I am doing a project for a friends sail boat. It's a small folding table made of mahogany. It will be exposed to the ocean sprays and sun. I was told to use a Spar Varnish, but reading about this on the net, it's such a broad subject. Locally, I can get Spar Varnish ($36 a quart), but it does not have Tung Oil in it. Is Tung Oil necessary. I am a big believer in Tung Oil, but not sure about this application. I would also like to use a Spar Varnish that can be diluted so that I can make it have a more hand rubbed look, by using several coats and sanding in between coats. HELP!