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valhalla360 · 27-11-2016, 17:01

Newer diesels are smaller and lighter than the old ones but gas engines can be significantly lighter for the same HP. For a small engine you want to lift on and off by hand, that weight difference is a major advantage.

Also, for planing dingy's the acceleration of a gas engine is an advantage allowing slightly lower HP to get on plane.

It's not an issue of manufacturers not wanting to provide it. It's an issue of the physics favors gas engines.

Sailuke · 28-11-2016, 06:50

i give it 10 years at most before they're a common sight

HopCar · 28-11-2016, 08:26

Quote BTW, from time to time you hear about OBs that have been converted to propane. Though I'm not sure if that would help, big picture wise. Since you'd probably need to get fuel for it a bit more often than with a gasoline one. So you still have multiple fuel types onboard, with propane being "scarier" than gas, to me anyway.[/QUOTE]

The Lehr outboards have been designed from the start to run on propane. They are not conversions. They have a higher compression ratio than gasoline engines so they can take advantage of propanes higher octane.

If the OP cooks with propane, he could eliminate one fuel from the boat.

To me propane is less scary than gasoline. Propane has a slightly narrower range of propane to air explosive ratios than gasoline and is a lot easier to get rid of if you spill some. I once sat in a gasoline powered boat for several hours waiting for gasoline in the bilge to evaporate and the fumes to ventilate. Propane would have dispersed much more quickly.

While I was sitting there, a police boat came along side. He asked why I was anchored in the channel. I told him my fuel line had broken and I had gasoline in my bilge. He left very quickly.

JJ77 · 28-11-2016, 09:53

Neander Shark just came along with a 50 hp,800 cc 111NM diesel outboard,Dtorque 111 or something they call it.It weighs 175 kg,yet it is quite economical.
It does require a big tender though,not sure if they are going to produce a smaller one.

Dtorque | TURBO DIESEL

DTORQUE | Dtorque

Cheers,
JJ

OrangeCrush · 28-11-2016, 09:59

Quote:

Originally Posted by Sailuke

i give it 10 years at most before they're a common sight

Call me skeptical on this one. The pressures inside a diesel are much higher than those of a gas engine, which means all the cylinders, pistons, etc must be thicker and heavier. This is not about to change (barring a revolution in metallurgy). It's nearly impossible to make a lightweight diesel engine, which is why you don't see many below 20hp, especially not in outboard form. (Good info on this in Nigel Calder's book)

**Adelie** · 28-11-2016, 10:11

Klaxon is currently making 4,6&9hp diesel outboards. They weigh about twice what a comparable 4stroke gas/petrol outboard would weigh.

Given the fuel efficiency I think you can make up the added engine weight in a smaller fuel tank, though that may not help weigh distribution problems.

I think they work well in certain niches, are a wash for most uses and wouldn't work well in a few instances.

I am considering the 4hp for my Cal20.

http://klaxondieseloutboards.com/m/c...sel-outboards/

Octopus · 28-11-2016, 11:26

Quote:

Originally Posted by OrangeCrush

Call me skeptical on this one. The pressures inside a diesel are much higher than those of a gas engine, which means all the cylinders, pistons, etc must be thicker and heavier.

That's not always true. When it was launched in 2008, the 2L Subaru boxer diesel was actually smaller, lighter, more powerful and more economical than its petrol cousin

https://www.youtube.com/watch?v=pMrHP3qXJnY

Subaru probably cut too many corners as they had a lot of crankshaft failures in the first two years (I know because I've had one of them).

No good for an outboard, but potentially a good inboard for a powerboat owing to the low CoG of the boxer format.

Octopus · 28-11-2016, 11:36

There are a few diesel outboards being produced in China, for example:
https://www.alibaba.com/product-deta...256926804.html

https://www.alibaba.com/product-deta...420642599.html

I particularly like this one, although I don't think it is actually a diesel (just the Chinese being flexible with the truth):

**a64pilot** · 28-11-2016, 13:52

There are spark ignition engines that burn Diesel.
Lycoming makes one for drones, and I believe Mercury Marine makes one for Special Forces, you see the Military many years ago went to one fuel, tanks, trucks, aircraft etc. all burn Jet-A which is very close to kerosene and works well in Diesels.
When I retired in 02 only thing left that burned gasoline was the cook stoves.

I think, maybe spark ignition engine that burned Diesel might do the job.

**StuM** · 28-11-2016, 14:35

Quote:

Originally Posted by a64pilot

When I retired in 02 only thing left that burned gasoline was the cook stoves.

Back in the 70s and 80s we had diesel stoves in field kitchens.

SV DestinyAscen · 28-11-2016, 14:42

Don't think it is possible to create a diesel engine that is light, economical and with good performance (emissions/reliability/fuel economy) in an outboard.

Diesels are more fuel efficient because they historically have higher compression ratio and the fuel has higher energy density.

To make a small form factor diesel you'll need to have extremely high rpm for a diesel and/or higher than standard compression ratio - which then requires you to use more expensive alloys and probably turbocharge to provide enough air in small volume. It won't be reliable, cheaPt.

**Adelie** · 28-11-2016, 15:11

Quote:

Originally Posted by Octopus

There are a few diesel outboards being produced in China, for example:
https://www.alibaba.com/product-deta...256926804.html

https://www.alibaba.com/product-deta...420642599.html

I particularly like this one, although I don't think it is actually a diesel (just the Chinese being flexible with the truth):

Those look like the Klaxon open engine models.

**a64pilot** · 28-11-2016, 15:23

Quote:

Originally Posted by StuM

Back in the 70s and 80s we had diesel stoves in field kitchens.

US Army?
We always had the M59 stove that ran on MOGAS, but after about the 90's there was no real cooking in field units as we had transitioned to T rations and all they needed was boiling water.
We had Diesel burning water heaters that ran off of a drip of fuel and our tent heaters were Diesel too, but the cook stove was the last thing that ran on MOGAS, well that and lanterns I guess, although when all the aircraft logbooks and manuals went on computers, the lanterns went away as we always had generators after then.