Balsa Composite Sandwich

[Lunchbox]

Wow nice pix surfdad... It looks like that dude can shred...

[da.bell]

Wow nice pix surfdad... It looks like that dude can shred...

Shhhh, don't tell anyone but that is his son and from the last that I knew, he was sponsored by Tige....

Okay, not to sure about that last statement but yes, James is awesome.

[Surfdad]

Thanks guys...James does know a thing or two about riding. I like to say I taught him everything he knows

[Jason B]

Nice pics. How did he like the ride?
Are you planning to make some for sale?????

[Surfdad]

No, I won't build any for sale. The construction with Balsa is exceptionally labor intensive, but also...wood is erratic. Even when graded by folks, the deviation from one piece to the next can be huge. This affects the quality of the ride, as well as construction.

The corecell skin makes a decent option, but again you are back to the balsa rails, to effect a lively board. The concepts originated with Bert Burger who is now with sunnova boards. He helped Firewire get their operation going. The big claim to fame is flex and spring back. The make boards for small grovely waves that are "sort of" like behind the boat, but not really. The smallest they make is a 5'8".

In the ocean, you have a fairly long distance a waves length may be 100 yards, but seldom will you ever find a wave that is 20 You can't paddle into that and ride it. That distance is what makes such a huge difference between wakesurfing and ocean surfing. There is just very little space to generate speed behind the boat and what is needed isn't terminal velocity. but acceleration/drive/squirt.

So...from a performance standpoint, I don't think the balsa sandwich is the answer...from a cosmetic standpoint they are very unique.

I believe that other composite construction may be more useful. This is a board made from divinycell and 1# EPS. Ugly as sin, but not a half-bad ride.

[Surfdad]

I have two projects in the works...both involve carbon fiber. One, I HOPE will be a hollow carbon and end grain balsa board, the other an eps, fiberglass, corecell and carbon composite. Both of those are intended to be exceptionally stiff.

[Ruune]

forgive me if you covered this already, but did you form the foam core by hand, or did you make a mold from something else?

[Surfdad]

Hey Ruune, not a problem. Basically all handshaped. The rocker on this project was taken from a TWP Bullet. I transferred that to masonite and hotwired those to create "cores" or blanks and also a rocker bed. So the bottom of the board is hotwired in. I have hand shaped and hotwired the deck, preferring to handshape. The outline I did with a jigsaw, so it too is handshaped.

I attempted to build a two piece mold, but quit on that project. It's easy enough to do with wax, putty, PVA and gel coat...then TONS of chopped strand mat and plywood reinforcement. The cost is crazy expensive and you can handshape these so easily it didn't make sense to pursue the mold.

[Ruune]

awesome! I've been wanting to get back into composites molding. My mental gears are turning... now if I could find the time to set aside for a project!

[Surfdad]

Ruune!!!!!! Do you have molding experience? I'm in the process of building a hollow carbon and balsa endgrain mat board, but rather than a mold, I'm going to do a Xylene washout. This is the board, in process, with carbon under and endgrain mat attached awaiting a final exterior carbon.

The cost of a single mold seems prohibitively expensive, but...I'd love to try it anyway (I am NOT obsessed! ). One of the issues I had was a part line. It seems the easiest place to put that is where the rails wrap to the bottom of the board. It also seems like the hardest to get the laminate around the rails and then pull vacuum.

If you were to design a two piece female mold, where would you put the part line?

[Jason B]

NO WAY!!!! That looks freaking awesome! Gotta give ya big props on the aesthetics of that board.

[Ruune]

A long time ago, in a galaxy far, far away...

haha anyways, assuming its not structurally prohibitive, I'd put it around the edge, so you could just mate the top half and the bottom with at the bisection. you could also embed some graphite in-between, or even use a honeycomb pattern layer of cloth for additional torsional stability and resistance to breaking.

Something else that I think would be cool is to add some phosphors in with your resin (if you're just going to leave it the carbon fiber pattern). That way, if you were to surf at night, your board would glow.

[Surfdad]

JasonB - I know I like the look of that endgrain, but it adds a ton of weight. The board in the photo is already at 5 pounds and still needs a final layer of carbon and fin boxes. After voiding the core with Xylene I'm guessing it will have a final weight of about 7 pounds...too heavy for any sort of performance board.

Runne, the rail line is where all the stress is located. I know that Hydro Epic, before the shut down, shifted the partline from the rail to the deck and hull and I guess created a four piece mold - seems really complicated. More to think on.

[Ruune]

good point. Perhaps something like a dish, where you mold up to the top of the rail, then do an insert where the rail meets the top deck?

[Surfdad]

Yeah, I just don't have enough knowldege in this area to give an informed response. I think it has a huge potential, but it's a big leap for a garage shaper like myself.

On a different topic, I received some Rohacell yesterday. I had to sign a release before they would ship the stuff to me. It's a crazy story, but I guess because this foam is designed to be radar transparent it's in huge demand by military around the world.