Ok, it’s time for me to shape a skimboard, but I still have a few questions. I have referred back to the archives but really havn’t found any good information. Its mostly posts about people wanting to make them out of home depot insulation followed by conflicting information.
I plan on making the board with 3/4" high density foam. I found a place in town that sells Aircell foam which I have been told is much like divinycell. My first question is what density is recommended for a strong core that isn’t too heavy. 6lb or 8lb? For the fiberglass I am just going to start out with 2 layers of 6oz e-glass on the bottom and 3 layers on the top. It was also be cool if someone can give me an estimate of how much polyester resin this is going to take. I want to use uv cure resin. I already have a shape so I’m ready to buy the foam. If anyone has any information on this please let me know.
alex, go with epoxy resin, the cloth sounds right, and wht weights does the Airex come in? There was someone on here, I think, who made skim boards the used a rocker table and vacbagedd them.
Hey man, I dont think Im not going to do the vacuum bag system on this board. I just cant get into that right now. The foam comes in desnities from 4lb to 10lb.
I made a ‘skimboard’ from an offcut of EPS that I got while hotwiring some blanks. 2lb EPS, 6x6 bottom, 6x6x6 top, stringerless. More than strong enough, I weigh in at 140 lb, and have yet to dent it. I made it too thick at 1.25", though, and not enough rocker, so it doesn’t skim anymore. Works great as a kid’s paipo, though. I gave it to a friend…
I used to shape and sell skimboards locally in the Tampa / St. Pete area. Ive seen a few videos from captiva and it looks damn fun on a cold front. I’ve made lots of boards and I have it down to a science. I’ve never vac bagged a skim board. All of mine were a basic hand lay-up. I had great sucess with 5/8" H-80 divinycell, 2 x 6oz bottom, 3 x 6oz on the top. You can experiment by replacing a few layers with 8 oz on the deck or bottom. Use 3:1 Epoxy laminating resin. first cut out your shape with a bandsaw. Use an appropriate router bit to round the rails of the foam. I solved the problem of splitting rails by rounding out the bottom of the rail about 1/4" radius (eventually the lost foam will be filled with glass and resin to create a sharp edge). Manufactured boards will eventualy crack through the rail because the foam is cut to a sharp 90 degree angle they are not solid. There is one kid who still regularly rides a board I made 5 years ago (the bottom has been resurfaced twice but the rail never cracked through). If you dont have a router, shape the foam with an utility knife and sand. I will post some more tips and pics later when I have some time.
Airex is indeed very similar to d-cell, but in many ways BETTER. It’s PVC foam, but it’s not crosslinked. This means that it’ll be more flexible, but less brittle, thus less prone to the crushing and dimpling you often see on d-cell cored skims.
6lb should be more than adequate with a decent glass schedule. You are more likely to add a ton of useless weight by not properly sealing the foam and letting too much resin seep in than you would add by using a more dense foam…if you get my drift; more dense core + little resin absorption = good. light core with lots of useless weight added via resin absorption = bad.
You’ll see that the foam cell size is quite large. First, I’d shape the board and then apply a bog of q-cell or microsphere filled resin with a squeegee such that the cells are filled. You can then glass overtop of this without worrying about the core sucking a ton of resin and giving you a stiff, heavy, dead feeling board.
No need for vacuum bag, though you will want to set some rocker into the board, so you will need to figure out a jig to hold some rocker into it while the resin cures.
For a VERY rough estimate or how much resin you’ll need, calculate surface area of your skim. Then, multiply how many square yards you calculate your skim to be by 5 in your case (2 layers glass bottom, 3 top). Then multiply by 6oz/yard. You’ll need at least the same amount of resin weight as calculated cloth weight just to saturate the cloth, and probably the same amount again to lay down a good hotcoat for fairing and sealing. Use the same calculation when glassing and you won’t waste your resin.
Thanks for the help guys. Everyone has been telling me to use epoxy. Is it because of its strength? I wanted to use UV Poly because of its ease and fast curing.
lpcdefg, Captiva is a really cool place to skim. Not a lot of shells and good shorebreak on the right conditions… Thanks for all the info! What kind of laps did you do on the boards to get the hard rail? My Zap started falling apart at the rails for that same reason.lol I hate it. I cant believe they can produce such a piece of crap and price it for what it is.
The next step after shaping the foam is to make a rocker table. You can make a table that has a constant rocker or you can make one which is adjustable. There are two critical design factors to a rocker table. First, the table must be true and square (no warps). Second, the table must be smaller than the board so your laps can hang off the edge. A constant rocker table is made much like a skateboard ramp. First cut the sides of the table on a bandsaw or jigsaw. The cut should be your rocker profile. Build a frame using the two sides and a few 2 x 4’s. Skin the top with a thin wood composite board. Home depot has a 1/8" brown board with a nice finish. It bends very easy.
