Carbon layup on race board

[peterwSUPr]

Hi all, the board is shaped and ready for cloth, but it turned out when I weighed the foam I got and did some calculations that what I have is more like 1.7lb foam, so my blank is a bit heavier and probably tougher than many blanks.  My original plan was a layer of 6oz carbon and a 4oz E over that, plus extra at the deck.  Does this still sound reasonable given my foam specs?  I have toyed with a single layer of carbon on the bottom (with rails doubled though), but wonder if that would be too brittle in terms of dings, plus I'm wondering if a single layer like that is harder to seal in terms of pinholes, and whether the finer 4oz cloth really helps to close things up.  Suggestions?  I'm pretty good at treating boards carefully, but don't want an eggshell.

I have to say the shaping was quite fun  (first SUP!).  I've shaped lots of boards over the years, but I did lots of diagonal and shallow cuts with the hotwire, since this board has more flat surfaces than most boards.  Totally different than other shaping.

Thanks,
Peter

[peterwSUPr]

I thought I might hear from someone who's been here before, but I guess not.  For the sake of the archives, here's the report.  I opted for just one layer of carbon for the bottom.  I sealed the porous parts of the blank (those that did not still have a hotwire-sealed finish)  with epoxy and microballoons.  The carbon was then wet-out in place without vacuum bagging.  I figured I can add more cloth to it later if needed, but 12 hours later the squeeze test on a flat surface feels pretty solid, so I think at this point I made the right call. 

Peter

[supuk]

I thought I might hear from someone who's been here before, but I guess not.  For the sake of the archives, here's the report.  I opted for just one layer of carbon for the bottom.  I sealed the porous parts of the blank (those that did not still have a hotwire-sealed finish)  with epoxy and microballoons.  The carbon was then wet-out in place without vacuum bagging.  I figured I can add more cloth to it later if needed, but 12 hours later the squeeze test on a flat surface feels pretty solid, so I think at this point I made the right call. 

Peter

Only just seen this unfortunately but looks like you are sorted, I have not done a full carbon hand layup yet but when ever i do a hand lam with it i like to use a 4 oz cloth over the top as it seams to help get it nice and tight and flatten the weave a little. Seeing as you have just used the carbon i would just make sure that you do you filler coats when the air temperature is falling as with carbon having quite a open weave it will just make sure you don't get any pin holes

[55NSup]

I used 225 g carbon twill with 155 g glass twill over it. Overlapped  rails so double on rails. Extra carbon on standing area. 1lb eps sealed with latex ultra light filler.
Hand layup. Its not super durable, but I think it will hold up as well as my friends carbon falcon.
Pretty light,  have not weighed it, but guess its 14-15 kgs. 16-5 x 26 in
Will do same next time but seal with epoxy and ballons, add some sort of carbon stringer and v-bag it.

[peterwSUPr]

Here's an interesting bit of info.  For the top I am putting some bamboo in the standing area - not the whole top, but about 4 feet long, so have to vacuum that into place.  So, I decided that I am doing the carbon top layer, then bamboo, and then let it cure before then doing the top glass layer.  SO, I decided to do the carbon layer on top of the board with a different method.  I sealed the blank with microballoons and epoxy, just like on the bottom, but this time I wet out the carbon on plastic, and then moved it onto the board.  I only wet out on a piece of plastic about 3 feet long, and roll the carbon up and slide it along into the working area as I go.

Anyway, where this is all going is  that I used 3/4 as much resin to wet out on the plastic and transfer to the board, with the same cloth weight, same foam etc compared to my wet layout right on top of the sealed foam.  So that's a good data point.   I think for the single layer on the bottom the wet-out in place was the right call and will make for a bit tougher skin.

BTW, for the vac bagging I'm only doing a "light" version of bagging.  After wet-out I covered the board with a thin layer of drop-sheet type plastic.  This allows me to smooth things out but hand, and I just use a pin to pop holes into the plastic anywhere I see a bubble.  This is instead of using perforated film.  I then threw on some foam and material as a breather,  and put it into a bag and turned on the shop vac.  The goal with this is to get a smooth(ish) finish and squeeze the bamboo in place, but not soak out any resin.  I've used this method with sandwich construction windsurfers before on the outer glass and it works well

Looking forward to turning off the noisy vacuum now......  Maybe in another hour.

Next steps after that will be to clean up the carbon at the rails and see if I need to touch up at all before it gets the final 4oz glass over the top and rails.

Peter

[PonoBill]

You might have problems with pinholes, I have a tough time getting a watertight surface with Carbon. I've been using a layer of 4oz S glass to help that. I have been bagging with ripstop nylon instead of perf film and then this 1/4" fuzzy padding stuff I get at a fabric sore to take up the excess resin. I'm experimenting with precoating the carbon on a table, squeegee, then roll it onto a mailing tube and unroll on the board. Only done it once but I liked it. Did the same with the S-glass but didn't squeegee--I'm thinking that might help with the holes. the S-glass holds the CF down nicely and makes it easier to lap. Wrap it all up in ripstop, then absorber, then the bag, and off we go.

I haven't shaped a board yet, just stripped and reglassed an F18. Stealing ideas from everywhere.

