Hi,
I'm in the process of re-varnishing my boat at the moment too (see the "to epoxy or not to epoxy" thread for more info.
For sanding, I would recommend you do it by hand, as the veneers are rather thin and you dont want to take off any more than you need to. Strip it with a good quality paint stripper, then wash out with white spirit or meths to neutralize the stripper. Sand back with an 80 grit then a 120 grit. Treat any black staining around screw holes with an Oxalic Acid based wood bleach (Liberon Wood Bleacher is one, but there are others). Repair and fill any damage ... SP or West epoxy is the stuff to use.
Finally rub back with 240 grit. I cannot stress enough, WITH ALL YOUR SANDING, ONLY EVER RUB ONLY ALONG THE GRAIN. A careless stroke with the sanding pad across the grain means you will have to sand it again, removing yet more veneer. In my opinion, rotary or orbital sanders have no place in preparation of fine wood like this, its a relatively small area, and a few afternoond of pottering about will have it done. Try not to think how long it will take to sand it back, think of the hours of skilled craftsmanship that went into building the boat, and it deserves a few afternoons with a sanding pad and elbow grease.
I am then epoxy coating mine, as it gives a protection and stability to the wood that you just don't get with varnish alone. On top of that will go several coats of two-pack polyurethane varnish. I'm using International Perfection Plus (about �38 for 750ml) .. not cheap, but there again, you do this once. The concensus seems to be to roller apply the coats and then lightly tip-off with a soft brush held at 45 degrees.
Theres a series of excellent videos on Google by International paints on how to apply paint to a hull ...
http://video.google.com/videoplay?docid=8091370633544497560#
About 80% of your time should go on preparation. Sand, fill, repair. The varnish will show any minor imperfections up and make them worse rather than hide them, so get that surface every bit as good as it needs to be.
Apat from that, all I know is I am yet to apply my varnish, I'm still sanding and will be for several days yet, but its worth it :)
Posted: 07/04/2010 23:06:53 By: Robin Szemeti |
Hi Steve,
I apologise in advance for the essay.
What you about to start is immensely rewarding. But it could be quite a big job if your fussy. I started a similar project 4 years ago on a similar age boat, without much idea. My plan was a quick coat of paint and then off you go, the boat looked pretty sound, I sailed it a few times, but it did leak.
The thing is, the more paint I stripped the more I thought, that doesnt look strong/right/like I want it, and kept cutting the nasty bits out until I found good wood. Before I knew it, no paint, no center board case, no deck, no transom, no thwart, just a few hull planks.
The reason it took me so long was two fold, I was unprepared to take the plunge and agree with myself to undertake some quite drastic repair work, such as replace side decks, then when I decided to do so I went mad, partly because my salary doubled in the time frame, partly because I was becoming much more capable. I decided to deck step, repair a snapped carbon mast, one string etc etc. See: http://www.facebook.com/album.php?aid=83656&id=564343407&l=5526308762
All in my humble and possibly ill educated opinion:
Assuming you are only going to repaint. As far sanding goes, you'll probably do quite a lot, so go buy one roll each of 3M sandpaper in grits 80, 120, 240, 320. It s not worth skimping on sand paper, its a false economy if you put a price on your time.
For decks its very easy to rip through the top laminate with a belt or orbital sander: use with extreme care and prior practice, I would try a hot air gun and 2" chisel sharpened to perfect edge then blunted slightly. Get most of the volume of epoxy/varnish off this way then hand sand. Hoover up the dust. degrease with acetone or SP solvent A. wipe down lightly with a tag rag to get rid of any remaining dust, then 2 coats epoxy (preferably wet on tacky). When cured wash down with slightly soapy water to remove amine residue from the epoxy, sand smooth finishing at 240 grit, 2 coats epiphanes 2 pack PU varnish. Done.
Hull inside and out, strip as above and sand. fill any holes with epoxy/ microballons. 2 coats of epoxy (SP320), 2 coats 2 pack PU paint, such as Serene paints 65 line.
As you start stripping back asses rot and weakness, especially in load bearing areas, around self bailers, deck eyes, shroud anchorages, rudder fixing, the plank next to the keel etc etc. If your concerned fix early, be bold. Its much easier to do before painting, which is expensive and takes a while. All bonding/ filling do with epoxy (SP106), buy some scales that are accurate to a gram and some plastic half pint glasses to mix in. Dont under estimate how much epoxy you may use, 1Kg packs dont go far, but they dont keep well either.
Good luck, it is worth it.
Posted: 07/04/2010 23:38:45 By: john |
It reminds me of my first DIY attempts ... moving a sink a in a bathroom and fitting a new bath ... tried to re-use the old plumbing and not disturb the tiles ... as both seemed jobs beyond me ... of course in the end, after messing about tring to fit modern 15mm taps to imperial pipe etc, ripped the whole lot out, including all the tiles, and started from scratch. It is in the end a lot easier. Same seems to apply to boats, rather than messing about trying to patch a bit of flaking paint, its often actually easier and more effective to strip the lot and start again.
Posted: 08/04/2010 10:46:19 By: Robin Szemeti |