looking for a suitable diesel/petrol engine for an 'unusual' model boat

Hello, everybody. I'm a good woodworker who has loved models all my life. And now in my later years I want to build a very special model. I live in the South of France, home to a traditional fishing boat called the 'pointu' = pointed at both ends and decked overall. Think of a classic lifeboat or the popular idea of Noah's Ark. It features a very beautiful and efficient form of sail, the "voile latine", a thousand years old or more. But most important to me, it has a motor that makes a long-stroking put-put-put noise, and that's my starting point. I am prepared for a big motor in model-making terms, and the boat will be scaled to fit. Might be as big as a single bed (and the hull form does offer huge space inside). But I have so far found not even the smallest clue that might lead me to the motor I seek. Something old that I could restore? That's favourite, but I have seen nothing small enough. The wonderful Bernard motors that once powered the peasant life down here are all absurdly too large. Find something brand new and modify it? Four-stroke motor-mower engines (like Briggs & Stratton) make roughly the right noise, and I have an idea for a forward/reverse/neutral 'gearbox' that would turn the drive through 90 degrees (as it must). But again, nothing so far that's small enough. Build it myself? Erm ... I have absolutely no hands-on experience of machining, nor the tools to do it. I have bathed in an infinity of YouTube instruction, thrilled by the skills, terrified by the investment I would have to make. I gotta box clever here, and allow the project to lead me where it will. With a blank sheet of paper, there's so many routes I might follow. So many exciting dimensions, even wood-carving the crew members. My wife says, why don't you just carve the crew and leave it at that? No! No engine, no project.

All thoughts gratefully received. And by the way: I note the opinion of hard-working respondents who expect some response in return. Me, I like to show off and don't especially care if no one responds to my copious woodworking posts. But I am asking for specific advice here, and so I do promise to respond.

And now if you'll excuse me I have twelve windows to make ...

Cheers

Mark

I would look at small boats that already have pointy ends and see what they use

Lifeboats for example all used to use Lister diesels

One thing you will find is that as the engine size goes down they need to run faster so you may not get that slow beat that you desire.

There are a couple of model single cylinder marine engines that would fit the bill but they both need to be made unless you can find someone willing to build you one at a reasonable cost.

Jerry Howell's "Bill" would be a good candidate and there is also the Hubbard by Heinz Kornmuller you should be able to find videos of both models running on You-Tube

J

I think it might be better to use an electric motor to power the boat, with an electronic sound unit - much easier to adjust power required for the size of the boat. You can also then 'tailor' the sounds to achieve what you want.

Mark , I assume you are looking for an ic engine in order to maintain authenticity , in which case my suggestion would be that since such engines used to be common place for driving small generators or pumps I would look in the adverts sections of such publications as Old Glory , Vintage Spirit or Stationary Engine . You may even consider placing a wanted advert in any of the aforementioned mags . Maybe there are equivalent French publications , or even fleabay ?

In the past I have seen such engines for sale at the farmers auction at Driffield Steam Rally , so maybe a similar local event may prove fruitfull ?

If you do go down the electrical route , there are some sound generators that can be programmed with your own sounds if those as supplied are not suitable . As an example , try looking at Harbor Models in USA . Not cheap , but am really pleased with mine . Also see Mtronics and Action Electronics . With regards to a motor , since you going to be swinging a large slow reving prop would suggeSt you need a high torque motor such as found on golf carts ( 12 volt ) or better still , as found on mobility scooters ( 24 volt ) . Maybe you have local repair shops for either of these ?

Hope you find abover helpful as initial options for consideration .

Trevor.

Although somewhat non-prototypical for your proposed boat I wonder if a smaller version of the Ricardo Dolphin motor might work. The originals were known for being able to run reliably at low speeds in fishing boat applications so at least the marine connection is there. No relation to the more modern two cylinder Dolphin two stroke marine motor tho'.

