I’m looking to get into compsand builds mainly just for fun but I’d also like to try and build something durable with potentially improved flex over EPS epoxy boards. I’m a materials engineer and work in aerospace composites so I’m comfortable with vacuum bagging. I’ve spent hours and hours reading every topic I could find here trying to find which combination of rail, foam density, and skin. Seems like there are a lot of combinations that people have liked but there’s a lot of conflicting information so I was hoping to get some advice what a good place to start would be.
My initial thought was doing something close to the Timberflex builds that Greg showed in the Cerritos videos, stringerless 1.5lb EPS with HD foam rails and thin veneers. This seems to be a pretty user friendly construction since HD foam would be easier to bend on the rails than balsa. I do wonder if the flex would be better with balsa since I’m guessing its a lot stiffer than D cell, especially using such a thin skin.
Cork also seems quite user friendly for both the rails and the skins but it’s heavy and I worry about flex again, although the thicker skin may make up for that. Maybe just leaving the rails EPS and adding a few layers of fiberglass tape with a cork skin would be a good combination?
Cost and availability are obviously a big factor as well. I live in North County SD and I haven’t found a local source for HD foam or balsa sheets. I also haven’t found 1.5lb EPS block. I’ve found a supplier of 2lb and 1lb EPS but I don’t think I want to mess with 1lb.
Any thoughts/suggestions? Maybe I should just stick with 2lb EPS with 6-6/4 glassing and just surf more haha.
All what you describe could be good board build. With 1.5lb foam a good durability improvement and still an “easy build” is to do a monolithic hand lam for bottom and rails and a sandwich deck.
On big project, more than 70 liters, full sandwich over 1lb foam allow the best strengh/weight but with a more difficult process.
Wood is good for strengh but need care with water soaking. HD foam like PVC work fine but are expensive and stiff.
Cork is cheaper and easy to work with. Good feeling with right fiber schedule (4 Cork 4 on 1.5 eps).
GL Veneer in Huntington Park, Insul Foam, Marko Foam and there is a foam company in Arizona that originated the “fused bead” EPS that U.S. Blank Foam now sells. Can’t remember their name. Marko doesn’t just make surfboard foam. So they have access to lots of sheet foam.
Thanks Lemat, I’ve studied your threads and posts on the matter so really appreciate the feedback. With the 1.5lb and just a deck skin do you think that would be stiff enough? I guess it depends on the skin thickness but I wasn’t sure if a thin veneer would be enough. Maybe 3mm cork would be better? For the cork sandwich you mentioned would you recommend just the deck?
Good to know about Marko, I didn’t realize they did more than just blanks. I reached out to Insulfoam and they pointed me to Industrial Foam Products but they only have 1 and 2lb, no 1.5lb. I’ll do some research on fused bead.
I’ll check out GL, I had heard they were a good source for veneers. I’d rather get it close by than order from Certainly wood.
My bad U.S. Blanks sells the fused bead. That formula came from “White Hot” EPS surfboard blanks. I don’t do any business with U.S. Blanks (formally) Clark Foam so I don’t know what they offer these daze. Millennium sells EPS Blanks and they are all hot wired. So maybe that would be a source.
Yeah you might be splitting hairs for .5. Universal Foam and Foam Inc. are two that come up in Arizona. Pretty sure one of them was “White Hot” back in the day. That company in Escondido is nice and close. I’d give them a try. If you go to any of the arcetechtural foam suppliers, you’re probably gonna have to buy a block. Check and see if WNC foam is still in business in San Diego. Forgot about them. I think that was their name. They cut blanks for awhile. Yeah WNC foam San Diego. At one time they had a blank catalog. All hotwired.
Yeah you’re probably right. For a 40L board the difference is .7lbs. Not sure I would notice that much of a difference. I’ll probably just get the 2lb from Industrial since they’re close.
I have a friend up here (Oregon)who goes by Johnny Fever. He makes boards like you are talking about. Foam core, wood deck and bottom, foam or wood rails all vacuum bagged. He posts on here once in awhile. Some of the nicest comp sand you’ll ever see. He sells them once in awhile, but not usually before he rides them.
On 1.5 eps for board up to 7+” standard wave ( =not high power), two layers 4oz bottom that lap around rails, ideally warp glass and on deck up to near rail apex, 4oz + 0.6 wood or 2mm cork then full 4oz that go around rail and you are good.
Because i mostly make boards for board breaker guys that surf in hollow high impact waves i use to add fiber stiffners ( T or V or U shape ribs) connected to skin combined to biax fiber (for one of 2 layers) to increase buckling strengh but keep some overall flex. You can also use a stingered blank for this purpose.
