Today I built a scrap wood prototype of the drive box to adapt the Hobie Mirage Drive to my skin on frame canoes. The first drive is a knock off of Hobie’s first generation Mirage drive called a Freedom Drive which retails for $325 and the second is Hobie’s current Mirage Drive 180 for $900 with reverse and kick up fins. I’m not sure if the reverse will be useful to me, but the kick up definitely will. The mounting geometry between both of these is different so I built the box specifically for the Hobie and the Freedom Drive will require some shims or a dedicated box.
As you can see, the concept is pretty simple but as always, the devil is in the details. The geometry for the drive has to be perfect and all the tolerances need to be within a 64th of an inch. (I’m gonna have to true up my saws before I build this for real out of marine ply.) I need to design a hold down system because the brackets that are designed for this won’t work here. I also need about twice as much room on my base plate flange to connect it to the canoe ribs, which is kind of a problem because I’m up against a pretty hard limit of how wide I can spread the stringers on the bottom of the canoe.
Finally, the entire thing needs to be removable so I can preserve the nesting function of the canoes. (my canoes nest together like Russian dolls, so you can carry multiples on top of the passenger car.) I actually have a plan for this that will also allow the canoe to be used without the drive but it will be way easier to show that later than to try to describe it.
I’m also trying to decide how much I want to raise the flange above the waterline of the canoe. Just based on my experience of how much water is generally left in a canoe when I’m trying to do a self rescue, I’m thinking that 7 inches will be fine although I’d be much happier with 6. (basically I don’t want water to pour through the hole while I’m doing a rescue).
The big accomplishment here was just getting myself a cut list and figuring out the gluing sequence so I can do this efficiently when I’m working with epoxy and not Titebond.
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