propane vs gas 5-6HP outboards?

[JBP]

Originally Posted by LibertyAtNight

Am I wrong to believe that it's like exchanging a propane tank for your grill?

You can get refillable propane tanks in 1/4 pound, 1 pound, 5 pound, and 10 pound. Refilling them is far cheaper than exchange, plus you don't have to use the huge 20lb tanks most exchange places carry.

If you have propane on your boat, you can refill them yourself. Note most 1 pound camp stove tanks are not refillable, you have to look for the refillable kind (though some people have figured out how to refill the non-refillable tanks).

[cottonsail]

Originally Posted by HopCar

I sold Lehr propane outboards. I got tired of rebuilding the carb of my gasoline 2 hp outboard every time I wanted to use it. The propane outboard started easily every time, once you learned the trick. The Lehr 2.5 would run for an hour at full throttle on a pound of propane. The 5 hp would run for half an hour on a pound of propane.

I think propane is an excellent fuel for small outboards. Unfortunately Bernardo, the owner of Lehr, envisioned making very large propane outboards. He should have concentrated on improving the quality of the small ones.

What is the trick?

[Mr. Kevin]

Originally Posted by Shaneesprit

...rowing is faster for the first few hundred meters / yards.

Perhaps you need an engine upgrade to extend the range?

[Nicholson58]

The answer depends entirely on where you plan to cruise.

Refilling in the Caribbean and almost anywhere outside of the US is way more expensive for propane, takes several days with a courier. French islands have no propane. LNG does not exist. Electric is incapable of long transits. It is slow especially with people and groceries. Distances are often two miles or more and sea/wind state frequently difficult. Charging will often require your generator. Three electric OBs failed utterly due to water ingress last season on the Salty Dawg rally. Many high density (non-LiFePO) are responsible for boat fires although the OBs have not been implicated.

Gasoline is ubiquitous. We run 15 HP. This is about the average. It can plane your boat, get you to a dive site with tanks, rescue your boat.

[HopCar]

Originally Posted by cottonsail

What is the trick?

You need to bleed the air out of the fuel line the first time you start the engine for the day. To do that you need to remove the cover and stick a small probe (paper clip or like) into the hole in the center of the regulator. Listen to it hiss for a few seconds as air is vented and engine is primed with propane. After this the engine should start on one or two pulls the rest of the day.

[SMBSF]

I had the Lehr 3.5 hp outboard for a few years.... The propane was great but the engine was a POS. Tried to do repairs and replace parts but was a never-ending PITA. The advantages of Propane and storage ability are really great assets unfortunately the LEHR engine I had was poorly designed and engineered for the use of propane which far offset its natural advantages.

[MikeHoncho]

Originally Posted by SMBSF

I had the Lehr 3.5 hp outboard for a few years.... The propane was great but the engine was a POS. Tried to do repairs and replace parts but was a never-ending PITA. The advantages of Propane and storage ability are really great assets unfortunately the LEHR engine I had was poorly designed and engineered for the use of propane which far offset its natural advantages.

100% agree. Luckily mine is still doing ok. Love the concept, hate the brand.

[Shaneesprit]

Originally Posted by Mr. Kevin

Perhaps you need an engine upgrade to extend the range?

Perhaps I am quite good at rowing and the rowing helps with my shoulder injury from a Skiing ⛷️ accident.
I am considering an outboard but only because of boat visitors.
Well I have 2 at present but easier to buy another than fix the old ones.

[FlyingScot]

Not very many satisified LEHR propane users and many more unsatisfied users. That should tell you to steer clear of the idea until more reliable brands come to market. Of course that may never happen.

Use case matters, but it is hard to beat some good old gasoline/petrol.

[Pete7]

Originally Posted by Nicholson58

French islands have no propane. LNG does not exist.

Do the French islands not have Camping Gaz?

Pete

[Jammer]

Tohatsu makes a 5hp propane outboard that is also sold under the Mercury brand. They have one in stock at my local West Marine. These are essentially the same as the gasoline engines with a regulator and mixer in place of a carb. They are available in a variety of shaft lengths and with either a standard or high-thrust lower unit.

