Model Boat Mayhem

Technical, Techniques, Hints, and Tips => DC Motors (Brushed) and Speed Controllers => Topic started by: AlanB on May 17, 2006, 07:38:54 pm

Title: What Motor to use ???
Post by: AlanB on May 17, 2006, 07:38:54 pm

I am looking for suggestions as to what motor to use for my next project.

The tug in question is 40" long and 11" beam

The running gear is a 110mm prop within a kort nozzle

I want to use the tug for towing, so the motor has to be powerfull.

The power source is 12v

Any ideas  ???

Title: Re: What Motor to use ???
Post by: Shipmate60 on May 17, 2006, 08:02:09 pm

I would suggest a 6:1 reduction MFA Motor, should still give about 2000 rpm at the prop and lower running power consumption.

Bob

Title: Re: What Motor to use ???
Post by: Pirate on May 18, 2006, 08:12:08 am

Good morning.....what a whopper!!!!! I think you need  too talk to Brian Ward at Mobile Marine Models as he not only makes and supplies but is a font of experience to draw on .
Good luck
Pirate
PS be nice to see some pics of the beast in the making and first launch......

Title: Re: What Motor to use ???
Post by: AlanB on May 18, 2006, 10:08:32 am

Thanks for the replies so far.

I have already built the MMM Portgarth and will post some pics later.
It has 2 x 12v motors running 2 x 70mm Prop Shop props within steerable korts.
The measured bollard pull is 8 - 9 lbs

The current or next project is a Tyne Models Crosby
As this is a single prop tug, albeit 110mm within a fixed kort, I need a motor with
plenty of grunt.
So far I have found a 100w 12v motor with an rpm of 2700.

My next question is - what sort of rpm should I be looking for at the prop end ?

I will give Brian a ring and see what he suggests as well.

Title: Re: What Motor to use ???
Post by: Shipmate60 on May 18, 2006, 01:31:56 pm

Also try Model Motors Direct, Alistaire seems to specialise in these motors,

Bob

Title: Re: What Motor to use ???
Post by: AlanB on May 18, 2006, 02:27:18 pm

Forgot all about Model Motors Direct

I will try him as well.


Still looking for an idea on what sort of rpm I should be looking for???

Title: Re: What Motor to use ???
Post by: Shipmate60 on May 18, 2006, 06:05:43 pm

Alan,
depends on the pitch, less pitch more revs.

Bob

Title: Re: What Motor to use ???
Post by: Shipmate60 on May 19, 2006, 11:09:11 am

As a very rough "rule of thumb" for scale boats with a brass or cast prop about 3000 rpm max.

Bob

Title: Re: What Motor to use ???
Post by: boatmanic942 on May 19, 2006, 11:30:37 am

robbe 1000 ?30 from westbourne i know some one and it powers a 4ft robbe jan

Title: Re: What Motor to use ???
Post by: Shipmate60 on May 23, 2006, 10:05:52 am

Or a car fan motor, but might need to be geared down.
Windscreen wiper motor could be good for you though!!

Bob

Title: Re: What Motor to use ???
Post by: AlanB on May 23, 2006, 12:01:59 pm

I have gone down the try it and see route now

Bought a Robbe 1000 and eventually found and bought a Graupner 900 BB Torque (like rocking horse droppings now)

The Robbe will run on 12v, the 900 on 6v to reduce the RPM to just over 3000

I will try both of these and report back the findings, also thought about an MFA 850 on a 3:1 gearing.

At this rate all the motors will cost more than the boat.

Title: Re: What Motor to use ???
Post by: Shipmate60 on May 24, 2006, 10:32:19 pm

Its half the fun!!!

Bob

Title: Re: What Motor to use ???
Post by: TorViking on July 04, 2006, 11:42:00 pm

Hi alan,
Just wondered when "crosby" had a fixed Kort fitted? She was a Runston diesel driving a contollable pitch prop in an Aquamaster steerable Kort Knozzle.Not being a "Knowall" but I scratchbuilt crosby back in the 70's with drawings supplied by Alexander towing.If you want anymore info please let me know.

Kind regards

andy.

Title: Re: What Motor to use ???
Post by: Kyle02 on August 03, 2008, 05:59:12 pm

Here Mate Your Best Bet Is On A Fan Blower Motor From A Car  O0 You'll Probably Be Able To Pick One Up From A Scrapyard From Around £5-£20

Title: Re: What Motor to use ???
Post by: tony23 on August 06, 2008, 12:53:25 am

have any of you guys looked a Buhlar motors I believe there the 'Rolls Royce' of motors

Title: Re: What Motor to use ???
Post by: malcolmfrary on August 06, 2008, 05:23:45 pm

As an alternative to the car fan motor, look for electric window motors.  With a 35-40 mm prop, should give enough power to embarrass if not towing, which is about right for a tug.

Title: Re: What Motor to use ???
Post by: nick_75au on August 22, 2008, 08:59:00 am

A 100 watt 24 volt motor from the razor scooters on 12 volt will give 1200 odd rpm. 2400 rpm on a 40 inch hull and 75mm prop lifts out of the water ;D
Regards
Nick

Title: Re: What Motor to use ???
Post by: Casper on August 23, 2008, 08:34:19 pm

Hello,

Hectoperm Maxipile 6:1 reduction. Not cheap, but the dogs wotsits on large models with props 100mm plus.

m