Jim, The quick answer is that you only need to covers it when the sun is out. That said, every day you can keep it covered, is one more day until you will need to refinish it. There are many different "varnishes" today. Some like the two part urethane products last quite well in high UV conditions. Bristol Finish is one I have had good luck with. The Awl Grip products are good too. One of the secrets of maintaining varnish is to re coat it before it looks like it needs it. In St. Lucia, you'l want to varnish 2-3 times per year if the wood is not protected with covers. Cheers, Tom 410.212.7898