macd
Well-Known Member
The latest 1832cc version has 118bhp at 5500rpm and 123lb.ft at 4000rpm. And cruise control. And surprisingly good brakes: if you could work out how to apply them to a boat, it'd cut down no end on marina accidents.
Motorbike engine
- Thread starter PabloPicasso
- Start date
The latest 1832cc version has 118bhp at 5500rpm and 123lb.ft at 4000rpm. And cruise control. And surprisingly good brakes: if you could work out how to apply them to a boat, it'd cut down no end on marina accidents.
Tranona
Well-Known Member
Vastly too much power. It is the propeller that moves the boat not the engine. All the engine does is provide enough power to achieve the necessary revs. The speed of your boat is limited to about 6.5 knots and this can be achieved with less than 10 hp in flat water. Your prop cannot absorb more power and adding power will not increase speed. Putting 110+ hp into a small displacement boat is a complete waste of time. Why do you think all small sailboat engines are low hp diesels? Clearly designers know more about it than you seem to.
JumbleDuck
Well-Known Member
A neighbour of mine in the boatyard where I overwinter has done that with his Victoria 800. The old engine (Volvo?) went and was replace by two remarkably large traction batteries of 150AH or so each and a remarkably small Lynch motor of about 20kW continuous rating. He carries a Honda generator to top it up as well as solar cells, and plans to use it only for relatively short periods of going in and out of harbours.
I understand - but this is second hand - that initial sea trials were not terribly satisfactory, and that a re-spec of the propeller may be needed.
SHUG
Well-Known Member
A motorbike engine is too comlicated and unsuitable for marine use.
What you really want is a nice simple ram jet engine.
That should move you along quite quickly.
What you really want is a nice simple ram jet engine.
That should move you along quite quickly.
MASH
N/A
It makes me laugh when anyone refers to a Lead Stump as a "motorbike".
ffiill
Well-Known Member
Many years ago now back in the 90s I fitted a Honda 8hp aircooled industrial engine to my old boat-its now 20 years old and runs quite happily.Exhaust outboard and quite capacious engine compartment.
PabloPicasso
Well-Known Member
Oh yeah right, how about a Honda CG125 engine then mr know all. Ya boo hoo
Tranona
Well-Known Member
I am sure if Honda thought it was a viable proposition they would have tried it! Fundamentally different requirements to powering a motorbike compared to powering a displacement boat so not surprisingly the engines used are fundamentally different.
jimmcgee
Well-Known Member
think outside the box 
, what size of pipe would you need for a 21 foot putt putt engine .
and i know there is someone out there who will work out the size lol.
, what size of pipe would you need for a 21 foot putt putt engine .and i know there is someone out there who will work out the size lol.
Avocet
Well-Known Member
I think the Honda CG engines were designed for plant weren't they? (lawn mowers, generators etc). They're pretty low revving, but the carburettors are intended for constant-speed use, with a governor, rather than variable speed use. I think part-throttle performance might be poor, as a result. They "idle" very fast and aren't really intended to do anything between "idle" and "governed speed".
Other than that, if you can keep them cool, route the exhaust somewhere it won't overheat, and don't mind having petrol going to the engine bay, I don't see why you couldn't use one. I had wondered about a pair of those nasty Chinese 5 horse industrial diesel engines for Avocet. Basically, either one would be able to power the boat (both together for the odd extreme set of conditions) and a degree of redundancy in all other cases (given that they're cheap, Chinese and not likely to last long). I've not done it though, and I imagine noise and vibration would be horrendous. My 12 horse inboard weighs something ridiculous like 110kg, so I'm sure I could fit two of those little babies in the same hole.
http://www.northerntooluk.com/engin...-other/1470e-shaft-diesel-engine-rs_170E.html
Other than that, if you can keep them cool, route the exhaust somewhere it won't overheat, and don't mind having petrol going to the engine bay, I don't see why you couldn't use one. I had wondered about a pair of those nasty Chinese 5 horse industrial diesel engines for Avocet. Basically, either one would be able to power the boat (both together for the odd extreme set of conditions) and a degree of redundancy in all other cases (given that they're cheap, Chinese and not likely to last long). I've not done it though, and I imagine noise and vibration would be horrendous. My 12 horse inboard weighs something ridiculous like 110kg, so I'm sure I could fit two of those little babies in the same hole.
http://www.northerntooluk.com/engin...-other/1470e-shaft-diesel-engine-rs_170E.html
rustybarge
Well-Known Member
I visited China a few years ago, and all the boats had a vertical drive leg with prop,clamped to the outside of the stern, with v belt pulley's. the big advantage was you could use any engine with a couple a pulleys to get the correct reduction. Old tractor engines, generator engines, old car engines....and that's exactly what they did.
