what engine for my launch?

[oldharry]

For a fairly light 16ft open launch, I reckon somewhere between 6 and 10hp would do.

I do not want a single cylinder diesel going donk donk donk.

Neither do I want an outboard.

So a petrol. Not averse to a 2 stroke. Perfer a twin cylinder I think. Bit smoother.

Stuart?

Vire?

Sole?

Brit?

Is there anything new?

Stuart. Rare and very variable reliability. Like the Old Seagull Outboard, it either went, on and on and on for ever. Or not. If Not even Stuart couldnt fathom out why. The former YardHand at DQ Marine used to buy them 10 to a pallet load. At least one would be a non starter, and would be sent back. Stuarts never queried or quibbled returns. Very prone to flooded or leaky carbs. I now I had 4 or 5 in different boats. They look amazing with the brass and copper all polished up, but an engine that doesnt go is a liability. Most Stuarts were just that.

Vire. A briliant little engine if you can find one. There is justy one guy in UK who specialises in them and can source )or make?) spares. he also does a a p/ex scheme if you have an old one for him to refurb. Good in the original 6hp rounded cylinder, better in the square shaped 7hp version, or the now very rare 12hp. A number of them still running round with owners quite happy, but spares are a concern.

Sole: Dunno, never had one.

Brit: Massively heavy slow running donk..... donk...... donker, huge vibration. But nowadyas only if you know where you can get bits! I think most brit owners have several dead ones in their garages. The problem being you need heavy lifting gear to move them!

No on your list, but mentioned by several: ALbin 021 022 twin cylinder petorl> My boat had one originally, and even at speed there was very liottle vibration! A beautifully smooth well engineered machine, and if you can find one thats still a runner, go for it! Spares availabe from one place in Finland. Why did I change mine? A mishap with heavy ground mooring chain pulled up into the prop at full belt coming out of a mudberth stopped the engine (with its heavy flywheel) in half a rev from around 1500rpm! The crank snapped. Albin in Finland was happy to send a new one - for £2k, 10 years ago. Other parts (bearings shells gaskets etc would have pushed the cost up to £2750 or therabouts.

 

[burgundyben]

I tend to assume someone working on a 16ft boat has a fairly tight budget. Which might be wrong.

There's effectively no budget limitation, none of the options would be out of reach.

I'm sure 10hp would suffice, and it could be brand new, I fancy something a bit more....I dunno...interesting.

Quiet and smooth would be nice. I was musing about steam today. Might take up a lot of space? Might take ages to get ready?

I fully get that at times it would be slow progress from say Keyhaven to Yarmouth against the spring ebb and I'd have to plan for that.

The Albin my favourite so far.

 

[scottie]

You might find a Volvo MB10A

 

[Sticky Fingers]

There's effectively no budget limitation, none of the options would be out of reach.

I'm sure 10hp would suffice, and it could be brand new, I fancy something a bit more....I dunno...interesting.

Quiet and smooth would be nice....

How about a gas engine? Example
https://www.ebay.co.uk/itm/Crossley...engine-Twin-sideshaft-Gas-engine/264023241330

You'd need something with a decent flywheel size. Easy fuelling with propane/butane. All torque no power but a gorgeous noise.

 

[prv]

I fancy something a bit more....I dunno...interesting.

Ok, that's a big steer for the direction that advice should be taking. A brand new 10hp Kubota (plus marinising in red or blue as desired) is the unarguable boring sensible answer, but in fact as a matter of preference we're looking for something interesting and a little historic - classic MGB rather than 18-month-old Fiesta?

Pete

 

[rotrax]

I seem to remember a flat twin diesel Enfield marine engine at Tony Olivers yard. He was a major player in renting out vehicles and associated kit to the film and TV people.

One of those should be nice and smooth-flat twins are inherently well balanced.

Or strap a marine gearbox onto a BMW flat twin motorbike engine........................

 

[DownWest]

Coventry Victor flat twin, if you can find one. Made for the job.

 

[oldharry]

There's effectively no budget limitation, none of the options would be out of reach.

I'm sure 10hp would suffice, and it could be brand new, I fancy something a bit more....I dunno...interesting.

Quiet and smooth would be nice. I was musing about steam today. Might take up a lot of space? Might take ages to get ready?

I fully get that at times it would be slow progress from say Keyhaven to Yarmouth against the spring ebb and I'd have to plan for that.

The Albin my favourite so far.

Steam is a different ball game, and you have to know what you are doing to operate one without blowing yourself up! But I understand that modern boilers can be flashed up in a very short space of time. They don't all have to sound like the Flying Scotsman at full bore, Indeed the few occasions I have had contact with a steam launch internals the most impressive feature has been the lack of noise compared to an infernal combustion engine. Even PS Waverley's 2000hp triple compound at normal cruising speed, you barely have to raise your voice in the engine room. Most of the noise comes from the paddle wheels anyway! But modern safety regs are a bit of a minefield with boiler certificates etc!

 

[AntarcticPilot]

I seem to remember a flat twin diesel Enfield marine engine at Tony Olivers yard. He was a major player in renting out vehicles and associated kit to the film and TV people.

One of those should be nice and smooth-flat twins are inherently well balanced.

Or strap a marine gearbox onto a BMW flat twin motorbike engine........................

HAs anyone ever marinized the engine from an old VW van? Like this: https://en.wikipedia.org/wiki/Volkswagen_air-cooled_engine?

Air cooled, reliable enough that it has been certified for use in home-build aircraft, flat 4 so instrinsically a smooth runner. Quite a lot going for it!

