Hull speed is doable with the right setup but it will suck down a moderate sized battery bank pretty quickly. If you can settle for about 40% hull speed you will increase your range quite a bit. A ME0913 motor and a Kelly sine wave controller will do the job. I would get the 800a 144v one, which I am getting for my CAL 2-27, simply because it is good for practically any marine BLDC application up to about 40' and could also be used in an electric car. However you can get by with a 300a 48v square wave Kelly controller. You will probably want a 48v bank and for my money a bank of L-16 batteries looks pretty good but if you are on a very tight budget, Enrgizer GC2 golf cart batteries will give you 220ah, 48v, for 8 of them in series. If you can mount about 400w of solar panels it will help, but to rely completely on solar charging you want about 2k of solar panels, which is a LOT to mount on a small boat. A Honda 2k to charge the batteries would be extremely inefficient but makes a cheap compact backup charging source when you are otherwise stranded. If budget allows, go with a bank of LiFeP04 cells, at least 200ah, for 48v which I think will be 13 cells. You would also need a BMS to manage the lithium cells. There are a lot of good reasons to go with this type of battery if you can afford them. You will need a reduction gear, either belt and pulley with a thrust bearing for the prop shaft, or an enclosed gearbox or marine transmission. The reduction ratio giving best results will depend on a lot of factors but mainly on the power of the motor, design rotational speed for peak power at the given voltage, prop size and pitch, and how easily the hull is pushed at e-boat speeds. 2:1 is a typical place to start in that size range at 48v with a 12x10 3 blade prop or thereabouts, just as an example. Very likely your sweet spot will be between about 2:1 and 3:1.
Thunderstruck makes a handy light duty belt and pulley reduction gear ready to go. You can fabricate yourself cheaper, using McMaster-Carr components and steel. ElectricMotorSportsEV.com (I might have that wrong) sells a very nice enclosed gearbox made by Baldor. The ME0913 brushless motor is available all over the place. Kelly controllers from www.kellycontroller.com or you might want to google for Sevcon controllers. Oh you could go with a brushed motor and a cheap PWM controller, too, but if you do, you cannot have any gasoline or propane accessories aboard, for obvious reasons. Golf cart and forklift motors can often be salvaged cheaply if you are a hardcore DIYer.
There are a lot of ways to set up electric drive and my way is just one of many. I have my reasons for preferring the motor, controller, reduction, and battery setup that I use and there are perfectly valid reasons to use different systems.
The best advice I think I can give is to not rush into this until you have done a lot of research. It is really easy to end up with stuff you don't really want that doesn't really do the job, and it usually requires a big adjustment in expectations before you accept the reality that is this:
1. You can have fairly long range.
2. You can have fairly good speed.
3. You can convert to electric fairly cheaply.
BUT:
The problem is, you have to pick one and only one, and just suck it up on the other two. The biggest limiting factor is charging and energy storage. It takes a tremendous bank of batteries to hold as much energy as say a 20gal tank of diesel.
If you just want to get the boat home, I would get a used 20hp gasoline outboard and a mount for same, carry lots of fuel, and pick a good weather window. Then when you get it home, take your time and experiment until you get it right.
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