Saturday, January 24, 2015

Pedal Platforms and Stabilizer Forming

The platforms for the Speedplay Frog pedals were coated on both sides with epoxy resin to seal the wood. After the resin had hardened, the excess resin needed to be removed in order for them to fit on the pedals. I used a Moto-tool with a flex shaft and a tiny cutting head to do this on the interior cavities, and the disc sander to remove the stuff along the edges.

The next step was to  apply a thin coating of resin to the top of the platforms and sprinkle some sand I scavenged from the backyard sandbox. I first toasted the sand with a propane torch to remove any organics, of which there was a bunch, as well as any moisture. Anyway, while applying the resin and then the sand I was careful to not get any on the threads of the T-nuts.

When the resin hardened the pedal platforms were put through the disc sander one more time, and the securing holes drilled again to permit the mounting bolts to pass through.

I ended up having to countersink the reverse side pedal mounting holes so the heads of the bolts would be flush. It didn't remove much of the plastic, so the strength of the pedal should not be compromised.

As can be seen in these photos, the platforms are flush with the pedal, and all the hardware is flush with the pedals as well. It remains to be seen how these platforms actually work in practice.

The new stabilizer float halves were epoxied together. I used a bunch of Cadence propeller strut blanks and some blocks of steel that were laying about to provide pressure to eliminate any gaps, thus making for a better bond.

To shape the stabilizers I decided to try a hot wire cutter. These seemed to be relatively simple to make and one ends up with a lot less styrofoam dust everywhere.

I read about how to make them from various web sites, and most suggest either using moderate gauge metal guitar strings or buying nichrome wire from Amazon or e-bay. Since I had a bunch of nichrome wire in the form of an electric heater with a frozen fan, I decided to scavenge it from there.

The wire in the heater was coiled; I wanted it straight. So, after cutting a suitable length of the coiled wire I used a metal tube as a form against which I stretched the coil. The wire ended up pretty straight after making a number of passes over the tube while maintaining a good amount of tension on the wire. I guess I could have used a smaller diameter tube or possibly even a piece of wood and more tension to have a straighter wire, but I think this was good enough.

One novel suggestion for the hot wire setup was to use a PC ATX power supply's 12V outputs to drive the wire. As I happened to have a couple of these around I put one to use and tried it out. It was just about perfect. The wire did not turn red, but it was the right temperature to make a decent cut at a reasonable speed.

One touch that I liked but probably didn't really help a whole lot was adding a spring and a turnbuckle to maintain tension on the wire. Since nichrome expands a lot when heating, I thought the spring would help. It turns out the setup has enough give in its structure that it probably isn't needed.

After testing the hot wire cutter on some scrap foam I was ready to cut the floats.

First, I marked the curves of the sides using an old float as a template. I then pushed the foam block through the hot wire, perhaps a bit too quickly. Note the waviness of the sides. I think if the upper arm of the cutter was closer to the foam, and there was not so much of an overhang the results would have been quite a bit better from the start.

After cutting both floats, I attacked them with the orbital sander. That managed to get them pretty close to what I wanted, though there were some low spots that will need to be filled before the outer skin of glass is applied.

I then marked the curve of the underside of the bow, again using the old float for a template. I decided to have the angle go a bit higher at the front, and have the piece that was removed from the bottom placed on the top. This might help a little to prevent the diving plane scenario, as well as provide a little more flotation.

After sanding the bow with the orbital sander, which did a great job of smoothing things out, I used a hand sander to smooth the concave curve of the pieces that would soon be mounted on top of the bow section of the floats.

After applying a layer of resin to the top of the floats at the front, the new top pieces were put in place. A number of weights were applied to try for a good bond.

The next step is to make the mounts for the floats. I'm planning to use both the grab tubes and the old float mounts on the boat to hold the same tubes as were used with the old floats. The distance between these two points is about 42.5 inches. Given the lack of precision in these two mounting points, I'll have to get the boat positioned so that the new floats are held in the correct place, and then install the mounts on the floats while the tubes are also in position on each side. It should be fun!

