I sanded down with 500 grit, sprayed three or four coats of conversion varnish sealer, wet sanded with 400 grit paper using VM&P Naptha as a lubricant, applied medium brown aniline dye until I got the color I liked, sprayed three or four more coats, wet sanded again until I was happy with the smoothness. I'm not being as picky as I would with a guitar, where you have to repeat this process many times before you get an absolutely glasslike finish. So there are some pores showing through. I know this is time consuming, but I'm doing other things on the boat while I'm waiting for the sealer to cure (30 minutes).
Conversion varnish isn't readily available to most of you, but since I'm a cabinet guy, I've got a gallon or two of this stuff in my cabinet. It's probably not an ideal coating for a boat either since it's probably lacking in UV protection, but I've done my own experiments with it, like leaving a door coated with conversion varnish exposed to direct sunlight for a couple of months with no visible signs of deterioration. So with my boat sitting under a shed covered with a boat cover, I expect this to last a long time.
You can wet sand polyurethane too, and I'm sure that epoxy systems are the best method, but I'm just using what I've already got in my shop.