Propane Outboards

[CJL]

Anybody seen these before??

LEHR Marine |

The chap who services my engine is selling them now and they seem an interesting alternative for the occasional boater.

Chris

[willk]

What advantages have they got over 4 stroke petrol engines?

[office888]

Originally Posted by willk

What advantages have they got over 4 stroke petrol engines?

Higher octane (about equal to avgas / race fuel)
Cheaper per equivalent gallon
No ethanol
Cleaner burning (less impurities)
Lower maintenance (less harmful residues left behind in the engine due to cleaner burning)

You can go longer on oil changes too since there aren't a lot of contaminates suspended in it.

[willk]

Originally Posted by office888

Higher octane (about equal to avgas / race fuel)
Cheaper per equivalent gallon
No ethanol
Cleaner burning (less impurities)
Lower maintenance (less harmful residues left behind in the engine due to cleaner burning)

You can go longer on oil changes too since there aren't a lot of contaminates suspended in it.

That's interesting. Lehr's promotional material (attached) suggest that despite the higher octane, the propane 2.5 HP is much less powerful than a Merc 2.5hp gas engine...

[office888]

Originally Posted by willk

That's interesting. Lehr's promotional material (attached) suggest that despite the higher octane, the propane 2.5 HP is much less powerful than a Merc 2.5hp gas engine...

That's not exactly what I would call scientific testing.

There may be gearing differences between the two units as well.

[willk]

Originally Posted by office888

That's not exactly what I would call scientific testing.

There may be gearing differences between the two units as well.

Point taken for sure. I think if I was Lehr, I'd use more scientific testing for my promotional material

[Crusher]

And you can easily refuel.... Where?

[ShinyShoe]

B&q...

[captnjack]

Originally Posted by Crusher

And you can easily refuel.... Where?

Propane is the standard yachting fuel for cooking over here. Alcohol and diesel stoves are a very distant 2nd + 3rd. Compressed natural gas (methane) is non-existant in the yachting world.

So pretty much every marina on the west coast of North America has propane. The 1lb canisters seem like a bad way to go though. They aren't really refillable while being heavy and taking up alot of room too. The composite tanks are rustproof and light.

Floodproof and quickstarting seem like pretty admirable qualities in a tender engine which might go long periods between use.

[Nos4r2]

As does fuel not going stale. You'd have to carry a lot of propane to run one as an auxiliary though and it wouldn't be easy to monitor fuel levels.

[Turbodiesel]

I spent a year or so trying to modify outboards to run on LPG with little success! We had some LPG experts helping out from a few companies but we could never get them to run well and yes they loose power when running on gas! The biggest problem we found we could never get the gas hot enough to burn properly, which cause the engine to stall when you shut the throttle down, also the massive assize head ache of trying to pass all the regulations for keeping LPG on a rib it was just not worth the hassle. We did sell about 10 15hp Mariners that were converted with t prins LPG system so they must be about somewhere, and we also converted a few Merc 60 four strokes. They never really ran very well when on has and we just used to run the on petrol most of the time!

[m chappelow]

http://youtu.be/X7Ynv_9H5KE unless you have oil injection down side for 2 strokes is oil lubrication lol or the easy way http://youtu.be/fpd-gG4ZIv0 Company i worked for in the mid 1970s when the fuel shortages & 3 day week was on decided to convert all the company cars 200 ford cortinas /granada' as well as a couple of the company boats with inboards ,They ran ok with just a tad down on power on motorway use ( cars) biggest problem in those days were that you had to start with petrol until the engine was warm before it would run on gas then every 60 miles swap back from gas to petrol for 5 mins or so to stop the valves burning out , owing to petrol in those being leaded & the propane not having any lead in it , modern engines built for unleaded should be ok as they have harder valves . Seem to remember some outboard company promotion in the Early 1990s saying that they had Delivered half a dozen lpg converted outboards for some harbour authority .

[jyasaki]

Originally Posted by office888

Higher octane (about equal to avgas / race fuel)

What does that have to do with operation?

Octane is a burn retardant; higher performance engines need higher octane ratings because the higher temps and compression ratios will cause detonation if you have gas with lower octane ratings. Octane does nothing for performance with a given engine.

Back on topic, I saw that, in the US, West Marine has started selling propane powered outboards, but I was on a mission, and didn't investigate any further.

jky

[gohelm]

Originally Posted by Turbodiesel

I spent a year or so trying to modify outboards to run on LPG with little success! We had some LPG experts helping out from a few companies but we could never get them to run well and yes they loose power when running on gas! The biggest problem we found we could never get the gas hot enough to burn properly, which cause the engine to stall when you shut the throttle down, also the massive assize head ache of trying to pass all the regulations for keeping LPG on a rib it was just not worth the hassle. We did sell about 10 15hp Mariners that were converted with t prins LPG system so they must be about somewhere, and we also converted a few Merc 60 four strokes. They never really ran very well when on has and we just used to run the on petrol most of the time!

I know there has been a project here in the netherlands as well with a dolphin / honda LPG RIB which is / has been running with the Amsterdam police for at least a year . Next to the fact that I would not let the builder/conversion company even near my boat for such conversion(see the bits about a certain suzuki 250 engine on this forum to understand why) I also understood that range with (limited fuel capacity) LPG is an issue (you need to carry your fueltank on deck or something?) next to above mentioned loss of power. Did you also notice a different throttle response?

[ShinyShoe]

Can see an issue with using up the 'dregs' in the tank...

So I take it for a bit of a jolly and use 3/4 of the gas up. I now have a 1/4 cylinder of gas.

Fine if next time out is a quick dash across harbour, but if its another 3/4 tank jolly I have to have 2 cylinders on board to only carry 1 1/4 cylinders of gas...

With petrol I'd just top the tank up...

If you have something else that can use the dregs up and takes the same gas fitting you might be sorted... (BBQ, patio heater, caravan, forklift...) of course they all use different fittings but there are means and ways...

[m chappelow]

Suppose those operating in cold climates may have issues with the gas bottle freezing up .

[Turbodiesel]

We also had problems with premature failures on fuel pumps as they just couldn't last when running on gas. We had big problems with storing gas on ribs, we build one with Ribcraft with the gas tank under the floor in the centre, but the regulations here say the gas locker must be vented to the outside of the boat below the lowest point in the locker which was under the water line, we couldn't use a blower as they said it could ignite the gas vapour if you had a leak. So we couldn't get a solution to vent the locker that they would accept. The only way was to have a tank on the deck but to get the range the tank has to be pretty big and they weigh a tonne! And take up quite a bit of space!

[Dirk Diggler]

We had great fun doing this at Windermere in 97, using mercury 2 strokes running on LPG

http://www.conistonpowerboatrecords....04tg1e9v2t.pdf

[Wild_Bill]

I think these engines are cool. I hope they become popular. I especially like the reduced emissions and that LPG can't be spilled in the water like gasoline. However, I would not buy one. I would worry about being able to tell how much fuel is left and also fuel availability. The killer for me, though, is that the Honda 20hp can be purchased for US$3,000 and weighs 104 pounds. The LEHR 15hp can be purchased for US$2,930 and weighs 110 pounds. That's apples to apples: both are short-shaft, tiller, rope-start.

[Jim Robinson]

My main concern would be parts back up. Obvious user will be yachtsman, if it goes wrong and you can't get ashore and parts arent available at the next stop you will be prety un happy, also the gas storage issue if you put the engine in a locker.