Go Up A Creek Without A Paddle

Kayaks are a some of the most versatile watercraft around. You can fish from them, go on backpacking trips, or just cruise around your local lake for a few hours. They’re inexpensive, lightweight, don’t require fuel, and typically don’t require a license or insurance to operate. They also make a great platform for a solar-powered boat like this one with only 150 watts of panels and a custom-built motor with parts from an RC airplane.

[William Frasier] built his solar-powered kayak using three solar panels, two mounted across the bow of the boat using pontoons to keep them from dipping into the water, and the other mounted aft. Separating the panels like this helps to prevent all three of them being shaded at once when passing under bridges. They’re all wired in parallel to a 12V custom-built motor which is an accomplishment in itself. It uses custom-turned parts from teak, a rot-resistant wood, is housed in an aluminum enclosure, and uses an RC airplane propeller for propulsion.

Without using the paddles and under full sun, the kayak can propel itself at about 4 knots (7 kmh) which is comparable to a kayak being propelled by a human with a paddle. With a battery, some of the shading problems could be eliminated, and adding an autopilot to it would make it almost 100% autonomous.

28 thoughts on “Go Up A Creek Without A Paddle


    Escaping from creatures name Jaws.

  2. I wonder if it could be made slightly more efficient still by angling the solar panels. Since there is a human there anyway and the angle isn’t that critical, you probably wouldn’t even need a powered mount for this, just have the human move them when needed.

    1. Neat design. Interesting to see the newer systems also like jet boards, jet hydrofoils and improvised designs.

      I made a 12V 55A power supply from an old desktop computer PSU (combined 12V rails, added fuse and I forget if added a resistor or just shorted the pwr on) that I plugged into a Honda 1000W generator, with a custom exhaust pipe to route the fumes, to use with the trolling motor for the canoe. I was too nervous to use with the kayak after testing out without extra pontoons. Was great to use to get upstream on the river in the canoe without pontoons/sponsons. I could hook up the deep cycle battery if I wanted to be quieter if not just float/paddle.

      Solar panels are a good idea and I’ve considered to implement in a future spray skirt design for the canoe on the canoe & kayak transom’ed with 2.5″ aluminum tubing with the old long windsurf board strapped underneath the transom design I’m working on.

  3. Why use an airplane propeller? More efficient to use one designed for water.
    Back when the Wright brothers built their flier, they thought they could just
    plug the different characteristics of air into the design models used in marine
    propellers to make their propellers. Turns out back then such models were
    not available, and they had to design/test the propellers themselves.

    1. if I remember correctly the typical marine design is more efficient at high RPMs and is designed to be weed free.
      Aircraft style props are good in water at lower RPMs but won’t cut through weeds.

  4. Excellent! I would include a battery for situations where it’s hard to get out of a dark spot. Also paddles. So many rivers beg to be traversed, but it’s tiring to paddle, so a little solar polar will be great.

    1. The equations are the same for any fluid as long as things like cavitation or shock waves are avoided. Appropriate values for density and viscosity has to be used for each fluid.

    2. A duct would improve efficiency but the benefits are generally limited to a very specific speed range. The duct design is not trivial and no duct is still better than a bad duct.

  5. I’m regularly astonished that there aren’t more solar powered small boats around…

    Open water has a good view of the sky most of the time, while cloudy days happen a paddle is a sufficient replacement for the sun/motor… even a paddle assisted system would be a plus.

    I’m fairly certain I could comfortable fit ~800w of solar on my tandem canoe… with a decent motor that’s an extra paddler or two worth of power.

    1. And it’s really too bad photovoltaics can’t scale to container ship size. It would be great to get those belchers to stop making all that mess out of sight, mucking up the environment.

      It’s really a darned shame the NS Savannah couldn’t make a go of it.

      1. I don’t see that happening any time soon. In spite of the fact we are dealing with a slow boat to/from China, you want to get across the Pacific puddle as quickly as possible so you can do it all over again and maximize the number of full loads you transfer each year and maximize the profit. Solar, although cool, would interfere with that unless diesel gets to be quite a bit more expensive.

  6. Thank you for reporting on my project. It is a steep but extremely rewarding learning curve. I will try to answer some questions raised.

    The project started out as an entry into a solar boat race, hence no battery. It has only been on the water twice. I will most likely add a battery later but it will require an efficient step-down buck converter or mppt since the panels operate best at 18V.

    Designing for pure solar power has forced me to look at the efficiency of each component and how it affects the system as a whole. My background is in aircraft design, so I took an old spreadsheet for propeller design and adapted it to water. Also added to the analysis were drag curves for the kayak and mathematical models to simulate the power and efficiencies of the electric motor and solar panels. The propeller was selected based on best overall system performance. The RC plane propeller happened to be a near perfect fit. There is actually very little flex on the blades under power.

    The motor is indeed quite noisy. The duct feeding the power leads down into the motor housing is still open and sealing it should reduce the noise.

    The articulating amas do not work well in wind chop and will need to be made rigid. They also need to be raised a bit higher so that the panels can be angled to the sun by heeling the kayak. Fore-aft tilting should not be too difficult to implement. The additional drag of tilted panels in a strong headwind might cancel any benefit of better tracking. With a tail-wind the benefits will be two-fold.

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