Oil Based spar urethane? Any tips on drying and curing? Thanks!

I worked a lot with varnish in home building before there was polyurethane. Great stuff, but it takes forever to dry. I've had doors take weeks to fully cure, even when left outdoors in the sun.

Thin coats are best. Don't apply the next coat until first one is dry and hard.

The easy cure for where you are now at is to wipe down the board with a soft cloth and paint thinner. That will dissolve the top soft layer. Leave it in a warm dry place for at least a week. Lightly sand it smooth and apply the last coat with some Japan dryer mixed in. Follow the directions on the side of the can for the mix ratio. Don't pour the mixed varnish back into the can with the fresh, or it will gum up the new. For the final sanding, I like 0000 steel wool better than sand paper. Don't apply any varnish after the steel wool, or you will get tiny little rust stains from whatever steel wool was left on the board.

In the future use at least three coats of a water based polyurethane.

Thanks! I was told I had to use oil based spar urethane over this particular gel stain since it was going into a wet environment