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Old Feb 06, 2013, 11:46 AM
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Joined Feb 2013
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Hi, 
I want to ask some technical question about by problem. I want to make a RC boat. This is my first experience, so I have no idea about so many issues. I'd appreciate it if you help
I want to explain briefly.
I have a catamaran boat which have 1m lenght, about 5kg weight. I would like to swim it with 5m/s speed in choppy water about 40 minutes. I want low speed and more power. I don't know which one to choose engine, battery, ESC....
Could you advise me about motor, esc and battery for this system
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Old Feb 06, 2013, 03:33 PM
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Joined Feb 2006
977 Posts
I am not sure what to suggest for a boat of that size, but it is a pretty big boat and it will require a fairly robust motor to get it moving, yet have a very low amp draw to get that sort of run time.

A Leopard 5692 at 730kv, running 4S 5000 lipo and a x645 prop is estimated by FeCalc to draw 7 amps, hit 20mph (9m/s) and run for 40 minutes. While that seems to meet the criteria, I don't know if that would actually work. It might just caviate and never get moving.

In general trying to get 40 minute run times with electric power is a problem.
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Old Feb 07, 2013, 11:24 AM
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Joined Dec 2010
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I have a 1 meter cat, total weight 3.8kg. I have no idea of its topspeed but I'm sure it is doing nothing less than 5 m/s. I did not built it for speed but rather for low power consumption as I use it for a fishing boat. It's got a very small outrunner, most will say it is too small for the hull, but sure enough, it works and stays cool without any watercooling. That is because it does not draw high amps.
The motor is a 3536 1000KV Turnigy outrunner, on just 2S. Prop is a no-name 55mm fully submurged prop running with a straight shaft. I supose with additional batteries I can run it without stopping for much more than 40 minutes.

@ Cyberhoops. I did not know such a big motor could even draw so little power.
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Old Feb 07, 2013, 01:16 PM
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Joined Feb 2013
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I would firstly like to thank @SARCFAN and @cyberhoops
I am planning to buy two leopard 3674 1300kv brushless engine, two swordfish 120A ESC and two relatively large prop about 55mm. As I understand it would be enough for my boat.
If you have more suggestions, please write to me
I will send videos when I finish the boat.
I am grateful for your support.
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Old Feb 07, 2013, 11:44 PM
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Well, as you don't want high speed but rather long runtime, two motors are overkill. But it's your money
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