40lb thrust trolling motor on GCat 5.7

Trying out my motor mount for the first time this weekend, I will be using a 40lb thrust trolling motor on my GCat 5.7. What expectations can I have as far as how well it will push the boat, do you think it would push me up some of the slow moving rivers around here?
Well, my wife weighs in at about 100 lbs and she can paddle up upstream fairly well using the port cover. Best part is she doesn't drink beer, so I get it all.
Those are my expectations.

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Sheet In!
Bob
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Prindle 18-2 #244 "Wakizashi"
Prindle 16 #3690 "Pegasus" Sold (sigh)
AZ Multihull Fleet 42 member
(Way) Past Commodore of Prindle Fleet 14
Arizona, USA
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It will be fine, the bigger question is what to do with the battery.
I moved my nacra 5.7 about 5 miles along a lake & 1 mile into a river in order to retrieve it. I used the crappiest electric you can find at Canadian Tire, mounted on a 2x4 nailed to the edge of a 2x6, that was strapped across the sterns, & powered it with my stinkpot starting battery..
There is not much resistance to a cat, the biggest problem was a strong Xwind. I didn't have a tiller extension, hell I only had 1 rudder in trail.
You will want long battery leads in order to put the battery up front & keep the bows in the water.
Depending on how far you have to go, don't go wide open, that will eat the battery much quicker.
If you plan on using it on a regular basis, spring for a true deep cycle battery, it will give years of use. Starting batteries don't live long if discharged often.

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Hobie 18 Magnum
Dart 15
Mystere 6.0XL Sold Was a handful solo
Nacra 5.7
Nacra 5.0
Bombardier Invitation (Now officially DEAD)
Various other Dock cluttering WaterCrap
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I have a 55lb thrust motor on my 2700lb Hunter 23 monohull. It'll push me around at 2-3 knots. I only use it for the 200 yards or so to get from my slip in the harbor to out past the breakwater and back. It has also been helpful on the rare occasions when the wind has died. I would imagine it would have no problem pushing a beach cat quite a bit faster.