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[tight-lines]

hi,ive been looking at getting two motors for my boat did have my heart set on some electronize ones ,but saw these at 10 pounds less,,they state they will draw 2 amps on 12v,,,will 2 motors have enuff power to push a 8 kilo catamaran boat in the water,,,or will they get hot,or pull more amps bcos of this weight, it should be easyer to pust than a tug,and wont be requierd to pull or push anything apart from its own weight,,,,,i dont think there 5 pole also,so could this play a part in deciding?,,,as always thanks for your help

[tight-lines]

anybody?,,,,could do with some idea on these please

[J.beazley]

Not sure if this will help but i have 4 of these motors in my 8' 4" battleship hull which should push her along very nicely, well over her scale speed.
Also depends what size prop your planning to use??

Jay

[tight-lines]

hi thanks,,,i plan on using 40ml  3 blade scale props,,,,conected to a 9" propshaft,,,should this be ok?,,,also what size props do you use,,,,and have you any ideas about the weight of your boat,,,thanks for helping

[Shipmate60]

Here is the performance data for these motors:

Specification
Nominal voltage 12 V
Operating voltage range 6 ... 12 V
No-load rpm 12000 min–1
No-load current drain 0,4 A
Current drain at max. efficiency 2 A
Current drain when stalled 10 A
Max. efficiency without gearbox 67 %
Length of case, excl. shaft 50 mm
Diameter 35,8 mm
Free shaft length 8,5 mm
Shaft diameter 3,17 mm
Weight 158 g

Bob

[stallspeed]

hi thanks,,,i plan on using 40ml  3 blade scale props,,,,conected to a 9" propshaft,,,should this be ok?,,,also what size props do you use,,,,and have you any ideas about the weight of your boat,,,thanks for helping

Jbeazley's props are probably smaller and bang on the money for the 500 E.
The motors will give you 30 watts at 12 volts so you have enough power if you match with the right prop.
 
Filling in the missing pieces in the published data.....
Peak power would be at 5,800 rpm and current drain would be 5.2 amp giving a power input of 62.5 w and power out .47 x 62.5 = 30 watts.
At the peak power point,which you don't want to exceed,500 E torque would only only be = power x 60/(2x Pi x rpm) or 50mNm.The stall torque comes out at ~ 100mNm or on a par with a typical model boat 600,540 or 545

I've done current rpm tests with various props and motors and any 40ml 3-blade scale props that I know of would be too big for the Graupner 500 E.
Either go for different props or a motor like this. On the listing against other motors you can make a comparison.

[tight-lines]

hi,thanks for the help,,,i realy strugled to understand this even thougth ive read it over ten times,,,,the one thing i have took from it thougth, is the fact that it will be pulling 5 amps,,,,,,,,,why do the company print 2 amps current when in use on it,,when it will pull 5 amps,thats missleading num nuts like me, bcos i will look at these figures,,and think my boat is only drawing 2 amps,,
5 amps is still small,,,but to much for what i want,,i need longer run times and about 7000 rpm,,,,

hey thanks for taking the time for helping,,,even if you have blown my head of with maths,,and left me at the drawing board again

[stallspeed]

If you are dead set on 40mm props then I gave you a link to a motor with about twice the torque of the 500E.If you go for smaller props then a bog standard £4 motor will do.

The 2 amp figure is at peak efficiency occuring at about 80% of the no load rpm.Maximum power is when rpm falls to just below 50% of the no load rpm......at which point the current is a touch over 50% the stall figure and efficiency is a touch under 50%.

It's all here in a flash demo that Shipmate60 posted a long while back.

[tight-lines]

hi,i have no problems with what size props to use,i can go smaller no problem,,,i just asumed to push 8 kilo,,that i would need bigish props,,,,,,
with this in mind could you show me some motors that would,push 8 kilo,,and get me to just over scale speed,,,or not to slow,as i can only guess what a scale speed is,

at this stage im most botherd about run times,,,and its ability to move effectively and with fair momentum,,,
as this boat has two motors,,,maybe you need to consider this,,,i dont know,,
as always thanks for your help,,,,!

[stallspeed]

As far as motors go,you could pick twenty of them,number them and throw a dart onto  a dartboard to make the choice.
The main requirement for each motor is that you run a prop that slows the motor down by at least 20% and to no slower than 50% of its free running speed.

[sheerline]

I concurr with Stallspeeds figures, you can't go direct drive with those props on a speed 500e. In fact, on tests, I have clocked in excess of his figures but his are sufficient to put you off the idea. If you want to use these motors, try a smaller 35mm 3 blade prop ,less load on the motors (2- 2 1/2A) but higher rpm giving excellent thrust. Two of these push our 25lb submarines along at a good walking pace when surfaced using the 35mm 3 blade props.

