This project was a way for me to do two different things.
1) Hopefully provide my Fiance with a beautiful, homemade, sturdy and most of all functional stand up paddle board.
2) test fiberglass/epoxy application that I hope to use on a canoe one day!
I researched several different websites during the planning phase and saw that a 'marine ply' body covered in fiber glass and epoxy was a popular and elegant design. However, with the goal of keeping the craft as light as possible, I decided to use Rigid Foam Insulation covered in epoxy and fiberglass for durability/protection. This website: http://vermontsup.com/diy-sup-vt/ essentially chronicles the same plan I am attempting to undertake with slight variations. Other plans around the interwebs such as those for surfboard making offered helpful hints on shaping and fiberglassing as well.
Step 1: Materials and Tools
-8'x4'x2" rigid foam insulation (I used 4 of em at around 17 dollars a piece from Home Depot. Big shout out to my buddy Jim who let me use his truck to transport these. They would have been ripped apart in a second if I had tried to strap them to the roof of my car)
-Liquid Nails, 2 to 3 tubes. ***** Make sure the liquid nails is rated for Foam Board and has low VOC content otherwise it may eat through the foam. The red label apparently eats through foam but the blue label seemed to be safe.
-1/4" ply wood (These will be ripped into 2" by 11' sections and used as "stringers" to support and distribute weight along the length of the craft). I used 1/4" because I had some left over but I can imagine that any plywood would work (apart from OSB maybe). I've even come across plans that use 1" dowels that run the length of the board.
-Epoxy and fiberglass (ordered online from US composites)
-Epoxy pigment (Optional but adds a nice bit of color to the design)
-Circular saw (or table saw) to rip the stringers
-hand saw(s) play around and see what works best for you.
-weights and bit of plywood (to apply clamping force while gluing)
-random orbital sander
Step 2: Putting Together a 'blank'
Firstly, a blank is what the surf board makers make their boards out of. The square piece that is carved and shaped and sealed so that it glides effortlessly over the water. The stand up paddle board I wanted to make (at its widest dimensions) was roughly:
11.5ft long, 31 inches wide, and 5.5 inches thick.
This was simply based off of some arbitrary measurements of paddle boards for sale around the web. I wanted to make sure it was plenty big enough for myself (around 220lbs) in case I ever felt inclined to take a trip on it.
Disclaimer: Much like Donedirtcheap, as he mentions in his instructable https://www.instructables.com/id/Paddle-Board/ , I must have a high center of gravity because while many people claim paddle boarding is easy, I've found myself falling off of them an embarrassing amount of times. So to accomplish this size (11.5ft long, 31 inches wide, and 5.5 inches thick) from the 8'x4'x2" foam boards, I required 4 pieces. Boards were cut and arranged accordingly, I tried my best to stagger the seams so that no weak spots would arise.
After the form was laid out, I ripped several 2" wide pieces of 1/4"plywood, making sure I had enough to span the length of the board. I then cut the top foam board into 3 long sections (two 9.5" sections and a center section that was about 12", instead of making the pieces equal widths I tried to mimic the position of ones footing while on the board) and sandwiched the plywood in between them. These are the stringers that add strength to the length of the board. Plywood isn't the only option but since I had an extra long piece, it was the most feasible.
Scrap foam was then added to the nose so that the board could bevel up past the deck and break waves much like the bow of a boat. Once I had the pieces laid out, I applied the liquid nails to all the surfaces, laid them on top of each other and put weights down to keep them in place. I placed some long plywood boards under the weights to prevent the metal weights from making indents in the foam. I didn't think it was super critical to completely cover the foam in glue since the epoxy and fiberglass will be the primary agent holding everything together in the end.
*****The liquid nails I used was junk. It didn't seem to ever dry once it had been sandwiched between two foam boards. I've read that the Elmers brand 'gorilla glue' works very well and is popular for foam models, however, I was unable to find any and opted for the liquid nails. I ended up using plain old white, all purpose elmers glue when the liquid nails failed.
Step 3: Shaping the Blank
Once the glue has dried (follow directions on the bottle), you can start to draw a template on the blank to guide your shaping. The specific designs are endless. Generally though you can make them skinny and pointed for speed, or wider and rounder for a smoother ride on rough waters. Being on a bigger lake I chose the later of the two.
