Howdy

my son broke the front 2 to 3 feet of my starboard windsup - snapped pretty much in two. I've seen a youtube of someone repair a similar type of break on a fanatic board. I went to buy a fibreglass repair kit, and was told I need to know if the board is a poyester or epoxy resin. Googling starboard windsup, it's the 10 foot by 34 inch one, they called it 'ASAP Whopper' - it looks to me that it is probably using epoxy resin. Does anyone know this?

By the way, as it is the board is pretty much hard rubbish, so even if the repair attempt fails I am no worse off. Anyone else out repaired a snapped almost in 2 windsup?

No, but I've repaired a few almost snapped in half boards, and the technique doesn't vary much.

The resin needed depends on the foam used, polystyrene needs epoxy, anything else will melt it. Urethane foam is less fussy, but polyester is normally used because it's cheaper. I would say it's 99.99% certain your board is polystyrene and definitely needs epoxy!

My approach is to sand the fibreglass back in a taper about 5cm wide. then tack the board back together as close to original as you can. It's common for a snap to compress the foam on one side. So that just butting up will make a kink in the rocker. Two ways out of this, fill the gap, or reface the foam. Once you have the two halves back together you can bandage up the join with fibreglass, 2 or 3 layers of 6oz/200gm should do the job. sand the overlap back a bit and bog to your satisfaction.

Other people like using short stringers, but I believe they're just a waste of time. You just need to be able to hold the 2 halves firmly together while tacking, stringers can help with this, if you get then right, if you don't they do more harm than good

Just as a side thought , not that I've tried , but heard , doesn't epoxy stick to polyester resin ? If it does , If in doubt use epoxy ? If it doesn't, totally disreguard this post . Like much of what I say . It could just help me making yet another mistake
As my father in law used to say ," anyone can do a stupid thing , but if you do it twice , your stupid ".

Epoxy will stick to polyester as long as it's rubbed up. Maybe a problem going on top of laminating resin, the surface of that doesn't set, so the next layer of polyester will bond to it. But filler and finishing resins have wax in them that forms an air seal at the surface so it sets thoroughly all through.
The trouble with polyester and epoxy happens when the polyester hasn't fully set, the gasses given off by the uncured polyester act as a retardant for epoxy. So for an old board, this wouldn't be a problem.

Now I'm interested Do builders mix harder polyester and tougher epoxy to achieve something special ?
Is it , could it , be a thing ?

After having a fin stay permanently soft, trying just that, I no longer allow Polyester in my workshop. It's too hard to keep mixing tubs and stirrers separate.

MEKP is nasty stuff. Many years ago I had half a pot of left over resin and added a few more drops just for fun , it caught fire with vengence
Chucked it into the backyard and was amused by the amount and type of smoke . After killing about 12 polar bears 20 thousand miles away , finally put it out .
Respect !

Many thanks for your advice Decrepit, I had come to same conclusion myself re epoxy, of course that was after first buying the wrong resin. Will post on how repair went in a week or two (three).

i had the same dramas and used the wrong resin.
It doesnt work out to well ,
But learnt a bit along the way and now the boards up and going again , all be it a little heavier