X5 – Motor Olsen

After a few sessions on the beach with the Sensei Sebastian, some friends of mine and I started kicking around the idea of creating a hybrid twintip made with surfboard construction. Drunk with power after successfully completing a surfboard on my first go I decided to give it a try.

Specs

• Designation: BPX5 – Motor Olsen
• Length: 150cm
• Width: 45cm
• Thickness: 1 7/8 inches
• Core: XPS foam
• Deck Glass:
  • 4oz Warp Glass
  • 6oz S-Glass
• Bottom Glass:
  • 4oz Warp Glass
  • 6oz S-Glass
• Resin: Resin Research 2000 CE Ultra Epoxy
• Hardener: Resin Research 2100S Slow Hardener
• Paint:
  • Acrylic applied by airbrush
• Soundtrack Highlight:
  • Kabaka Pyramid – Kontraband
  • Various other Reggae

Building the Board

I knew I wouldn’t be able to find a surfboard blank that could work as a twin-tip so I decided to make my own. Before diving into that I decided to make my own hotwire cutter.

You can find plenty of instructions online about how to build a hotwire cutter and you can find videos of twelve-year-olds plugging wall warts into outlets with the leads electrical taped to a strand of framing wire and attached to popsicle sticks to cut foam for RC modelling. In general, you need something to act as a resistor to generate heat, and something to regulate the power going through that resistor. Nichrome wire is the recommended resistor wire but folks use all sorts of things.

Just about all of the instructions I found called for buying a transformer, some sort of dimmer switch, various enclosures, and maybe a fuse so you don’t die. Just about all of the instructions I found are about 5+ years old and apparently the cost of power supplies have come down a lot since then. For about the same cost you can buy a decent power supply with some nice features like current and voltage limiters.

My hotwire cutter is basically some nichrome wire stretched across some eye rings and attached to some 12 gauge speaker wire that came with banana plugs attached which saved me some soldering, were a whole lot cheaper and plugged right into the power supply. I added lighted switch were I place my hands so I can turn it on and off without needed to turn around to the power supply.

After building the hotwire cutter, I started on building my own blank. I cut a profile template from whiteboard material. Since this is a twintip I only needed to cut a half template then flip it over. I picked up some MDF baseboard material which was cheap, easy to cut and close to the size I needed it. I traced my template onto two pieces of that to use as a guide for the hotwire cutter.

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I also traced the template onto a piece of PVC foam sign material I picked up from a local plastics shop. This stuff is super cheap, light and really strong so I thought I’d try it as a stringer.

For the foam core, I picked up a piece of XPS insulation foam from my local hardware store. You can get this in a 2’x8′ sheet that is 2″ thick. Between that and the stringer material, I’m able to make a blank for about $30 which is about $50 less than buying a blank.

My first step was to cut foam in half to glue the stringer. For this I used a hand saw and a board as a guide. I flipped the cut pieces around to use the outside edges, which had clean flat surfaces rather than the sawed surfaced, against the stringer.

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I glued one side, let that set, then glued the other half on with Gorilla Glue. Now that the stringer was in, I clamped on the hotwire guide and cut the bottom shape. I didn’t bother cutting the deck since I wasn’t doing any big cuts there. Also, by keeping the deck square, it was easier to line up the various templates. The center mark was also very helpful in keeping everything lined up.

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I cut one side with the hotwire then cut the other side. There are some fumes produced so make sure to wear appropriate safety gear. The cutting itself took seconds.

With the profile cut, it was time to put the blank on the racks and trace out the template. Since I was going for a twintip design, I decided to use the same template I had used for my first two boards. I did a rough cut with a hand saw of the outline and then shaped it to my marks. I finished it up by squaring the rails with a rail runner tool.

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Now it was time to lay out the rail bands. For this I went as knifey as I felt comfortable going and kept enough space at the top flat for my foot pads.

Shaping rails is probably my favorite step of building surfboards. The board really takes shape with this step and seems to come to life.

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XPS is a closed cell foam so you don’t need to seal it to prevent epoxy seeping in like you do with EPS foam but you still need to fill any gouges, scrapes or other oopsies. This is done with DAP Fast n’ Final spackling diluted a little thinner than toothpaste with distilled water. This is a super unsexy part of the process because apparently I never think to take a picture of this step.

