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[787Eng]

Hello,
I have 2 of the Robbe Navy compact number 4105 with the standard motors and 3.3:1ratio. They are getting on now in age and would like to replace them with some better ones. Has anyone got recommendation's for some better motors that will fit.

The standard Motors are running on 6V and have Mtronic25's on each motor. What I would like to gain is more performance, and would perfer not to have to go to 12V for the upgrade.

Regards
Mark

[andrewh]

Mark

Can't answer your question directly - as I don't know what "better" means.  It could mean quieter, or lower current draw, or FASTER

The motors fitted are standard 600/540/550 size motors, and i know nothing about them, and havn't been able to discover their habits or wind details.

They LOOK like buggy motors, in which case running at 6V (presumably a lead-acid battery) will hardly have woken them up as they are wound for 7.2/8.4V.  Are you able to give them a try at 7.2V - nimh  buggy pack?

Possible replacements could come out of the Graupner speed range - any S500 or S600 will fit, but they vary enormously in speed and violence.
Basically any motor with a name starting in 5XX or 6XX will physically fit - even if you have to transfer the pinion to the new motor
Or you could go brushless (inrunner) with the knid of motor used by the racing car fraternity, but your battery won't like that!

Hope this helps,
andrew

[mike_victoriabc]

I have those in 3-4 boats - both in single and twin format. What do you expect to see happen?
Mine run only in a fresh water environment and never have swamped the hull. Always leave the hull open after running to air it out.
A lot of us here run them - be interested to hear.

[Shipmate60]

787Eng
What model are these motors in?
What size props is it running?

Bob

[787Eng]

Andrewh
Motors are about 15 years old and normally have around 1-2hrs of use a sailing and brushes are getting low now.
My statement about better is really meant as better quality of motor as they look (remember 15 year old) buggy motors these have no flux ring. Faster is what I'm after.

Boat is the Robbe Dusseldorf fire boat, with custom 30mm PropShop props.
running on 2x 6V, 12Ah battery's

[mike_victoriabc]

Ummm....interesting! The first kit I purchased was a Robbe fireboat kit - I too bought those units for it. My son was 10, now 32 and its still not finished! Wandered off building tugs, Springers, other tugs and still look at the fireboat and its half completed monitors!
As my motors and gearboxes on that one have never seen water - should be ok.
You probably need the racing guys to comment if speed is an issue.

[Shipmate60]

If you want faster go to a 2:1 gearbox or direct drive.
30mm props will be fine on direct drive.
You should be running the props at 2-3000 rpm so anything that will give about 5000 rpm will show a decent increase.

Bob

[andrewh]

Changing everything would certainly work, but so would changing the motors to something younger which spin faster on the same voltage.

We don't exactly know the specification of the motors, but they are clearly "mature".  The words suggest they are wound for 6 to 12V operation, so this is a fairly "soft" wind, almost certainly 20 to 25T.  As I said before they will be pretty dull on 6V.

I'm not sure, Mark, if you are able to try them on a nicad pack of 6 or 7 cells (7.2 or 8.4 Volts), but this is what they are made for. 

If we knew their details we could suggest a replacement that was "Hotter" and would produce more revs at 6V (ie a higher KV)
I have had a look through the Graupner range - and the ones that seem to be promising are:

S600 - any 7.2V version  (NOT the eco)
S500-  any 7.2 version

or go into a shop which does buggy racing and have a look at replacement buggy motors - look for the cheapest with outside brushes and a "Moderate wind" - about 16 to 20T.  These will still spin fast on 6V
http://www.modelsport.co.uk/?CallFunction=Category&CategoryID=99202515
 is a typical selection
remember you are looking for an "05" size, or a 540, or 550 or 600 (all the same)  - take a motor in to be sure

It may well be that just replacing the motors with ANY new motor will revitalise the drives - while you are doing the replacement don't forget to take it all apart and lubricate everything well for the next couple of decades

Sorry I can't be very specific, or offer any very guaranteed solutions
If you upgrade the motors enormously, the current draw will increase - perhaps out of the range of comfort of the lead batteruies you are using - they are not great friends with Mr. Amp

Or you could go to a pair of brushless, and your fireboat would then not need the monitors - the roostertail would extinguish anything!

Happy to help if I can
andrew

[Shipmate60]

The original Robbe Navy Kompakt were 550 motors on a 2 or 3:1 reduction g/box.

Bob

[DickyD]

Have you checked out Deans Marine motors.

If you click on the picture of the motor it will give you the spec and what type of boat they are recommended for.

I have several of their motors and they are excellent.

http://deansmarine.co.uk/shop/index.php/cPath/5_13

[andrewh]

I have 550s from 2.4V (3 turns of fencewire) to 125V (1000 turns of hair).  one of them would work

[787Eng]

Thanks all,
Great suggestions, and its nice to see a forum that provides constructive information and posts.

Just replaced the aged single Robbe 330 speed controller that finally passed away with 2 Mtronic 25's, so motors are next.
One intresting thing is that the existing motors now run cool with the Mtronics..

Mike,
Get her built, great fun at shows with the kid's...they just love the working monitors.

Thanks again
Mark

[Martin (Admin)]

We expect photos as payment Mark! 

[787Eng]

When I fit them, A full report will be provided

Mark