I'll start a discussion on a product which I've only used on a paddle because the weather is a bit cold for application to my finished boat in the garage. System Three has a product called WR-LPU which is a high gloss linear polyurethane topcoat. Before you all go ballistic, read the spec sheets on their site, both their technical info and the material safety data sheets are at the link below. It's water soluble and the basic material is less hazardous than varnish. For the last coat you mix in a very small amount of cross linking agent (8 drops per fluid ounce) which hardens a already hard material even more. That cross linking agent is rated the same hazard level as varnish.

I've used the basic material on a paddle and with a bit of thinning it went on perfect and dried to recoat in less than an hour. It's is water clear and doesn't impart the yellow tinge you get with varnish. It's got much higher UV resistance than varnish and if you want to believe System 3 lasts about 5 years before a recoat is necessary.

I spent a lot of time selecting the woods used in my boat and I really didn't like the yellowing caused by varnish, it flattens the relatively small but I think very cool variations in the wood colors. I'll report back once the weather warms up sufficiently to use it. I also very much like the time between coats being an hour not a day. I wasn't looking forward to 2 weeks of varnish smell. This stuff is odorless.