Board construction

Hi, i'am a franch mechanical engineering teacher and a 35 years garage board builder, my main hobby. Build surf, sup, kite, foil, windsurf, try all kind of build tech and materials. All "big brands" have single skin in their catalogue. Starboard starlite, fanatic HRS, rrd e-tech, tabou MTE, etc.. all are light eps, fiberglass, resin (some use foaming one), some wood veneer under foot, some use thin asa skin over lire all bic/tahe for years.
With eps 20 to 25 kg/m3, stringer with UD cap hand lam multiaxial fiber bottom lap on rail then some kind of sandwich deck, you can made a board that do the job, not the stronger, not the lighter, but easier to build correctly. French seaclone do custom monolithic speed and wave boards with linen hand lam over eps stringered blank. Far cheaper than his sandwich boards. From what i know users are happy with his boards.
A small, old trick, is to volumized (foamed) lam resin by adding around 30% (volume) of glass microsphere. With 3 layers of 4 oz open plain wave glass well saturated you can be surprise.

With the final board (so far) i put in a 15mm (3x5mm laminated) pvc stringer, mainly to widen the blank and hopefully stiffen it, and more importantly a carbon strip on the bottom to prevent creasing. I routed out a 5mm deep disc under my front jump side foot-strap, and sandwiched 5mm pvc, and 4oz glass, so a mini sandwich. This board has held up ok, but i got a flikka custom, so it hasn't had as much use.

Same as you: glass microsphere for volumize/lightening; silica for gelify and keep resin where i want, microfibers for strengh.

I guess a few here will be old enough to remember the Astra Surf, Waitata boards? My first epoxy slalom board, in the early 80's, was a Waitata. 9' x 24" if I remember correctly. Those boards were made in Australia and were EPS core covered with, (I think), mainly chopped strand glass wetted with foaming epoxy resin and enclosed in a mould, reportedly under quite large pressure created by the foaming resin.

As I understand it, the company went on to become AHD (Advanced Hull Dynamics?) and made Slalom, Freeride and Race boards in Australia for a few years. The owner reportedly relocated his business overseas, maybe to the USA first and later to Europe.

In any case, Tom Leudeke was sponsored by AHD in the late 80's and early 90's, and I was able to obtain a few of his used AHD boards around 1989-90. I used a couple in the Victorian Slalom Championship series (which I won in 1991 ). Those boards were the same foamed epoxy resin moulded constrution as the Waitata, and were quite stiff and light. They lasted very well and I still have the 9'6'' version in my shed somewhere. Their one weakness, that I found, was the Tuttle box cavity was simply moulded with the same process, all on one shot, and was subject to damage fairly easily when you struck something with the fin. I did many repairs on mine.

Later, Steve McGeary started the 'Speed' windsurfing board company and acquired the technology off the founder of the aforementioned companies. All those boards were made with EPS cores and no sandwich, were fast and light (quite comparable to the Euro Epoxy raceboards of the time) and generally quite durable. I had a few Speed Slalom and Raceboards and the only issue I had with them was with my first Speed PanAm 250 Raceboard. It was light and stiff but the foaming resin was incomplete along the rail and there were pinholes where it leaked and took on water very quickly. To his high credit, when Steve heard about this he turned up the the next race I entered in Melbourne with a new board for me and took the old one back. I still have that board in my shed too, and it is still sound and fun to ride once in a blue moon. Somewhere I still have Speed 9'4" slalom board too. Maybe I should find it and take it to Lake George this season for a spin around the Lake.

Steve eventually shut down his business, and I heard, sadly, that he was suffering from illness related to the materials he had worked with.

The next related thing I heard that pertains to this topic, is that one of the people already mentioned, I forget who, sold the technology to the founder of 'Extreme', (who I think was Steve Hayden?) who attemped to go into production in Western Victoria - perhaps Ballarat? I got one of the very first Extreme 280 Slalom boards, #2 I think. It actually had a Powerbox and I was not pleased as I had no PB fins and a good collection of Tuttle fins. Before I could even race this board, I heard that he had broken the mould on the 3rd board and given up on the idea of local production. He went to Cobra and got EPS sandwich boards made (with Tuttle boxes. ). There lies the end of Moulded foaming epoxy boards in Australia to the best of my knowlege. (I also still have the #2 280 Extreme and the sandwich 270 from Cobra. )

And yes, I got a Starboard Go for my kids in the 2000's that I believe is also EPS core and Foaming resin skin.

I have always been fascinated with this tec, but it thought it was best suited too Moulding. It would be very interesting indeed to see how it goes with straight laminating (without a mould). The idea is that the foaming of the resin forms a thick, high density rigid skin under the pressurised containment of the mould, that make the board quite stiff and de-lam resistant. How this could be achieved without a mould is the question?

Edit. Ahh! I forgot another angle of this story. At some time in the late 80's or very early 90's, Windrush also experimented with the no sandwich, eps, foaming construction. I dont know how far they got with it, but I did obtain a 6foot 'ish tri fin surfboard made by them with this construction. It was unbelievably strong and tough. They told me I could rap it with a hammer and probably not damage it, and it certainly seemed like that but I was not really game to try it. I sold it to a young bloke who was embarrking on an around Australia surfing safari for a few years, and I recon it would have been just the thing to have rattling around in the back of his ute. I am guessing it would have taken some very heady wipeouts and still come up for more. It's hard to remember exactly now, but I don't believe it was any heavier than a standard custom polyester board of the time.

Perhaps some of our WA readers will know more about this Windrush episode. I thought they had big plans for this tec, but it seemed to disappear quite quickly and I don't think it made it into their windsurfing boards.

Yes foaming resin skin are made in mold. Can be tough for not so much weight. Somewhere between sandwich skin and single skin. Without mold you can use sphertex wich is glass fiber with microsphere embeded. There are other bulker that can be used. You can also add microsphere in lam resin with an appropriate tech for saturated fiber. You can also spread micro between fiber layers.