My thoughs are to fit 2 wood stringers separated from a 3cm wide XPS slice, so I can easily drill the mast and fin boxes holes without damaging the wood.
This is what’s suposed to be after wood, EPS and XPS slices will be cut, using a rocker template and a jigsaw:
This is what’s suposed to be after the whole bunch of slices are glued:
BTW: Which method will be best for glueing???:
Slices glued using just non-solvent contact cement
Slices glued using just epoxy resin
Slices glued using a fiberglass layer wet with epoxy resin between each pair of them (kind of multi-glass-stringer)
I have made a few sandwhich sailboards out of EPS and XPS I do not understand why you want to combine both materials If you glue all EPS with a contact adhesive you will get a very light board or if you use all XPS the board will be about 1.2 kg heavier but water proof.
On EPS boards I use 5mm 80kg divinycell top and bottom and on XPS 3mm 80 kg div top and bottom I have also used 2.4 mm balsa top and bottom on XPS.
I have never had to glue it up before as I used to get both materials in thick blocks eg 2500mm x 600mm x 200mm
I can no longer get thick XPS any more only 50mm thick ones I too would like to know what else I could use to glue them up because if I use epoxy with microballoons I calculate this would add about 1kg!!!
I do not think you need stringers as these would add another 800gms or more. By making the board yourself you will be able have a laminate with more glass in it than the production board that you broke therefore a stronger board.
Sit the fin box in divinycell 60mm wide by 320mm long going from bottom to deck and the mast in a div block at least 300mm x 120mm x 40mm a big block really helps spread the load I have used smaller but they have eventually given away after a couple of years.
I have some 30mm XPS sheets at home, sheets I used when I was a custom bodyboards builder.
I’d like to glue some EPS slices since they are thicker (100mm), so I’d need less slices to achieve 74cm width.
For glueing XPS and EPS I use “non-solvent contact cement” or “EPS contact cement”. It’s very easy to find here in Spain, but I know it’s not so easy to find at USA.
Dyvinicell or other PVC foams are impossible for me to buy in short amounts. I’ll go the traditional way on glassing.
For mast and fin boxes I’m planning to do this:
BTW: My old TenCate285 hadn’t glass at all. It was just 2 PE moulds (5mm thick) heat-sealed together, then filled with yellow PU foam. It’s amazing it didn’t break before!!!
Ok I guess you will be putting a lot of glass over the EPS as it is quite fragile. I have had another idea If you can’t get divinicell how about a 5mm balsa sandwhich over eps?
use a bandsaw if you have one or can borrow one instead of a jigsaw. A jigsaw won’t cut perpendicular - it will always splay out a little and so you have to then cut with a little extra tolerance which in turn requires more clean up on the blank when you get it all stuck together. It makes lining things up for glueing more difficult too when it’s all a bit uneven.
I windsurf too, for already 12 years, but my boards have evoluted with me.
So your XPS/EPS board will be heavier than that JP, because that one is made in sandwich.
That EPS, what density does it have? I hope more than 35kg/m³ otherwise you’ll need lots of glass.
But that EPS/XPS board will be lighter than your tencate and you will feel a whole progression for your tencate to your new copy, in lightness and shape. But don’t forget that your copy will be less bouyant than the original, because of the weight.
Anything ever come of this project? I’m looking into glueing up a blank with about 10, 11 2 inch wide horizontal slices, either all xps or a combo of xps/eps. has anyone tried anything like this recently. Ive searched the forums and cant really find much of anything.
A friend of mine here at my local break makes them all the time. He avoids xps usually and is fond of lightweight eps. Goes with no perimeter stringer or any stringers between the pieces. Just a difficult to shape glue line and loads of cloth.
