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motorcycle engine for a boat
this is more of a theoretical question more than anything else but a
couple of mates and i were chatting about boat building and engines in general. basicly ive heard a lot of engines are based upon marinised car engine based but i got to thinking how simple it would be to use a shaft drive bike engine {1} since theres a wide range of shaft drive engines from 550s to 1100cc especialy the 900cc yamaha diversion engine which is dirt cheap. i know the engines wouldnt last as long but sing they start at £80 from breakers{2} means it could be treated as disposable item like petrol. im just posting to see if there is any serious flaws in the idea such as not enough torque or other variables {1} i guess i would have to work out the forces and calculate propeller assuming the revs arent to high {2} breakers tend to sell all the stuff that breaks in a crash like plastic and bits that rust leaving them with the engine which most folk dont want to replace |
One thing you have to deal with is thrust from the propellor and shaft.
Car and motorcycle engines and transmissions don't have thrust bearings as in a marine transmission. |
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Didn't Junk-Yard-Wars do a boat race with one contestant using an engine
from a bike? "ewan" wrote in message ... this is more of a theoretical question more than anything else but a couple of mates and i were chatting about boat building and engines in general. basicly ive heard a lot of engines are based upon marinised car engine based but i got to thinking how simple it would be to use a shaft drive bike engine {1} since theres a wide range of shaft drive engines from 550s to 1100cc especialy the 900cc yamaha diversion engine which is dirt cheap. i know the engines wouldnt last as long but sing they start at £80 from breakers{2} means it could be treated as disposable item like petrol. im just posting to see if there is any serious flaws in the idea such as not enough torque or other variables {1} i guess i would have to work out the forces and calculate propeller assuming the revs arent to high {2} breakers tend to sell all the stuff that breaks in a crash like plastic and bits that rust leaving them with the engine which most folk dont want to replace |
On Mon, 07 Feb 2005 21:47:17 -0500, Wayne.B wrote:
On 7 Feb 2005 17:17:10 -0800, wrote: One thing you have to deal with is thrust from the propellor and shaft. Car and motorcycle engines and transmissions don't have thrust bearings as in a marine transmission. ================================ There are some other issues such as adequate cooling air, corrosion control and dealing with a dry (hot) exhaust. The speed/torque characteristics are not well matched either, and you would need a substantial reduction ratio. another thought would be to use an impeller, i havent looked at them since uni when we had to calculate the fin angles and other crap{1} but dont they require higher revs/lower torque. to be honest i can barely rember anything about it and cant even visulise the forces{2}, would an impeller need a thrust bearing as for exhaust gases, i may be mistaken but surly any engine will produce them, i know some bike engines have special tuning put exhaust(exup valves etc) but not any i was thinking of do marine engines handle it diferently. i was also thinking of a watercooled engine since the only semi modern engines which arent water cooled are crome crusers which a regard as expensive crap. {1} quite possible the most boring and utimatly pointless class of my life {2} it is 5am and i havent looked at this stuff for 5 years |
You could mount it on a swivel mount on the back of an open boat with a
shaft and prop sticking out, like this: http://www.scavengerbackwater.com/scavenger.html I've even seen folks use little gas powered weed eaters, replacing the fishing line cutter with a little prop. Noisy, but inexpensive and basically disposable after a couple of seasons. -- Keith __ AAAAAA: American Association Against Acronym Abuse and Ambiguity. "ewan" wrote in message ... this is more of a theoretical question more than anything else but a couple of mates and i were chatting about boat building and engines in general. basicly ive heard a lot of engines are based upon marinised car engine based but i got to thinking how simple it would be to use a shaft drive bike engine {1} since theres a wide range of shaft drive engines from 550s to 1100cc especialy the 900cc yamaha diversion engine which is dirt cheap. i know the engines wouldnt last as long but sing they start at £80 from breakers{2} means it could be treated as disposable item like petrol. im just posting to see if there is any serious flaws in the idea such as not enough torque or other variables {1} i guess i would have to work out the forces and calculate propeller assuming the revs arent to high {2} breakers tend to sell all the stuff that breaks in a crash like plastic and bits that rust leaving them with the engine which most folk dont want to replace |
My hunch is that water-cooled motorcycle engines are essentially the