When you consider the cost of even small outboards, let alone sail-drives and marines engines, it makes total sense.
That Chinese diesel looks perfect....rated continuous speed is just 1500 revs.....wow it should run all day long on a gallon of fuel.
macd
Well-Known Member
The pushrod CG was certainly more basic than its ohc CB125 stablemate, but I wouldn't describe a substantially oversquare design producing almost 90bhp/litre a plant engine.
woozy-UK
Well-Known Member
interesting read. I ride a Honda varadero 125 to work everyday, it has been drenched in a downpour lots and always runs. yet outboards seem to be **** when they get wet despite being for marine use. always wondered why they cannot use motorcycle engines instead.
great read!
great read!
macd
Well-Known Member
Probably the biggest single electrical killer of bikes made in the last 30 years or so (i.e. since Joe Lucas, the legendary Prince of Darkness, stopped making electrical systems for them) is a short in the side-stand cut-out switch, which obviously lived in one of the most cruddy and exposed parts of the bike. Wet, salty roads and a couple of adjacent blade connectors don't mix well.
No doubt we can expect the OP to come along next and suggest reasons for fitting a motorcycle side-stand to an outboard. How about it, Pablo?
2nd_apprentice
Well-Known Member
I visited China a few years ago, and all the boats had a vertical drive leg with prop,clamped to the outside of the stern, with v belt pulley's. the big advantage was you could use any engine with a couple a pulleys to get the correct reduction. Old tractor engines, generator engines, old car engines....and that's exactly what they did.
When you consider the cost of even small outboards, let alone sail-drives and marines engines, it makes total sense.
That Chinese diesel looks perfect....rated continuous speed is just 1500 revs.....wow it should run all day long on a gallon of fuel.
I wonder how bad these would be:
http://www.klaxondieseloutboards.com/category/outboards/fhseries/
Yes, they're not exactly lightweight but the same goes for an inboard. They'll be loud as hell of course, not sure about the quality and parts might be a problem. On the other hand I'm now running a petrol outboard in a well and the cost to convert toa diesel inboard would be prohibitive.
You'll also find more 3rd world aircooled-on-a-leg engines
Checking with alibaba the one above seems to be madeby RunSun.
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MASH
N/A
I don't suppose they've called it "Klaxon" without a reason!
80Kg - ouch!
A Mercury 9.9 os just 44Kg.
80Kg - ouch!
A Mercury 9.9 os just 44Kg.
2nd_apprentice
Well-Known Member
Yeah, but how well does it run on diesel? Apart from the safety issue lugging a weeks supply of petrol from the nearest filling station isn't exactly fun without a car.
Tranona
Well-Known Member
Been many attempts over the years at diesel outboards, including made by Yanmar. All suffer from the same problems, weight, noise and lack of refinement, even when they look like petrol ones! As you can see by the website the target market is for semi-permanent installation on work boats where the downsides are less of a problem and outweighed (possibly) by the savings in fuel costs and increased safety of the fuel. If you have ever been on a boat fitted with one you will know why they have never made any impact in the pleasure boat market. That particular brand you have to buy direct from China, so no effective warranty or backup, so hardly a consumer product.
Nudge
Well-Known Member
Using a motorcycle engine in a boat is not new.... My father and Uncle constructed a launch using plans from "The Motorboat" Magazine before WWII. The spec had a 10hp morris car engine, but my intrepid forebears opted for a JAP 1100cc 45hp watercooled 45 deg V twin from a Morgan 3 wheeler supersport. Sadly while they were firing large guns in Burma and wheeling about the sky in a Beaufighter, the timbers of the launch rotted away. I still have the drawings (not pretty!!) and the bronze prop that Dad cast for it and I think the shaft became the axle for the launching trolley of a subsequent sailing dinghy. The engine sat in the garage for years but was given to a Morgan restorer around 1968.
Legend has it that the stub exhausts shot flames and were deafening, and a silk coffin cord was used as the pull start on the flywheel to get the necessary strength and number of turns.
Crazy stuff!!
Legend has it that the stub exhausts shot flames and were deafening, and a silk coffin cord was used as the pull start on the flywheel to get the necessary strength and number of turns.
Crazy stuff!!
macd
Well-Known Member
I'll say not. Alfred Scott's first two-stroke twin prototype powered a small boat (the Petrel, if memory serves) for a while, back in around 1904. It had rather more success when they stuck wheels on it.