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11 July 2010 at 12:32 #27606
StuartM
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@stuartm
As a new comer Imust first say Hi to everyone. My main hobby is 16mm / 32 gauge railways. Iam at the moment constructing a radio controled shunter. Whats this got to do with boats?

Well as I am one of lifes perpetual fidlers and having just bought myself a basic 2 channel RC combo it occured to me that I could also suitabley equip a boat which I could take away with me in my caravan.

A few years back I purchased for £4 what I believe is a Fairmile mtb hull from a market stall. Its 35 ” long and about 6.5 at its widest point, 4″ deep. The scallops have been filled in. The moulding has had a rough life and looks it. It is however recoverable.

I fancy building it into a representation of an Edwardian Electric Launch. The object of the execise is to get something on the water rather than a scale replica of anything. I don’t want anything High speed just a sedate gentlemanly speed.

What would be the best size motor to drive the hull. Also what size prop.

My feeling is a large diameter prop at slow revs but I don’t really know where to start. Any advice would be good.

Thanks
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11 July 2010 at 12:32 #1985
StuartM
Participant
@stuartm
Motor / prop
11 July 2010 at 16:29 #27608
Ian Gardner
Participant
@iangardner62867
Hi Stuart,

I am also a 16mm railway enthusiast as well as a model boater. The main trouble is keeping it all going!

My feeling is that if you wish to use a large prop then it might be best to find a geared motor. The launch in the picture has a Graupner Speed 500 with a 2” prop which is too big- the motor gets a bit hot and she’s a bit sluggish- a smaller prop will go on eventually. The two inch prop is a legacy from when the boat was steam driven- as you will know steam engines are sloggers – a large prop works whereas electric motors need to be kept spinning or they draw too much current.

MFA do some 500 size motors with various reduction gearboxes but they are quite powerful and a bit noisy. I have a 25lb boat with one in with a 2.5:1 reduction on a 2” prop and it fairly flies.

May I welcome you to the forum and let us know how it all goes.

This boat is 36” by 9” and weighs about 9lb if it’s any help.
11 July 2010 at 18:10 #27614
StuartM
Participant
@stuartm
Ian,

Thanks for the help, I’ve trawled through the topics all of which were enlightening. I really want a slow boat, quite, with no wash.

Taking note of your launch set up I will try a 380 size motor with a 35 – 40 mm prop. If it needs gearing down from that I ‘ll fit a gearbox. I’ll leave room on the propeller clearence to go to a 2″ prop as its the intention to put a steam plant in.

Thats when I’ve finished the verticle boilered loco that is presentley on the bench awaiting the completion of the track buidling in the garden. As you can see I spread myself a bit thin on the modelling front.

I’ve made a start on the hull renovation and am now contemplating chopping the stern around and re glassing it into a counter stern.

Thanks for help again its given me a starting point.

StuartM

Edited By StuartM on 11/07/2010 18:12:38
11 July 2010 at 20:07 #27616
ashley needham
Participant
@ashleyneedham69188
Stuart. A 35-40mm prop is a bit big for a 380 motor.

If I was building something like you are contemplating, an MFA 540/1 (a low powered 540) from Maplins or somewhere and a 35mm prop on 6v might be my choice.

Unfortunately this subject is like the “how do i stop my propshaft leaking” and comes under the personal preference banner.

For a modest speed on that size hull, a speed 400 and 30mm prop, 540 and 35mm prop, geared 540 & 45mm prop, 800 motor and 50mm prop would all fit the bill….they would all “do”, but exhibit different characteristics. Small motor, =buzzy, 800 motor very torquey, geared unit possibly a bit noisy. Yer takes yer choice on this one.

Ashley
11 July 2010 at 22:26 #27620
StuartM
Participant
@stuartm
Hi Ashley,

Thanks for the advice, I’ve got 6 or so unidentifiable motors the smallest had the same dimensions as a 380. However i’ve got a local Maplins so i’ll pick up a 540/1 if it does’nt work out i’ll stick it in a loco.

At least i’ve got some idea where to start, i’ll let you know how it goes.

Thanks again

StuartM
14 July 2010 at 21:45 #27680
StuartM
Participant
@stuartm
I’ve just been rumaging through my spares box and found an RS 555sh motor. Do you any of you learned gentlemen know anything about the charectoristics of this motor. I’ve tried it on a 6v SLA battery and it runs slow and is difficult to stall/ stop. Thanks

StuartM
14 July 2010 at 23:02 #27682
ashley needham
Participant
@ashleyneedham69188
Yup.. If its like the 555`s model motors direct (or someone similar) they run up to 24V and as you say on 6v its a bit slooooooow.

They are very torqy tho, and I run 2 of these turning 5-bladed 40mm props on my T42 destroyer on 12v , just the job.

It may well turn a larger prop direct on 6v, i think you need to try a few props on it, in the water and see what current it draws. It may actually be what you are looking for…

Ashley
14 July 2010 at 23:41 #27689
StuartM
Participant
@stuartm
Hi Ashley, Thanks for the reply

I’ve just tested this motor on my manual tacho and it gives 200rpm at 12v from two 6V 1.2 amphour SLA in series. Is this going to drive the hull with a 35 – 40mm prop?

Bearing in mind I only want a slow speed wake free speed in keeping with an Edwardian Electric Launch.

Thanks

Stuart M.
16 July 2010 at 18:40 #27714
ashley needham
Participant
@ashleyneedham69188
I think we are not talking of the same sort of motor here….not that I know, but at 6v my 555`s spin at at least a few thousand rpm,

200rpm seems very low and with a 35mm prop will leave you dead in the water!!

Ashley
16 July 2010 at 22:39 #27715
StuartM
Participant
@stuartm
Right that one can go back under the bench with all the other usefull / less bits that I have aquired over the years. I’l stick with the RS540 combination.

I’ve also dug out of the back of the shed a canal barge that I started many years ago and due to various moves was never completed. Thats now in the vicinity of the work bench for some TLC.

So hopefully I should have something floating If not powered soon.

StuartM
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