motor size

[Jerry YoungParticipant @jerryyoung62912]

hi

need help

im am building a 1930’s us coast guard picket boat. model length is 39" beam is 61/2", plank on frame construction (plywood)

i have done a bit of research on the net and found the full size boat to have a  max speed of 15 knots and a cruising speed of 10 knots.

question-

what motor size and propeller size would any modellers out there suggest to attain a scale speed?

any help would be greatfull. i do’nt want to burn out motors or capsize her on a sharp turn. just want her to look right on the water.

[Paul TParticipant @pault84577]

Hi Jerry

A couple of questions about your boat.

What type of hull does your boat have i.e. does it plane over the water like a speedboat or does it sit in the water like a barge?

How heavy do you expect the model to be when finished?

Do you want to use electric or I.C. power?

All the best

Paul

[Jerry YoungParticipant @jerryyoung62912]

quite flat towards the stern and sharp towards the bows. i would say , considering it to be a life boat, it needs to be quick., so it would plane.

finished weight is unknown at the moment. all ribs are 1/8 ply, hull and deck is 1/16 ply cabin is 1/8 ply.

and yes i missed the all important bit. it will be electric, sorry.

[Paul TParticipant @pault84577]

Hi Jerry

In the absence of any better advice I would suggest a 600 size motor driving a 3 bladed prop of about 20 > 25mm dia. Check on the amp draw of the motor before buying the batteries, bear in mind that these will also make great ballast so you might wish to choose a larger size of battery if you need the extra weight.

Hope this helps.

All the best

Paul

[Jerry YoungParticipant @jerryyoung62912]

hi paul

sorry i didn’t get bak to you straight away, been called out on a breakdown at work

thanks for the info i can start looking straight away.

battery size will be dictated by space and weather it’s a series or parallell set up i think

thanks for your help

jerry  

[Jerry YoungParticipant @jerryyoung62912]

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