New Rio EP prop questions

[Assocracer]

I'm new to boats, just picked up a Rio EP. I've got a Novak SLYDR brushless speedo with a 10.5 motor i was thinking of shoe horning into the boat and was wondering about prop choices. Not sure what to go with, i just know that the last time i had a boat (Kyosho Jet Arrow) i put a modified motor in it and didn't change the prop and started a fire in the boat :) Any help would me much appreciated!

[Brushless55]

what is the kv of that motor, and are your running 2s or 3s?

[Assocracer]

KV is approximately 4200Kv and it's a 2s Orion 3600 20C pack.

[BakedMopar]

Start with a X432. If temps are okay go up to a X632 or a Y534 (although its plastic). You will have heating propblem if you don't cool it properly. Fqdawld has run a CC sidewinder 4600 combo in his. Heres a vid.

http://www.youtube.com/watch?v=--TxpnBjdGs

[Brushless55]

That thing looks good man!