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[John W E]

Hi there, as far as I understand Derek was taking ratings from the 20 rpm

I wouldn't think it would be the same for the 200 rpm.   The way I understand this at the moment is we are using the same motor but different gear ratios to give us the same speed; but, with changing gear ratios were are also changing the torque settings.

In all honesty we can look at the theory side of stuff and say in theory yes this should work; but in practice it doesn't.  Therefore, its a case of 'suck it and see' as they say.

You will have to fit the 200 rpm motors into your model - try it in the tesk tank (the bath) and see.   So, in theory it should work but to be on the safe side, best check.
john

[Subculture]

You can easily work out how much force you need to turn the paddle round. Just make a simple crank that attaches to the paddle shaft, and hang small weights off of the end until you can just get the paddle to turn with the model in a test tank. The weight plus the length of crank required will enable you to calculate how much torque you need.

Theory doesn't always get you there 100%, but it can get you a good part of the way, and save time and money over empirical methods.

[derekwarner]

bluebird...there are a few constants & a few anomalies here 

World wide, most WEB sites show these e-cheapo 12V DC geared motors with output speeds from 20:1 to 150:1 as having the gearbox output shaft on the same axis as the motor

12V DC geared motors with output speeds of 200 and ⁺ RPM have the gearbox output shaft on a different axis to the motor. The gearbox canister diameter is also larger for these latter ratios, however with the same motor sizing

Colin.......clearly the spec page I copied was for the 20 RPM output speed.............. Derek

[Colin Duerden]

Hi John and thank you for your message. I will have the 200 RPM motors fitted and try it out as you suggest. Hopefully this will work as this is my last option with this method. I will let you know when the motors are fitted. Thanks for all your suggestions and help with this project. I am keeping my fingers crossed. Kind Regards Colin D. Thank you to all others who have contributed with helpful suggestions and helpful hints.

[dirkske]

I'm testing with gimball motors; looks promising for 1:1 direct drive
Not ready to do on-the-water tests yet

http://www.modelboatmayhem.co.uk/forum/index.php/topic,56317.msg596793.html#msg596793

[John W E]

Hi Colin here is my effort at the tug
http://www.modelboatmayhem.co.uk/forum/index.php/topic,57145.0.html

john

[Colin Duerden]

Thank you for your message. I have now got the 200 RPM motors installed on a 1 to 1 ratio like you nearly ready for a test in the bath. They work very well out of the water. The reason I havent tested them yet in water is that I am worried it wont work OK. I must get some confidence and give it a go. Kind Regards Colin Let me know how you go on.

[Colin Duerden]

Hi John thanks for your interest. The pictures suggest that a lot of love and effort with your build and I prefer a plank on frame construction anyway. Unfortunately mine isnt. I am ready to test so wish me luck. Colin D