I’ve built a Marko 1.9# RR-Epoxy short board(6oz warp bottom-6/4oz top), and while spending the day at the beach the stringer started to protrude through the glass. I had it covered by a towel to keep it out of direct sunlight. It only happened on the bottom,on the tail. It may have not been completely covered?
This is not the first time I’ve had this happen to the EPS/Epoxy boards I’ve owned or made. What is it? Pressure changes, shrinking foam, or swelling stringer?
I have dinged plenty of PU/PE boards and never had the stringers stand proud like this.
I like the board a lot. Would a vent prevent this? The build method is straight out Greg Loehrs videos, spackle and all…
I’ve built a Marko 1.9# RR-Epoxy short board(6oz warp bottom-6/4oz top), and while spending the day at the beach the stringer started to protrude through the glass. I had it covered by a towel to keep it out of direct sunlight. It only happened on the bottom,on the tail. It may have not been completely covered?
This is not the first time I’ve had this happen to the EPS/Epoxy boards I’ve owned or made. What is it? Pressure changes, shrinking foam, or swelling stringer?
I have dinged plenty of PU/PE boards and never had the stringers stand proud like this.
I like the board a lot. Would a vent prevent this? The build method is straight out Greg Loehrs videos, spackle and all…
Thanks,
I believe your stringer has absorbed water. Don’t know why EPS does this and not PU, but the only times I’ve seen it is when one of the ones I’ve glassed has gotten a ding. If you don’t have a ding yet, you need to find the pinholes and fix all of them. They’er easy to get in EPS. One more reason to go with a different stringer material or stringerless. You CANNOT make the stringer go back to its original dimensions. Even once you have thoroughly dried the board, which you must, it will remain raised.
I had a eps board get dinged and the stringer wicked water then swelled just like this one. We called the manufacturerof the blank and they claimed that they had a batch of stringers that were not cured properly. This apparently was a big problem back in the days when windsurfing moved to eps/epoxy.
Anyway, I glassed this one myself. So, It could likely be full of all kinds of holes. I did a cheat secondary hot coat to try and fill any pin holes. I also have probox boxes in that I installed and they are not capped or set in HD foam. So, maybe they leaked a little and the hot day created steam?
Is this happening to the highend custom EPS/Epoxy manufactures like Stretch, Rusty, etc?
It’s a shame because this board served me well through last weeks epic south swell. A couple of groms even said the board looked “sic”.
I am thinking about stringerless as well. I even have the blanks, but my R&D budget is not boundless.
Still looking for a better backyard construction method.
Hey, I’m glad you mentioned this. This is definitely a problem. The stringer on one of my older epoxy is like 1/8 raised and I can’t find any dings on it. I’m surprised like you that none of the pros seem to have this problem–or do they? Anyway, my board still surfs fine; no performance negative that I can feel. Just annoying.
Another thing I’ve had recently occur–and I am by no means good at glassing–is a gooey leak from one of my fin boxes. It’s like a few ounces of resin w/o hardener that’s come from this one box. Any ideas? The rest of the boxes (all done with the same resin/hardener mix) don’t have this problem.
Some Pros do have this problem because I have had two Pro built boards that have done it.
It sucks because the epoxy glassing schedule of 6+4oz top with patches and 6oz bottom over 2# foam seems to be a winning combo for light and durable.
I’m starting to think about switching to Poly blanks. The weight may increase but the stringer swelling is unacceptable. A board should be able to sustain a ding and then be repaired properly without having the stringer swell.
Could a vent be the answer? Open a plug when not surfing? I could live with that as well. I have had no problems with the vent on my firewire.
There are a ton of Stretch/Marko and Rusty epoxies in the water, has anybody seen their stringers swell threw the glass with water contact?
Hey, I’m glad you mentioned this. This is definitely a problem. The stringer on one of my older epoxy is like 1/8 raised and I can’t find any dings on it. I’m surprised like you that none of the pros seem to have this problem–or do they? Anyway, my board still surfs fine; no performance negative that I can feel. Just annoying.