Full sandwich board can also be good with lighter foam but add some complexity to build. For me it’s not worth it for most surfboards.
Oh yeah his boards look incredible. I had thought about doing one of his lessons when I lived in Washington and now I really wish I would have since I’ve moved.
Ah ok that’s great information, really appreciate it. For the stiffeners that are T U and V shaped, are those your springers? Or is that something else? I had thought from your posts you were routing out a flat section and adding fibers but maybe that was a T rib. V and U seem quite challenging.
Do you use Amorim cork? If not, any suggestions on sourcing cork? Do you seal it with thickened epoxy before making your sandwich?
Yes that’s my springers. First i do T then i move to V now i do U or more a kind of Omega rib inserted in board. Always work to improve this tech to the minimalist, faster and easier lowtech way to do it.
Corecork is the dedicate product but i buy mine localy to a compagny that build cork technical product since near 100 years.
Yes i use secret sauce fillers in cork. Cork is easy to use but can be on the heavier side with common foam sandwich tech and schedule.
Drew Baggett used (uses) Amorim for exposed surface cork on surfboards. Last time I checked Amorim was pricey and had purchase volume requirements.
I’m no pro, just a retired scientist who likes to experiment. I have been playing with roll cork. You can buy smaller quantities. My approach is to do test panels.
My logic is that the primary objective is a composite cork sandwich skin (FG-Cork-FG) for impact absorption. The FG on either side protects the cork from other types of mechanical wear. IMO the sandwich significantly improves skin strength. However, my observation from what bb30 did is that vac bagging sucks resin into/through the cork sheet.
“Cork is also able to absorb a lot of punishment. Its cells have a unique 14 sided polyhedron structure that can be compressed to 15% of their normal volume and then regain most or all of its size and shape slowly. This compression capacity combined with a very slow rebound allows cork to act as a very effective energy dampener, thus its popular use in flooring and noise proofing.”
Cork also provides some degree of thermal insulation from outer skin heat.
Where are you located? Just scanned again. I see you are in SD. I have an affordable roll cork supplier for my experiments — free shipping for orders over $35.
I use pricy corecork for first go then i move to cheap cork for floor, work the same for me. Now i use localy build.
There is two way to sandwich cork. First is to use it like a lam table (like bb30), lay fiber dry on cork then lam, and flip back on blank and pull vaccum. This way you pull lot of resin in cork, that’s way bb30 find good too use peel ply to drain excess. Second is to lam fiber, slightly resin rich, on fresh sealed blank then unroll cork on it and vaccum. This way there is less resin in cork from bagging, and more from lam over.
Actually i use bb30 tech for partial sandwich and second way for full cover.
This will be my approach for my next 1.5-pcf foam (XPS or EPS) and glass build. Debating cork sandwich skins on deck and bottom for stringerless. Cork sandwich skin for deck only with stringer.
I like symmetrical FG schedules.
To minimize resin penetration into cork, my latest experimental panel was sanded (with 150 grit) epoxy sealed foam, then apply another thin resin coat, wait until second resin coat forms stiff peaks (paper plate test) but returns to flat, then apply rolled cork sheet by hand with a pastry roller. Then apply a thin resin seal to top of cork with fast-set resin, gently sand/score cork surface smooth with 150-220 grit, laminate cloth over pre-sealed cork.
Will try something similar with FG under and over cork on my next test panel.
I have used the wide end (4-inch) to apply deck pad, hand-cut from adhesive backed HydroTurf sheet. I use a standard, flat-cylinder, large rolling pin for final smoothing pressure after the thorough pastry roller application.
I do not like the Marko foam blanks’ rockers. I prefer the US Blanks catalog. You have to download the catalog not just look at their website as there are many more models in the catalog. Plus they will adjust the rocker of any blank (I believe at no cost for block cut EPS). They also have a super fused foam option but only for the EA (Eric Arakawa) blanks which I find have a little too much rocker for most California boards. I use 2lb foam which is plenty light. I used to use 1.5 but if you are vacuuming bagging you have to have a rocker table or you will lose rocker. Rocker is so important to a board’s performance I don’t like not having complete control over it. I use 2lb foam and then do one layer of glass over the deck before I do any vacuum bagging to ensure I keep the intended rocker. Oh, and all my boards are stringerless, similar to GL timber flex but no HD rails. I do not think they are necessary. Wood boards tend to be stiffer as it is. They are plenty strong. The only boards I have had snap deserved to be snapped. That is, I think just about any build would have snapped given the situations.
