Ok gang, I an working on new project I am building an Acadamey submarine and it come with a speed 280, I am going to upgrade the speed 280 to a Graupner 6v speed 280 race or even my astro 10. I am familiar with air props and their pitch etc.. but lost with boats. Ok back to the point, the model is about 12 inches long and 1.5 wide. I am going direct drive with a lipo battery at 11.1 volts or less. What prop would give me a nice mix of speed and a nice mix of run time. Lets say the battery is 600 mah to start off with. Any help is welcome. Thank you all for your help.

Jason