Sailboat Engines- Seems like a Lima would be good.

[Chapap]

Why do (moderni) sailboats always have diesels? Do they handle sitting for long perionds? I'm sailboat shopping and many have bad motors. Seems like a lima would be a good fit. Doesn't need much cooling, more than enough power (20-30hp is typical), good size, plentiful.

Not sure what's special about a "marine" engine. Cooling goes through an exchanger, so it just sees salt air, but not sure how that would differ from a marine engine. A coat of paint might be in order.

 

[Curious Hound]

Why do (moderni) sailboats always have diesels? Do they handle sitting for long perionds? I'm sailboat shopping and many have bad motors. Seems like a lima would be a good fit. Doesn't need much cooling, more than enough power (20-30hp is typical), good size, plentiful.

Not sure what's special about a "marine" engine. Cooling goes through an exchanger, so it just sees salt air, but not sure how that would differ from a marine engine. A coat of paint might be in order.

Gas fumes will pool in the bilge and could cause an explosion. Diesel is a lot safer that way.

And, as you mentioned, cooling is different. The engine coolant goes through a heat exchanger to shed itself heat to the seawater instead of to the air. But many times, the exhaust is also cooled. That way you don’t have hot exhaust pipes penetrating the hull. It’s much easier to keep the cooler components seals to the hull where they penetrate. Older, more simple diesels have much less electrical or electronic parts to corrode in a wet, salty environment. No distributor or points, no spark plugs to get wet, no ignition module, etc. Basically, apart from a starter motor, a diesel can be operated with no electricity.

 

[alwaysFlOoReD]

I witnessed a fishing boat towed into port many years ago. Somehow the fuel line was cut. The deck was slick from people walking thru the fuel. Pretty sure the 2 man crew was stoned out of their minds. Good thing it was diesel, not gasoline.

 

[don4331]

Gas fumes will pool in the bilge and could cause an explosion. Diesel is a lot safer that way.

And, as you mentioned, cooling is different. The engine coolant goes through a heat exchanger to shed itself heat to the seawater instead of to the air. But many times, the exhaust is also cooled. That way you don’t have hot exhaust pipes penetrating the hull. It’s much easier to keep the cooler components seals to the hull where they penetrate. Older, more simple diesels have much less electrical or electronic parts to corrode in a wet, salty environment. No distributor or points, no spark plugs to get wet, no ignition module, etc. Basically, apart from a starter motor, a diesel can be operated with no electricity.

The #1 reason is fumes - if you have a gas engine, everything needs to have a spark arrestor, so an accidental leak doesn't cause an explosion - which gets expensive.
The #2 reason is gasoline engines create carbon monoxide - which is why the forklift inside the plant runs on propane, not gasoline.

Diesel is way safer.

Now, as far as a 'marine' engine; they are built with heavier duty parts as the load on the engine is much higher. Driving 60mph, you're Ranger is only requiring 10 hp, (5% of what your 4.0 can output). Running your sailboat 10 kn, is requiring the 20 hp diesel to output 15 or more. (75+% of max).

 

[racsan]

Theres something called a “bilge blower” in boats with a engine inside the hull, the exhaust manifold is marine-specific, its water cooled. Theres no air cleaner but a metal spark arrestor made up of thin metal plates, (in case of backfiring). the starter and alternator are supposed to be sealed in a manner that prevents any bilge fumes from being ignited. Back when point distributors were used they only had a mechanical advance, no vacuum. It’s possible theres a “marine profile” camshaft but other than that, theres not much difference between a automotive engine vs a stern drive boat engine.
I have seen 2.3 lima’s in boat application, back in the late ‘80’s starcraft had a aluminum cabin cruiser/fishing boat called the islander. Most of the 19-22 ft ones I saw had the 2.3 lima, I think their rating in a boat was 120.
Boat horsepower ratings seemed to be higher than automotive, the chevy 350 was rated at 260 back in the day, a 454 was 330.
I have no idea what is up in todays boats, I worked at a family owned boat dealership right out of high school in the late ‘80’s to the mid-90’s.

 

[Chapap]

Didn’t think of the explosive gas part. That alone I think is reason enough to ditch the idea. I’ve also wondered why there aren’t any diesel outboards. Ive found some 20ish hp outboards for commercial use, but it seems that diesel would be much better suited for any marine engine.