To accurately draw a symmetric shape on the board I made measurements at different intervals and beveled the shape of the curves as best as I could with a sharpie. For the Bow, I used a piece of paper as a template, shaping one side then flipping it over to do the opposite side. Once the lines were all drawn, I cut the large pieces off with a hand saw. It's easy to go fast cutting through the foam so make sure you take your time when you do this. It's tempting to blast through the foam with force but try to let the saw do most of the work and apply as little pressure as necessary to get smooth edges.
After the shape of the board was roughed out I began to shape the board with the surform rasp, the rasp eats through the foam like butter. Move the rasp lightly across the craft, and like the saw, don't apply too much pressure or you'll take out big chunks of foam. I've read projects that use a 2nd hand cheese grater, but whatever you do, make sure you do it in an enclosed area where you can clean up. Those little foam particles would wreak havoc if left to be scattered by the wind. Using the rasp I beveled all the edges, the bottom a bit more than the top. Eyeballing from time to time to make sure each side was symmetric.
Then, I formed the bow of the board, shaping down from a pre-determined center line. Marking opposite sides with a sharpie can help you when your determining how much to take off in order to keep the bevel uniform across the bow as well as across the edges.
Once the board has been shaped to the builders satisfaction, go over it once more to make sure you are rid of any rough looking spots, particularly on the bottom as this will affect speed as well as how the board tracks through the water. For big dents or uneven sections (like where the top of the bow met the deck), I applied joint compound and smoothed it all out to make the craft more aerodynamic. I experimented this same process with painters caulk but it didn't sand as nearly as well.
Step 4: Adding Handle Box
These boards are massive (although fairly light), therefore, it is beneficial to have a spot that can assist in carrying the beast. I've seen these on commercial boards, don't know what the official name is so I call it a 'handle box'. It's essentially a small hole. the size of ones hand, in the middle of the board that lets you carry it in one arm.
First I located the center of the boards gravity by tying a bit of rope around the middle and seeing exactly where it balanced. This is liable to change as epoxy and fiberglass is added but it's a good starting point. Then, using a razor knife, I carved a rectangular section off of the first layer of foam (2 inches thick!). This section should be about 1/2 an inch bigger than what could accommodate a persons hand. After cleaning the carved section out, I lined it with 1/4" plywood (left over from the stringers) to add For this I used scrap bits of stringer (the 1/4" thick, 2" wide).
Step 5: Sanding
I honestly was surprised that an orbital sander worked as well as it did....
Using 200 grit (I started pretty fine to avoid ripping big chuncks out of the board), I went over the whole board until it was smooth. Same tips apply: don't use force, let the sander do it's job. You can actually see the foam cells smooth down which means your doing the job. I also made sure to hit any areas where joint compound was added and the edges of the fin and handle boxes. From this point on, any edge or divot will be transferred through the epoxy, so take your time with this step.
Following sanding, I wiped it down with a wet rag to clean off the majority of the particles that would prevent the epoxy from binding to the board. Then I moved it outside to the garage in preparation for the fiberglassing.
Now you've got what should look like a functional paddle board (albeit ugly), although without epoxy reinforcement it's probably still too weak to actually use. Maybe not,
Step 6: Fiberglassing
*********Where gloves, goggles and an N-95 mask when doing this and stay in a well ventilated area. I had no issues whatsoever following this recommendation and I wouldn't risk not doing it. *********
So after doing some research about fiberglassing and buying some stuff from US composites (I went with the 3:1 hardener (forget the quantity but it's sold with the resin), epoxy resin (1gal), fiberglass (8 yards at 38" -again the exact type escapes me but the type I bought was indicated on their website for watercrafts), pigment (4 oz.), 2 pumps for dispersing the resin and hardener. I also used solo cups, plastic spoons, cheap paint brushes and a plastic paint scraper.
I've listed this process in several steps to guide people along but I'm far from being anywhere near decent at this process. This is the first time i've ever fiberglassed and honestly I'd much prefer people watch a few YouTube videos and read a book on canoe building than listen to anything I have to say. Before you start though, set up your epoxy and hardener with the pumps and set them in front of a heat or work lamp. This heats the liquid and makes it less viscose and easier to work with.
1) I started with the top so I could practice technique on the non-functional side of the board. Start by laying your fiberglass along the length of the board and center it best you can. Using a paint brush, brush out the spots where it lifts off of the foam body. Now, my board was about 31" wide and the fiberglass was 38" wide but I didn't cut it to size. I wanted to be able to wrap around the edges a bit and also leave some excess to catch drips.
