Morning Lockers! I am doing my first EPS SUP shape, wanted to do a carbon strip down the deck and hull in place of a stringer. Should install the handle (FCS) and centre fin box (Futures) as usual pre glass then glass the carbon on the top and sand down later, or put everything in post hot coat? Cheers!
I’d like to comment that this carbon tape doesn’t add any buckling resistance to the strength of the board, which is the main purpose of a stringer.
I’m not saying that it doesn’t have an effect on the strength, I’m saying that it is nowhere near a replacement for a stringer.
On your question, install the boxes under the glass/carbon, to minimize the creation of a weak link.
I added 3" tape top and bottom to an 8’-6" board that I built recently. I used the carbon tape that’s weaved with fiberglass because I was told it will flex better than full carbon tape. I don’t know if I did this the right way but here’s what I did… I put the carbon tape on top of the foam and then immediately proceeded with laminating the cloth. I did my Futures boxes pre-glass but there’s no stress on a deck handle so I did the deck handle last and put a small patch of 4 oz on top of it. I confirmed with a glasser that it was okay to add the deck handle last.
Would I do carbon tape in the future instead of a stringer? I’m still figuring that out because some say it works in place of a wood stringer and some say it doesn’t. What I do know is that it bubbled up in a few areas which required a lot of time to deal with and the stuff costs a lot more than a wood stringer. And lastly, a stringer is really nice to have when you’re shaping, and not just as a reference point, but also to use as a guide when doing double concaves and V’s.
By the way, I also put a 5.7 oz full carbon patch where you stand and I don’t think I’ll ever do that again unless I learn how to vacuum bag. The problem was that the carbon patch sucked up resin like crazy and when I sanded off the rough areas around the edges of the carbon later BEFORE the hot coat, the black powder of the carbon “stained” the cloth around it and the only way I could hide it was to paint it the freaking board later. Oh gawd, what a clusterF that was. Point being, don’t put the carbon down in a way that will require you to have to sand it later!
Thanks for the reply, great advice.
I was going to put the 3" strip on the blank, then lam the deck patch in between the layers of 6oz then vac bag the whole thing, thus avoiding sanding too much carbon. I don’t know how I can avoid sanding carbon over the centre longbox, unless I just install post glass.
It will definately work in stiffenening the board, that would otherwise be too flexible without stringer.
But I don’t think it will add much strength against breaking.
I was thinking I would do a 6E+6E+4E+Carbon deck patch deck, and a 6E+4E bottom. Should be strong enough anyway, I was just hoping to add a bit of stiffness with the tape. I might do carbon rails and forget the centre strip.
The center long box I used was post glass so there was no problem with the carbon dust contaminating the surrounding area.
Carbon on the rails could be good if you can avoid having to sand through before the hot coat. Like I said before, I’m not sure I’ll go with carbon the next time unless I figure out how to vacuum bag because bagging should keep the carbon cloth down and flat. Also, if you do use carbon cloth, I would go with 4 oz instead of 5.7 oz like I did because it won’t suck up as much resin and won’t be as thick which means it would lay closer to the foam even without bagging.
Instead of carbon tape or rails anywhere, I wonder if shaping a channel on the top of each rail on the deck might serve the same purpose? It would require more babysitting while glassing and sanding without sanding through would be a challenge.
I was really concerned about weight so I did double 4 oz S top and bottom with the 5.7 oz carbon patch under the deck pad plus the 3" carbon/glass tape top and bottom. The board was 8-6 x 29 x 4 and came out pretty light at 15 pounds including the deck pad and fins in spite of all my dumb mistakes.
This was the first board I had built since about 25 years ago and I learned a lot from it. I was happy with the shape but I screwed up the laminating because I did it when it was 95+ degrees out.
What are the dimensions and volume of your board? Are you shaping it yourself or CNC?
I’m thinking I might forget the centre strip and try the rails.
No danger of those kind of temperatures in southern England!
This board is a 10’x30"x4" got it as a CNC.
I couldn’t find any S glass wide enough to lap a board of this size.
The least expensive source I found for 4 oz S that was wide enough (I think it was 40") was Fiberglass Hawaii. I suppose the shipping would be insanely expensive for you though.
Yeah I looked at getting glass shipped over from the US, but the shipping and taxes were just mental.
There’s a guy on the Standup Zone Forum named “supuk” from the UK who has built quite a few really nice standups. You could contact him through the forum or comment at one of his build threads and ask what cloth he is using and where he buys it.
All in all everything that add stiffness increase buckling strengh. The more effective way to increase flexural stiffness is to increase thickness.
Offset the handle to one side or the other of the carbon. It makes no sense to lay down 12 strands of carbon to eventually sand through 10. Defeats the purpose and creates a weak point.