Real quick for you.  .  Watts = Volts x Amps

The motor is what will ultimately draw as many amps as it wants, so start there.

Your motor's supper huge ultimate power output is rated at 3500watts

In a chart this means

2s (7.4V) x  472.97 = 3500 watts

3s (11.1V) x 315.31 = 3500 watts

4s (14.8V) x 236.48A = 3500 watts

6s (22.2V) x 157.65A = 3500 watts

Now given that you can put out 3500 watts at only 2s 7.4V the size of the wires required to handle almost 500 amps would be huge, and all efficiency would be lost.  You would also have to swing such a huge prop because RPM would be so slow.  It can be done though.

A quick guide.

Watts is equal to Horse Power, in the sense that it is a measurement of power.  Power is what moves the boat (well work is. . .)

1 HP = 745 Watts

Watts = Volts x Amps, so no matter how you move electricity, via amps or volts, the combined output is the watts.

it is easier to move electricity in the form of volts, less loss occurs.

As for RPM, 30,000 is the goal.  So your motor spinning at 15,000 RPM/V (1500Kv) will turn 33,300 RPM  Just right. (these are all unloaded RPM)