Model Boat Mayhem
Mess Deck: General Section => Model Boating => Topic started by: Buccaneer on August 17, 2016, 08:47:17 pm
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I have just completed a Caldercraft Talacre Coaster that I picked up on EBay and today gave it it's first Sea Trial. Basically it goes alright but I require full power to get even a reasonable speed from it. It came fitted with an MFA Geared Motor, 11:1 Ratio, and a 36mm four bladed propeller. I have fitted a 7.2V 4300 mAH Battery Pack and an Action P80 ESC. The maximum prop size I could fit would be 44mm. If I were able to remove the motor, which looks like a somewhat doubtful option, I have an MFA 2.5:1 which I could slot in, or I am considering a Mabuchi 555.
I have a number of other Tugs and Merchant ships so I have a rough idea of what performance looks right but this one definitely under performs. I would be interested to hear from other Talacre owners about what they have fitted, or any thoughts from anybody else.
John
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I have built the Talacre and used an MFA 500 motor direct to the prop with no gears and it went quite realistically on the water.
There is a build blog on here somewhere. I'll have a look for you.
Cheers
ken
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I have a Billings Nordkap, it's very close to the Talacre's dimentions & runs nicely at scale speed, with a bit of 'oomph' in hand for get out of trouble speed, it's powered by a good ol' Mabuchi 555 on 12v, running a 40mm 3 blade brass prop.
I also have a Model Slipway 'Dutch Courage' tug, it is getting twin Mabuchi 555 power, swinging 60mm 3 blade props in fixed korts & they don't struggle to give above scale speed. :-))
(http://i2.photobucket.com/albums/y21/deltic13/Boats/Laurel%20II_zpsddsn34ps.jpg)
(http://i2.photobucket.com/albums/y21/deltic13/Boats/Straight%20line%202016_zpsisdm2mvh.jpg)
(http://i2.photobucket.com/albums/y21/deltic13/Boats/8%20Winch%20fitted_zpshwodpnay.jpg)
Your Photobucket pictures are missing!?!
Try direct from your computer as long as they are under 200K. I find that 150K is satisfactory
Ken
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Hi Buc...The 555 driving direct will do the job, the gear reduction you have now on a relatively small prop, as you have found, is ineffective.
If you can measure the current taken when prop is in the water you should be looking for about 2 to 3 amps to give 15+ Watts of power.
regards Roy
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The previous owner probably thought that if the real thing turned its prop at a given speed, so should the model, hence the rather silly gearing. The usual advice for better performance is "smaller prop", but in this case a larger prop an a lower gear ratio would be the answer. For scale looking performance, the techy answer is a scale prop turning at full size speed TIMES the square root of the scale.
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Aim for a shaft speed of 4000-5000RPM. That should give you a decent speed without overcooking things.
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Send me the photos, I'll post them for you! :-)
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The 2.5 gear reduction should be OK. 11:1 is far too much.
Colin
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Missing pics :-)
(http://i2.photobucket.com/albums/y21/deltic13/Boats/3e9cebd0-2dd4-40c0-986e-2edab9a76342_zpsm0cq22hr.jpg)
(http://i2.photobucket.com/albums/y21/deltic13/Boats/Straight20line202016_zpsisdm2mvh.jpg)
(http://i2.photobucket.com/albums/y21/deltic13/Boats/820Winch20fitted_zpshwodpnay.jpg)
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Problem solved, I hope. Thank you to everybody for their contributions, many thinking along the same line as me. I ended up fitting a 3 Blade 40 mm Propeller and the 2.5:1 Motor. Fitting the motor was a 'challenge' (That's the nice way of putting it!) Removing the mounting bracket by undoing the four bolts was not on as these came up through a wooden base that had been epoxied to the hull and two of the nuts were just not accessible by spanner. Then I had a bright idea, why not just change the gearbox. This fell apart when I found out that the gearboxes were fixed with different size bolts. Finally by removing the gearbox, then the retaining ring that holds the motor onto the mount, I was able to extract the motor. Repeat the process in reverse with the 2.5:1 motor and we were there. I just need a calm day at the pond to see how it performs, but whatever the result I think this will probably be as good as it gets.
John