[J.beazley]

Tight-lines i will eventually be running 4 blade 45mm brass props on my battleship, the hull itself dry (empty hull no shafts, motors etc) is over the 8kilos your wanting to push along.

I would give them a go, for ballasting my hull and test running i will be using 3blade 35mm plastic props as noone makes LH and RH 45mm 4blades

Jay

[DickyD]

Tight-lines i will eventually be running 4 blade 45mm brass props on my battleship, the hull itself dry (empty hull no shafts, motors etc) is over the 8kilos your wanting to push along.

I would give them a go, for ballasting my hull and test running i will be using 3blade 35mm plastic props as noone makes LH and RH 45mm 4blades

Jay

Deans Marine do the 4 blade in brass Jay.

http://www.deansmarine.co.uk/html/4_blades.html

[tight-lines]

hi,i think im starting to understand what you mean,,,,on that post where you did the maths for me,,the reason i was pulling 5+ amps a motor,was bcos you worked them figures out using the 40ml props,,am i right?,,,,,,
if so i will now be using 30ml 3blade plastic scale prop blades,,,,and in doing so,i should be able to get good runtimes of most motors?,,,

eg,,,,graupner 500e,,,,,running on a 30ml 3 blade scale prop= less amps

and as such should still be able to push a stream lined twin hull boat,,,

please keep helping guys as im getting my head around it a bit now,,i think!,,,,,

i will use any motor with any prop,,,providing the boat isnt to very slow,,and drawing as little as possible,of the amps,,

[stallspeed]

No,the stall  torque figure for a motor that helps you pick a suitable prop and I so just did some calculation to get it.It came out at 100mNm which is the same figure as the most common 540 and 545 motors.
For a 500e you would pick a prop or geared prop that exerts a load torque of between 25 and 50mNm.I know from past tests that a 40ml 3 bladed is out the ball park.

[tight-lines]

ok thanks,,,,,i think its official ,,i have no clue about what motor to choose,,,you seem to understand it better than i ever could,,,
so,one thing i do think i know is,that the 500e motor will not power my boat effectively,,,at less than 2 amps,per motor,,,

my head is in a fuzzy state,of numbers and questions,,

i think it best to get a motor and prop you guys recomend,,,,,
twin hull,8 kilo weight,,,not to slow,,
so if you have any ideas,,please ,,,let me know

[DickyD]

Hi Mr Tightlines

I see you have had the normal, straight out of the Techno nerds handbook,lecture from some(body).
***moderated personal comments about other member(s)***"

Might I suggest that if you want information that you can understand you contact someone like Bluebird who not only knows what he is talking about, will explain it to you in laymans English.

He has done numerous builds on here and his work is exceptional.
At present he is building an all singing and dancing Type 42 Destroyer that has 2 Speed 500 motors on direct drive with 30mm 5 bladed props which are the equivalent of 40mm 3 bladed props.
http://www.modelboatmayhem.co.uk/forum/index.php?topic=15073.msg148126#msg148126

Hope this is of some help.

It is always best to get advice from people that do, rather than people that just talk endlessly about it.

[John W E]

Hi there

I thought I had woken up back in the 1960s at college - when I read some of the calculations - horrible things .... designed to confuse a sane man.   However, tight lines!  If Stallspeed's calculations are correct, then there is something desparately wrong with my Type 45 - it has 2 Graupner speed 500s in - driving 5-blade x 30mm brass props and the blade area will be equivalent to a 40mm x 3 blade prop - and it is only pulling 7 amps per motor on bath tests.

What Stallspeed has forgotten to mention is not really the diameter of the propeller, it is the blade area and pitch of the blade - in other words the angle the blade is set which creates the workload on the motor.

aye
john e
bluebird

[tight-lines]

thanks guys,,,blue bird i dont supose you could hazard a wild guess at a motor set up that would run well,pushing a 8 kilo catamaran?
would like it just above scale speed,,,,
this is what i was thinking,,,

2x    12v graupner speed 500 eco,,,,both matched upto,,,,a 3 blade 30 ml prop,,,,,

or

2x electronize 545-12,,,,,,,both matched up to a 30ml or a 35ml 3 blade prop,,,,,which im pretty sure will give me a good low amp draw,,,but maybe be to slow???,,,

as always thanks to any one that can help,,,please give it to me with out any maths,,as my head realy does hurt

[John W E]

hi there tight-lines

A couple of questions first;

I take it that it is a fishing-bait boat that you are refurbishing/updating?  If this is the case, I think it would be best to sit back and think about what the bait boat is going to do and also, how it is going to be used;

The way I would think about this is:-

a)    It is going to be only used for very short periods of time; in other words filled with bait; and sent out to the fishing ground maybe 100 yards offshore, discharge its bait and then returned;   total running time 10 minutes (if that).   So, how many times will it be used during a fishing trip - say 3-4 times

b)    How fast does it need to go?   When you speak of scale speed, what is the scale speed of a bait boat?    To me, its has to have to enough speed and power at its disposal to overcome wind - so this speed is controlled by a throttle stick; and how fast it goes it is really up to you.

c)    It must be capable of pushing 8 kilos - and for this I would suggest you may have a look at the topic on this forum - where scale model tugs are towing their operators around in rowing boats. Some of these tugs will be powered by 540-550 + some 800 style motors, driving roughly about a 50-60 mm prop.

