Hi there

I see that you still talk all the time about cells.

Adding cells is not a solution for making boat faster. Each motor is designed to be used with it's voltage.
Making voltage higher means changing everything.

Usually standard or selected 8.4 v 500, 600 class motor is not ready for being powered using 12 v. It will be damaged in short time. All information about motor voltage should be given in it's manual. Moreover, each serious firm put into motor box it's characteristics.

An european, german Speed 700 Turbo with 5 piece armature ( 5 piece rotor ) uses 9.6 - 12 v and is specially designed for Mono class electric speed boats. When you want to use 14.4 then you have to add water cooling. The time of performance is about 3 minutes.

That's all from me about that. I hope your project will be ok, speed king. Your previous version with 700 was right. Your choice.

When boat is running only falf of prop should work in the water. So, how to determine where to put the prop shaft when is not running, during assembly, to get such effect? I know how to do it, does Ryan too? Any theoretical opinions? Maybe some mathematics?

Regards
Peter