In a previous post I highlighted differences in attitudes
towards doing up an old boat. Preservation, Conservation or Renovation. A good
friend and well respected reader and a blogger in his own right, (The Unlikeley Boat Builder) suggested that in my case 'prevarication' might
be more appropriate term. He might as well have said ‘Just get on with it why
don’t you?’. I can take a hint.
So, the last few dry days have been spent taking home every bit of moveable wood from the boat (to sand and treat in relative comfort) and working on the
rubbing strake to try to improve and protect it before the worst of the winter
comes. The original manual for the boat describes the wood as ‘African
Teak’ and further research on the internet suggests that this was a euphemism
for Iroko. According to the internet, it is a teak-like wood but slightly
courser and more brittle.
The rubbing streak was sound but dirty and neglected so I
opted for sanding to begin with and I was pleasantly surprised how little
effort was required to get back to new looking wood. I used a Boch detail
sander for this job with 80 grade sandpaper to get at the worst, followed by 120
grade to smooth it out before applying a preservative.
Firstly a few comments on the Boch. This is my third sander
in as many months – in renovating the house I have used and burned out a Black
and Decker and a McAlister. For the boat therefore I chose to spend a little
more money in the hope that the increased investment would pay off through
longer life. So far so good – although already I’ve had to replace the sanding
pad. Maybe I’m doing something wrong. I’ll keep you posted.
Having got back to clean wood the big question had to be
about the choice of preservative. There is a good deal of literature suggesting
that varnish is not good with teak or teak-like woods. They’re too oily and
varnish won’t adhere, so the argument goes. On the other hand, there seems to
be an equal number of people who advise against oil coatings – according to
them, they don’t last and they don’t produce the mirror like shine you can get
with varnish. Others, long distance voyagers in particular, suggest avoiding all
oils and varnishes in favour of paint which is a much tougher coating. So what
to do? I was especially confused because yet another school of thought suggests
that if you really want to preserve wood you should epoxy it as a kind of GRP
sheathing.
In the end, I decided that for this year at least, I would
use a variety of techniques and then, having found the best one, apply that
technique everywhere ‘as and when’ I had occasion to renew or refresh wooden
parts. SO, for the rubbing strake I have applied a new International Paints
Product known as Woodskin.
According to the literature, it is part wood
sealer, part oil, and, so long as you sand between coats, you can add more
coats whenever required. A can cost me 44 Euros so it had better be good! The
manufacturers say it can be used as a stand-alone product or a base prior to
varnishing. I’ve got two coats on and I’ll varnish before launching. For now
though, I’m pleased to have seen an improvement and to have got some protection
into and onto the wood, which has come up a beautiful honey colour. Not shiny,
but with enough sheen to glow in the winter sunlight.
Seaward
Oil and varnish are on a continuum, with oil (in the boat world) usually being linseed oil, and varnish a combination of linseed oil, pine tar, and turpentine. That's why it's fine to oil wood before varnishing.
ReplyDeleteI never heard of Woodskin before, but from their website, it sound like it's somewhere on the oil-varnish continuum, leaning towards the oil end.
The main problem with teak oil as an exterior finish is that you need to renew it too often… like every week or so. Of course, no one keeps up with it, so it goes to pot by the end of the summer.
The main (and perhaps only) problem with varnish is that it takes so long to apply. Basically, you can only do one coat a day — fewer in lousy weather — so it might take you a few weeks to finish the job. Most people don't have the patience, BUT patience is a skill worth practicing when it comes to boats. Properly applied, varnish is a superb finish that requires minimal maintenance. My varnished boomkins looked just as nice at the end of the summer as they did at the beginning. I wish I could say the same for all my finishes.
On the other hand, varnish is not a great finish for a rub rail… by definition, the rail going to take some knocks. That means cracks in the surface and potential water intrusion. You can easily touch up varnish, but it would be an unnecessary fight on a rub rail. I'd stick with your Woodskin for a season, and see how it holds up.
For the same reason I would NOT — repeat NOT — epoxy the rub rail. The first time you bang against a dock, the epoxy will crack, water will get underneath it and not be able to get out, and rot will commence. Epoxy is not so easy to touch up as varnish.
IMHO, it would be a crime to paint the rub rail, with paint or any of the paint-like stains that are marketed as varnish replacements. Not only are they ugly, they will have the same wear problems as varnish or epoxy.
Finally, I'm guessing Commander Rayner knew what he was doing when he chose Iroko for a rub rail. From Wikipedia:
"It is a very durable wood; iroko does not require regular treatment with oil or varnish when used outdoors. Although it is almost as durable as teak, it does not have the same stability"
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