Allegedly its quite easy to convert a two stage piston compressor into a Dolphin style engine :- **LINK** . Quite easy is of course a somewhat elastic concept but that one looks very much shade tree engineering yet apparently runs quite well. It runs too fast for you but the layout provides considerable scope for throttling and the independence of induction cylinder compression and air delivery from the power cylinder compression ratio suggests that adding an air bleed or pressure relief valve might enhance low speed running.

Section for a proper Dolphin here :-  http://www-g.eng.cam.ac.uk/125/achievements/ricardo/page07.htm. Note automatic inlet valve. Possibly a proper cam operated one would enhance low speed running albeit at considerable extra complexity. I imagine that the compressor conversion merely has exhaust ports cut in the bottom of the low pressure (power) cylinder and a new, flat base cylinder head with bulb type combustion chamber on top to take the spark plug and inlet valve.

Gordons suggestion is by far the easiest way of course. A flat out cheat but whatever works!

Clive.

Edited By Clive Foster on 21/01/2018 13:44:42

maybe one of the Smaller Stuart Turner marine IC engines would be another possibility if you are going to make a really big model. Several for sale on Preston's site the R3M would be the smallest

Edited By JasonB on 21/01/2018 13:54:46

Hi Mark,

First of all, what size of engine do you think you require?

for around 4 hp you could look at one of the Seagull outboards - 2 stroke, slow runner, can be mounted at virtually any angle as it doesnt have a sump.

A problem would be that although it has a gearbox that turns the drive through 90 degrees only the silver century model has a clutch unit and no reverse.

So, as Jason says, the Stuart engines are good, but getting very hard to obtain, and the very small ones (1.5hp) only have a centrifugal clutch.

Another option would be to couple up suitable engine to one of the ride on mower gearboxes via belt drive, (seagull or briggs would suffice) long stroke two stroke may sound more to your requirements if run a little rich and allowed to 'four stroke'

Regards

Lofty

A friend has had some success getting a 150cc 2-stroke lawn-mower engine to run quite slowly by fitting a large flywheel made from one of the cast iron weights used in weight-lifting. Should be equally possible on a B&S 4-stroke. A smaller carb would also help as those normally fitted are designed for full power at full revs. I read somewhere on one of the miniature engine sites that the carby off a 25cc strimmer, when fitted to a larger 4-stroke, provided plenty of 'juice' for smooth operation at lower speeds with adequate power. If i find that site again i'll post a link.

Geoff P.

Perko7 beat me to it.

I would try a small 4 stroke engine of around 100-200cc with a large flywheel and self regulating throttle so it can increase torque without increasing engine speed too much.

**LINK**

Hi Mark,

How big is your model to be? To support some of the suggested engines it will have to be pretty big. If you don't have engineering facilities I think the electric motor and sound generator is going to be the easiest solution for you.

Russell

(in Pyrenees Orientale)

Although a small, relatively modern, engine with small carburettor and large flywheel can be coerced into running at a suitably low speed it won't give the "long stroke put-put-put" noise desired by the OP. This is characteristic of the low compression, hot bulb semi-diesel engines once popular when robust simplicity and long running reliability were more important than compact power.

Getting that sound out of modern style engine might be possible with careful exhaust tuning but I suspect anything suitable will inevitably run too fast. Using a four stroke will help but the exhaust will probably still have too much of a harsh bark and natural speed too high if developing useful power.

Semi-diesels are almost invariably very slow running, maybe 90 to 200 rpm in normal operation, near constant speed two stroke devices. They are also very, very large for their modest power output, maybe a horsepower per litre swept volume at best, usually less.

Decent running small and model size hot bulb engines have been made but small incarnations tend to be fuel fussy, unlike the original which will burn pretty much anything inflammable thin enough to be pumped, and usually require continuous heating of the bulb for reliable running.

