Ludakris,

Write this down somewhere and post it on your wall.

SPORT SETUP
[Kv] Motor X [Volt] Battery = RPM/KV

For Sport Setup The RPM/KV is around 20K - 25K
For Oval Setup The RPM/KV is around 25K - 30K
Anything over the 30K is strictly for SAW RACING.

So back to what was mentioned by SRT10, I am going to use lipos as an example. Each cell is about 3.7V, now that multiply by 2S, 3S, 4S etc... gives your the total volts for the pack.
For choosing a Motor/Battery, I will use the motor Kv that you had mentioned of 3000KV, So for a sport setup If you took 3.7V x 3S = 11.1V, now multiply 11.1 x 3000[motor Kv] = 33,3000 RPM/KV. You're way into the SAW Racing setup.
IF you went with a lower KV motor say 1520KV x 4S[14.8V] = 22,496 RPM/KV. Which is about where you would want to be. A lower KV motor has more torque, which will allow you to run a bigger prop. Start with a 40-45mm prop. Start small and work up in diameter. Always check after a minute to see how much heat you are drawing on your motor and esc.

I take that you are a SPORT Boater. And not a Racer! This is merely a guideline, as no one setups a boat the same as the next guy. The saying goes " there are a hundred ways to skin a cat ". This is a great example of that. First you need to know some basics of FE boating. And as far as a ESC goes always get a marine esc, with water cooling. A fan might not do too much, specially if you're circulating hot air inside a sealed hull. You want to draw away the heat, not circulate the heat. And never run the boat half throttle, always WOT (wide open throttle), You will build up heat on the esc. I always like to give myself an extra margin when it comes to the Amp on the Esc. I would get a 70-90 Amp esc. Pref a 90A. That way you need not upgrade the esc down the road.