motive basis for many/most impeller-driven jet-skis. The problem, methinks, would be in developing/creating a "conventional" marine transmission (i.e. for a propeller-based boat) if only because these otherwise powerful and light engines tend to produce best at very high RPMs -- the reduction gearing needed would be, ummm, interesting... I'm also assuming that you've already properly discarded the idea of using an air-cooled V-twin... ;-) - paul ewan wrote: this is more of a theoretical question more than anything else but a couple of mates and i were chatting about boat building and engines in general. basicly ive heard a lot of engines are based upon marinised car engine based but i got to thinking how simple it would be to use a shaft drive bike engine {1} since theres a wide range of shaft drive engines from 550s to 1100cc especialy the 900cc yamaha diversion engine which is dirt cheap. i know the engines wouldnt last as long but sing they start at £80 from breakers{2} means it could be treated as disposable item like petrol. im just posting to see if there is any serious flaws in the idea such as not enough torque or other variables {1} i guess i would have to work out the forces and calculate propeller assuming the revs arent to high {2} breakers tend to sell all the stuff that breaks in a crash like plastic and bits that rust leaving them with the engine which most folk dont want to replace |
My Honda CBR1000F has a primary drive reduction rate 1.786:1 and gear ratios from 2.75:1
to 1.045:1 and final drive (chain sprockets) 2.47:1 so I think it is no problem to find a suitable ratio somewhere along the line. If you take out moderate horsepower (say 50-70) by sticking to lower revs, the engine should not overload. I would be more concerned about sufficient cooling. Perhaps a larger automotive-type cooler would be appropriate. These engines should last about 100000 miles without overhaul which translates to about 3000 engine hours. Check http://www.timothypilgrim.com/bike/japengines.jpg for details :-) BTW, everything above except the first line to "2.47:1" is pure amateur speculation. Heikki ewan wrote: this is more of a theoretical question more than anything else but a couple of mates and i were chatting about boat building and engines in general. basicly ive heard a lot of engines are based upon marinised car engine based but i got to thinking how simple it would be to use a shaft drive bike engine {1} since theres a wide range of shaft drive engines from 550s to 1100cc especialy the 900cc yamaha diversion engine which is dirt cheap. i know the engines wouldnt last as long but sing they start at £80 from breakers{2} means it could be treated as disposable item like petrol. im just posting to see if there is any serious flaws in the idea such as not enough torque or other variables {1} i guess i would have to work out the forces and calculate propeller assuming the revs arent to high {2} breakers tend to sell all the stuff that breaks in a crash like plastic and bits that rust leaving them with the engine which most folk dont want to replace |
"JAXAshby" wrote in message ... One thing you have to deal with is thrust from the propellor and shaft. Car and motorcycle engines and transmissions don't have thrust bearings as in a marine transmission. They sure do. If they didn't, they wouldn't last very long. What utter rubbish! There are motorcycles out there that will withstand thrust directly down the output shaft? Frankly i dont belive you. even shaft driven bikes tranfer thier power through turning motion only the shaft is only subected to torque. not thrust. A boat prop Pushes the shaft forwards... which via the gearbox bearings......pushes the engine... which takes the boat forwards with it cos its bolted to the boat! Its one of the reasons that boat engine mounts are a tad more costly than engine mounts for almost any other use. Select reverse.. (not a lot of bikes have reverse... a few.. but not many) and the shaft pulls .. I'd guess that would be very sudden death for most non marine gearboxes. |
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JAX says:
It appears you don't have a clew what a thrust bearing is. At least he knows how to spell "clue" ;-) The thrust bearingin a shaft-drive mo'cycle engine does NOT take care of thrust in line with the shaft. Steve "go for it, Jax, you know you want to...." |
It's cheap, it's easy - go for it. If it lasts two weeks, then so be
it, but at least we'll have some form of quantitative data on the topic in this newsgroup. You could build a free standing bearing structure which the prop shaft bears against (laterally) and couple it to the motor - maybe with a flexible drive. Or a similar arrangement with the chain drive preserved (covered of course). There's always the pump route - but not exactly cheap if you have to go with new parts. |
Oops - also the issue of spark proofing the various electrical bits,
and the flame arrestor on the carb. Not sure what you would do about those - could just leaving the whole thing in the open for the time being. |
Since the original idea was to use the engine off a 'cycle that was
