That was an awesome post. Thank you
hi,
i joined this forum to try and find answers to a pin hole problem in molded carbon fins i’ve been making, but i may have some relevant comments for you concerning board building.
Been making vac bagged styro boards since 1990.
Your OP is way too ambitious in my opinion. The instructions in the previous link are pretty good.
The 2 main ways that SUPs are made here other than molded are hand laid up glass over 2lb styro with clear surfboard epoxy, and vac bagged corecell over 1 pound styro; then glassed with glass and carbon re-enforcements. The latter comes out lighter and more durable.
There are many steps to the second type. Combining steps is good but there is a limit to how many steps that can be combined.
Most board builders here stay away from kevlar these days.
We use tubular plastic that comes on a roll for the bag and slip it on like a sock, or make the bag with plastic and tape before mixing the resin.
Some prefer doing a hand lam over the core cell after a pre bog/cure/sand out. Others prefer to table lam the glass or carbon, then get it on the board, stretch plastic over it, put a bleeder pad over that and slip it in the vac bag.
When we wrap the deck with core cell, we use a heat gun to bend it around the rails and pre fit it ahead of the vac bag step. Also there is a rocker stick in the bag to hold the rocker which is critical to the shape. The whole board is re shaped after that step.
To keep weight down, only certain areas are re-enforced with extra layers. If you were to put say, double or triple 6 oz. over the whole board it would be pretty heavy.
Try to pour most of your resin out of the bucket and on to the project at the very beginning to give you the most working time possible.
Test projects are a good idea.
hope this helps.
I’ve been making longboard skate boards for three years now and I would agree with other posters that your project seems ambitious for first time vacuum bagging in one step. I’ve made every mistake three times – it’s all about preparation and leaving hours and hours available once you start.
I use core cell as it has superior sheer strength and it’s closed cell structure absorbs little resin. EPS is soft and it will accentuate print through from any wrinkles in your peel ply or bag. And bagging a paddle board is a huge potential sloppy venture as a first go around. Wet lay up or infusion, either are very challenging.
The problem with core cell is the expense. I CNC my foam and avoid 90 deg edges as it’s hard to get the CF to lay down in corners.
Kevlar doesn’t sand so I never use it near an exposed edge. I’ve tried dyneema (Spectra) but it’s even worse. I use strips of either but keep them inboard from the edges. Kevlar degrades in UV so if any exposed you need a UV resistant clear coat.
I’ve had some success with tubular bags I get cheap at Uline. But they have no stretch so they must be pleated.
Any board failures I’ve had have failed on the top or compression side. CF is best in tension as is Kevlar. CF is good in compression but Kevlar isn’t. I now use 5 layers of 3k tow CF on top and three on bottom, (maybe throw in a few strips of CF/Kevlar hybrid), corecell and resin epoxy with no failures. Don’t know how this would translate to a paddle board which is supported uniformly and doesn’t have a central high stress area like a longboard skateboard.
West systems has a video on a skim board wet lay up without vacuum. Still required lots of wet sanding.
What was the result 