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[Angus64]

Hi Boys. It's been a long time since I posted on this forum, But I have looked in on it a few times. Hope you are all well. I want to upgrade the motor in my boat from brushed to brusheless motor. But I have haven't had any experience with brushless motors & ESC, The boat is 1 Meter in length X 28 Cm beam X 130 mm draft. I have a graupner 720 BB in there at the moment but it is under powered & keeps cutting out under load & I have to wait for it to cool before it will go again. So I will upgrade the motor & ESC. Can anyone out there tell me what I need as a motor & ESC I would rather it was over powered than under powered. I have included A picture of the boat so you can see what I want to power up.
Angus64. 

[thething84]

don't know about the motor, but she is a lovely looking vessel you have there.

[radiojoe]

Hi Angus,  I've got a 900 brushed motor geared 6 to 1 in my tug which is 44" long giving ample power, rarely use more than half throttle, you don't say whether yours is geared or not but if a 700 is stalling my guess is it's not.
Very nice boat you have there. 

[TugCowboy]

I'd probably look at going for something like this:

http://hobbyking.co.uk/hobbyking/store/__18177__Turnigy_Aerodrive_SK3_5065_320kv_Brushless_Outrunner_Motor.html

and

http://hobbyking.co.uk/hobbyking/store/__74073__Turnigy_Marine_120A_BEC_Waterproof_Speed_Controller_with_Water_Cooling.html

I have that setup in some big tugs and it works very well indeed.

[inertia]

I'd probably look at going for something like this:

http://hobbyking.co.uk/hobbyking/store/__18177__Turnigy_Aerodrive_SK3_5065_320kv_Brushless_Outrunner_Motor.html

and

http://hobbyking.co.uk/hobbyking/store/__74073__Turnigy_Marine_120A_BEC_Waterproof_Speed_Controller_with_Water_Cooling.html

I have that setup in some big tugs and it works very well indeed.

T-C
I don't imagine you're running it on 37v (10S LiPo) though. What battery voltage and type are you using?
Angus
Unusual for a 720BB Torque to behave like that. What voltage are you using (and what make of ESC)?
DM

[Angus64]

Hi radiojoe. The 720BB is direct drive & won't run very long without cutting out, I'm using 12 V. 12 amp hour lead acid sealed battery with a 50 amp ESC driving a 55mm raboesch D type propeller  which is probably a bit over the top for that motor. Could you tell me where you got your 900 geared motor & what ESC you are using. Thanks
Angus.

[TugCowboy]

DM,

Sorry I did mean to include by battery setup in there!
I'm currently using one battery per motor (just because I have the space and it helps with weight distribution) and I have a choice of batteries depending on what I'm doing.

For "Scale" stuff I use a couple of  7.4V 5200mAh 30C "Floureon" Lipo which gives great performance at Scale Tug speeds and  I have no idea how long they last because I've never run them out.

For more adventurous towing competitions etc I have some 11.1v 2200mAh 25C sets which work very well and I find give about 45 minutes continuous running time under a hard load.

All in all I think it cost me about Ģ65 last year for the 4 batteries and a balance charger for them - good value if you ask me.

[inertia]

with a 50 amp ESC

It wouldn't be a blue anodised one like this (which also has 20A reverse) would it? As you say, a 55mm prop is a bit OTT even for a 720BB Torque. If my suspicions about the type of ESC are correct then a speed controller transplant and a 45mm prop should fix the problem.
T-C
Many thanks - it's all useful stuff for the brushless database!
DM

[radiojoe]

Hi radiojoe. The 720BB is direct drive & won't run very long without cutting out, I'm using 12 V. 12 amp hour lead acid sealed battery with a 50 amp ESC driving a 55mm raboesch D type propeller  which is probably a bit over the top for that motor. Could you tell me where you got your 900 geared motor & what ESC you are using. Thanks
Angus.

Hi Angus,  mine is a MFA 919D 6:1 geared motor run on 12volt 7amph  40 amp ESC turning a 70mm four blade prop, it runs for hours and only gets barely warm,  if I give her full throttle the speed is OTT but when towing there is ample power, the MFA motors are available from www.cornwallmodelboats.co.uk in various ratios but 6:1 is recommended for large heavy boats. 

