Warren's 2006 Human Powered Boat Construction
HPB Construction 2006
The Necky HPB worked well last year for having slapped it together just before the event. It wasn't much faster than the Sidewinder though, mostly because of the inability to turn the boat with it's tiny kayak rudder. This year I will be tweaking the design to remove the rough edges and improve the speed. Here's what I need to do:
  • Fair the drivetrain 
  • Reinforce rudder mount and build a big rudder
  • Rebuild the seat and move it back a bit. 
I wrapped the lower half of the drive unit in ABS plastic to form a nice leading and trailing edge, and covered it with a couple layers of fiberglass. In this picture you can see the electrical tape I used to tape the edges of the plastic through the fiberglass. This should help a bunch as the triangular shape of the drive unit surely caused a lot of turmoil under the boat.
I covered the fiberglass in epoxy/micro balloons to fill in the rough fiberglass weave, holes and irregularities. I then sanded it with the belt sander. Next step is to spray a couple layers of primer and fine sand it.

Also visible in the picture is a new rudder I was working on with integrated mounts that I was going to epoxy to the stern. I abandoned it in favor of making a different rudder to utilize the existing rudder mounting hardware. I hope it's heavy duty enough...

I was in a quandary about what to do about the seat. Last year it was too upright and painful. Replace the seat base altogether? How to attach  the new seat?

I ended up hacking the seat pan off of a perfectly good Optima hard shell recumbent seat (which was too short for me), and mounting it to the existing seat pan in the Kayak. I had to do some major surgery on the shell to get it to lean back far enough. It feels nice and comfy now.

Since the seat is leaned so much further back, my center of gravity will be lower, which I hope means it will be easier to balance. This year I will be racing without the stabilizing floats, and I hope I can complete the events without capsizing.
I was going to create a whole new rudder assembly and steering mechanism, but the original one was nicely made, and move heavy-duty than I would have thought, so I'm just going to make a rudder that's 3 times as big as the original out of luan plywood, cover it with some fiberglass, and epoxy on a strip of carbon fiber to make it nice and stiff.

In this picture the rudder is jammed into the mounting plate. I still need to bolt it in. The carbon fiber strips are on the other side.

The steering is still cable actuated. The cables go though sealed channels in the hull, and that was too cool to change. Because you have to pull on the cables to make the rudder turn, and the fact that they are coming from the back of the boat, I had to use idler pulleys in the front of the engine bay to redirect the ropes I attached to the cables. There are now handles attached to the rope that I can pull on. The ropes are attached to bungee cords which keep the whole system tight and make sure the ropes don't fall off the pulleys. This should work much better than last year's jury-rigged arrangement.
I'm thinking about using a "noodle", one of those long skinny foam rods that are sold as pool toys as "emergency floats". These would normally be out of the water, but would touch down when the boat came close to capsizing, or possibly when in a tight corner.  These noodles are hollow cored, so an aluminum tube (or conduit), could be inserted through them to provide some rigidity. 

I wasn't able to find any noodles, so I have decided to race this year without any stabilizers (!). 

This years Hydrobowl was one of the best ever. The top 4 competitors were all very close in overall performance, which made it fun as it was not easy to predict who would win any specific event. We had an amazing 10 boats, though not all raced. The weather, though not ideal, did not cause any issues, and it was good to see that the boats all worked well in choppy water. We saw some interesting new boats. Some worked amazingly well, some needed tweaking. We had a lot of mechanical issues this year. The bollard pull "static thrurst" event in particular seems to be designed to break drivetrains. I supposed that's to be expected as most of us are neither engineers or machinists. Now we know what to fix and reinforce for next year!

My best event is always the 2K. This race is 8.5 laps around a rectangular course 100 meters by about 60 ft in dimension. I race recumbent bikes and I'm not a sprinter, so this event is what my "engine" is tuned for.
This year was no exception. The race started with Dan, Jake and Steve sprinting ahead, and me pedaling hard and trying to keep my boat under control. I was able to catch up to Steve and pass him within a lap or so, and then started cranking to bridge the gap between me and Jake, with Steve hanging right on my rudder. Jake is hard to get around. He goes pretty fast in the straights, then slows way down in the corners, and he has those big amavons sticking about 8ft either side of the boat.
Picture by Richard Hodgkins

Picture by Richard Hodgkins
On the turns I would go way on the outside to try to get next to him and sprint past him in the straightaway way on the outside. Eventually I made it by him, and set my sights on Dan, who was a good quarter lap ahead by then. I would gain a little on him each lap, and finally was on his tail. Dan is even harder to pass than Jake, because every time I tried to pass, he would kick it up a notch.
Finally I had a bit of luck and Dan ran into traffic, and had to slow down to go around another boat. I was able to squeak ahead of him before the nest corner, then I gained more on him through the corner. With a lap or two left I was working as hard as I could to keep Dan from re-passing me. Finally it came down to the last straightaway to the finish line. Both Dan and I were yelling to Bob on shore to find out if it was really the last lap and cranking as hard as we could at the same time. I ended up beating Dan by a couple boat lengths. Fun.
Picture by Richard Hodgkins
I learned some things at this year's Hydrobowl. The most interesting thing was that when you turn a large rudder in a narrow monohull boat, it makes the boat lean into the turn. When the turn is long, the boat eventually rights itself, returning to vertical. When you move the rudder back the other way to straighten the boat out, it makes the boat lean the other way, which is toward the outside of the turn you are just completing. That feels like the boat is capsizing and is just downright scary. 

Bill Goldthorpe had an interesting rudder, which he said corrected this behavior. Instead of having a single flat plate that went straight down into the water, he used two plates at a diverging angle (picture an upside down V). He said that this corrected the rudder induced leaning that he had experienced on his boat. 
It was largely because of this phenomenon that I made the decision not to race the Necky HPB. Fortunately I was rescued by Peg Cipolla, who had some inflatable "Sea Wings" pontoons that I strapped to the side of the Kayak. I was able to push them down when I felt particularly tilted, and then they rode free of the water when I was going straight. It was still hard to go straight and fast, so this is probably not the ideal solution, but it did allow me to race!  An active stabilizer like on the wavebike would be the ideal solution for this boat. Stabilizer pontoon(s) would be easier though, and less complex. 

Photo by Dan Grow

Picture by Peg Cippola
The Necky Kayak did turn really well and efficiently this year, as is evidenced by my 2K results. I did spend a lot of energy keeping the boat upright though, so if I could add stability without slowing the boat down, I'm confident that could do even better.

I also learned a Kayak is a "wet boat". I was always nice and dry when riding the sidewinder catamaran. In the Necky Kayak, water shoots out of the top of the back side of the drive well at high speeds. A better seal will be needed to prevent that, as the boat gets a lot of water in it.

Also when the waves get choppy, water slops into the boat over the sides. I'll need to add some sideboards to reduce that effect. The new seat in the kayak is much more comfortable than last
year's model, but it still sits practically in the bottom of the boat, so anytime there is more than an
inch or so of water in the bottom, I'm wet. I would definitely need some type of bailing device for any open water venture I would undertake in this boat.



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