… plus, finding a good prop to match it would take a few attempts.

 

[MISWFL]

Diesel is a far better industrial fuel than gasoline and is/should be cheaper as it's basically a by product of gasoline production. I don't mean the modern low sulfur nonsense. Diesel has an almost indefinite shelf life, if you can deal with the "algae" that sometimes grows in it.

 

[85_Ranger4x4]

Fuel efficiency would probably greatly favor the diesel as well. If your sailboat can only carry say 10gal of fuel since that isn't intended to be its primary mode of propulsion and something goes sidways and it becomes your primary mode of propulsion... 10gal of diesel will probably get you farther.

 

[don4331]

I’ve also wondered why there aren’t any diesel outboards. Ive found some 20ish hp outboards for commercial use, but it seems that diesel would be much better suited for any marine engine.

… plus, finding a good prop to match it would take a few attempts.

The issue for a diesel outboard was power to weight: The 2.2 Ranger diesel made 59hp while the 2.3 Lima made 112hp - almost double and a 2 stroke, as used historically in outboard would make even more power per displacement. And the 2.2 is heavier then Lima while outboard was made from aluminium so 1/2 weight of Lima.

With current technology, a diesel outboard might get competitive on power to displacement, but its still going to weigh substantially more.

 

[racsan]

another thing with the diesel outboard idea- epa would probably shoot it down. New 2-cycle outboards havent been made for quite a few years now due to the epa.

 

[Blmpkn]

another thing with the diesel outboard idea- epa would probably shoot it down. New 2-cycle outboards havent been made for quite a few years now due to the epa.

2 stroke outboards are still getting made.. mabey not by the traditional names but there are all sorts of smokers available new on ebay and the like.

 

[scotts90ranger]

The issue for a diesel outboard was power to weight: The 2.2 Ranger diesel made 59hp while the 2.3 Lima made 112hp - almost double and a 2 stroke, as used historically in outboard would make even more power per displacement. And the 2.2 is heavier then Lima while outboard was made from aluminium so 1/2 weight of Lima.

With current technology, a diesel outboard might get competitive on power to displacement, but its still going to weigh substantially more.

The 2.3L lima offered at the same time as the diesel options was rated closer to 80 or 85hp, it didn't go up to 112 until I think '95... but other than semantics I agree completely

 

[4x4prepper]

> Why do (moderni) sailboats always have diesels?

I do not know about always,.

As others have pointed out, it is mostly the explosion issue. Diesel can be found the world over in ports, quality gasoline, not so much.

Sailboats need more torque then HP, so, there is that. Diesels get far better MPG. Diesel fuel can sit for months and be viable, gasoline can not.

But, one of the main reasons for having a diesel on a sailboat is to recharge the house batteries. A diesel at relatively low RPMs sips fuel compared to a high reving gasoline engine.

Many small diesels can be both key started and pulled started as a backup if the electric starter fails. Which is one reason I bought a Yanmar N100 clone.

There is no fuel bowl or a carb that can flood in high and rough seas while being pitched all over the place.

You can also use the diesel fuel in portable heaters.

A diesel does not produce EFI which might interfere with navigation and communications.

All the reasons I can think of from my view of things and from some very limited mechanical work on customer's boats.

 

[85_Ranger4x4]

> Why do (moderni) sailboats always have diesels?

I do not know about always,.

As others have pointed out, it is mostly the explosion issue. Diesel can be found the world over in ports, quality gasoline, not so much.

Sailboats need more torque then HP, so, there is that. Diesels get far better MPG. Diesel fuel can sit for months and be viable, gasoline can not.

But, one of the main reasons for having a diesel on a sailboat is to recharge the house batteries. A diesel at relatively low RPMs sips fuel compared to a high reving gasoline engine.

Many small diesels can be both key started and pulled started as a backup if the electric starter fails. Which is one reason I bought a Yanmar N100 clone.

There is no fuel bowl or a carb that can flood in high and rough seas while being pitched all over the place.

You can also use the diesel fuel in portable heaters.

A diesel does not produce EFI which might interfere with navigation and communications.

All the reasons I can think of from my view of things and from some very limited mechanical work on customer's boats.

Is pull starting a boat a thing?

 

[Curious Hound]

Is pull starting a boat a thing?

Not really