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[malcolmfrary]

As a personal opinion, I would always avoid connecting motors in series.  The result is that both motors get the same current, but due to the fact that it is impossible to guarantee that both motors are equally efficient, and that both are identically loaded, one will "win", and hog power from the other.  This makes for a boat that will be determined to sail in circles.

[Martin (Admin)]

When wiring 2 motors in series AND using them with contrarotating propellers(one motor reversed), won't one motor be MUCH more efficient than the other... something to do with motor / commutator timing?

Another 540 (Speed 600) sized motor to consider are:

 'Model Motors Direct's  - 555

 'MFA's' - RE - 550/1 (3 POLE )

..... and if you really want to 'push the boat out'.... a medical motor like the Charles Austen Pumps motors! ( aka CROUZET motors)
A real Rolls Royce motor! - A friend gave me a "bad" 2nd hand motor and it's still better than anything I've seen before... then again, a 540 motor at £93 each plus VAT!!!!

   Have a look at the Farnell website to see what real motors are available.... if your pocket is deep enough!
     http://uk.farnell.com/jsp/search2/browse.jsp?N=500015+1004985

[Tug-Kenny RIP]

Great list on Farnel, Martin. You're right about 'pockets' though.

Another question springs to mind.  What revs are the norm for model boat propulsion. I appreciate that it depends on the prop, but I was thinking of the noise level.   Being a Volvo driver, I'm not used to hearing the engine, and wondered if this could be carried over to model boats.


Cheers...ken

[FullLeatherJacket]

one will "win", and hog power from the other.  This makes for a boat that will be determined to sail in circles.

When wiring 2 motors in series AND using them with contrarotating propellers(one motor reversed), won't one motor be MUCH more efficient than the other... something to do with motor / commutator timing?

Yep! That's at least two of the reasons I can think of...........any more offers?
Logic and experience both say 2 x Motors = 2 x ESCs + 2 x Batteries + 2 x Rx outputs + 2 x sticks on the tranny (you'll need steering and throttle with a mixer). Owt less is more trouble, especially for a relative novice to the game.

[portside II]

gOD I HATE COMPUTERS 
i had wrote a reply and at the lend of it after i had done the spell check decided to insert a smiley then post it
and thats all you got ,a smiley!.
thanks for the imput F.M.J. thats what the forum is here for and all imput wheather good or bad is greatfully recieved will have a think about what i am doing with the motor set up and maybe put a couple of electronise 540's in with a pair of bearing shafts .
will keep you all posted
daz

[Shipmate60]

As a rule of thumb, for scale boats with scale props somewhere between 2500 - 3000 rpm.
Small tugs with large props less, fast partol boats more.
Deccaperms run about 2750 from geared end.

Bob

[Tug-Kenny RIP]

Thank you Shipmate 60

Happy new Year


Cheers...Ken

[portside II]

Whoa some of the parts for this hobby are pricey enough without looking at motors from the Farnell website  ,damn they are expensive  some of the geared motors would make great radars and a fully operational towing winch (just make sure it's strapped down).
A big thanks to Mayhem Martin and all the members who give their knowledge so freely .
A happy new year to you all 

[wombat]

Looking at the motor in question, it looks like the motors shipped with the Club500. Having a brief look on the Johnson web-site for matching motors, the closest match seems to be for ride on cars. In this case the stall curent is around 90Amps

The critical factor on this motor, and the similar ones are rated for operation at a maximum of 9V - they are designed for operation off a 7.2V pack.

Tim the Wombat

[HUNTER]

Oh dear  thanks for the doom and gloom ,i wonder what next year will bring .Don't worry about the diversion ,i'ts nice to wander .
right let's se if i can recall some sanity i have taken one of the motors out of gramesy for you all to look at they are marked as
www.huntersystems.co.uk
RS540SF
fan cooled 27x1
order code HS3
and if the pic comes up all the better as they don't look like the ones posted by Mayhem (well not from this angle)
AM I DOOMED?? ???

