Varchasvini, i will help you to make the specified mini project. What I all want is how is it going to be designed in your expectation. make a deteailed reply on your project.how about a toy car that'll be more easier than a boat riding in water?
A school project is for learning the lessons while constructing the things by theirown. it is much like a practical implementation of a year or more long luctures and theories.let him do it by his own ideas and procedures u need a UHF level receiver working over 400MHz range.
You can pull the $10.00 toy apart and put the H-bridge on a separate board and use the 5-channel decoder to do other things.
You can pull the transmitter apart and use the parts to produce 4 channels. There is absolutley no way you are going to buy the parts for $10.00 as separate items as the TX3 and RX3 IC's cost more than $10.00 alone.
With a boat, you seldom need reverse, wouldn't bother for a mini project. You would need two channels, one for rudder, one for the propeller. Wouldn't even consider building my own transmitter/receiver, as that is not a 'mini-project' (not even close).
Instead of a rudder, you could use duel propellers. If this is small and simple, wouldn't bother with speed control.