"totalled", is it possible to find a wrecked jetski, buy it with the salvage tag, then strip it for your larger boat? I assume that you would have to alter it for the larger payload/ more drag issues (etc), but I assume that a lot of the 'extras' and "little pieces" would save time trying to find them to retro the cycle engine in the first place. Or, (to play devil's advocate) are jet ski mishaps "just total write-offs", and not worth trying to salvage (due to submersion, etc)? good luck w/ the research, I'll be the row-boater you pass with the 5horse John deere hidden in the "picnic cooler". On Mon, 07 Feb 2005 20:41:30 GMT, ewan wrote: this is more of a theoretical question more than anything else but a couple of mates and i were chatting about boat building and engines in general. basicly ive heard a lot of engines are based upon marinised car engine based but i got to thinking how simple it would be to use a shaft drive bike engine {1} since theres a wide range of shaft drive engines from 550s to 1100cc especialy the 900cc yamaha diversion engine which is dirt cheap. i know the engines wouldnt last as long but sing they start at £80 from breakers{2} means it could be treated as disposable item like petrol. im just posting to see if there is any serious flaws in the idea such as not enough torque or other variables {1} i guess i would have to work out the forces and calculate propeller assuming the revs arent to high {2} breakers tend to sell all the stuff that breaks in a crash like plastic and bits that rust leaving them with the engine which most folk dont want to replace |
On Mon, 07 Feb 2005 20:41:30 GMT, ewan wrote:
this is more of a theoretical question more than anything else but a couple of mates and i were chatting about boat building and engines in general. basicly ive heard a lot of engines are based upon marinised car engine based but i got to thinking how simple it would be to use a shaft drive bike engine {1} since theres a wide range of shaft drive engines from 550s to 1100cc especialy the 900cc yamaha diversion engine which is dirt cheap. i know the engines wouldnt last as long but sing they start at £80 from breakers{2} means it could be treated as disposable item like petrol. im just posting to see if there is any serious flaws in the idea such as not enough torque or other variables {1} i guess i would have to work out the forces and calculate propeller assuming the revs arent to high {2} breakers tend to sell all the stuff that breaks in a crash like plastic and bits that rust leaving them with the engine which most folk dont want to replace I will kick the idea around a little - if you wish. I hear that one engine fitted in a Harley comes from the Ford [KIA] Festiva - this is a water-cooled 1.3 liter engine - it's a good one, no doubt. This is a free-reving, spritely compact-car engine. It uses electronic engine control - one secret of auto engine longevity these days .... a lean engine is a clean engine .... A sensible gear box that can take plenty of thrust is a requirement. But the self contained water-cooling avoids the salt I guess. Or how about an air cooled engine? Loud, needs cooling Auto engines are not the best at slogging hour after hour. (That's when you need an egine - the mast or sails have given up...) Brian W |
On Mon, 07 Feb 2005 20:41:30 GMT, ewan vaguely
proposed a theory .......and in reply I say!: remove ns from my header address to reply via email IMO, unless the boat is small and fast (rapidly up on plane), and the engine is exposed to the air (noise), you will have troubles. Boat engines are made to either slog, or have plenty of cooling to allow for the hard yakka. Bike engines are made to flow freely, and usually the harder they really work (that's grunt, not revs) the more air is flowing over them. This would apply even to wayter-cooled ones, where fins are simply replaced by the radiator unit, which needs its own air flow. I suppose you could use a huge belt-drive fan, a la cars/trucks. More power gone. More noise. You can get gearing to allow for the rev problems. As somebody said, a bike has a gearbox. You could proably get something to work, or even "change gears". You can put in any number of bearings to allow for thrust problems. You can put in fans to remove fuel vapours (although an engine stuck up in the air is not going to be so bad here) But how far do you go. Basically, bike and VW engines are used for _planes_, not boats. They are lightweight for power, and thrive on lighter loads and/or good airflow. this is more of a theoretical question more than anything else but a couple of mates and i were chatting about boat building and engines in general. basicly ive heard a lot of engines are based upon marinised car engine based but i got to thinking how simple it would be to use a shaft |
As far as I know, marine internal combustion engine needs:
1. Ouboard water heat exchanger for engine coolant, 2. Engine sump water coil or oil heat exchanger for oil cooling, 3. Engine exhaust manifold with cooling jacket, 4. Exhaust cooling by water injection and water ingestion blockage by proper exhaust elbow, 5. Water jacket for cooling marine gearbox and propeller shaft thrust bearing, 6. Proper self priming outboard water pump supplying above circuits. A propeller driven Florida Swamp Airboat is the only boat without these items! Regards, Tadeusz |