2) Once your fiberglass is in place move to the epoxy phase. Mix the proper ratio of resin and hardener and mix thoroughly, you can also add about half a teaspoon of pigment at this point (as i've found, a little pigment goes a long way and it doesn't really matter if you add the precisely exact amount with each mix). Next pour the epoxy along they center of the board and spread it back and forth, up and down, side to side with the plastic paint scraper until it fully saturates the area. Once done, move to the next area and add more. The sides were a bit tricky with the paint scraper so I just smeared it on with a rubber glove. Once you've covered the whole piece of fiberglass, wait about 2 hours.
3) After letting the resin bind to the fiberglass for 2 hours, you can do what people call a 'fill coat'. This is essentially just an additional coat to fill any spots you missed on the first round. Some people recommend the use of a glue roller to apply the resin on this round. The mixing process is the same as above. Once you've put two coats on, let the whole thing sit for a few days.
4) after everything has hardened for a few days, trim the excess fiberglass that has hardened and sticks out from the form in a catty-whompus fashion. Trimming with scissors can't get every fiber so after this I took an orbital sander to smooth the edges down. Once the edges are smooth you can turn the board over and fiberglass the opposite side.
5) For the bottom side, I trimmed the fiberglass to match the width of the board along with some overlap to the edges that had already been glassed. scissors work just fine for cutting the fiberglass but make sure that the sheet hasn't shifted, causing you to cut off too much.
6) Use the same process outlined in Substep 2 to epoxy the opposite side of the board.
7) once each side has been coated with the two initial base coats and left to dry for a couple days, one can begin to use additional coats of epoxy to smooth out the hull and deck of the boat. Using a 'one time' paint brush works well for this process. I think that the heat lamp method is most critical hear as the thinner resin tends to leave fewer imperfections.
8) after the hull and deck have been glasses to ones satisfaction, sand it with a high grit sand paper to rid the form of any burs or edges. I think anything above 400 upwards to 1000 would suffice. It really depends on how much of a perfectionist you are at this point.
Step 7: Adding the Fin Box
I'm sure that one could make a fin from plywood covered in epoxy but I wanted the fin to be as precise as possible, so I found a fin box and a fin on Amazon at a decent price. The fin keeps the board from turning an excessive amount when paddling while adding stability to the craft as well. You can choose from a variety of styles and configurations, but I just used a large single fin in the center of the board about a foot from the back.
To mount the fin box I first cut out a piece of epoxy/fiberglass and carved out the foam, poured in some epoxy and put it in place. Once the epoxy was dry and the fin box was in place, I put a piece of tape over the fin slot to prevent epoxy from accidentally dripping in and ruining the configuration. Then I used more epoxy to smooth/reinforce the edges where the finbox met the hull of the board.
Placing the fin in the fin box was a bit tricky and I had to consult YouTube to figure it out. The finbox has a center hole that leads to a slot running the length of the box. The idea is to maneuver the fin into the slot starting with the bit that locks and following with the peg, then secure it in place with a Philips head screwdriver. I think fins may be removed so that they can be stored better but also in case they break, it's a very clever design that prevents the whole thing from being useless in the event of running over a rock or dropping it off your car.
Step 8: Adding Color -Optional
I'm not sure how well this will hold up during use but here goes.
Using some latex paint and painters tape I made a couple stripes along the body of the board. After the paint dried I put one additional and final coat of epoxy to protect the paint (I feel like the more epoxy you use the sturdy the board will be anyways). It makes the whole board 'Pop'.
Step 9: Conclusion
Overall, the project was relatively easy. Time consuming with the epoxy'ing process but worth it in the end. The board worked well on the first test run. I actually made it a bit too big as it can easily carry the weight of myself and another. Plans for future upgrades include a eye in the bow where an anchor can be attached to allow one to kick back and sunbath if paddling gets old. Also, some stick on foam to make your footing a bit more stable as the epoxy gets pretty slick when wet.
Thanks for viewing and feel free to comment! Hopefully over the winter we can get ahold of an actual SUP paddle and leave the kayak paddle for kayaking. It's a drag that I didn't get around to doing this until the end of the summer (being in Michigan) but we hope to get lots of use next summer!