An adjustable table is a bit more complicated. However, it is very useful if you want to experiment with different boards. I will post a pic of my table soon. It basicly involves a small flat table with tracks out each end. The tracks have a few slider blocks which can be horizontally positioned. Each slider block has an aditional block which can be positioned verticaly. Just slide the blocks in position and press the board against them with some sand bags after glassing.
Glass schedule:
I recomend adding a dye to your all resin used on the board to give your board a cool color. Have fun and mix different colors and swirl them or draw a picture on the board. Beware!! The color of pure resin on Divinycell foam looks like poop or vomit.
1: Spackle with microbaloons before laying glass on foam like GreatWhiteNorthsaid. allow to get tacky, not fully cure.
2: glass one layer of 6 oz on bottom. Allow this layer to cure with the board on a flat surface. This will stiffen the foam. The foam by itself is too flexible and I have found that I would occasionally get inconsistent rocker when not glassing the first layer flat. Lap only the 1/4" radius curve on the bottom of the core. Trim the edge off at the extreme edge of the rail. Sand flush with the foam. Rough the entire bottom surface with 50 grit sandpaper.
2: glass 3 layers of 6 oz on top. Allow the lap to hang down verticly off the board at least 1" all the way around. Lay the board on your table. Spread some wax paper or visquene on the whole board’s surface and squeege out to smooth the cloth fibers. place a few sandbags to hold it down.
3: Flip the board upside down. The hanging lap from step 2 now creates a barrier around a groove in the bottom rail. Fill the groove with resin and chopped glass fibers. trim the lap and the fibers flush with the bottom of the board.
4: Glass the bottom with the last layer of 6 oz. once again use wax paper or visquene to smooth the fibers. Trim the edge flush with the corner of the rail.
5: The finish on the board usually involves sanding the rail profile (as sharp or dull as you want) remember you have plenty of material to sand into. I usually sanded the entire board to 100 grit, then did a “cheater resin coat” I would sand the bottom absolutly smooth and flat to 600 wet sand paper for max speed in the water. Buffing usually made it a bit slower I dont know why. The top would be dry sanded to 300 and then thin some epoxy with alcohol 1:1 and brush only the top with a foam brush. This will make it shine.
Have fun. I’m very excited to see someone on sways shaping a skimmer!!
Thanks for all the info and the visual on the rails. I will deffinitely be doing it that way. I gave my friend the foam order today so it should be here some time next week. I cant wait to get started.
So, fiberglass wont adhere to wax paper? I was just going to copy the rocker on the board I have but the laminate cant be drying to it.
Another question: When you seal the foam with the resin and microbaloons, does it totally cover the board? Like if I died the sealer coat would the blank be that color? I dont like the color of the foam and I wanted to make the foam white and the resin light blue. I read that you are just filling the top cells so i figured if you color the sealer and seal it, it wont be totally covered.
Put some die in with the resin/microbaloons. I would not seal all the foam at once. Only seal the area which you are going to glass (either top or bottom). The idea is you want the sealing coat to be tacky but not hard when you glass it. This ensures a good chemical bond. Also this will elmiminate the need to sand in between coats. The color of the board will slowley go away after a few layers of glass. Remember that resin is clear so there will always be a tendency for the foam to show through.
Hey lpcdefg, Im getting close to starting on this project. What do you mean when you say to smooth out the cloth with a sheet of wax paper? Ive neve really heard of doing this. How exactly is it done?
After you lay your cloth down and wet it out, put a large sheet of wax paper over it and smooth out all the bubbles and wrinkles with a spreader. Don’t worry about laying the wax paper over the rails. After the cloth dries, peel up the wax paper and if done properly you will have a smooth surface which requires MUCH less sanding than a surface which cures without wax paper. Be carefull not to let bumps form under the wax paper. A bump will occur if there is a surplus of resin in any area. This technique only works with a skimboard because the board only curves in one dimention. A surfboard curves in two dimentions and the wax paper will wrinkle while going around the curve in the second dimention. Remember: The wax paper will leave a light wax residue on the fiberglass. Wipe it down with a solvent like acetone before sanding.
I was reading your other post about autocad and I noticed that you said “flat bottom”. I would make a flat center and have a tiny bit of tail rocker. Early on I made a true flat bottom board and it rode like a dog. I put the slightest bit of tail rocker in to keep the tail from dragging too much.
Thanks so much for getting some skim info out there. I’ve been wanting to shape one out of foam myself, because up here in the pacific northwest, the plywood models de-lam rather quickly.
I was thinking of capping the deck or bottom with wood.
thanks, I get it now. I meant that the board wasnt going to have any type of concave on the deck or bottom. My board will definitely have tail rocker. The foam could be in any day now. Ill post pictures and what not of the process.
What’s the waste amount in resin, tubing, etc.?