[Time Bandit]

My honest opinion.
Keep the motor (itīs perfect for that boat) and get a proper ESC.

The motor itself is not cutting out, in fact he should be pretty bored by a 55mm prop. The thing that gets hot (why ever) ist the ESC.
I ran it on 12V with a 65 mm prop in a boat probabaly the same size as this and it stayed completely cool.
If it gets hot, the motor might be broken somewhere inside.

Brushless is not sooo good in boats like that.
No low rpm possible, starting noise.... In a fast boat no question, but for displacing hulls I still prefer brushed motors.
I really love those ESC here, not too cheap but completely noiseless and I NEVER killed one 
The BEC might be a little small for strong digital servos.
http://www.modellbau-regler.de/shop/index.php?cPath=1&MODsid=fhjnnlvrrp0691cu3hhs1nldv3
15A should be enough and they post to UK.

[Angus64]

Hi Boys.Thanks for all the information.The ESC looks exactly like the one you have put up there 50amp forward 20amp reverse. i think I will try another ESC before I do anything else. if that doesn't fix it,I will fit another geared motor like radiojoe is using. Thank you.
angus.

[Angus64]

Hi. I meant to ask if anyone out there could suggest a ESC that would be suitable to use with the Graupner 720bb motor. I have A couple in a box, But would like to get some advise on this before I go ahead. Thank you.
Angus.

[TugCowboy]

Brushless is not sooo good in boats like that.
No low rpm possible, starting noise.... In a fast boat no question, but for displacing hulls I still prefer brushed motors.

I know it's not the way it's going but I'd just like to say that the above is incorrect.

Low RPM with VERY high torque is exactly what Brushless motors are good at. You just need to get the right one.
The 320KV motor I linked to gives 2,400 RPM running on the 7.4v LiPo's.
Almost exactly the same performance as the old Robbe 1000 Power series brushed motors favoured by many in the huge models but in a much smaller package and with a longer run time.

Just didn't want people reading this thread in future to think brushless is a bad option.

[inertia]

The 'Blue Meanie' ESC has a reputation for not being able to carry the rated current; we've had several blow at no more than 15A. Electronize FR15, ACTion P93 or P98, MTroniks Viper 15A would all do the job. For a twin-motor model an ACTion P94 is a no-brainer. All can be obtained by mail order from UK manufacturers.
Dave M

[Martin (Admin)]

.... Electronize FR15, ACTion P93 or P98, MTroniks Viper 15A would all do the job. .....

You all right Dave?!?       
  Have you been visited by Aliens or something????

[malcolmfrary]

I know it's not the way it's going but I'd just like to say that the above is incorrect.

Low RPM with VERY high torque is exactly what Brushless motors are good at. You just need to get the right one.
The 320KV motor I linked to gives 2,400 RPM running on the 7.4v LiPo's.
Almost exactly the same performance as the old Robbe 1000 Power series brushed motors favoured by many in the huge models but in a much smaller package and with a longer run time.

Just didn't want people reading this thread in future to think brushless is a bad option.

They do need the right ESC as well.  Early ones were developed by people who only understood "fast, and faster".  Times are changing and I believe that appropriate controllers are appearing.  I'm waiting for somebody to tell me which they are.

[inertia]

You all right Dave?!?       
  Have you been visited by Aliens or something????

I have to acknowledge the fact that some people swear by these things rather than at them, m'duck. I'm led to believe that they're also quite easy to obtain - even in Tasmania. That doesn't mean that I'd use one myself - but I don't have to, do I? 
DM

[boaterjim]

Hello all, sorry if you think I am barging in.
 I have used both brushed and brushless motors and ESC and they all have their own uses, but in a large tug or scale model were you need the torque grunt I have been using the 12 volt car fan cooling motor and using the fan speed control switch (usually 3 to 5 fan speed positions) this setup will easily drive a 100mm 4 blade prop at sensible revs but do use a fuse in the wiring.
Mounting the motor and prop shaft coupling may take some thought. I usually stick mine in the hull with filler, put the motor in a plastic bag, embed a large hose clamp in the filler, when its gone off, remove motor from the bag and refit using clamp.
It is all very cheap, as your local scrap yard will yield all the bits at a fraction of the price of new items. maybe even a 12 volt battery. works for me.
Jim