My canoe's rails are finished with polyurethane (Minwax Helmsman Polyurethane Spar Varnish). The finish has weathered enough that I should refinish them somehow. I have been putting it off because I thought that I needed to sand off all the old varnish and start with bare wood. But another member of my club, with lots of experience with wood finishing and canoes, tells me I can just sand the peeling areas, then add varnish to the bare parts.
Any opinions? I don't care if it looks a little funny, but I do want to protect the wood well.
I saw on another thread that two people prefer a Varathane polyurethane spar to the Minwax. Are the two finishes compatible in this partial-refinishing plan?
While I'm asking: do things get worse if I put an oil finish on the bare wood, rather than more polyurethane? I figure that's less likely to be compatible, but I prefer an oil finish, so maybe I can be lazy and slowly convert the varnish to oil. I suspect the oil will make the varnished areas sticky, but will otherwise be okay. The oil in question is my eight-year-old can of Watco, if that is still usable.
Oh, always another question: Should I remove the rails and varnish (or oil?) the screw holes and the insides of the rails? Both areas have blackened a little, presumably from lack of protection from water. I have never removed gunwales and have no idea how likely I am to mess it up. I have access to basic tools like drills, nothing fancy.
The boat is a Placid Boatworks RapidFire, by the way. I have had it six years and have done very little maintenance to the rails. It has been stored exclusively inside, but it is used in brackish water (rinsed off with freshwater after most trips), and it is exposed to New York City's temperature and humidity.