The aforementioned Dolphin engine shares most of the running characteristics and sound of the semi-diesel but is much smaller for similar output. The single power cylinder ones used in the Newhaven fishing fleet boats were, I think, around 3 1/3 litres. In those days a semi-diesel engine would have been the preferred choice of motor but the boats were too small to carry one. Hence the use of the Dolphin which had much the same characteristics and robust simplicity in a far more compact package.

Spark ignition forces the use of petrol for fuel but will almost certainly make for much more reliable running.

Although there is no way to purchase a Dolphin type motor today the Vee twin compressor conversion of the style linked to in my original post doesn't look unreasonably difficult for someone with adequate workshop facilities.

Clive.

Edited By Clive Foster on 22/01/2018 11:48:01

Mark
​Size of a single bed! That's one big model but even so scaling down a realistic engine sound will be tricky I think. You already said that the most important thing is the sound so why don't you start there. As other have suggested using a sound module can give you exactly what you want. You could start be sampling the real thing at your local harbour including backfires, rattles, whines and whatever else makes it authentic. Assuming you are going to fit radio control (although at that size small people might do) you can link the sound to the throttle and even include a start up. There are various software programs (musicians use them) to change the tempo of music without altering the pitch. If you really want to you could have a separate channel to make a seagull sounds, and to go the whole hog, the skipper giving instructions to the wooden crew using whatever choice language you can get away with. That's your sound sorted.
​With electric propulsion you could use a low kv brushless motor in which case the battery can go anywhere and can be useful ballast as it des not change weight as it runs down. If you want to swing a scale propeller you may still need a reduction gearbox.
​That's two things sorted out but now you can make a dummy Bernard engine which I have looked up and is mostly hidden with casings. But anyway you could create all the scale detail you want or go for an equally authentic engine like a Baudouin semi diesel that seems like it only fires on alternate days of the week.
​You can choose the size instead of being driven by something that will need craning out of your workshop and you can make the whole thing as easy or as complicated as you like.
Let us know what you decide and if it saves your marriage!
Tim

I think Hatz made a quite tiny diesel a very long time ago (before the 7*/7*8 range). They rarely come up for sale, but might be worth watching out for - but they are not cheap even if a non-runner - and quite possibly they would not run slowly enough.

I am overwhelmed by the responses to my first post. Overwhelmed by the generosity, and (I have to say) overwhelmed by the prospect ahead. Let me walk it through. The motor decides the size of the boat. But I always had in mind to design the boat as a platform for successive motor options. It just has to be big enough for whatever might turn up. But not too big. Thank you, Jerry, for tipping me Jerry Howell's 'Bill'. A 1906 motor? That's going back a bit, but no matter. It's about 7in tall, so maybe that sets the scale. Use an electric motor and fake the sound? Sorry, Tim, I just couldn't stoop that low. What I mean is, it's basic to the project that the sound is real. But yes actually, it will have an electric motor as auxilliary, so I can bring my precious toy to land if/when the i/c motor fails. Small 'full scale' motors of the agricultural sort? At this moment, I just don't believe that I will ever find something remotely suitable. But note my point about the boat being a platform for successive motor options. Maybe, who knows? I will think about Seagull (I like Seagull) and Stuart Turner, of course. I will think about everything that everyone is suggesting here. Meanwhile, let me tell you how I am resolved to attack this mad project - and ask some questions arising.

I am for the time being resolved to make the engine myself. Yes, I know, I have absolutely no hands-on experience of machining. But hey, I'm a workshop person. I really want that skill, and I am ready to learn. First question: what space (height) below deck do forum members think I should allow? Armed with that answer, I will set about finding plans for the hull, visit the pretty harbours where pointu enthusiasts keep their boats, gather in the materials - and set about the woodworking. All in my comfort zone thus far.

Meanwhile, in parallel ...

I will buy a lathe and a milling machine, and set about teaching myself how to use these entirely unfamiliar tools. I will buy new and I will buy cheap, and I will start right away to make an engine. Bill, for instance. I will make a ton of mistakes and it will be a miracle if that first engine works. But that's the best way to learn, right?

