RC controlled electric motor boat!

[sagarqwer]

Heyy guys.. I need help on this one. I need to build an Rc controlled electric boat with the following specifications:
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Machine specifications

Dimension and Fabrication

Maximum length of the boat: 20 inches.
Maximum width of the boat: 7 inches.
The boat has to be controlled by a wireless remote control mechanism throughout the competition.
The boat must not be made from Lego parts, or any ready-made assembly kits.
Remote control systems from toys might be used. Remote control systems available in the market may also be used.
Balsa wood or fibre glass or any other light in weight but strong material can be used for the construction.
Motor specifications

The boat must have an onboard power supply to provide power to any mechanism requiring electric power.
Only dc motor should be used for the power supply.
The maximum allowed speed of an electric motor is 7000 r.p.m.(i.e. Participants can also use dc motor of 5000 r.p.m or any other dc motor lower in speed than 7000 r.p.m).
The electric voltage provided to the motor should not be more than 7.2V.
Speed controller should be used so as to control the the speed of the dc motor.

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Pls help me out with the design and construction of such a boat! Thank you.

Regards,
Sagar

[vineethn88]

i think u're preparing for NFS aqua @ nit trichy . humm...i'd suggest u to design the boat such a way that , it is lightest as possible. the weight should be minmum . it is not practical to calculate the resistance and choose appropriate motor for it . So my suggestion is to go for trial and error method.
use different motors and different propellers . try out all combinations & get the best speed & controllablity work.
best of luck.
and yeah..try ..to come out with something innovative..
think out of the box..anyways..its jus a speed competition , so try different possible design..
need not stick to conventional systems

[Obsession]

I'm glad you knew what this was for vineethn88 as the OP didn't say what the objective was or what the course was (do you have to contend with waves? How long does it have to run?) There are a lot of RC boats raced - there are hundreds available off the shelf - look at existing designs that win in similar conditions as a start - easier than trying to scale full size as you likely have access to the same motors, etc. as the existing rc boats. Though if you do something innovative that will be cooler!