I've worked with and around propane engines for years. Had a family friend who had a propane-powered Chevrolet Suburban back in the 1970s. Neighbors with tractors. Forklifts. Standby generators at radio and cellular installations. Standby generator at a family member's farm.

Propane has two advantages:

1) The fuel does not deteriorate over time, because it is not exposed to air and because it is chemically more stable.

2) There is improved engine reliability in standby applications (where there are long periods of disuse) because fuel is vaporized in the tank rather than in a carburetor.

That's it. Propane is harder to handle because you can't pour it from one container to another. There are fewer places to buy propane. Unless you're buying it 100 gallons at a time or more, it is generally more expensive.


I would consider a propane outboard for standby or occasional use where annual service is not feasible, for example as a spare in an inaccessible cottage (e.g. fly-in or water access only), or for a duck boat where it is known that it won't be used except for 4 weeks a year.


But despite the many, many threads on carburetor/fuel/ethanol/etc problems the reality I have experienced is that ordinary gasoline out of the pump works reliably. Carburetors do require replacement or overhaul every few years and care must be taken to discard old fuel and store fuel in sealed containers out of the sun.

[MikeHoncho]

Originally Posted by FlyingScot

Not very many satisified LEHR propane users and many more unsatisfied users. That should tell you to steer clear of the idea until more reliable brands come to market. Of course that may never happen.

Use case matters, but it is hard to beat some good old gasoline/petrol.

Most major brands offer propane versions.

[MikeHoncho]

Originally Posted by Jammer

Tohatsu makes a 5hp propane outboard that is also sold under the Mercury brand. They have one in stock at my local West Marine. These are essentially the same as the gasoline engines with a regulator and mixer in place of a carb.



I've worked with and around propane engines for years. Had a family friend who had a propane-powered Chevrolet Suburban back in the 1970s. Neighbors with tractors. Forklifts. Standby generators at radio and cellular installations. Standby generator at a family member's farm.


Propane has two advantages:


1) The fuel does not deteriorate over time, because it is not exposed to air and because it is chemically more stable.


2) There is improved engine reliability in standby applications (where there are long periods of disuse) because fuel is vaporized in the tank rather than in a carburetor.


That's it. Propane is harder to handle because you can't pour it from one container to another. There are fewer places to buy propane. Unless you're buying it 100 gallons at a time or more, it is generally more expensive.

Your missing my biggest positive…. I don’t have to store a flammable liquid on the boat in a plastic container requiring 3 fuel types.

[Jammer]

Originally Posted by Shaneesprit

So I am not the only one who prefers to row. If I take the maintenance and the lifting into the travel time - rowing is faster for the first few hundred meters / yards.

I have hard (non-inflatable) dinghies because they row well.

There is an upper bound on how far it is reasonable to row. Just the other day I was using the motor for an 8 mile upriver (8 up/ 8 back) exploration. I think of 2 miles each way as being more or less the limit for me, for rowing.

[Nicholson58]

Originally Posted by Pete7

Do the French islands not have Camping Gaz?

Pete

Yes, however, that is butane and may require orifice modification of the appliance and adapters to connect to your system. Your propane tanks will not be filled there. Only swap tanks are available so you must buy tank #1. Tanks are steel, blue paint and almost always rusty. The connection port is usually beat up and scary. Do you want two sets of tanks, propane and gaz, on board? Is your locker big enough? What do you do with the gaz tanks when you leave?

Best gas deal in the Caribbean is Trini-mix on Trinidad. A 20# tank provided cooking last season, 7 months, and is still not empty. It is propane and a few other gasses straight off the wells. This 20 pounds packs more BTUs than propane alone. It runs fine in all applications. Refill is a bargain at less than 20 TT, about $3 US. We load everyone’s bottles into a rental and take them to the gas refiner.

Trinidad diesel is also a good deal except at the marina. Same rent car plan to regular fuel stations or arrange with a commercial hauler. My last fill was 250 gallons at $2.50/gallon.