So that's my question to you all, if you are willing to advise: what machines, and what form of 'tutorial'? It is question I have googled already, of course, and I got a thread (possibly/probably Model Engineering) that slapped the poor sap down, how long do you want your piece of string to be, there is no standard answer. But it is THE question that any beginner wants to ask, and there surely is an answer.

Why buy new? Transport is one issue. There's zero chance that I might find something second-hand that's trustworthy in these parts. The southern French don't do machine engineering. In fact, some would say they don't do much of anything. I'd have to go to Germany, and that's a very, very long (and boring) drive. My favorite would be to buy Chinese from a friendly English dealer with good customer service, and pay the shipping cost. The machine-tool equivalent of Axminster (for instance).

So what's it to be? No, don't go away. A Myford Super 7 is surely not the only game in town. Tell me what you know.

That's enough for now, I think. My sincerest thanks to you all for your thoughts to this point, and I do hope that you will find the patience to offer me more.

Cheers

Mark

well the original Bill engine was designed for hulls about 18ft long so as the model engine is 1/3rd scale you are probably looking at a hull in the region of 6ft long so your bed size was about right. At least with the Bill engine you will not have to worry about a 90deg change of direction in the drive train, looking at images of the hull structure on line you can just mount the engine on the bearers and take the propshaft out the back.

As for new machines something like a SC4 lathe and SX2 or SX2.7mill from ARC should handle it easily.

Maybe check out the engine fitted to these things out there in France?. -LINK-

Similar size that were fitted to what I remember as 'Dumpers' seen on building sites many years ago. 2 Cylinder Diesel and I think water cooled. I'm sure there must be some in a local Scrap Yard there?. I see many when over there in rural areas and they sound like the old 'Thumpers'. Just a thought, and way easier and quicker than learning to and building your own.

I have one - had it for 58 years & it still runs great. Centrifugal clutch is a new one on me & we have a few in out sailing club. But if you want one then you go to---- "Saving old Seagulls" in Tillingham, Essex. It is where they go to die then get reincarnated by a really nice fellow who lives & breaths Seagull outboards.

If you mount it out of plumb for long you will never start it though.

Edited By Sam Longley 1 on 22/01/2018 22:10:57

Not a particularly long stroke engine, but a four stroke OHV engine, was that fitted to the Mercette moped. A superb little jobbie. I had a Mercette back in the late ‘50s/early ‘60s and thrashed it unmercifully around the fields. Unfortunately it was left at the farm and skipped at the end of the ‘90s (by my brother). I should have recovered it before then - but isn’t hindsight good!

Now a very, very rare machine, of course, but I believe there are some engines still around as they were a ‘bought-in item (the maker’s name begins with a P, I think). The last machine I saw for sale was priced at four grand! Apparently only four known examples were remaining, I recall reading somewhere

There may be other small engines for mounting on bicycles, but I don’t know of any four strokers. There is one small engine on a bicycle in the Ipswich Transport Museum which originally had plans for home construction (although I could not locate any, about five years ago).

The museum is well worth a visit, mainly for other forms of local historical travel. I think I may return for another visit later this year....

Two stroke engines might include the 25 or 32cc cyclemaster engine (fitted to the rear wheel) or a powerpak (the engine drives the bike by lowering the engine onto the rear tyre. (Mine needs a new chain connecting link. They are, I think, slightly wider than a normal bike chain).

I know there were some French offerings made...

So, perhaps yet another angle to investigate?

Ah! Before my last post I missed that you had said bed size for your model - must be my age!

As far as machine tools delivered from U.K. to France is concerned I have had good experience with Arc Eurotrade and Ketan who posts here is very helpful. There are a number of sellers of Chinese machine tools here but the prices are higher than the UK even after transport. Optimachines are one popular one.

Russell