Boby’s Motorised W kayak, by Dennis Hodgetts

Boby from Birkenhead is one of the local Wavewalk owners who has motorised it.

He says:

I am fiddling around with it as I go or as I need to.
I made up an outboard aluminum bracket to takes short and long shaft motors. I have 3.5 HP 4 strokes short shaft on it at the moment (actuator plate level with the kayak hull) but its too powerful and water can splash up when it go a bit faster when is choppy day (need spray skirt for this).
The outboard bracket is made from 5mm ALI plate and hollow box section – weight approx 3kg (6.5 lbs)
I’m looking around for 2nd hand 2HP 4 strokes long shaft (actuator plate will be 3″ to 5″ lower than kayak hull) hoping to eliminate water splash up problem.
I have my anchor system, trolley, paddle holder, etc sorted.
I am still thinking of the best way to mount a fish finder.
The front bar of the rod holder battery is 1″ stainless with an eye bolt in the middle. It goes between the 2 “Scotties” (rod holders) side holes. It is my anchor rope holder. It work really well in strong current and much better than kayak anchor trolley.

With regard to the splashing, I wonder if (a) the motor mount is too high for a short shaft motor and (b) the motor is just too big.

Dennis Hodgetts,

Auckland, New Zealand

Click images to enlarge

2 thoughts on “Boby’s Motorised W kayak, by Dennis Hodgetts”

  1. Thanks Dennis,

    This is pretty impressive.
    3.5 hp sounds just about right, and the excessive splashing is probably due to the propeller being too close to the surface, between the hulls, as Boby pointed out.
    Further trimming the propeller and driving from the middle of the cockpit using a long, jointed (articulated) tiller extension could help too.

    Here’s how W’s mount for a 15″ propeller shaft outboard motor looks:

    kayak transom motor mount for short (15') shaft

    Note that the top is just a little over 1″ higher than the hull tips’ topside, and the bottom doesn’t go lower than the gussets on the saddle’s underside. Compared to Boby’s design, this design would lower the propeller by about 3 inches.

    Yoav

  2. Here’s a comment Gary Thorberg sent by email:

    Maybe a little too much power! I agree that the mount may be a little high for a short shaft. Trim is an issue with mounts that don’t incorporate a little transom angle built into them. 10 to 15 degrees is ideal, but anything will help with trim issues. All boats designed for transom mounted outboards have this built in, but seldom do we see it in diy mounts. It could help with a lot of the things he is
    experiencing. Nice looking mount, though. Similar to some of our first designs.

    Gary

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