The Right Way to Run a Diesel

[captain58sailin]

FWIW I was referring to vessel engineers, not mechanical engineers. I have no point.

[psneeld]

Originally Posted by captain58sailin

FWIW I was referring to vessel engineers, not mechanical engineers. I have no point.

From my experience.. many ship engineers have little experience with small high performance diesels and vice versa...all I'm saying one size don't fit all...every vessel's drive train is unique (unless a class vessel with stock propulsion)...even then loading can affect top performance....so to throw out sweeping statements or to take them to heart may not do your particular diesel any favors...

Just like oil viscosity and multi-weights...more opinions out there than facts...

[deckofficer]

As psneeld said, "one size don't fit all" amen. The one point I would like to make is don't make your diesel work hard or rev fast until complete temperature equalization due to the non-uniform expansion rates of engine parts vs the mass of the moving part. To drive home this point, my last diesel produced 65,000 hp @ 118 rpm and the computer would draw out ramping up from full ahead (14 kts) to full ahead sea speed (18 kts) for 1 hour.

[off-the-grid]

Well...according to the Westerbeke manual, there really isn't any recommendation after the break in period.

Considering I'm the 4th owner and the boat is 11 years old, I guess I'm already either golden or screwed.

[Cheechako]

Originally Posted by grunzster

Well...according to the Westerbeke manual, there really isn't any recommendation after the break in period.

Considering I'm the 4th owner and the boat is 11 years old, I guess I'm already either golden or screwed.

Yeah, alot of fuss about nuttin'! Just warm it up and use it however it works for you. Ya'll can hear/feel the sweet spot ! It's a tool, use it how you need it.

[off-the-grid]

True, you can just tell when it's happy or not.

[Jim Cate]

Here's another way to look at things:

Modern automotive diesels are closer in design parameters to our little marine applications than are big truck/tractor engines. In a typical auto, top speed might well be circa 100 mph, yet most miles are covered at 65 mph or less. This would approximate using the engine at less than 1/2 its maximum power output, and in-town driving less than that. This operation doesn't seem to cause glazing or all the other ills forecast by the doom-sayers above.

I reckon that we're worrying too much about these things. Not lugging the engine, not running at elevated or seriously depressed temperatures and changing fluids on schedule will provide a useful lifetime for our engines.

Cheers,

Jim

[Tim Schaaf]

I have always felt this is one huge advantage for well powered catamarans and other twin engined boats. Designers of single engine boats have a tough compromise. Use a smaller engine to keep it loaded (a true "auxiliary") and you may not get to hull speed, especially when punching into the wind and waves. Use an engine that can do that, which is what most customers will ask for, and you are seriously overpowered the rest of the time which means your engine is not sufficiently loaded ( I am talking about pleasure boats here, and sailboats, mostly).

On a cat with good sized engines, on the other hand, you can run on just one engine most of the time, and run both on those situations where you need more power. In either configuration, the engine(s) are loaded up. On my cat, I can cruise all day at 7 knots at 2850 rpm. With two engines, same RPM, I get maybe 8.5, and after that, I just push more water. I can get 8 knots with both engines at about 2650-2700 rpm. Guess what is my favorite mode, most economical, least wear and maintenance (one engine) and well loaded up.

It frustrates me to see cats with smaller engines, because they are back in the same soup as the single engined boats, except with twice the maintenance. The bigger engines help maneuvering in wind, too. I can come off a mooring in 20 - 25 knots of wind with mainsail up, and do a 360, almost in place.

[Jd1]

Is there such a thing as a feathering prop that has pitch control at the helm similar to aircraft propellors ? You can then run the engine at any speed you like and adjust pitch to the chosen engine load. I guess it would require a replacement prop shaft to allow for a pitch control of some kind. A bit more complex but I would be curious how much of an overall performance or engine life gain could be achieved.

[Chief Engineer]

Yes...Hundestadt (sp) is the MFR. I have experience with them on a large Sailing Yacht....very popular on Fishing boats that have no marine transmission. Feathers forward/aft. EGR gauges are very important in this case.

Originally Posted by Jd1

Is there such a thing as a feathering prop that has pitch control at the helm similar to aircraft propellors ? You can then run the engine at any speed you like and adjust pitch to the chosen engine load. I guess it would require a replacement prop shaft to allow for a pitch control of some kind. A bit more complex but I would be curious how much of an overall performance or engine life gain could be achieved.

I have also worked on smaller ones on Albins (volvo engine)

[psneeld]

Originally Posted by Jd1

Is there such a thing as a feathering prop that has pitch control at the helm similar to aircraft propellors ? You can then run the engine at any speed you like and adjust pitch to the chosen engine load. I guess it would require a replacement prop shaft to allow for a pitch control of some kind. A bit more complex but I would be curious how much of an overall performance or engine life gain could be achieved.

Avariable pitch prop might cost more than the engine, is high in maintenance usually for what it is...and VERY easy to seriously damage...but other than those and I'm not sure they make small ones...try one!!!

[Jd1]

Originally Posted by psneeld

Avariable pitch prop might cost more than the engine, is high in maintenance usually for what it is...and VERY easy to seriously damage...but other than those and I'm not sure they make small ones...try one!!!

Do you know this based on experience or on guessing ? It could very well be correct but I see no reason why they would be substantially different in terms of maintenance and potential damage than a feathering prop. The primary difference being a small hole in the center of the propshaft for hydraulic control of a spool that controls the blade pitch.

[psneeld]

Originally Posted by Jd1

Do you know this based on experience or on guessing ? It could very well be correct but I see no reason why they would be substantially different in terms of maintenance and potential damage than a feathering prop. The primary difference being a small hole in the center of the propshaft for hydraulic control of a spool that controls the blade pitch.

Guessing... but I do know all those attributes to be true of the larger ones found on military ships.

If you think that adding that complexity is not much...you might be right... but it's still way more than a standard prop will ever be...

[sabray]

Let the thing warm up before you load it. Run it once and awhile don't baby it when you run the thing. Do the pm. Don't use those valve vacuum breaks use a break that pees a little water. Sail alot and don't rely on the thing. Forget abuut turbo stuff. Use a simple aspirated engine. Don't let the engine be your elephant. Soon you will have tanks strapped to your tanks. Multiple outboards hanging in your rails. Spate carbs and cleaners gas cans additives. A nice simple dumb engine will do. A good rowing dinghy is ample.

[TeddyDiver]

Originally Posted by psneeld

Guessing...

You are guessing wrong.. another thing is that today there's not much for small or sailing vessels, and the Norwegian manufacturer doesn't answer a simple quote which pisses me of..