Adapting a double ended canoe to an outboard

Discussion in 'Boat Design' started by YotaTruck, Aug 10, 2014.

  1. YotaTruck
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    YotaTruck Junior Member

    I have a fiberglass 17' Sears canoe. The plate states that it will take a 3 HP, 750lbs capacity, persons, gear and motor. I have a 3.5 HP Gamefisher outboard and I'm trying to think of how to best adapt the canoe to using the motor. The most common option I've seen is a thwart that bolts to the gunwales and allows the motor to be sidemounted. I'm not crazy about this idea-maybe it works fine, it's just a little counter-intuitive, having a outboard mounted off center.

    The next option would be to construct some kind of outboard mount that would be permanently attached to the stern of the canoe. Right now the gunwales are topped with a flimsy aluminum coping so I'm planning on replacing it with a cedar sheer clamp/rubrail/gunwale, so it could be incorporated into that. I'm a little concerned about how much weight it will add since it will have to be adequately braced.

    Finally, the most radical option would be to turn it into a square stern canoe. The bow and stern both have flotation compartments, so on the inside it's squared off anyway-no internal space would be lost by squaring off the stern. A 1" laminated plywood transom screwed and epoxied to the fiberglass hull with a fillet all the way around would be the plan. I'm curious to hear which of these options folks think here would be best.
     
  2. Mr Efficiency
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    Mr Efficiency Senior Member

    You could create a well toward the stern, but not right aft. Would not need to be very big, just enough to slip the motor leg down through it, and not affect the steering rotation, the only problem is the leg would not be able to kick up fully. Not such a great problem at such speeds as you are likely to travel , though.
     
  3. wayne nicol
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    wayne nicol Senior Member

    i mounted my 2.5 hp seagull on a 15 footer, on a side mount i built.
    worked better than right astern, cos i could run the steering arm perfectly while sitting in the stern. think about it, when one sits in a skiff- one always sits to one side so that it is easy to run the motor. didnt notrice any issues or difficulties with the side mount!
     
  4. YotaTruck
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    YotaTruck Junior Member

    Interesting idea. I would lose some internal space but less hull area than lopping off the stern. Definitely worth investigating.

    I was actually sitting in the stern seat today trying to figure out how I would work the tiller and figured I'd have to sit sideways. I just can't shake the feeling that the boat would want to go in circles with the motor offset. Did you ever feel like you had to compensate for that when trying to travel dead ahead?
     
  5. gonzo
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    gonzo Senior Member

    A small offset will not make the boat go in circles. A small compensation with the thrust angle (steering) takes care of it.
     
  6. Rocky Mtn Russ
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    Rocky Mtn Russ Junior Member

    I agree with gonzo... side mount is fine. I have a 2.5 hp outboard side mounted on an 18 foot kayak. Just a few degrees of thrust angle is all it takes to run straight. With the prop at/below the bottom of the boat, you can also turn the boat using the outboard. And you have the safety of enabling the motor to kick up if you do hit something.
     
  7. rwatson
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    rwatson Senior Member

    By co-incidence, I was just having a think about putting an engine in my canadian canoe today.

    If the canoe is typical of most of the flat bottom canadian canoes, there may be a case for some kind of skeg up near the bow.

    I notice if I sit in the rear seat ( as i would with a motor ), winds push the bow around quite a lot, and make directional control a bit if work.

    I had envisaged some small leeboards about a third of the way back from the bow.

    Either that, or put the fuel tank up in the bow. It doesn't get the 'wanders' if its carrying a load.
     
  8. philSweet
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    philSweet Senior Member

    A side mount works best IMO. It is more important to get the canoe trimmed properly fore-aft than to get the thrust centered. You can cock the leg under the boat by about 15 degrees and there isn't much in it anyway, just make sure it kicks up clear. I usually just build a clamp for one gunwale, rather than a thwart. If you have any weight at all in the boat it will track just fine. It's much easier on your back to have the tiller handle just beside you, rather than having to reach behind you.
     
  9. SamSam
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    SamSam Senior Member

    It would also be easier to start if it's off to the side.
    You just aim the motor a very little to the side to compensate. Kicker motors for sailboats or for slow trolling in large motor boats are always mounted off center and have no steering problems.
    Cutting the end off will make it kind of crappy for paddling as then you drag water around in the transom suction.
     
