Carbon stringer strips

Hey everyone. This is my first post so sorry if I’m breaking any rules. I’m kind of in a bit of a sticky situation and need advice.

I’m currently building my first stringerless EPs board with flax fibres and was wondering for my carbon stringer strips, do I need to add another layer of flax ontop of it or will it suffice if I added the carbon and then direct hotcoat ontop?

Im Looking for function and not form. The board weighs around 2.6kgs right now without finboxes and im hesitant to add 2 layers of glass/flax onto it …

Anyone have any experience? I’ve read that railpat he’s can be added to the top of the board (i.e last layer)…but never heard for carbon stringers…


I place mine directly to the blank and glass over.

carbon goes directly on the foam. Putting it on top is nearly worthless as the board flexes the carbon on top would potentially buckle separately from the glass and separate.

It does more on the rails. A racing stripe on the deck does almost nothing.

Well, heck, Acqua. I have an unbroken string of “agreement” with you until now. The further away from the neutral axis you place the tape the more stress it will take up. If it buckles or breaks, you didn’t use enough.

And as Everysurfer implies, when you use it on the rails you benefit from the form factor strength of the channel shape, which is very strong.

I have some from GraphiteMaster, but have not used it yet. When I do I’ll go with the belt and suspenders approach. Can’t afford snapage. And bench testing is impractical. Even pointless.

I need more coffee.

All the best

Im talking like he mentioned, unless I read it wrong. Putting it directly on top of a lam vs under it on the deck. the Carbon is stiffer and wont flex the same. So what happens if you use the tapes like ribz or whatever is it buckles in little creases up and down the deck, causing bigger than spider cracks and in a few cases i’ve seen full separations you can dig a nail into. I’ve seen a bunch of guys cheat because they forgot to include it on order cards, and seen many of those come back with those issues.

Well, you can’t argue with actual results. Thanks for the data point. I’m surprised that the tape didn’t bond. Sounds like another issue, tho. But I take your point on the cracking.

All the best

I think it was massiveswell, but maybe someone else who had a good description of what carbon/ glass does. The carbon takes all the load, until it fails. After failure, the fiberglass starts taking load.

It could be that if the carbon is breaking when over the glass, then it is also breaking under the glass, you just don’t see it.

Exactly. Carbon has significantly greater strength over fiber glass. Use fiberglass as a sacrificial sanding layer only. Otherwise dead weight.

Hoping my screen shot works. The book referenced is really required reading for composite builders. “Understanding Aircraft Composite Construction” by Zeke Smith.

racing stripes WILL stiffen the board particularly if on both sides… using it on the rails will stiffen the board to a higher degree… using it in the best combination to suit the rest of your construction is the key element…

Great point Dave. Also hiding the construction under paint or wood also takes away the BS factor with the CF. You can flex a surfboard all day long and with out reflex it becomes irrelevent. Not to mince words or definitions, but reflex in surfboards is where the performance kicks in.

hey i agree… and most of the flex people feel is the deck sponging under thier feet…

For sure, many years i say this here. First time i hear about this was from guys behind salomon blue blanks, they made many tests that show us that stiff deck give stiff feeling board even if board is flexier. I do this test too, two same shape, on board stringerless with balsa sandwich deck, other stringered eps epoxy. All surfer who test find the blasa deck board stiffer than other, but on 3 point flex test it was 20% less stiff.

That is very interesting. There is so much about surfing that is subjective and counter to what can be measured.

All the best

My other observation about any CF product ,in regards to actually making a better board or making it look cool, is if you ask if the CF was hand laid or vacuum bagged? Vacuum bagging CF to make a true composite board is literally squeezing the full potential of the CF into it. I have seen some beautiful hand laid CF boards but don’t understand why you would spend all the extra $$ for the CF then half ass the full potential of it. Then there is always the wise guy who asks if I vacuum bagged my board or vacuum autoclaved it?