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Is there an easily made engine/boiler?

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Martin Field16/09/2020 18:07:54
68 forum posts


I have a very large model of the P.S.Waverley and am torn between a steam plant and an electric mechanism for the paddle wheels.

Is there a good steaming boiler that will provide enough steam without requiring a boiler inspection? I have no idea where to get a test done or what's involved, but I can't see a Mamod type boiler giving enough steam to operate the wheels. I don't want to buy a plant.

Any suggestions gratefully received.


Phil H116/09/2020 20:01:44
311 forum posts
31 photos


How long is the model? I have articles for a plant capable of driving a 4 foot long model and the engine for a 6 foot version is still available from Reeves.

Phil H

Bazyle16/09/2020 20:55:32
5393 forum posts
206 photos

People tend to over engine model boats, or rather they make the engine then think about a boat to put it in that they can fit in their car. So a typical one is a Stuart D10 or launch engine in a 4ft model when they can easily provide scae power for a 6-7ft one. Part of the trouble is the Stuart Launch engine looks the right proportions in a 4ft launch but then only needs about 20lbs pressure to turn it into a speedboat.

There is a design for an twin cylinder oscillating engine and launch in the old MAP plans called Miranda. The proportions are not great for a launch (ok lets be honest it looks awful). However some dozen years ago someone on the Paddleducks forum pointed out that you can turn the engine design upside down, keeping the framework the same way up so the crankshaft is over the top. It then closely resembles the sort of oscillator used in paddlwheelers in the mid 19th century. I don't think Waverly actually has that type of engine but still worth consideration.

Otherwise assuming you don't want a double diagonal have you looked at the "Marcher" engine design which should do for a 4ft boat.

Martin Field16/09/2020 21:53:58
68 forum posts

I really should have mentioned the size of the boat. It's 5 ft-6in long with paddle wheels about 6" diameter. It's a big devil. I know the Miranda engine, having built one years ago. A launch engine wouldn't be suitable, but it's the boiler I'm most worried about, as a conventional (non pot) boiler needs the inspection for insurance and that's a lot of faff as I've no idea where to get that done.

It looks more and more like electric power is going in.



Nigel Graham 216/09/2020 23:03:37
720 forum posts
16 photos

I am assuming you live in the UK here.

You will need the boiler testing for public or club running, yes, but most of us have our models' boilers tested via the model-engineering club scheme.

You do of course need to be a full member of a club associated ( most, via one of the Federations) with the scheme - but this includes most model-engineering societies and more specifically the Model Power Boat Association..

You are right: Waverley's engine is not an oscillator, but a triple-expansion diagonal with conventional fixed cylinders and Stephenson's link-motion.

Martin Field16/09/2020 23:51:02
68 forum posts

I do live in the UK, Nigel, but am not a member of a Model Engineering Society. The only one near me was so unfriendly when I visited I came straight home! And it's bad enough having to join the BMFA to insure my model aircraft, without doing it all over again just for a model boat! So, electric it is.

Thanks everyone.


clogs17/09/2020 08:10:36
576 forum posts
12 photos

Martin try another club first.....they are all not so bad.....

I remember being the old fart in the space suit once......

all change when they needed a 100hp 4x4 tractor......long storey......still never joined tho....hahaha....

independance is a fine thing.....enjoy.....

JasonB17/09/2020 08:19:19
18640 forum posts
2047 photos
1 articles

Look for a model boat club as they may be more accommodating and offer have their own pond or lake. If using steam then the gas tank will also need testing and certification

Martin Field17/09/2020 08:35:24
68 forum posts

The nearest model boat club is way too far away and there are no other model engineering clubs.

I'd forgotten about the gas tank thing as well.

No, I don't do asking permission very well, so electric it definitely is, but thanks, gents.


Adrian R217/09/2020 09:18:31
33 forum posts
5 photos

How long do you want it to run for? Could you power a steam engine from a refillable Co2 bottle as used on small welders or soda streams? Or use an electric compressor to fill an air tank?

(Tin hat on, I have no idea what the consumption of a suitable engine would be and haven't done the sums...)

Martin Field17/09/2020 10:38:31
68 forum posts

Adrian, I have already been put off by the rules and regs and likely expense, so will go electric.



Bazyle17/09/2020 12:07:20
5393 forum posts
206 photos

Check out the Paddleducks forum (speciality paddle boat forum) and Modelboatmayhem forum for advice on what size electric motor to go for. Unless you have an old one you want o make use of there is a new world in electric motors that can double your battery life (or halve its cost).

Both the above forums are amateur not-for-profit as far as i'm aware.

Circlip17/09/2020 12:18:45
1169 forum posts

Have you put a dent in the bows for authenticity?

Regards Ian.

Martin Field17/09/2020 12:20:08
68 forum posts

I'll try paddleducks, thanks. ModelBoatmayhem I was chucked off years ago for criticising somebody's prices. I think he's dead now but they still won't have me!

I would rather use an older motor in keeping with the model. I have several Taycols and clever electrical bits to allow the use of a modern ESC with the field wound Taycol motor.


Martin Field17/09/2020 12:23:21
68 forum posts

Is there one, Ian? What did it hit?

I know very little about it, but it was a birthday p[resent and has to be finished.


V8Eng17/09/2020 13:39:19
1463 forum posts
28 photos
Posted by Martin Field on 17/09/2020 12:23:21:

Is there one, Ian? What did it hit?

I know very little about it, but it was a birthday p[resent and has to be finished.


I think it hit the pier on Arran earlier this month.
Found the story now, link here:-


Bazyle17/09/2020 13:55:17
5393 forum posts
206 photos

Good to hear someone is still using Tycols. I have a Supermarine which in a way would be suitable with the shaft being available both ends. A bit of chain drive would be sort of in keeping too.

Edited By Bazyle on 17/09/2020 13:55:51

Circlip17/09/2020 15:50:32
1169 forum posts

"Is there one, Ian? What did it hit?"

Yep, straight out of boiler rebuild, first passenger trip and BOING! As the late S/J would have said "C-B". As it's of a "Size", separate drives to paddles using a couple of reversible crash gearboxes coupled to Taycol would work. Simply made to a "Beek" design.

Regards Ian.

Martin Field17/09/2020 16:17:12
68 forum posts

Taycols were fine once, they still are. A chap from another forum designed and built me some electric boxes of tricks that enable me to use current brushed ESCs with a Taycol motor, so I'll use one of those for Waverley.

As someone pointed out independent paddle wheels only causes roll, so a BIG rudder may be in order.

Bazyle, chain drive could work if I can get a big enough sprocket for the shaft to get the reduction. And, of course, I have no idea what speed the wheels should turn.


Neil Wyatt17/09/2020 16:30:22
18135 forum posts
713 photos
77 articles

My dad would recommend one of the hefty double-ended cab fan motors used by JCB.

He has a couple that found their way out of the reject bin for being too noisy but they are not very noisy at all, JCB must be very fussy.


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