  10. YotaTruck
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    YotaTruck Junior Member

    Makes sense-I'll have plenty of weight in the canoe with my wife sitting forward and two kids in the middle so tracking/trim should be just fine. Can I/should I use epoxy to glue the new gunwales? I'm assuming that the old fiberglass was laid up with polyester resin. I'd also like patch some of the small cracks and repaint the entire thing. What would be the best paint to use?
     
  11. Squidly-Diddly
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    Squidly-Diddly Senior Member

    what Gonzo said....

    plus your phat-arse on the other side, comfortably seated so as to provide perfect ergo metric hand on the tiller reaching across, rather than arm twisted behind back.....

    lets just say it is the American White Trash version of those Italian boat dudes in Venice with the oar on one side that SUPPOSEDLY track straight.

    (we all know those Venice oarsmen basically do what any 1/2 decent paddler does and corrects on every stroke. I learned all about this at about age 6 when riding a bike, crashing it so as to bend the forks slightly, then quickly adjusting so that when I got on a straight bike it seemed off)


    I hear there are lots of Real World advantages to offset motor mount, such as having one side 'clear' and also being able to have the motor on the seaward side of the boat when landing, for more water under the prop.


    PS-I hear epoxy will bond to poly no problem but not the other way around, but I'm sure much more exp. folks will chime in with better details soon.

    I don't think sawing up a perfectly good fiberglass canoe is a good idea, unless you want a new major project.

    Find someone who has run a double ender with outboard and he will put your mind at ease.

    I only did it briefly on someone else's rig. Seemed A-OK.
     
  12. Manfred.pech
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    Manfred.pech Senior Member

  13. Easy Rider
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    Easy Rider Senior Member

    I've had lots of experience outboards on canoes.

    Had a "Y" stern Aluma Craft canoe w a 3hp Evinrude. Worked quite well.

    Have had a 16' Winona canoe for many years. Powered it w a good side mount and two different outboards. The 3hp OMC with the angle drive worked well. My 2hp Suzuki did OK until you turned it … even a little. Cavitation was bad. Turning was so so w the Evinrude but quite a bit of water splash from the nearly round lower unit. Out on the ocean side of Vancouver Is I finished a run, took everything out of the canoe and ran up into the bushes to relieve myself. While I was doing that the canoe rolled over on it's side and put the engine in the water. I know it was stupid but I was in need and it was calm and looked stable. I finally threw in the towel on side mounting.

    Bought an 18' Clipper Mckenzie Freight canoe (kevlar). Very tough and strong. The "Mac" is 18' long, 40" wide and 17" deep. A big canoe. It is made from a 20' double end freight canoe. They used a dam (board in the mold) to make the 18' square sterned canoe.

    Usually I'm w my wife and she sits low in the bow. But when I'm solo I take a 7 gallon and 5 gallon plastic container and fill them w water at launch. Put them in the bow. Dump the water when I pull out.

    Clipper recommended 3-4hp but said a guy in Alaska had a 6hp on his and that he said it worked fine but they wouldn't recommend it. Of course I promptly put a 6hp Johnson on the canoe. Goes really fast. Don't know exactly how fast but it's definitely "wind in the face canoeing" … probably 12 knots or ? I need to be very careful in sharp or fairly sharp turns. Ease the tiller in or out smoothly and slowly. I find it easy to control actually and I usually run about 6 to 8 knots. Equates to about half throttle and 1/4 noise. Very smooth and pleasant.

    I've not done it but I had in mind when I bought the canoe that we'd go far into the Canadian wilderness. Bought a new 8hp Yamaha basically for dependability. It weighs the same as the 6 Johnson and as far as I know it goes no faster.

    I've never experienced cavitation w the transom mount and turning is as one would expect from a proper boat. And good balance is obvious.

    For very slow running of 2 or 3 knots the side mount works fairly well if the engine dos'nt cavitate. It's easy and almost any canoe will do. One should consider cutting the stern off and making a plywood transom or rigging an outrigger. Larger would be better than smaller. I ran my Wenonah 16' canoe backwards. The bow is deeper and w all that weight I made the stern the bow. That worked very well as it was a rather low freeboard boat.

    Re the cavitation an OB is made to mount on a transom w the bottom of the boat just ahead of the cavitation plate. The water inflow to the lower unit off the bottom I think is necessary for normal performance. It just works better and was/is meant to be. But side mounting does work.
     

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  14. SCHWIMMWANNEN
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    SCHWIMMWANNEN Junior Member

    I built a boat with a lifting drive shaft.







     

  15. garydierking
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    garydierking Senior Member

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