I am thinking about making a 3D printed RC boat. My plan is to use my FSIA6B transmitter and use it with a FSIA6 receiver and to use my Arduino to get the signal from the receiver and control the motor with a L293D driver. I would use a 7.2V battery to power both the arduino and the motor.
Can I just plug the arduino and th driver in derivation to the battery or do I need additionnal setup ?
Post a link to the motor specifications or data sheet. The ancient, inefficient L293D driver may not be sufficient to drive it, and in any case, a significant fraction of the battery power will be wasted as heat.
You need a motor driver than can easily handle the stall current of the motor. Pololu has a good selection of modern, energy efficient and inexpensive motor drivers.
I don't know the DC motor specs but it comes from an old rc boat and was working with a 7.2V battery.
I don't know the DC motor specs
Measure the resistance across the motor connections and Ohm's Law says I=V/R.
Sadly I have no multimeter
If you intend to continue the hobby, buy a multimeter. It is an essential tool.