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[titoneri]

Recently purchased and now installed a pair of Model Slipways (MS-900 BB) 6-18 Volt electric motors for my big 50 inch long tug, they are exactly what slipway state Low noise and high torque. The amount of power my tug now has when towing looks just like the real thing. If I had purchased Graupner ones which look very similar it would have cost me twice the price. So have obtained another for my Our Lass II kit. Bargains are hard to come by so get them when you can in my opinion as when they are gone there gone.

[stallspeed]

Redbank models list the Graupner SPEED 900 BB at £26.59 with carriage at cost.
Here is what you will find on the Graupner one:

Specs
Nominal voltage 12 V Operating voltage range 6 ... 40 V No-load rpm 6500 min
No-load current drain 1,1 A Current drain at max. efficiency 8 A Current drain when stalled 54 A
Length of case, excl. shaft 85 mm Shaft diameter 6 mm Weight 645 g

From the above ,I reckon the Graupner 900 has a stall torque of 850-1,000 mNm

Here is what Model Slipway website says on the 900-type (sic) motor:

12v ELECTRIC MOTOR
MS-900 BB

We have taken delivery of a large number of 6-18 volt 900-type motors.
   

12v electric motor MS 900 BB

Ballraced - low noise - high torque
12-pole armature
No-load RPM 6500 at 12 V
No-load current drain 1.1 Amp
Length of case excl. shaft 85mm - Shaft diameter 5mm - Weight 645g

Ideal for direct-drive of larger models with 50-70mm dia. propellers.

Slight "storage tarnishing" but still new and unused.

Motor £25 and Coupling £6.50 + £3.80 for UK pp

By the substitution method,amp readings with a submerged prop will actually tell you if the motors do the same.

[DickyD]

Recently purchased and now installed a pair of Model Slipways (MS-900 BB) 6-18 Volt electric motors for my big 50 inch long tug, they are exactly what slipway state Low noise and high torque. The amount of power my tug now has when towing looks just like the real thing. If I had purchased Graupner ones which look very similar it would have cost me twice the price. So have obtained another for my Our Lass II kit. Bargains are hard to come by so get them when you can in my opinion as when they are gone there gone.

This is the same motor that MMB and ACTion sell and the one that everyone has been raving about for running their Perkasas on on 24 volts. ie Stavros.

[red181]

has anyone else actually run this motor in a fast scale boat, other than the stavros video that gets a regular showing everytime motors are mentioned?, and perhaps in a boat with a bit of weight to it?

I run Graupner, 700bb's, 12v, and the 9.6 and 8.4. These motors are happy to be used well over voltage to achieve excellent performance figures, and are designed for the task. I would like to try one of the other motors, but remember reading that although they can easily run over 24v (which I would like to try) if they are not water cooled warranty is invalid, would love to see some evidence of a fast electric set up with some actual data, gps speed, amp draw etc.

I cant see how people are raving about a motor that has a no load rpm of only 6500 and say it goes fast, when a graupner 700bb turbo has almost twice the rpm at same 12v

taken from corwall model boats:

Graupner Speed 700BB Turbo 12V (6317)
Ballraced motor with internal fan. Suitable for POWER GEAR 2:1 and direct drive.

Specification
Nominal voltage 12 V
Operating voltage range 7,2-19,2 V
No-load rpm 11600 min–1
No-load current drain 2 A
Current drain at max. efficiency 12,5 A
Current drain when stalled 43A
Max. efficiency without gearbox 75 %
Length of case, excl. shaft 67mm
Diameter 44mm
Free shaft length 14mm
Shaft diameter 5mm
Weight 350 g
Part No: G6317

Price: £24.99 (Including VAT at 15%)

I would have thought Titoneri's findings are correct, loads of torque, ideal for a tug, but not the speed people are raving about, any info regarding speed appreciated
Thanks

[Marks Model Bits]

I have sold loads of these motors to modellers with big Huntsmans, Perkassas, Sea Queens ect, (usually replacing MFA 850s) and I am sorry for not getting videos showing all these models running!!!!!!!!!! However RPMs are not the be all and end all for a fast scale boat, torque is also an important factor, My motors are capable of spinning a pretty large prop compared to a 700 motor (think of a 2.0 litre 4 cylinder engine and compare that to a 6.6 litre V8, the larger engine is slower revving than the smaller one but which one will make a car go faster?)
These motors are not suitable for light weight or small fast electrics as they are big, heavy motors. I do not make extravagent claims about what my motors are capable of, I just know they work well in the right set up...... As the old saying goes "it's horses for courses" Use them for what they are suited for!!! (It's not rocket science)

As for my warranty regarding water cooling I sell the motors and if you don't follow my recommendations do not expect it to be replaced..... Simple as that...