Next project is the tunnel hull Speedboard. Starts tomorrow. Also gets ponosteering mid rudder with autopilot. How likely is all this to work? I give it a 90 percent chance for fiasco.

[peterwSUPr]

I think the risk of pinholes goes up when you use less resin, either through peelply and vac or wetout on a separate table.  The deck of my board will have a 4oz glass layer put on top of it (wetted on the board), so should be less of a concern there.  On the bottom of my board with just the carbon, it was a regular layup on the board which looks pretty tight weaved, except around some rail wraps, but my one glass layer from the top will cover the top and all of the rails right to the bottom.   

We'll see how the finishing goes.  I have to say, the Resin Research epoxy with additive F sands like a dream.  I'm not sure why we had such gummy resin that did not sand well in the old days, could be brand or bad mix ratio, probably both.

I might throw in 3 extra FCS leash cups on the deck ahead of the standing area in case I want a small gear tie-down.  I assume I would put them immediately ahead of where I might normally stand on flatwater.  Sound about right?

Thx,
Peter

[PonoBill]

I've gotten away from using leash cups--more places to have a leak. I use either the pre-taped aftermarket leash thingies or epoxy on some OFish'l domes.

contrary to my previous post, I don't think saturated 4OZ is the solution to leaks. I think I can get really low resin ratio glass onto a board and then seal the pinholes with a scraped on layer of epoxy and microballons or cabosil. I just did two test pieces to see the weight difference in the approach. More than 20 percent (28 to be more exact) for a one foot square test. I don't know if the sealed sample is more leakproof than saturated cloth, but it seems to me that it should be.

I'm thinking I like microbaloons better than cabosil. Man, that stuff is hard to handle. I got it everywhere. Kind of a bitch to sand too.

I'm thinking that drawing a very light vacuum on the board while applying the sealing coat might be valuable. 

I'm going to do a more complete test when my ultrasonic leak detector shows up. I'm getting smarter at this very quickly thanks to a coach I won't name who has been sending me VERY valuable PMs.

[supuk]

One of the keys to pin holes is make sure the blank and the room are at a stable temperature or falling so the board does not gas out and create the small holes, this is even more important on the filler coat so any holes draw the epoxy in rather than blow bubbles out. So generally if you are glassing in a garage glass in the evening when you can see the temperature start to drop.  This will have the same effect as putting it on a vacuum without any were like the troubles a vacuum can cause.


If you want a sandable filler just use micro balloons, cab-o turns extremely hard and does not sand well at all  it is only used as agent to prevent slumping.

[peterwSUPr]

That's a good tip about the falling temperatures, and I've been doing that.  So far looks like this is sealing pretty well.  I think the higher density foam and sealing the blank first probably all helped too.

One thing I've found on a windsurfer is that I can put a vacuum, with a vacuum reservoir onto the board through the vent hole.  If it's nicely sealed and there is a tank with a vacuum in it, you can turn off the pump and see if things are perfectly airtight.  (Of course, you only want gentle vacuum).  I was checking around footstrap inserts that time, and you could hear slight leaks.  I wonder what the flow would be through a pinhole?

I put the board in the river for a minute to check standing area and where the pad will go.  Looking good, and about 24 to 25 lbs right now, with mostly just paint left.

Peter

[PonoBill]

I've built a vacuum system that allows very precise control of the vacuum. I use a variable vacuum switch to control the pump which sets the pressure in the accumulator within a three inch HG band, then a reworked regulator on the output with a bleed valve downstream of it. I have a lot of experience in controlling vacuum from my days as an amateur scientist trying to accelerate particles. That was four stages of pumps with hot mercury diffusion as the last stage. The reflex to control remains. I can certainly control within an inch of water. Overkill, but that's how I roll. I'll shoot some pictures soon. 6 CFM pump, accumulator tank, resin catch tank, copper plumbing, blah, blah.

I think I'm done with Carbosil. I think I have some trying to sneak up my butt as I type. Who dreamed that stuff up. Microballons are fine. I'm gonna be blowing that crap out of my nose at Christmas.

If you want to find leaks, get an ultrasonic detector. I borrowed one from a refrigeration guy today and my vac system sounded like a Calliope. I found seven leaks. Two around the flanges of my resin trap that I can't seem to eliminate. I think a redesign is in order. My very own ultrasonic detector should be here tomorrow.

Pinholes should be VERY noisy, as long as your detector can handle very high frequencies.

[peterwSUPr]

Ah, OK, so are you using a vacuum like I was suggesting and just using much better noise detection?

Another good way to detect pinholes is when wet sanding.  If you wet-sand the board, the white goo from sanding gets stuck in the pinhole and does not rinse off so you can see it once you clean it up.  Of course, I'm ASSUMING that I won't waterlog the board while wet sanding!

In 1983 or 84 we built a windsurfer with EPS.  Never heard of pinholes.  Vent?  What's a vent?  Didn't see the need to get a deck  perfectly smooth since will be textured anyway.  Paint did not fill the holes well either.   To say we had 100 pinholes is a huge understatement.  We probably had 1000's.  The board was just oozing water when we put it into a hot car, until we did a major overhaul on the board 

Peter

[Bean]

On the other hand, I bet it dried out really fast...