There was a debate with friends as to whether I should make this hybrid twintip strapped, strapless or both. I decided to go strapped and forgo the traction pad, although I guess if you wanted to, you could wax it up and try it strapless. For the footpads, I was going to need to install inserts. I thought I’d try using another piece of PVC foam as an insert panel. I cut a piece, shaped it and marked where the inserts should go. Then I drilled holes for the inserts and used a 5 minute epoxy to hold them in the panel.

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On the board, I traced out the panel and routed the board and stringer out to the thickness of the panel. I did this totally freehand. The fit was (near) perfect but I definitely needed a drink afterwards to relax the tension of doing that without a guide.

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Hey! I didn’t totally screw up the board routing out the insert panel so now I could flip it over and cut the fin boxes. I used half inch fin boxes all around since the original idea was to use rear quad fins.

That was pretty much it for shaping so it was on to painting. I applied a coat of block out white by hand. After making several boards that didn’t quite have that banana look I was going for, I decided to try an air brush. I had never used an air brush before and after giving it a shot, I’m in love. Once I got the hang of it, I feel I used less paint and got better results.

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To sell the banana look, I did some bruises at random. Although, at one point I dropped a pair of scissors that stuck in the foam. I stared at the damage for a while trying to decide how I wanted to fix it. My solution was to apply some black paint to it and make it another spot on the banana and move on. I realized how well that worked when I had to point it out to a friend who was inspecting the board later.

After painting, I mixed up some epoxy thickened with cabosil and pigmented green to install the insert panel. In weighing down the insert panel to make sure it was flush, some epoxy pushed out around the sides and got under my masking tape. This left a bit of a mess around the panel so I covered it up with a pinstripe.

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Once that was done, I flipped over the board and installed the fin boxes. I used clear epoxy this time.

Now it was time to tape up the fin boxes. The inserts I use come with clear caps already that you simply drill through when you’re done fiberglassing. Fiberglassing this time around went much smoother than my previous board. I had learned my lessons from before and wore a Tyvek suit, I cut my cloth to a better fit ahead of time and I was much more aggressive sanding the cut laps down from the bottom before glassing over them with the deck or hot coating.

Hot coating also went nice and easy, I feel like I’ve got that down.

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I did leave the chewed up foam from the bottom cut lap this time around instead of repainting it. I did that as a forcing function to make me follow the time honored tradition of pin striping the deck to hide your crimes.

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After pin striping the cut lap on the deck, I gave it a spray with an UV protecting acrylic clear coat. I was debating doing that or applying another layer of epoxy and decided to give the clear coat a try since it was faster, easier and would add less weight.

At this point I thought I was done but my son offered to 3D print some fins. He was printing the fin on its side to get the layers in an orientation that would be better to resist the forces it would experience. But, this made the bottom side a bit rough because gravity would pull the first layer or two. After a couple of test runs we decided to roll with it but to five the fins a coat of epoxy. For this I mixed up some epoxy with micro-balloons for the rough side and some straight epoxy for the smooth side. The results feel very strong.

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The Ride

For the first ride of the Motor Olsen, I took it out in exactly the wrong conditions. This is a light wind board made for the fairly flat conditions of Jetty Island. I took it out to Double Bluff on a fairly intense day. The wind had been light and everyone had recommended taking my biggest kite. So I rigged a 13.5. Around the time that I launched the wind kicked up and was cranking. I easily got over powered and found that the surfboard rails on this board had a hard time digging in under those conditions. The fins held up nicely under some pretty intense conditions which was exciting since we were concerned that 3D printed fins might not hold up. This board also transitioned like a dream. I might be using this to help folks practice transitioning since it’s incredibly forgiving when losing speed.

I’m looking forward to giving it another go but will be holding off until we’re back at Jetty Island this summer.

About Rob Olsen

The PNW kiteboarding community is truly astounding and Rob Oslen was the first person I met out in the wild. When I was getting started, he was super welcoming. He really took the time to show me the ropes and answer all of my questions. Rob is always supporting our great community by helping out however he can. Whether that’s cleaning up after the Light Wind Olympics, offering to help with wind sensors or giving you a hand on the beach, Rob is a person you can count on to lift you up.

It’s folks like Rob that give kiteboarding it’s good name as an open and friendly sport. I’m stoked to be able to honor someone for just being super cool to everyone in the small way that I can!