Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length.

[rob]

good morning gents,
Scale 4 bladed prop with 65 mm diameter from Raboesh, on the stern of a 43 inch Mountfleet Drifter.
Motor options are MFA 800 at approx 5000 RPM,
                           MMB 900 at approx 2500 RPM
Which motor of the two do you think would be best ?
I know that if I phone Propshop, I will be able to match one of his cast masterpieces to either of the motors mentioned, just thought I might ask on here first.

[Shipmate60]

MFA 800,
If it is a little fast you can always not use all the stick.
On the 900 you will need to up the voltage to get more revs.


Bob

[Time Bandit]

MMB900
2500rpm will still give 30-50% over hullspeed with a nice bow wave.

5000rpm are just a waste of battery power.

[rob]

Thankyou both, that 1 all at the moment then

[Calimero]

I'm with Time Bandit. Even if the 900 were to hold the rated RPM (which I doubt), it would be more than enough for a 65mm  on a slow boat.

[Buccaneer]

I assume you already have both motors and are wondering which one to fit. I would go for the 900. I had a 900 fitted to my 48" Lloydsman Tug and it went very well on virtually no throttle at all. My Mountfleet Ben Ain is fitted with the same size prop as your Drifter and goes very well on a Mobile Marine Models T12.(Quoted Max 4600 rpm) At typical speed you can see the prop rotating - you will not require anything like the revs quoted from your motors.

John

[rob]

You are 100% correct Buccaneer, I should have phrased my question better.
900 it is then.
Thankyou all.

[Tugtower]

A club member has the mountfleet steam drifter and runs it on a mobile marines T12. Tts far quiiter then a torpedo motor (those things are noisy), has been able to run it all day on a single 12v 3.4Ah LA battery.

[rob]

Thankyou Tugtower, very interesting. The T12 is obviously a very good motor.

[Shipmate60]

Most builders, myself included, do tend to overpower models.
I justify this with the wind and waves not being scale.
Also I do prefer a little speed in hand to get away from a possible collision.
I have used both motors on roughly that size of prop and found the 900 just too slow unless the voltage was increased.
I do find lots of modellers have a downer on MFA 800's and 850's but I find them reliable and not power hungry unless overpowering them.


The T12 is a good but expensive motor, quiet and powerful.


Bob