 

[AntarcticPilot]

Steam is a different ball game, and you have to know what you are doing to operate one without blowing yourself up! But I understand that modern boilers can be flashed up in a very short space of time. They don't all have to sound like the Flying Scotsman at full bore, Indeed the few occasions I have had contact with a steam launch internals the most impressive feature has been the lack of noise compared to an infernal combustion engine. Even PS Waverley's 2000hp triple compound at normal cruising speed, you barely have to raise your voice in the engine room. Most of the noise comes from the paddle wheels anyway! But modern safety regs are a bit of a minefield with boiler certificates etc!

Having sailed on the Clyde, Waverley's home waters, I can vouch for her silence - she has crept up on me unawares several times! Her colour scheme also seems to be chosen to camouflage her as well; the black seems to disappear against the tide-marks on the shoreline.

 

[DownWest]

Suberu flat fours have been marinized, bit quieter as water cooled, but more trhan 10hp, too powerful?

 

[rotrax]

The Thai's seem to use any old car engine in their "Longtail" outboard drives.

Getting the unit balanced seems to be the trick with those.

Seen some Yank rednecks on the Swamp People TV programme using what look like the Honda industrial air cooled petrol engines-single cylinder as well as the Vee twin- fixed to someone elses outboard bottom end.

Perhaps the flat twin diesel I saw was a Coventry Victor?

 

[scottie]

Coventry Victor flat twin, if you can find one. Made for the job.

difficult to balance cooling as I recall

 

[Praxinoscope]

There's effectively no budget limitation, none of the options would be out of reach.

I'm sure 10hp would suffice, and it could be brand new, I fancy something a bit more....I dunno...interesting.

Quiet and smooth would be nice. I was musing about steam today. Might take up a lot of space? Might take ages to get ready?

I fully get that at times it would be slow progress from say Keyhaven to Yarmouth against the spring ebb and I'd have to plan for that.

The Albin my favourite so far.

Oh it would be lovely to have steam, have a friend who had the most delightful little steam launch, the smell of stem coal and the gentle ‘puff puff’ was out of this world, but Oldharry is right, there are boiler certificates to be concerned about, it does take some time to raise steam and not sure I would really want to be shovelling coal into a firebox in anything but relatively calm waters. I suppose one could look at gas for the heat source, rather than coal?
If you really want something different, then maybe look at building your own inboard electric engine, but you’ll need a large bank of batteries to have any range and power to handle strong tidal flows.

 

[JumbleDuck]

Oh it would be lovely to have steam, have a friend who had the most delightful little steam launch, the smell of stem coal and the gentle ‘puff puff’ was out of this world, but Oldharry is right, there are boiler certificates to be concerned about ...

Not necessarily. Boiler certificates are only needed above a minimum diameter (6", from memory) so flash steam generators - not boilers - don't need them. This information from a friend of mine who has built two steam landrovers, based on Dobel designs.

Or you could go the other way and use an atmospheric steam engine, as used on some Victorian steam launches. On these you use steam at atmospheric pressure and rely on the ~15psi suck of the condenser to do all the work. The downside is that you need a larger cylinder but doubling the bore and stroke of a standard launch engine still doesn't make it unduly big and with 8 times the swept volume will give the atmospheric engine the output of a standard engine running at 105psi.

I'm planning to make one when I retire.

 

[burgundyben]

I'm warming to the idea of steam.

I'll go do some research.

I can't see that certifying a boiler can be that much bother, its just a pressure test.

 

[DownWest]

There was a piece in PBO about steam recently. It explained the certifying and types of boilers. Elswhere I saw twin cylinder refridgeration compressors being used as steam engines.

 

[JumbleDuck]

I'm warming to the idea of steam.

I'll go do some research.

I can't see that certifying a boiler can be that much bother, its just a pressure test.

You have to strip off lagging and insulation too, I think, but only every ten years. The Steam Boat Association looks like a good place to start: https://steamboatassociation.co.uk/

 

[Daydream believer]

Not necessarily. Boiler certificates are only needed above a minimum diameter (6", from memory)

.

Sorry to disagree but I am building a model traction engine ( my winter hobby) & the boiler is 100mm diameter. That has to have a boiler cert & built to quite exacting standards before I can run it near any public or at a club. The same applies to some of the smaller ones as well.
Model engineering clubs have nominated inspectors who one has to show the design & discuss the build with prior to certification.
Flash steam generators are a different item & i have been to numerous model exhibitions & never seen things such as large model traction engines ( so similar in operation to a boat engine) running on flash steam.
Point being that the OP should research this first. I suggest taking advice from a model engineering club who will know all about this & be very willing to help. It is not a case of just lobbing some coal on a fire & off you go.
It takes skill just to light the fire let alone run the engine & maintain it correctly.
Fun though:encouragement:

 

[oldharry]

. I was musing about steam today. Might take up a lot of space? Might take ages to get ready?

I fully get that at times it would be slow progress from say Keyhaven to Yarmouth against the spring ebb and I'd have to plan for that.

The Albin my favourite so far.

Why? Steam power is no different to diesel or petrol. The right size steam engine will push her along every bit as well and be a great deal smaller and lighter than a petrol or diesel of the same power. That is mainly because a steam engine doesnt require a water jacket to keep it cool. Low HP petrol and diesels usually need a hefty flywheel to keep the engine turning through the compression cycle. These can add significantly to the overall weight of the unit. Steam engines do not pre-compress so can have much lighter flywheels.