some facts about propultion that i learned from my experience.. if you hae low RPM gearbox, or low RPM due to half voltage instead of needed, can use it for high torque, by adding big diameter prop, with very high angle.. these props can make from aluminum sheets, or brass sheets.. can alter the pitch of the blades as trial and error.. if you have a high speed gear box, please do not feed a 6 volt motor to 12 volt, as it burns, can use small dia props with shallow angle.. but if you are a person who can rework on any motor, you can decide the RPM and power of the motor in a look.. most of the time, i saw , lots of power is wasted in the form of cavitation and slippage.. to avoid that we can make our own props and rework on motors, will allow us a perfect combination of power set up.. these are can be seen my latest boats and ships, one uses the basic idea i expalined.. running time for hours.. performance.. for long time.. no cavitation.. here you can increase the speed by altering the pitch of the blade, or by increasing the motor speed.. a mere 3 volt motor can pump out your craft over water.. but still will take good rework..rework it.. fix it.. enjoy Rcying.. 

Is The material used is sun board.? Can I start with 4mm strong foam .? Say depron?

radiocraft yes it is sun board 3mm for sides and 4mm for deck it is easily available  for boat building you should not use depron and sun board is very cheap too in my place 3feet by 6feet 3mm sheet is not more than 250/- i build 2 boats with sun board all 3mm no problem and simply remember the basic ratio of boat width and length ex: boat length is 24" boat width should be minimum of 6" width*4 OK

@Radiocraft, this thread is very informative, but the one who stared this is no more active on the forum, so if your qs. is intended to him , no use of it ...

Ty everyone!

Sir plzz how you wired servo.... Plzz sir kindly send me schenatic diagram of electronics on boat....

Roopeshkrishna is now activated on Facebook and u can join him