Use a LiPo 11.1V is OK. How many A is depend on your need. If you ship is big enough, you may buy a LiPo of 5000mA or 10000mA, the performance will be much better than the old lead battery.
Hi C hing, i also see you has big tug boat, you use 12V and ?? Ah ar?? can use how long time?
Because before i use 6V 5A in my Robbe Paula III, can only use about 20mins ja wow.
I will build a big tug boat, can you give me some suggestion.