HI Corey
I think this can be easily fixed. What size of prop shaft do you have on it? 1/8" ,3/16" or 4mm threaded? Something else?
Nothing is wrong that a good prop can't fix. If you hydro is only 20inches long ,you will not need a large prop. You boat is rather small to use 12 cells though. Should go fast once you get it up though. If you have a 4mm threaded shaft you could use a large number of low cost Graupner CF props. Right now I guessing that you have a 3/16" prop shaft. The 3/16" props seem to start at about 38mm and go up from there. You only have the option of metal or CF props here as you have too much power for most ordinary plastic props.
Let us know more about what you have. n.h.schmidt