TO THOSE OF YOU WISHING TO MOUNT A MOTOR TO A BOAT YOU BOUGHT ONLINE... Look at your state laws before trying it. I just went through a few weeks of hell with my own inflatable boat here in New Jersey.
Again, YMMV, but this was my experience...
I bought an Intex Excursion 5 (a larger inflatable) from Amazon at the beginning of July. I also bought a small electric trolling motor to attach to the transom of this thing because the thought of paddling it down a river made me sick.
Now, according to NJ state law, if you attach ANY kind of motor to a boat, it MUST be registered with the DMV. Yes, even an electric trolling motor. To register the boat, you'll of course need proof that you bought the boat (invoice from Amazon), AND that you're the first owner of the boat (Manufacturer's Certificate of Origin). Ugh.
Obviously, if you buy a boat online, there is no "Certificate of Origin" with it, because there's no "dealer" to "assign" the boat to you after purchase. Luckily(?), Intex (and I assume other manufacturers) have a "fill in your Hull ID number and print out a Certificate" thing on their website...well, NJ didn't like the printed copy, they wanted the original signed copy direct from the manufacturer, and then I'd have to send it to Amazon to get someone to sign it saying I was the first owner of the boat. Ugh.
OK, so great...I got all that figured out, it took about two to three weeks of sending things around the country, but I got my paperwork finalized, and finally got the boat registered, and affixed the Reg number on both sides of the boat, along with the NJ decals, etc.
So I'm reading through the DMV manuals for boating, and I realize...to operate a powered boat on any NJ waterway, tidal or not, I need to take an 8-hour course and get a NJ State boating safety certificate. GOOD LORD...
I figured, why the heck not, I'm already so invested...so I signed up for the course, passed it, got my boating certificate, and I'm good to go...or am I?
Turns out, that if I want to operate my powered vessel on a NON-TIDAL waterway, I also need to go BACK to the DMV with my new Boating certificate and get a boating endorsement on my license.
After everything was said and done, my $120 boat cost me around $500, and countless hours/days/weeks of aggravation. If your state has similar laws, I suggest you forget powering your boat in any way other than by paddling it.