Hi Guys
Just to let you all know that the motor in question is not the dreaded 550 that alot of people have had problems with. It is, as the label says RS540-SF and comes from the Mabuchi stable via the States as it is not imported in this country apart from by us. It is a fan cooled 27 turn motor that due to its physical built-in fan runs cooler than most motors. The idea is that the cooler a motor runs the more inefficient it is - this relates to less power loss and higher revs. (you get more running time for your bucks).
It has a wider voltage range too 4.8 to 12 volts. And yes, it is available at the above on-line shop.
Hope this clears up the questions

[roycv]

Hi all, good information from Shipmate60
 Many years ago I made a tachometer to measure rpm of model boat props.
It came in useful when trying to get the power right on a steam driven "Streamlinia" 40 inch launch.  It was using a 50mm brass prop.  It needed  1800 rpm to just about plane.  The steam plant could not maintain this power, which was about 30lbs cont.
So I converted to electric, I had a Duplexcraft 9 volt motor (550 size)  with a gear reduction of about 2.3 : 1 and 12 volts applied.  Running quite cool at the high end of its' rev range, not possible with a direct drive to this size prop.
Current (measured) was 2.8 amps so giving just under 30 watts of power and she planes very nicely with rpm of 2000, and used to run for about 25 mins. from a 12 volt 3Ah SLA battery.
I could have used a smaller propeller but the gear box looks a lot like a steam turbine and now has a "plastic" boiler to hide the battery and maintain the fiction of steam.

I have one of the dreaded motors mentioned above (a gift), I have never used it as it is only useful at about 3 volts which means that you would need to use a mechanical controller, but that, if matched electrically would work.

Some years ago Model Boats published an article on the 540 family of motors.  If you can get the 4 numbers that follow, i.e. 540 / 5 / xxxx (5 pole motor) I think the first pair of x's are the armature wire dia. and the 2nd. pair the number of turns on the armature.
For model boats look for lots of turns on the armature like 30+.
The low number of turn motors give high acceleration characteristics useful to  model cars.

The "higher voltage less current and more efficient"  remarks earlier are applicable to say the Graupner or Marx range of motors where there is a similar power design motor available at different voltages.  Then it is mainly the lower losses across the brushes at the higher voltage that make them a few % more efficient.

The reference to the Farnell motors shows precision motors intended in the main to be used as servo motors.  All good motors, but unless you buy in bulk too expensive.
I would suggest that model boats do not need precision motors to drive a propeller in a pond.  But if you can get them cheap then great.

Our friends at Model motors Direct and Electronize have looked through the 1000's of different specs of motors, and suggest specific motors for various tasks.
I take their advice! It is simpler in the long run.

Hope I have not gone on too long, regards to all, Roy

[portside II]

thankyou Hunter
i shal keep the motors in Greamsey as they are running ok and just getting warm and not hot like some of the other motors available at least thats all cleared up .
cant fault them and the electronize 15a esc runs them together
daz

[tobyker]

It takes a worried man.....

I was sold a pair of the "rogue" Johnson 550s pictured by Martin as speed 600s to power a perkasa on 6v, and advised they would give a moderate planing performance as opposed to 700s which would cost a lot more, but would give superb performance. Do I fit them anyway and restrict them to 6 or at most 7.2 V, or am I wasting my time? Are they intrinsically bad motors, or can they just not take more than 6V?

 

[FullLeatherJacket]

Tobyker
There's nothing intrinsically bad  about the Johnson motors. As someone pointed out earlier, they are supplied with the Club 500 racers. It's just that they are not suitable for, say, a scale ferry or trawler - especially on 12 volts. Planing boats are a different matter. As you've bought them then why not give them a shot, but keep the pack size down to 6 cells? Water-cooling might be a good idea as well, although not perhaps vital.
Maybe you'd let us know how you get on?
Good luck.
FLJ

[tobyker]

Thanks, FLJ - I'll press on and report back idc. I wonder if the problem is that some people are trying to get too much torque out of them in heavy scale boats?

[Shipmate60]

They run OK up to 7.2 volts and are fast, 9000 plus if my memory is correct, anything over 7.2 volts and they draw excessice currents.

Bob