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[Roadrunner]

OK i gotta good question to ask those who are are as nuts as me.

Im using the mfa 2.5:1 geared motors in my tug http://www.cornwallmodelboats.co.uk/acatalog/MFA_919D251.html these ones, running 12v off ACTions P94 along with a whole load of other parts.

But i want more power! Now since my tugs a shoalbuster i have 6 inches of hull space to the deck, the prop shafts sit 3/4" from the base of the hull, so i picked the MFA motors as the gear spindle which the UV fits to is low enough to get the motors in using my Fixed coupling.

All keeping up so far?

My question is this .. without resorting to using belt drives ( i have no room!) to fit larger motors such as the T12 ( which won't fit anyway I tried!) if i take the gear system of the MFA motor and fit to a larger motor, What's the largest size this gear set will fit too, without me buying another larger esc, Will a 600, or 600BB size fit?

Or are there other motors out there that are the same case size as the  '555' motors that the original gear system is fitted to?

I'm running fixed korts with 45mm 4 bladed korts props ( prop shop )

Thanks in advance guys!

[ACTion]

What voltage are you using?

[Roadrunner]

12v 3AH, ( its a slim line LA)  i get about an hour with the current motors usage, i know larger motors will reduce my run time with that battery, but this boats space is at a seriuse premium so i have to pick the largest battery that will fit in the hull. originally i wanted 12v 7ah but I've not found a slim line version yet.

[Timo2]

Hi

Try Brushless motor

   Will post motor details later running out net time

  Timo2

[Timo2]

Hi


  Try            you fit to the gearbox ?


          http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idproduct=9447

Timo2

[Roadrunner]

Thanks for the suggestion Timo but i don't want to go down the brushless route as that will mean changing the ESC which is more expense then needed.

[DickyD]

See you are using 2.5:1 gear box on 12 volts. This gear box is recommended for 6 volts.

6:1 gear box is recommended for 12 volts, so using the right gearbox might help.

[Roadrunner]

 The motor allows for up to 15v .... it says 6v as a guide line for minimum voltage..

Operating Voltage 4.5-15 volts.
Current approx.2.1A at max efficiency 6v.
Current approx.2.85A at max efficiency 12v.
RPM at 6.0v - 6180 at max efficiency.
RPM at 12.0v - 13360 at max efficiency.

Unfortunately the reason i use 2.5:1 is due to the tidal currents at our lake, its handy to have more speed then out right torque given our lake conditions, 6:1 is more suitable when i pop to ponds or lakes that are not directly connected to the sea, i'm limited to my surroundings    I did try 6:1 during my trials as they were my first purchase of motors & they sucked big style!

[nick_75au]

I would like to know  if the motor is bogging down, IE is the speed of the motor dropping by more than half from out of the water to into the water, if not then the problem is not not having enough power, if it is dropping 25% of its RPM then its running perfectly. If its dropping less then a bigger prop is in order.

What I suspect is you need more RPM, to utilise the same gearbox you need to increase the voltage, say a 12 cell Ni-XX pack for 14.4 volts. That would solve your space problem as well

Also the motor specs you quoted are for the motor only? not the output of the gearbox, correct?

Cheers
Nick