I countersink deep into my 1/4. And it's now 6 seasons on the same UHMW poly. Worth the investment. I'll see if I have any pics of the countersink depth. If not I'll take some.
good to know. i was getting quotes on 1/2" UHMW so we'll see about the 1/4" stuff. transport to tahoe (3 hour drive) to my buddies place where we are building it might be an issue as well, but first things first.