what engine for my launch?

I think a Kent based engine would be lovely, smooth and quiet in such a launch.

Bare engines however are quite pricey as there is ongoing demand from people still racing formula ford or historic marques.
But as a result there are lots of parts including everything you need to make a reliable, safe motor.

There's an elderly guy at Dell Quay boatyard who has had one in his 30ft yacht for decades with perfect reliability.
 
Look up Dolphin,

http://www.dolphinengines.co.uk/features.php

Older versions have no gearbox, just flick the switch andstart them up 'backwards'.

I didn't take my own advice. I put a 20hp Beta in 16ft open boat. Overpowered maybe but excellent. One of the benefits of so much power on an inboard is the ability to stop very quickly...and tow a few dinghies!
 
In the 1960s, my Dad had a Trotter (a version of the Pandora) fitted with a Briggs and Stratton air-cooled engine. It worked! The engine was fitted by the builder (Grimsby Marine Plastics) as original equipment. We didn't think anything of it at the time, but I've never seen that engine since. Basically a large lawnmower engine!

Presumably something like these: https://www.briggsandstratton.com/as/en_ph/products/engines/horizontal-shaft-engines.html
 
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Motor_Sailor said:
I think a Kent based engine would be lovely, smooth and quiet in such a launch.

Bare engines however are quite pricey as there is ongoing demand from people still racing formula ford or historic marques.
But as a result there are lots of parts including everything you need to make a reliable, safe motor.

There's an elderly guy at Dell Quay boatyard who has had one in his 30ft yacht for decades with perfect reliability.
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Why would you want 30hp+ in a 16' displacement launch? Never mind the weight and space it would take up?
 
burgundyben said:
Thank all.

It would be nice if it was all aluminium and air cooled, although I suspect air cooled would be noisy and need some kind of fan.
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Do you have the stern gear already installed? If you do then that will substantially reduce the cost and work involved plus give you more choice. Plenty of old sub 10hp engines both petrol and diesel available at modest cost that can be made viable for your limited requirements.

However electric power is also probably viable given your limited range requirements provided you have a means of 240v charging after use.
 
Two cylinder diesels aren't - in my experience - much less rattly than single-cylinder ones because the two pistons move up and down together. You get a power stroke every rotation rather than every second, which makes tickover a bit smoother, but under way my Nanni N2.14 vibrates no less than the Yanmar 1GM10 which preceded it. Of the two I'd use the 1GM10 in your launch. It's cheaper (though parts are not) and much simpler.

If you want a small petrol engine, how about a Reliant car engine? Anything from 21hp (600cc) to 40hp (850cc) all of which would be a bit much, but of course you don't have to run them at full power and they are small, light (all aluminium) and very smooth-running. Oh, what's that on my workbench? Why, it's a spare Reliant 850cc engine. What a coincidence.

Or, of course, you could go for pure style.

Cygnet%20in%201970.jpg


Preston Services have a few suitable engines for sale.
 
Tranona said:
Why would you want 30hp+ in a 16' displacement launch? Never mind the weight and space it would take up?
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Well, we had 35hp in a number of Cheverton Champs which are only 18ft long and they were great workboats / launches.

I think that's still the option in them new. You don't have to run them flat out.
 
A lot of river cruisers have been 4 cyl petrol engines.
A mate had one on the Thames for a while, mostly a 1HP horse would have been enough speed, but a 30hp (?) Ford or BMC lump pottering along at low load is a nice quiet solution.
 
It'll never do anything more than 4.5 kts through the water regardless of engine size. Against a 2 kt tide, means 2.5 mph. To have speed in a 16 footer you'll need a planing hull & outboard with a fwd steering position.
 
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Motor_Sailor said:
Well, we had 35hp in a number of Cheverton Champs which are only 18ft long and they were great workboats / launches.

I think that's still the option in them new. You don't have to run them flat out.
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But he is not looking for a workboat - just pottering around the Solent and 10hp will be more than adequate.
 
I can understand why you don't want a single cylinder diesel, but lots of the small modern diesels (Nanni and Beta etc) are based on two or three cylinder Kubota engines and they are very smooth and quiet in the right installation. Much more reliable (and safer) than a petrol engine in a small open launch IMHO.

Lomardini make small diesels as well. The small ones are two cylinder and if you insist on three then its 27 hp which many would suggest is too big.

I've fitted a small modern Yanmar diesel and a 3 cylinder Nanni diesel and they were both quiet and efficient.
 
lw395 said:
I tend to assume someone working on a 16ft boat has a fairly tight budget. Which might be wrong.
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There are used Beta/Nanni engines around (Beta 14 £1900) The OP doesn’t want an outboard or a single cylinder diesel, so either petrol inboard or diesel, personally I would go for diesel every time.
 
Back in the 70s we moulded an 8ft dinghy with a 2.5 Honda stationary engine inboard. £22.50 (they were trying to edge out the likes of JAP and Villiers) The prop was on a U/V joint in a tunnel attached to the rudder, so, you could run it up a beach with the prop tucked up. The engine lived under the center thwart and was quite quiet. We rhought it was a bit short for production, but had several years of use before the engine failed (ignition..)
The engine has a 2:1 reduction built in, so ideal. No reverse, but nor did many O/Bs then
 
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