[stallspeed]

The maximum power you can get out those motors is about 0.22 xI_stall x V.
In reality you are limited by the surface area.Cooling allows about 15% increase in current.

[Proteus]

I have sold loads of these motors to modellers with big Huntsmans, Perkassas, Sea Queens ect, (usually replacing MFA 850s) and I am sorry for not getting videos showing all these models running!!!!!!!!!! However RPMs are not the be all and end all for a fast scale boat, torque is also an important factor, My motors are capable of spinning a pretty large prop compared to a 700 motor (think of a 2.0 litre 4 cylinder engine and compare that to a 6.6 litre V8, the larger engine is slower revving than the smaller one but which one will make a car go faster?)
These motors are not suitable for light weight or small fast electrics as they are big, heavy motors. I do not make extravagent claims about what my motors are capable of, I just know they work well in the right set up...... As the old saying goes "it's horses for courses" Use them for what they are suited for!!! (It's not rocket science)

As for my warranty regarding water cooling I sell the motors and if you don't follow my recommendations do not expect it to be replaced..... Simple as that...

Out of interest what amps do these motors pull on 24v in a fast boat Perkassas, Sea Queens ect with the right prop  ? I have been trying to find out. I know they pull 8 amps on 12v at max power

Proteus

[stallspeed]

Out of interest what amps do these motors pull on 24v in a fast boat Perkassas, Sea Queens ect with the right prop  ? I have been trying to find out. I know they pull 8 amps on 12v at max power

Proteus

Depends on the prop and the Graupner 900 will takes a much larger prop than the 700bb turbo.
Try 26 amp on 12v at maximum power at about 45% efficiency-Graupner again.

[wombat]

has anyone else actually run this motor in a fast scale boat, other than the stavros video that gets a regular showing everytime motors are mentioned?, and perhaps in a boat with a bit of weight to it?

I cant see how people are raving about a motor that has a no load rpm of only 6500 and say it goes fast, when a graupner 700bb turbo has almost twice the rpm at same 12v

I would have thought Titoneri's findings are correct, loads of torque, ideal for a tug, but not the speed people are raving about, any info regarding speed appreciated
Thanks

Remember it all depends on what size of prop you are running - the limiting factor on the rotational speed of a propellor is the speed at the tip - once you get over a certain limit you are spinning the prop faster than the water can actually move because of its viscosity. What happens then is that you get the formation of vacuum bubbles around the prop (caviation) which wears the prop out and lowers the efficiency drastically.

The speed of a boat depends on the volume of water shoved out of the back by the propellor - for a single revolution a large prop will shove out proportionally more water than a small prop - so the trade off is between small props spinning fast or large props spinning slower. You then have to consider the weight of the boat - how much water do you need to shove out of the back to get the speed. On a large boat, you may find that you need more small props thaan you have room for on the stern - so you go for bigger props - which need bigger motors to supply the torque - but only spin to a much slower speed before cavitation starts. A small prop may happily spin at 12,000 RPM before it starts to cavitate - but double the diameter and it will only spin to 6,000 rpm before cavitation starts. It is all about making the appropriate engineering choices

Wom

[Flying Sparks]

Interesting reading peoples thoughts on motors. But a really good motor will not have any brushes in it 

[grasshopper]

Interesting reading peoples thoughts on motors. But a really good motor will not have any brushes in it

Agree there Sparks, it'll have cylinders, pistons and fuel injection!

[Marks Model Bits]

Out of interest what amps do these motors pull on 24v in a fast boat Perkassas, Sea Queens ect with the right prop  ? I have been trying to find out. I know they pull 8 amps on 12v at max power

Proteus

On 24 volts they pull approx 6 amps when driving a 52.5mm plastic 2 blade 'X' prop, this is the setup I have in my Perkassa and this ties in with the 45 min run time I get with 4300mah nimh batteries. This will vary depending on which prop you use but it gives a good benchmark to start from.

Mark.

[SteamboatPhil]

I have quite a few of the MMB motors as do a few of my club members in all sorts of differnt style boats, from Tugs to scale warships, working on voltage ranging from 6-18v.
and they seem to run forever.
I have got one in one of my straight runners on 24 volts (with water cooling) using a 62.5mm prop. Running time (its always full speed as there is no radio) 40mins, which means it will cover well over a mile at 12mph (confirmed speed).

As has been said its horses for courses, but it does it for me, I'm about to put one in a 5ft straight runner now. 

[Flying Sparks]

Agree there Sparks, it'll have cylinders, pistons and fuel injection!

Nah, they are called engines