Another thing I’ve had recently occur–and I am by no means good at glassing–is a gooey leak from one of my fin boxes. It’s like a few ounces of resin w/o hardener that’s come from this one box. Any ideas? The rest of the boxes (all done with the same resin/hardener mix) don’t have this problem.
Thanks,
C
The ooze from the box is the result of improperly mixed resin/hardener that was used for the box. Sometimes it is hard to get the right ratio when doing small batches. I switch my digital scale to grams for doing boxes. When the board heats up the eps swells and pushes out the gooey mix. The bummer is when you go in the water and the board cools it will suck water.
Your going to have to grind off the glass and reinstall the box. I had the same thing happen to a few boards I did until I got a scale. The board was so full of water I had to drill a hole in the tail and stand the board up to drain the water.
I’ve seen this happening (although a somewhat slower process) on a number of production SUP’s, especially the darker colored ones. If you periodically caliper the thickness along the sides of the stringer, it would appear that the foam is shrinking. The problem is that EPS will expand and contract with temperature differences. Because of the adhesives/clamping used in gluing up the stringer (and the stringer itself), the expansion and contraction is not uniform along it. The stringer and the adhesive blocks the foam from expanding, and this causes increased internal pressure on the foam beads/air gaps (higher than anywhere else), so the foam doesn’t fully recover the original thickness when cooled down. This is analogous to a compression spring which exceeded its load limit; the height becomes smaller. When glassing, more resin soaks in along the stringer and this also contributes.
Would venting help? It will may make the process longer, but not eliminate the the problem. Most of what I’ve seen is from solar loading/non-uniform heating in localized areas, and this can be very unpredictable. This is why some people have this problem and others don’t. If you had lots of pinholes on your glass job, the board would already been vented anyhow. Fixing the problem in you case may be simple. Once shrunk, the foam will not get any smaller. I would sand the stringer down to the correct height and put layers of 4" wide cloth over it. Just remember not to leave an EPS board in the sun, not even in a bag (which is just becomes an oven). Please post some photos, put a straight-edge across the board and take a shot looking down the deck.
I have ONLY seen the swelling stringer when water intrusion was happening. Not a huge sample, but over 600 EPS/epoxies the last 2.5 years is a fair number of boards. If there are other reasons it happens, I haven’t seen it in Marko or US Blanks products with my glassjobs.
Interesting stuff…I never spend the whole day at the beach so I guess my EPS boards live a more stable life…Ha Ha…
Now I’m worried about the boards I sold and If they will hold up …
After my third epoxy glass job I solved most of my problems by doing a second hot coat (gloss coat?). This seals all the pin holes and other problem areas.
If you really want to know if your EPS/epoxy is leaking, weigh the board before you ever take it in the water (with wax). If there’s a big suspicion of water inside, drill a small hole at the nose and tail and see if it weaps when hit with a hair dryer at either hole. If you find water, the best way to get it out is to use a vacuum pump (see www.boardlady.com for details). If the board is stringered, you need to treat each side independently. If the stringer is waterlogged, you’ll have to expose at least 1/2 (on one side only) to dry it out. Water inside will create delam problems, especially if you used spackle.
EPS expansion/contraction may indeed be a problem, combined with some moisture in the board would make for trouble. I have it on one board with a ply stringer, at first I thought it was denting in the deck but on the bottom it used to be flat and now is more “v” …
I would say go stringerless and spend the extra weight gain on the glassing.
I love the board ladies web site! She is not too fond of this type of construction. She doesn’t think it’s much better than pu/pe.
I like the idea of EPS/Epoxy because it seems simple enough to iterate designs and not complicate the build process too much.
But the stringer issue has been a problem for me. I don’t want to have to worry too much about boards imploding with reasonable sun exposure, or not being able to handle some water exposure.
Did I mention that this Board is Orange. Maybe white or light pastel colors are safer if you want to take them to the beach for the day.
I made one stringerless fish with a friend and I’m waiting to see how it holds up.