Help for my students

[rhodge]

I have several high school students that are designing a "cargo ship" (approx. 52" long x 14" at the beam, max. draft 5" and will carry approx. 100 to 125 lbs),for an engineering challenge. I have no knowledge in RC boats. I am asking for help setting up the motor and propeller, (and propeller size), servo for rudder and any other ideas that may help. A good "starter book" in RC boats would help. Any ideas?
Bob

[Hydro Junkie]

I'm no expert on electrics, but what I would recommend is a 500 to 700(or two) sized motor with high torque and a rudder servo with between 80 to 125 inch ounces of torque. Are you giving them a minimum or maximum speed their "ship" must be capable of? I know www.shipsnthings.com has several sizes and styles of ship props to choose from as well as fittings and detail parts if you and your students are so inclined.

[rhodge]

Thanks for your help, I know my students are greatful. AThe contest is to design a ship that is 66" total (length & beam) - my kids have come up with 51 long by 15 at the beam. It is to carry as much weight as possible in the fastest time over a fig. 8 course (several hundred feet) in the Baltimore harbor. There are lot of other restrictions but too much to go into here. We will get an electric motor for the people running the contest - we must use the one they provide. We need help on how to hook up everything; motor, prop, speed controller, servor and rudder etc.
Thanks!!!!!!

[Fluid]

We need alot more information to be of much help. What are the specifications of the motor? How many volts/what kind of battery will you be using?

As far as the servo goes, you do not need a powerful one. Any standard, inexpensive servo supplying ca 35-40 in/oz of torque will be plenty.

[rhodge]

I am not sure on the motor spec's yet but it is a 12 volt motor. As for the battery, I am not sure on the type or size yet but weight is important as well as the power from the battery. The servo will need to turn the rudder of a ship that has a projected weigth of 100 + pounds. I would love to send you the PDF file for the spec's on the contest if you let me know how I can get it to you.
Thanks for the kids!!!!

[Chris LaPanse]

My reccomendation for a servo would be a cheap 1/4 scale servo. More power than the small ones, inexpensive, and more than good enough for that application. I would look at ones in the range of 80-100oz/in of torque. This is probably a little excessive, but it will alow precise and fast control of the rudder.