I’ve done pour foam rails. The “blank” on the far left is 1.5 pcf eps core and 5# polyu rails. I made a latex glove mold from the offcuts when making the perimeter stringer core. Reinforced that with CSM then poured the polyu into that latex mold to make the rails.
Yeah - that’s my son James. The rails are fine, but we’ve had issues with the 'glass tearing at the stringer. James lands pretty hard and puts some significant heel dents right next to the stringer. The EPS compresses…but the stringer doesn’t. After about 3 months, the heel dents got so deep that it started a delam and then eventually tore the glass at the seam and then about 1 inch towards the tail past the heel dent the tear made a right angle and spilt towards the middle of the board. I’ve also had the same issue with just the HD foam on the rails and no stringers. The HD foam rail material doesn’t compress or at least not at the same rate as the EPS and the 'glass tears at the seam.
I stole this concept from Greg L and Warvel - I couldn’t get them to make me a blank for our tiny wakesurfers and so just 'garaged it.
As far as the foam on the rails - no dents or dings, a breeze to shape…but I can only get three months service before the seam failure on the deck. I am going to try an additional cap layer over the stringers to see if that prevents the tearing.
I molded the rails in one pour. Basically what I did was shape the outline “close” before hotwiring the core where the perimeter stringers would go. Then I saved the offcuts - which would up being very close to what the final rail would end up after shaping. OK for hand shaping, but not for a CNC machine.
The foam I used was 5 pcf. I purchased it from Smooth-On. The product is called Foam-it! It comes in various densities and you can order different voulumes of the product. I found their “test size” (I think is what they call it) was just right for my rails.
durbs, I’m sorry…not sure if I was clear. The offcuts became the buck for my mold. Next I glued them to some plywood, waxed them up with mold release. Then built up 21 layers of latex mold builder from TAP. When that had cured, I built up two layers of CSM to act as a rigid base for the mold - mold release in between the latex and CSM. When THAT all cured. I peeled them all apart and I was ready to pour.
I played with one mold where I shaped the bottom rocker before making the offcut. It’s possible, I guess, that you could make up a mold that would be specific for one board, or a more generic one like I did above.
One last thing. You’ll notice that the rails are green or blue, I can’t remember what color I used now. The pour foam comes out tan, which I wasn’t thrilled with, so I added some pigment to the mixture. I know that some folks talk about pour foam have nasty voids in the middle, but I didn’t experience that with this. Gurus told me that those boids are the result of poor or inadequate mixing - so I used a squirrel mixer attached to an electric drill. I stirred the pigment into the side A I believe, for 2 minutes and the the two components for 2 minutes before pouring.
im interested in how your corecell skin goes. Ive been thinking about that very seriously for a few days now. Are you going to use it with poly resin or epoxy?
3 mm A500 Corecell deck skin over the perimeter stringers is my next project.
