Fitting out a tug

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22 September 2016 at 19:42 #67808
Martin Field 1
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@martinfield1
My son has my Sun tug that came from a steam deal. I'm not remotely interested in tugs, but the lad seems to like them. It's a Kingston Mouldings Sun XXI. What motor and ESC would he need for this. He won't be doing towing or anything fancy.

Thanks,

Martin
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22 September 2016 at 19:42 #5444
Martin Field 1
Participant
@martinfield1
23 September 2016 at 19:19 #67817
Paul T
Participant
@pault84577
Hi Martin

As the tug wont be doing anything strenuous you could use an MFA 800 plenty of grunt but easy on the amps.

The motor is rated at 5.3amps so any speed controller of minimum 10amps should do but before buying a speed controller you should do the max amp draw test.

http://www.mfacomodrills.com/motors/800.html

Paul

Edited By Paul T on 23/09/2016 19:20:57
23 September 2016 at 19:31 #67818
Martin Field 1
Participant
@martinfield1
Thanks, Paul,

I'll pass that on to him.

Cheers,

Martin
23 September 2016 at 19:41 #67821
Martin Field 1
Participant
@martinfield1
Seem a bit pricey. Would a geared 540 be OK on amps? We have a few of those kicking around (old minidrills, etc)

Cheers,

Martin
23 September 2016 at 19:54 #67824
Paul T
Participant
@pault84577
Possibly a bit pricey at £25 buts a fully ballasted 3ft tug takes some moving and the 800 is ideal,

Using a 540 would depend upon the gearing as the tug has a big propeller producing a lot of torque and the 540 might struggle…..and eat the amps.

Paul
23 September 2016 at 19:57 #67825
Martin Field 1
Participant
@martinfield1
Yes this tug has a 3" prop. It was the amps I was worried about as he doesn't want to be blowing a fortune on an ESC! Swings and roundabouts I suppose. Many thanks.

Martin
23 September 2016 at 19:58 #67827
Bob Abell 2
Participant
@bobabell2
Sorry Paul and Martin

Paul's figure of 5.3 amps and a 10 amp controller sounds way too low for a MFA 800 motor?

Going off memory, my VGC uses four MFA 850 motors and four 25amp speed controllers

I could be wrong, but can't find my thread at the moment

Bob
23 September 2016 at 19:59 #67828
Paul T
Participant
@pault84577
Martin

No problem, glad to be helpful

Bob

There is a world of difference between the 800 and 850.

The 800 spec is as follows.

Approx motor diameter 50mm by 70mm long.
Operating Voltage 12 volts.
Current approx. 5.28A at max efficiency.
RPM at 12.0v – 4289 at max efficiency.
Weight 595g (approx)
Shaft Diameter – 6.35mm

The 850 spec

Operating Voltage 12 volts.
Current approx. 10.82A at max efficiency.
RPM at 12.0v – 9778 at max efficiency.
Weight 595g (approx)
Shaft Diameter – 6.35mm (1/4&quot

Paul

Edited By Paul T on 23/09/2016 20:05:09
23 September 2016 at 19:59 #67829
Ian Gardner
Participant
@iangardner62867
I use a geared 540- the MFA 6:1 ratio- in a 3' boat that weighs 25lb. It's on 12v with a 2'' prop and she goes like a train.

**LINK**

Hope this helps.

Ian
23 September 2016 at 20:19 #67831
Martin Field 1
Participant
@martinfield1
Hey I do like that Dunlin, Ian. I have huge respect for Underhill and his drawings . His books helped me become a professional modelmaker and lover of small wooden sailing boat models. I made a Zulu using his plans for a client a few years ago. Through Brown and Ferguson the drawings are very expensive, but nice to have.

Thanks for the confirmation about the geared 540 too.

Bob, FOUR motors???

Cheers,

Martin
23 September 2016 at 20:44 #67832
Ian Gardner
Participant
@iangardner62867
Thanks Martin,

Yes Harold Underhill was a real master and I love his drawings too. Dunlin (my name) is a good few years old now and needs a bit of TLC- it occurs to me she hasn't had a wet bottom this year but still one of my favourites. The MFA geared motors go very well but are a bit noisy. I have just put some resin timing pulleys and rubber belt in my Veleta (2.5:1) but haven't tried it yet. It's very smooth and quiet on the bench though. They were from SHG- a very helpful company.

Ian
23 September 2016 at 20:48 #67833
Bob Abell 2
Participant
@bobabell2
Sorry to shock you, Martin……..Yes four motors!