Since the original idea was to use the engine off a 'cycle that was "totalled", is it possible to find a wrecked jetski, buy it with the salvage tag, then strip it for your larger boat? snip Or, (to play devil's advocate) are jet ski mishaps "just total write-offs", and not worth trying to salvage (due to submersion, etc)? Sort of like http://www.glen-l.com/jetski/jetjon-index.html ? There used to be a jetjon site dedicated to using old jetski powerplants in bigger boats, but it seems to be defunct... |
On 08 Feb 2005 14:29:20 GMT, (JAXAshby) wrote:
Posts like this are helpful in knowing whose posts to ignore' all engines have a a thrust bearing, except any engine owned "James" (who will be googleing for the next 24 hours trying to figure out how he could be so ignorant). From: "James" Date: 2/8/2005 9:03 A.M. Eastern Standard Time Message-id: "JAXAshby" wrote in message ... One thing you have to deal with is thrust from the propellor and shaft. Car and motorcycle engines and transmissions don't have thrust bearings as in a marine transmission. They sure do. If they didn't, they wouldn't last very long. What utter rubbish! There are motorcycles out there that will withstand thrust directly down the output shaft? Frankly i dont belive you. even shaft driven bikes tranfer thier power through turning motion only the shaft is only subected to torque. not thrust. A boat prop Pushes the shaft forwards... which via the gearbox bearings......pushes the engine... which takes the boat forwards with it cos its bolted to the boat! Its one of the reasons that boat engine mounts are a tad more costly than engine mounts for almost any other use. Select reverse.. (not a lot of bikes have reverse... a few.. but not many) and the shaft pulls .. I'd guess that would be very sudden death for most non marine gearboxes. |
On Tue, 08 Feb 2005 12:28:59 GMT, "Keith"
wrote: http://www.scavengerbackwater.com/scavenger.html I've even seen folks use little gas powered weed eaters, replacing the fishing line cutter with a little prop. Noisy, but inexpensive and basically disposable after a couple of seasons. I have one of those. It's loud but it works well. Much better than a battery powered trolling motor. Batteries die quickly but I have went 5 miles on a pint of gas in my canoe. What it really needs is gearing though. I have worked out a few designs but have not came up with anything that would be easy to build and would work well. If I could make that little 2 cycle engine go double the rpm I would have twice the power and the engine would run better. Little 2 cycles don't like low rpms. I got tired of the weedeater engine and converted the canoe into a 4 stroke inboard. Used a 2hp Briggs and Stratton motor. Little canoe was quite fast in that incarnation. Then I got an old fiberglass semi-v jon boat with a 15 hp outboard. The canoe sat until the sawhorses I kept it on collapsed and tiny black ants felt like my transom was a good home. I may rebuild it again someday. I have rebuilt that canoe like 10 times in the 15 years I have owned it. But first I need to build me a new boat. The semi-v is over 40 years old and the fiberglass acts more and more like it is going to just give one day. What I need is a method of boat building that doesn't cost much of anything. I have thought about using cheap materials, but all the cheap ones will make the boat less safe than the one I have now. I need to build a 15ft boat that is capable of carrying 6 people for less than $200. Is it possible? Caveat being that is has to be a safe boat that will last more than one season. |
I've noticed a few ads in "Ducks Unlimited" magazine for Harley-Davidson
Evolution engines in duck hunting boats (shallow draft john boats, like Polar-Craft) using the far east style long shaft open prop. Several U.S. manufacturers. Anyone out there got a Ducks Unlimited mag handy to give an address? I don't have one. I saw the mag in a hospital waiting room a year ago. They looked well made and were expensive, knowing how $$$Harleys$$ are. You could steal ideas from the ads. Seems I remember the were using 4 blade chopper props for working in weeds and muddy waters. Good luck. "ewan" wrote in message ... this is more of a theoretical question more than anything else but a couple of mates and i were chatting about boat building and engines in general. basicly ive heard a lot of engines are based upon marinised car engine based but i got to thinking how simple it would be to use a shaft drive bike engine {1} since theres a wide range of shaft drive engines from 550s to 1100cc especialy the 900cc yamaha diversion engine which is dirt cheap. i know the engines wouldnt last as long but sing they start at £80 from breakers{2} means it could be treated as disposable item like petrol. im just posting to see if there is any serious flaws in the idea such as not enough torque or other variables {1} i guess i would have to work out the forces and calculate propeller assuming the revs arent to high {2} breakers tend to sell all the stuff that breaks in a crash like plastic and bits that rust leaving them with the engine which most folk dont want to replace |
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