Some guys had a 12 foot john boat. It had a gas weed wacker ratchet strapped to the back. The spool of line was removed and replaced with a prop from a trolling motor. Craziest thing ever.

Was it an actual weed whacker or was it a mud motor?  The guys on all those swamp shows have the mud motors to navigate shallow water.

Hands down weed wacker from Home Depot. Saw that beast up close and personal. Didn't want to snap a pic because I didn't want to make them feel weird. It was all rigged up and sounded like a true weed eater.

i am surprised it could even move the boat as they don't have a ton of torque.  

Awesome, I've been saying it forever that I want to try it.  Did it work well?  What was the top speed? 

It was still on the trailer after we loaded up. I can't see how it would be plausible.

Got some buddies that use it on their layout duck boats. Work perfect and only have $150-$200 in them.

There is an actual boat motor that they made once upon a time (mid 90's I think).  They must have not made them for long.  My buddy has one that he said needed a new powerhead.  Yes, I think many people have tried putting props on weedwackers.  One of my friends did once when we were 16 or 17, but the prop was WAY too big for it to work.