Paul and I worked on a Gentleman`s Vintage Cruiser for nearly two years….2014 – 2015

Paul designed it and I built it

It was such a large bulky 60" model, we went a bit overboard with the motor drive!

Here she is………Stand well back

Magnificent?

We had great fun at last year`s Haydock Show!

We changed anybody 10p to see it run!………All for Charity of course

Bob
23 September 2016 at 23:27 #67837
Martin Field 1
Participant
@martinfield1
Good grief! I suppose in a 60" model 4 motors isn't too far overboard. I take it they're paired as driving twin shafts?

I have a promise of something special for twin screws in that my chum in America has a matched, handed pair of Krokers, built bespoke for chum's Dad by the man himself. Now for an old electric motor buff like me that's something to look forward to! I need only to decide on a suitable boat to put 'em in!

Cheers,

Martin
23 September 2016 at 23:29 #67838
Martin Field 1
Participant
@martinfield1
Ian, I'm not at all bothered by noise, like so many people seem to be. I love the growl of a Taycol and the urgent hum of a Multum (SEL). I imagine I would thrill to the sound of a geared drive.

Martin
24 September 2016 at 07:25 #67840
Bob Abell 2
Participant
@bobabell2
Martin…….I have to show my ignorance and ask you….

What are Krokers?

Bob
24 September 2016 at 07:59 #67843
Martin Field 1
Participant
@martinfield1
Bob,

Krokers are hand made electric motors of considerable performance made in the USA in the 70s. They were sold over here and used in racing boats at the time as they would take considerable over powering, but used as intended they are just beautifully made motors. To have a matched pair, left and right handed is a real gift!

Cheers,

Martin
24 September 2016 at 09:47 #67848
John W E
Participant
@johnwe
hi there

I helped a friend build his first model of the Sun XX1 tug from the MAP Plans way back when you could buy a pint of beer for less than 50pence – the motor fitted then was a 540 MFA – it was fitted to a 2:1 belt drive gear box which sadly seems to be no longer available from MFA – anyhoo – I know the model has gone through many a revamp and I believe now it is sitting with a 555 motor from Component Shop – rated at 12 volts – but I believe he runs it at about 7.2 driving a 3 blade 50 mm brass prop. Now if we go over to Mayhem – I built the MSC Archer which is a slightly smaller tug but it has a 4 blade 50 mm prop fitted. It is also fitted with the 555 motor running on 7.2 and it has an ACTion speed controller of the 10 amp (I think its the 10 amp one) and that goes along at a fair wack on full throttle enough for the bow wave to swamp the model – so plenty of power.

John

Edited By bluebird on 24/09/2016 09:53:24
24 September 2016 at 11:58 #67850
Martin Field 1
Participant
@martinfield1
John, many thanks for the advice and the nice pics.

I will pass all this on to my son.

Cheers,

Martin
29 September 2016 at 09:41 #67905
Martin Field 1
Participant
@martinfield1
Right,

I found 3 of what I call Buggy motors or minidrill motors, because mine will all have come from broken minidrills. Yes I do get through them, but I used to use a minidrill for a few hours every day when I was a professional maker of brass model car masters.

What we seem to have are two 555 Johnsons, (5 pole) and a similarly sized 3 pole with much heftier wind wire.

A selection of toothed belts and pulleys from broken down machines completes the pile of goodies.

The other query is that, the prop shaft is horizontal and therefore inevitably below water level, so how do you all keep the shafts of your tugs waterproof?

Cheers,

Martin
29 September 2016 at 16:38 #67909
John W E
Participant
@johnwe
Hi there Martin

These motors you have – the Johnsons 555 – do they have a fan in the rear of them inside the casing? If so, these are beasts to say the least – rather too thirsty on the amperage I would have thought. I have 2 of them mounted in my RAF Rescue Launch – and it planes across the water very nicely on 7.2 volts. Each motor is eaten away nicely at 15 amps driving a 35 mm x 3 blade prop. So please be a bit wary of using this type of motor in a model boat.

As for sealing the prop shaft, this is a long and well debated subject – but – it all boils down to the majority of us using either a grease of some description or a mixture of grease/oil. I would suggest that you do a web search and make your own decisions on the topic.

Good luck

John
29 September 2016 at 16:51 #67912
Martin Field 1
Participant
@martinfield1
Hi John,

so, the 555s could be heavy consumers? What about the similarly sized, but unmarked 3 pole? Any ideas?

The 555s don't have internal fans, but do have external fans fitted as you'd expect of a minidrill motor.

I figured the answer to prop shafts was a greaser of some kind. I'm sure I can make him something that'll work.

Thanks for your help.

Cheers,

Martin
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