9.6 mph With a 3HP Outboard Gas Engine On A W500 Fishing Kayak, By Gary Thorberg, MN

Gary Thorberg, from Minnyaks, in Farmington, Minnesota, mounted a 3HP outboard gas engine on his W500 fishing kayak. His goal was to break the speed record for this kind of watercraft, and he did it, big time, clocking 9.6 mph. Interestingly, there was no difference between upwind and downwind, which raises the possibility that Gary simply reached the upper limit of this motor’s speed, which is limited by factors such as RPM, propeller size, pitch, etc.

Gary Thorberg, from Farmington, Minnesota, mounted a 3HP outboard gas engine on his W500 fishing kayak. His goal was to break the speed record for this kind of watercraft, and he did it, big time, clocking 9.6 mph. Interestingly, there was no difference between upwind and downwind, which raises the possibility that Gary simply reached the upper limit of this motor’s speed, which is set by factors such as RPM, propeller size, pitch, etc.

9.6 mph is over twice the W500’s hull speed. Hull speed (a.k.a. Froude Number) is a constant number that increases relatively to the hull’s length at waterline. In other words, it’s harder to make shorter boats go at higher speed than it is to make longer boats to go at high speed.
Gary’s W500 was planing.
In comparison, here is a quote from an article about dinghies outfitted with outboard motors:
“Another option is an outboard motor. Two horsepower per meter can reach hull speed. Ten horsepower per metre will put a flat-bottomed dinghy on plane. A 10-foot (3.0 m) dinghy with a hard V-bottom hull and a fifteen horsepower outboard can reach speeds of 25 mph (40 km/h).”

To put things in perspective, the W500 is about 3.5 meters long…

NOTE: This video shows an experiment, as part of a research and development (R&D) effort.

Read more about motorizing your fishing kayak »


More northern kayak fishing insight from Gary »

10 thoughts on “9.6 mph With a 3HP Outboard Gas Engine On A W500 Fishing Kayak, By Gary Thorberg, MN”

  1. I agree completely. More HP would have made the ride faster, but I felt unsafe at about 9mph. It was relatively calm during the test, which allowed for a safer ride. Fun and exciting, but for demonstration only!
    Gary

  2. Here’s a quote from a website that specializes in sales of outboard motors:
    ” 2 hp – 4 hp (Less than 35lbs) ……….. Performance:
    Expect these engines to glide through the water at about 5-10 mph…. ”

    This reinforces my impression that Gary’s 3HP outboard motor is simply not designed for speeds higher than what he achieved today.

  3. I would bet you’d hit higher speeds with one of those aftermarket foils attached to the cavitation plate of the motor and possibly trimming the motor higher unless it was already at top trim. Of course you’d probably have stability problems since they aren’t exactly planing hulls. I believe Jeff mentioned this in a post on Yoav’s maiden gas powered run. Be safe with your play time.

    Looks like fun. I miss the small lakes with leaves changing in the background. Oh well, then again, I fish all winter and don’t have to cut holes in the ice to do so anymore.

  4. Awesome video, but I still see spray coming in between your mount and W cock pit.
    May be a foam noodle cut to fit in place where you have gaps.

    But it was Awesome!!

    Motor safe all.
    Rox

  5. I saw this and had to wonder what is going to happen as the future generations of the W concept get bigger. This is just the beginning.

  6. Remarkable, yet hazardous.
    The W seems to handle this speed well, but having said that, I think it’s not advisable to go at such speeds in this kind of craft, simply because the higher the speed the smaller your margin for error gets…
    Pete

  7. According to the National Marine Manufacturers Association (NMMA) there are some 16 million leisure boats registered in the US, and most of them are motorboats. Even sailboats often have some kind of motor on board. The overwhelming majority of boats are gas powered.*
    Americans love the power and convenience these engines offer.
    So far, the kayak segment of the boat market has been the only one to show significant interest in electric motors, but that’s probably due to the fact that putting a gas outboard on a sit-in or SOT fishing kayak isn’t a viable option.
    We’ve shown how easy and convenient it is to outfit a W500 with an electric trolling motor, and now we’ve begun showing how easy, convenient and EXCITING it is to outfit a W500 kayak with an outboard gas engine.

    Yoav

    * For the benefit our readers who are not fluent with American English: “gas powered” means powered with gasoline, and not propane, butane, etc….

  8. Do you offer an aluminum motor mount for a gas engine for your wavewalk kayaks?

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