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[phillnjack3]

How can I tell is a Decaperm is 6 or 12 volt ?
ive had this motor kicking around for like 30 odd years.
its in good condition and not sure if its 6 volt or 12 volt

also what sort of prop would it be capable of pushing in something like a 39 inch patrol boat.

[unbuiltnautilus]

No way to tell really. You could try it on 6v, if it sounds gutless try it on 12v. If at 12v it sounds like it is screwing its nuts off, then it is probably 6v. Not scientific but there it is!
Prop size via the gearbox 50 to 55mm easily, through the direct drive output, about 40mm. On a 39" patrol boat it will be a good 1970s/80s plodder. Better in a tug or fishing boat.

[derekwarner]

40 something years ago, a group of Electro-Tech type people at Australias Home Naval Base concluded they were the same


Whilst marketed as either 6 or 12 volts varients, the specifications were I believe relative to the input voltage


6V = X RPM unloaded @ Y amps
12V = 2*X RPM unloaded @ 2*Y amps


Hence the conclusion they were the same motor 


[mind you these people were employed to practice their craft on 400V green steam  ]


Derek

[phillnjack3]

Mmm interesting thought on the 6v 12 v  thing
I have seen some of these with 6 volt stickers and some with 12 v .. they do seem to look the same.
but I have also seen one earlier that had 3 bolts holding the case on at the gearbox end/ might be someone just added a bolt ?

I will try this on the 6 and 12 like you say. infact ill do that right now and see what it pulls amps wise with no load.

[phillnjack3]

Well I just tried it on a battery charger with both 6 volt and 12 volt. I have high and low power on the charger
and it didn't make a diference what I put it on I could not see any draw for amps.
on that it starts the amp ready at 1 to 1 1/2 amps.. so either way it seems very low draw at either voltage.

now I know this is not exactly scientific. I think I will chuck it in the boat and run with a 7.2 volt pack for a while with
a x 40 prop on and see if it gets warm and what sort time it takes to kill a 7.2 volt battery.

I might have enough cells to jump it up to 12 volt in the box of bits.  I definitely have 2 packs of 7 .2 but that might just be too much
and get the motor hot.

I dont think these got too warm if I remember right ?
been about 35 years since I actually had it fitted in a boat.
I dont have anything to check the rpm..

[derekwarner]

As an alternate, try & find an old Marx electric motor catalogue, .....


https://www.google.com/url?sa=i&url=http%3A%2F%2Fwww.jotika-ltd.com%2FPages%2F1024768%2FFittings%2FM68040.htm&psig=AOvVaw3RMD0de2fu2FVO1Zhxgp6f&ust=1621295767554000&source=images&cd=vfe&ved=2ahUKEwiO0dbDs8_wAhWQBisKHZzWB_4Qr4kDegUIARCtBA


If your battery charger is for a wet cell battery, the actual voltage could be ~~7.? V and ~~13.V


Derek

[phillnjack3]

thanks for that.

 could help once I get a battery connected to it.. to see the amps with a prop on in water (bath)

[malcolmfrary]

Well I just tried it on a battery charger with both 6 volt and 12 volt. I have high and low power on the charger
and it didn't make a diference what I put it on I could not see any draw for amps.
on that it starts the amp ready at 1 to 1 1/2 amps.. so either way it seems very low draw at either voltage.

now I know this is not exactly scientific. I think I will chuck it in the boat and run with a 7.2 volt pack for a while with
a x 40 prop on and see if it gets warm and what sort time it takes to kill a 7.2 volt battery.

I might have enough cells to jump it up to 12 volt in the box of bits.  I definitely have 2 packs of 7 .2 but that might just be too much
and get the motor hot.

I dont think these got too warm if I remember right ?
been about 35 years since I actually had it fitted in a boat.
I dont have anything to check the rpm..

Supplying it from a charger might have restricted its speed and performance, thus making it perform the same on both stated voltages.  Unloaded, there might reasonably be little difference in the current drawn.  Good batteries is the way to go. 
Not having a machine to check the rpm is not the end of checking.  As unbuiltnatilus said earlier, you can listen to the noises it makes.  Agonised screaming at 12 volts indicates a 6 volt motor, being unable to pull the skin off a rice pudding on 6 volts indicates a 12 volt one.

[Subculture]

These charts might be of some help?

[phillnjack3]

Thanks for the charts SUBCULTURE..  Fantastic information right there, couldn't get much better than that..
now I will go ahead and fit it and try it out.
Hopefully I can get around 6,000 rpm under load with around 2 inch pitch prop on 12 volt. this could give me around 8 to 10 mph
after adding in slip percentages etc, that would do the job perfect.. if it goes faster then even better. but my goal is 8 to 10 mph in extreme conditions.
 could always add a couple of little wing motors in just for towing back power.. ..

[Subculture]

6-7mph tops I would think. Much better off with brushless if you want a bit of speed, and you could get a very nice rig and pocket a good few quid if you flogged that Marx motor- a lot of modellers collect them. Don't know why, they were considered the dogs doo-daas back in the day, and boy were they expensive but totally outclassed by what you can get now IMO.

[phillnjack3]

i cannot see what is so good about them myself neither.
ill give it a go, but will probably sell it for sure if i can get a brushless to do the job better.


i would 100% swap it for a brushless motor and battery, but not got a clue what size of brushless i would need ..
the absolute ideal speed for the boat would be this, but ill settle for a little bit slower.
Ken Dyer's Fairey Swordsman cabin cruiser - YouTube


i dont expect racing speeds. ive got the big glow motors for that..
i would like about fifteen minute run time or more if possible.