Thursday, January 01, 2015

A New Year and Work Begins

Since the last posting I had a few more races (Budd Inlet being the last official one) and participated in a prototype race on Lake Washington called "Length of the Lake", abbreviated LOL. In that race, held on Thanksgiving weekend, the conditions were a bit too rough and a recent modification made to the prop strut mount contributed to my need for a rescue by the Harbor Patrol and a trip to the Harborview ER to quickly restore my body temperature.

So... the winglets and the displacement provided by the floats at a 3 foot distance on either side of the V15-6M were not adequate in the face of a 25+ knot wind and 3+ foot waves to keep the boat from capsizing. The rudders were also inadequate in such conditions to keep the boat pointed where I wanted to go. The modification to the prop strut mount prevented the strut from being locked in the fully extended position, which caused the propeller to frequently hit the protective plate mounted on the bottom of the hull as the waves tossed the boat about. Lastly, the Speedplay Frog pedals, while very good at having but a single moving part (the pedal body about the axle), make for a painful pedaling experience if one happens to lose their bike sandals in a mishap - as I did.

The easiest thing to fix was the problem with the propeller hitting the hull. It turned out that a quarter turn of the clamp screw fixing the tension cable to the strut was all that was needed to enable the strut securing pin to slide into place. If only I had noticed this before the race started it would have been a fix I could have made on the calm water at the beginning of the event.
Blunt limiter
Green arrow shows limiter. Red arrow shows where strut was being worn away by strut mount edge.
The pedal fix is a bit more complex. I really like the Speedplay Frog pedals, so I came up with a conversion for one side of the pedals to become a platform that would be compatible with bare feet. This platform bolts onto the pedal, requiring only a very slight modification of the two bolt holes to allow countersinking a slightly larger bolt. The platforms are comprised of two pieces of marine grade plywood carved to fit over the pedal clip and glued together. The finished platforms will be completed sealed and either have some Shoe Goo applied or perhaps a sprinkling of sand on a fresh coat of epoxy resin to help keep one's foot from sliding off.

Underside of platform pedal
Platform pedal. T-nuts will be encased with resin or Shoe Goo.
The floats will require replacement. I thought about going and getting some longer ones made from Okoume marine plywood like the originals, but the shop that CNC cut the originals would not be able to get them to me before late March. The cost would also have been pretty high, too, as it would have had to meet their minimum charge of $280 - plus the cost of the plywood.

Instead, I decided to go to Home Depot and pick up a 2 foot by 8 foot by 2 inch Styrofoam insulation sheet and have them cut it lengthwise into four equal width pieces. The total cost was about $25.

Taking the pieces home I discovered that they will fit inside my Toyota Matrix, so I'm happy to not have to bind them to a rooftop carrier. Yay!
On the shelving unit workbench previously used to make the V15-6M I clamped all four pieces together and found that one piece was about a quarter inch wider than the rest. That was pretty easy to fix with a finishing sander hooked to a shop vac. If one piece was narrower that would have been a bit more of a problem.
Old float on top of sanded new float blanks.

The next step is to glue the pieces into pairs, followed by tracing the lines of the old floats onto the new ones, stretching out the middle. I'm thinking of not tapering the stern sections, or at least not tapering them very much. This would increase their displacement from what would otherwise be about 25% more volume to nearly 75% more. Also, with the weight of the old floats in the 5.5 pound range and the new floats currently at about 2 pounds, there is a reasonable budget for the exterior layer of glass, resin and mounting tubes.

I'm planning on using the same method of mounting the floats as before; i.e., using the same fiberglass tubes and mount behind the seat back. This will enable me to use the same akas. In addition, the grab tubes will be used for a forward set of mounts. I still have a pair of somewhat shorter fiberglass tubes previously used as akas that will work in this position. This should provide a fairly stiff mount for the floats and allow for quick assembly and disassembly.

The last issue, i.e., the rudder, will have to wait. I have some ideas for a kick-up style of rudder used in kayaking that may work reasonably well, but nothing concrete at this moment.