Originally Posted by mattman
Look at some of the textured deck coatings out there, maybe try Home Repo website.
Could always sprinkle some sand on top of wet spar varnish or deck stain.
BTW, I've never had a problem with my side boards being slick, our southwestern rivers sand the shine right off of them, instantly!
I've tried behr deckover - at first I liked it but it really didn't stick well long term. Further research indicated that it's designed to penetrate porous wood (old checked decking) and when the wood is too new or dense it doesn't penetrate and flakes off. That's what I had happen, nor horribly but when I did a redesign of my decks, I went back to spar varnish and aluminum oxide. I've used sand in the past but it's too coarse and eventually pops out. The fine grit of AL-oxide is far superior in my opinion. In the end it has a similar feel to the deckover type products but appears to be much more durable. The AL-oxide is sold as a a no-skid additive but is very fine grained, perfect for decks in my opinion.
As far as no additive goes, I left my back deck (actually a table) just as straight varnish (no additive) and on one of the first days I used it I jumped on it from the bank and slid across. Nothing serious but it was clear to me that the additive makes a big difference. It also makes a big difference for my dogs, they'll slide on the back deck but stick like glue to the front and side decks.