[DHutch]

I have just bought a 36" model tug with a Decaperm installed, no ESC or other equipment.


And I am consider either using it, or replacing it with a Brushless motor and ESC.


Is there a market for these motors? Are they worth anything?




Thanks

[HMS Invisible]

If you are satisfied with 300 rpm as minimum then go brushless.
If you want to watch the blades tick round slowly stick with what you have.

A 555 motor will do the same electromechanical job as a 12 volt decaperm's geared shaft so I don't understand why anyone would buy second hand other than for mounting and shaft alignment.

[roycv]

The Marx motors last forever! The Marx with the gearbox can sound very loud, but otherwise still a good buy.  I agree the 555 is good and I use a few of them.

Brushless motors that I have used do not perform well at low speeds, but that could be me. 
I have a small cargo boat with a 555 in direct drive and can watch the prop turning, all under control.  So for me, for low power I use Monoperm and Monoperm supers as I have a few of them still.

Another consideration for low power is to use a 20 - 24 volt motor on 7.2 volts, this will turn a big prop as well.  Often this voltage motor is quite cheap.
Best not to use ex-drill motors though.
Roy
 

[HMS Invisible]

I'm going to selectively quote Subculture from 17 May 2021 because I think my second point to DanielH is going to get lost.
 I expect, as I think Subculture  might, the number of buyer's for a second hand decaperm does not match longstanding messageboard posts.

...Don't know why, they were considered the dogs doo-daas back in the day, and boy were they expensive but totally outclassed by what you can get now IMO.

A decaperm had sufficient torque to drive a scale prop by virtue of the reduction gearbox so you would get a good sale price for a second hand decaperm in years gone by.
This is 2024, so just over a decade ago, a six-figure quantity of 55 turn Mabuchi RS555-3255 was dumped on the surplus market at under $1 each. Importation of small retail consignments from the orient is more common too.
  By virtue of the 555 magnet strength or air gap (it's nowt to do with their 55 turns!) the 555 will do the same job as a noisy 12 volt decaperm's geared shaft.
 When I had cartons of 555 motors stacked to the ceiling I recommended to aquintance's they shouldn't get mugged into buying decaperms but I'd not encourage any to replace with a 555 to make a profit.
 I wouldn't recommend replacing with a 3-wire brushless (sensorless) either. Until rotation is above a minimum speed there isn't an emf for a sensorless brushless controller to detect rotor positon and sequence output to the motor for controlled speed. They need to be started in brute force mode.

[DHutch]

If you are satisfied with 300 rpm as minimum then go brushless.
If you want to watch the blades tick round slowly stick with what you have.

Yeah, it seems if you want slow speed running with brushless, you need a sensored setup which the rock crawler guys use, which is then like £200 starting price for a motor and esc. Interesting but not for today.


I am not planning to watch the blades go round and while might be interesting to have a go in a boating lake doing a bit of tugging with it, I think mainly it will get used when I am boat festivals to boat around on the canal/river, so I am not worried about achieving a correct 'scale speed' or anything, and while clearly its not a planning hull being able to run a reasonable turn of speed would be nice in the larger water. I don't know how the hull form will cope with running above hull speed?


Hull speed for a 3ft boat is around 2.7mph, 15 seconds to cover the length of a 60-70ft narrowboat.... Mmmm! We shall see.

[HMS Invisible]

If you only lack top speed then one of these at £22 and a fortnight's wait will cope with 4s Lipo if you have a 12v decaperm.
2s Lipo, requiring a different choice in esc would give more speed to a 6v decaperm.

[Circlip]

" But the Captain want's to go water skiing!"   


 Regards  Ian.

[DHutch]

A 555 motor will do the same electromechanical job as a 12 volt decaperm's geared shaft so I don't understand why anyone would buy second hand other than for mounting and shaft alignment.

I agree the 555 is good and I use a few of them.

Sounds like a 555 is the way to go, an 8## type has also been suggested when I have been talking about this elsewhere?

I don't really want to start the game off basing the boat around a vintage motor. It has no sentimental value for me, gearboxes appear to be the wrong way to go given modern motors and speed controllers, and it would be pain if it died on me too.

Because I wont be able to collect the model for a few weeks (annoyingly, just after rather than just before Easter) I have asked the seller to confirm what the current prop on it is. But from what I can see it appears to be a fairly large dir 4-5 blader fairly in keeping with what the real thing would have had. Pitch unknown.

[DHutch]

Spoke with the guy selling my the model TID tug I have just bought, it has a 60mm dia 4blade prop, pitch unknown. Currently paired to a 6v Decaperm.

[roycv]

Hi subculture, the very detailed motor spec chart.  Is it possible for me to have a copy or pdf I can print from?
Is it from a magazine?

I have many of the motors mentioned and would like to follow each motor spec across the sheet.
Hope you can help.
Kind regards
Roy

[Subculture]

There are two motor spec charts I posted, and they're both quite detailed, however I think you may be referring to the second image? This was from Vic Smeed's Model Maker Annual 1963.

[roycv]

Hi subculture I have not got that annual.  Any chance of a scan?
Roy

[Subculture]

Okay this is a scan which should print well, or you can extract the information and put it into a spreadsheet. Just right click and save to your computer.