Can you see where I am coming from    The Graupner 500s speed motors driving 40 mm x 3 blade props should be ample for what your needs are 

The other thing I would suggest is - and this comes from my personal experience with Graupner motors - is - if you havent bought them; have a quick telephone conversation with FLJ (Dave, from ACTion as when I was helping Dave at the show, Dave did have a box full of motors - I didn't have time to have a good look - but I am sure Dave had some 540 low-drain motors there - they looked a lot better than Graupner.    Sometimes I find Graupner motors a bit on the noisy side, compared to others.

Hope this helps.

Aye
john e
bluebird

[tight-lines]

that did help thank you,,some times the boat will be used alot more times than that,and some times as much as you said,,,
but you are right in what your saying,,,,

i think im just gona get the electronize,,545-12's
,,i think they will have the tourk,,and low amp draw i need,,,maybe a bit slow,,,but i cant have every thing,,,,
and to top it off ,ive just blown a brand new 11.1v 4000mah lipo battery,,,,,touching the power and earth wires to gether by accident while putting on the conectors ,,,,thats 25 down the pan,,

i can see when stripping open the pack it has blown the solder off,,i could just resolder it,,,but it might be like a time bomb now,,
and i dont want it sinking my ,,new boat!

[tight-lines]

Hi there

I thought I had woken up back in the 1960s at college - when I read some of the calculations - horrible things .... designed to confuse a sane man.   However, tight lines!  If Stallspeed's calculations are correct, then there is something desparately wrong with my Type 45 - it has 2 Graupner speed 500s in - driving 5-blade x 30mm brass props and the blade area will be equivalent to a 40mm x 3 blade prop - and it is only pulling 7 amps per motor on bath tests.

What Stallspeed has forgotten to mention is not really the diameter of the propeller, it is the blade area and pitch of the blade - in other words the angle the blade is set which creates the workload on the motor.

aye
john e
bluebird

hi blue bird,,,i might be wrong,but the motors in your picture look to be,the graupner speed 500,which i think are marked at 7.2v nominal,,,,
having looked at cornwall models website it says that yours have a higher amp rating than the 500E,,,,and as such if you are pulling 7 amps a motor in a bath,,,than it still might be possible for me to pull around the 2 amp mark using the 500E with small scale props on the fishing boat,open water,,
please let me know if these are the motors that your using and if you think it would be a smaller amp draw on the 500E using say a 3 blade 30ml prop,,,this is going to be my last question as i get paid tomorow and will be ordering these or the electronize 545-12,,,many thanks

[John W E]

Tight-lines Hi there

my honest opinion about Electronize motors - is that they are rather 'overpriced' for what they actually are'.

You will possibly find that Mr Full Leather Jacket - aka - ACTion - Dave sells a very much similar motor to the Electronize one.   I am unsure, but it may be half the price you would pay from Electronize.....

Also, a quick email or telephone call to Dave during working hours (telephone: 0115 9607951) will answer all your queries professionally without any Tech Blurb   .    The reason I would advise this is you will find people such as Electronize, MTroniks, Graupner, Deans all use a set supplier for their motors - and you may possibly find that the majority of motors come from either the manufacturer Johnston or Mitsibushi and there is another one/

So...when you purchase something like Electronize motor - just cos its got Electronize sticker etc., on it .... you are paying for the name sometimes.

aye
John E
Bluebird

[tight-lines]

thanks,,,im gona be ordering one of his mixer units any day now so when i ring him ill ask his advice,,

[tight-lines]

right ive gone for the speed 500e,,,,im gona be using 30ml 3 blade props,,,,,,,,also im gona try some 32ml 2 blade 52 pitch,,,,,full on racing props,,,just to see what the crack is ,with amp draws,,,im gona set it all up,,,and run it down the canal with me walking by the side of it reading the amp draws of the different props and the weight(load in the weight of bait its carrying)and(load in the weight of batterys its carrying) and a mix of all the above,and props,,,,,,,,and take a few pictures,,,,,,,then im gona post it on here for anyone to see,,,i know most of the members dont use bait boats,,but should be of some use to some one,,,and if nothing,,,just to see what a idiot can get upto messing with stuff ,,,,,,

if i can get these motors to run at around 2 amps give or take a tiny bit,,,,,,ill be a very very happy man ,,,

if not ill be realy miffed, ,
just got to finish building it now,,,,should be about two weeks,,still got stuff to order