud of the hull (it also works well filling screw holes). Once the mix has hardened off, gently fair the seams with a very sharp knife or broad wood chisel, taking care not to "undercut" into the planking. Souse the hull again with the oil/paraffin mix and allow to dry, sand the hull thoroughly with 120 grit aluminium oxide paper on an orbital sander. If you can get hold of oil based aluminised wood primer, thin this right down for the first 2 coats so that it soaks well into the wood. Try to apply the second coat whilst the first is tacky then allow it all to harden thoroughly. sand the primed hull again with 240 grit paper and if you notice any imperfections at this stage, use the mix described earlier to fill them out and sand flush before the next step, which is to build at least another 2 coats of unthinned primer, allow to harden off and sand with 320 grade between coats. now you are ready to apply 5 coats of a suitable undercoat of a shade that will suit your topcat, thinning the first 2 coats slightly, allowing each coat to harden and (as usual!) a light sanding between each coat. on the last coat before the enamel/ antifouling topcoat, mix in a small ammount of the enamel with the undercoat, strike through your waterline (slightly lower than the design if the boat is really dry), mask off and apply 2 coats of the primer/ topcoat mix. Sand with a 500 or 600 grit paper between coats at this stage. Apply 2 more coats of enamel (I agree that 2 pot paint is a waste of time, money and effort on a wooden boat) and only sand lightly after the first coat with 600 grade paper, just enough to provide a "key" for the final coat. once the final coat is fairly "tacky", gently and carefully remove the masking and (if the rest of the vessel is ready!) launch your vessel on a "half tide" mooring, monitoring how many pump strokes it takes to empty her out after each high tide. If you have been thorough with your "caulking and paying" she should take up pretty quickly (dont forget to replace and nip up your stern gland packings before launch if you have an inboard engine) After around 10 days in the water, "trim" your boat up with internal ballast (I use shaped lead blocks to fit the bilges in alongside the hog/ keelson) an re- mark your waterline. scrub off any light fouling, and sand the underside lighly. you can now apply 2 coats of antifouling below the waterline. All being well, you will now get away with scrubbing off and re antifouling each year and lightly sanding and re enamelling your topsides every other year for quite some time!
Sorry for going on a bit and if any of this sounds like "Teaching my Granny to suck eggs" I appologise but I am just passing on the knowledge I have picked up from growing up with and learning to sail and maintain (with traditional methods!) nice old wooden boats
Posted: Sun March 9th, 2008, 10:42 pm
Thank you for the very thorough advice. There is so much information that I will have to print it off. I will, however, follow it to the letter. I do know of a place where red lead can still be bought in Liverpool. Is the method you describe suitable for clinker built boats such as my three tonner or is it just for carvel boats?
Posted: Thu March 13th, 2008, 6:11 pm
I hope you got my reply via a private message. just a thought, if you cant get hold of red lead, some engineering consumables stockists (try arco) will be able to supply you with "red ochre" powder. It is used as marking when mixed with oil for scraping in bearings, metal to metal joints and flanges etc. This is basically red lead powder and can be mixed with your oil based primer to create a red lead primer. Happy restoring!!
Posted: Sun March 16th, 2008, 7:41 pm
I have a 24ft eventide built of solid teak. Your advise as above sounds awesome and just what I have been looking for. Many have told me to stay away from the old traditional method but that is what I want to use.
In New Zealand I can buy white lead paste and red lead paint.
What is the ratio I should mix the white lead paste and linseed oil putty. To thin the putty should I use raw or boiled linseed oil and I have heard that you also mix a small amount of engine grease with it, is that correct.
Any further advise you ahve that would assist me would be most appreciated either here or to my email. firstname.lastname@example.org