I'm trying to wrap my head around what you guys are calling 'UV'... I hope you are not paying high prices for clothing that claims to have special features that block UV rays; I'm not even going to Google it to try to get to the bottom of it... Its a rip-off and I'll stand by that backed up by real world experience.
I've been out in some of the worst UV conditions that a person can experience... On boats and US Navy Ships (like many of you as well) but add to that the Middle East and pretty dang close to the Arctic Circle. On top of that, as a welder every time I fire up my any of my welding machines I am generating a plasma arc that is brighter than the sun and will sun-burn your exposed skin very quickly. All I use to protect my forearms for welding? A long sleeve cotton T shirt (a synthetic fabric would melt if touched by anything hot).
The only performance fabric I know of that has a specified purpose for UV rays is the opposite of protection, they are bathing suits for the ladies that allows UV through for even tanning. Just about any fabric that isn't so loosely weaved that it allows light through is going to protect your skin from burning. Ask millions of people who like in the Middle East, they wear cotton, silk, and synthetics to cover their heads, faces and necks with no special 'UV' features. If you are buying some liquid to wash into your clothes that is supposed to protect your skin from UV exposure you are wasting your money. The fabric does fine on its own blocking the sun, the additive you just washed into your clothing is only protecting the fabric from fading to UV exposure.
If you want to buy performance fabrics for warm weather sailing other than the clothing lines marketed to the sailing crowd, try REI or EMS (Eastern Mountain Sports), both have websites as well as brick and mortar stores. Brands like Columbia, the North Face, Marmot, Patagonia etc. (along with the REI and EMS store label stuff) all make excellent synthetic fabric performance clothing that wicks moisture, dries fast, keeps you cool... and look pretty sharp too. Both stores mentioned above have outstanding return/exchange policies, mostly because what they sell isn't crap in the first place. Expensive, but you get what you pay for. Remember, cotton kills... in cold climates, but in tropical climates it gets moldy!