lortap said...
I had discounted custom poly boards because my impression was that, relative to an equivalent size and strength epoxy board, they tend to be a bit heavier. Is that fair? I had considered a customer expoxy board from Dave at Katana - anyone used his boards for kiting?
Hi Lortap
I can give you my 2 c worth on board construction, I made my first windsurfer in 1980
out of closed cell polystyrene which is having a come back called XPS, and tried just about all combinations of foam over the years to get the perfect weight to strength ratio in windsurfers and from 2000, on for kite boards.
A poly urethane blank is always goingto be heavier than a EPS or XPS blank, although there have been some experiments with light PU blanks, which again have the drawback of loosing strength, proportional to the weight.
lightest boards on the market at the moment are high density EPS (expanded, open cell polystyrene)blanks glassed with epoxy and standard glass lay up. you cant put plugs into these boards unless theres a chunk of harder foam in the plug area. these baords will ding up pretty quick and just calculate that its going to break if you jump it, also due to the open cell structure they will suck in the water like a sponge if you get a hole in the skin.
The EPS blank is also sold as so called tough lights and some other brand name, differance is, the whole blank has been wraped in Diviny cell from nose to tail, thats a PVC foam, used in sandwich construction, the EPS used on these boards is usually low desity, thy are very durable, a lot stiffer than standard boards, you can have plugs in these boards, but they will suck water even faster if the diviny cell gets a crack .
XPS, this is extruded polystyrene, chemicaly identical to EPS but has closed cells, glassed with epoxy resin and looks more like a real foam, not the esky stuff (EPS) with ball stuckture.
This stuff gets a new run every couple of years or so. Every new generation of board builders will discover it new, as the answer, its tough realy hard to break and almost as light as EPS. The experiments with XPS always end in heart break(you can read all the tales about it on SWAY LOCKS forum), the problem with XPS is, the surface structure will break under stress, resulting in delamination on the deck and on impact areas on the bottom, you can give the board the diviny cell wrap, but you lose the weight advantage.
PU - Poly urethane the traditional board foam, this stuff is closed cell, so wont fill up with water ( but will penetrate in 1 cm or so)
Is still a great option, problem is, put a lot of glass on the board, it gets quite heavy, So what to do?
Take your favorite surf board to a good shaper, and get it shaped a lot thinner in PU, then have him vacuum down a diviny cell layer on the deck only, doesnt have to go all the way to the rails or the nose, one layer of 4 ounce between the PU and DC. 2 layers of glass on the top and bottom.
by thinning out the blank the board still flexes and wont gain that much weight, the sorface wont ding up quick.
Its the best of both worlds.
Or just keep replacing the boards each year with a cheap poly board.
Theres a guy In Lancelin who actually glasses a lot of boards for other shapers in Perth, he builds boards for Lano locals too, who want to take off at main break and land 20m high jumps with out the board caving in on them.
, it is Radman trying out my Oceanline 
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