As a rule, varnish is like signing a sentence. One that subjects you to an annual maintenance cycle that you should actually strive to make smaller, not larger.
Varnish, my choice of varnish is INTERLUX SCHOONER. It goes on thick, cures slow, and sands nicely between coats. Always sand between coats.
I chose to do the salon table for a couple of reasons. Originally it was just oiled maple wood, which had dried out. So it was decorated with a decade of coffee cup rings and generally didn’t ‘show’ well. I sanded it down to clean wood, and did a first coat with half mineral spirits and the thick schooner varnish. This is my normal SOP, first coat is half mineral spirits. A whole 24 hours to cure, then a light sand with 220 grit, and then a second coat with just a splash of mineral spirits. I feel that the spirits helps it to grab onto the wood, get into the grain if you will. The result is that there is some woody patches after the first coat, so the same strategy is employed again. The third coat always goes on as it is from the can.
This table top was 5 coats, I expect it to need a light sand and new coat once per year as it is a high wear area and the varnish is a one part polyurethane which is softer than a hard two part varnish.
Every pour from the varnish goes through a painters filter, and into a jar that I dip from. Any extra varnish in the jar can saved. I keep all my mason jars from spaghetti sauce.
The advantage of a softer one part varnish is if you sand and touch up, or fix a damaged area it generally blends in much better than doing the same on two part varnish.
If you aren’t sure which varnish to use, there has to be a million YOUTUBE videos on this subject but do consider that you have to look at it every day. It isn’t a bad idea to try a few sample pieces, three coats should be enough, to decide if you like that varnish. If you do, buy the bigger can, if you don’t like the varnish then save it for where it isn’t as obvious or trade it with your neighbour for something else.
*There is nothing else inside the boat that is varnished like this, everything else is oiled. The exterior two hatches are varnished and that is it.