RC Boat

[BBray_T1296]

So my friends and I are planning and designing a fairly large scale (25ish lbs) R/C boat really just for fun.
We have opted to design for a single propeller, and in particular, this one, because it is metal and it is hard to find propellers near that size anywhere else conveniently.
Unfortunately, the few specs you see on the page are the only specs available, lacking pitch and max speed/torque figures.
We have little knowledge of designing nautical propulsion, and without the propeller in hand, it is hard to do anything but guess as to what will work best

Please tell me what you think of our proposed setup, which has been provided in the attachments below.

We do not want to do anything very exotic, as we are keeping it relatively cheap and want the construction to be simple, with preferably no difficult parts.

I feel like 30 RPS seems reasonable for how shallow the propeller looks and its diameter. The small ratio lets us put the propeller further down in the hull than with a larger spur gear. using the VexPro 11t pinion is also an option, though I question its durability. The boat is not intended to be particularly fast, we just want it to move at a reasonable clip of maybe 5'/s top speed
I estimate the pitch of the blades to travel ~4" per revolution, assuming perfect bite, that equates to 10'/s, but there will obviously be plenty of slip, so I believe 5'/s is reasonable. There is also, at normal load, 9lb-in of torque which with 2" blades, is reasonable to me. Of course there are inefficiencies in the power train as well.

Again, we really don't know what the actual load on the motor will be, because we don't know the load on the propeller without buying it. We are using the CIM's "normal load" spec as a best case.

The electronics will be a combination of an aircraft receiver, and an arduino. The signal outs on the reciever will enter the arduino which will interpret several inputs for other various functions the boat will do, and pass the throttle to the CIM by means of a motor controller. We are likely to use just a 2 way relay like a spike, for either full forwards or reverse, but may use a motor-controller, though we want to keep cost down on devices that might short out. The main battery is a 12v sealed lead acid one similar to the FRC ones, but only 9Ah (~6lbs), and some AAs for running the electronics

We feel that a CIM with some added silicon sealant will be capable of surviving in a potentially damp environment, especially compared to other motors

Any suggestions/questions/comments/concerns are more than welcome.

CIM info here