Using Only One Engine ?

[skipperjon]

SIMONMD, it does work on a monohull. My boat is only 31', but earlier this summer I couldn't restart one of my engines and had to return to my anchorage on one engine. It ran and tracked just fine both on autopilot and manual.
John

[simonmd]

Oh sure, you can go on just one engine, of couse. What i'm saying is that it's not a 'normal' thing to do. The main point of the question was whether it would be worth doing to save fuel, etc. With one engine it will have to work harder and you'll have more drag in the water due to the rudder being almost hard over to keep in the straight line so i can't see any advantage.

After all, most twin engine aircraft can safely fly with one engine. But they would never do so by choice for the same reasons. With the price of fuel these days if it was worth it, they'd all be doing it!

[skipperjon]

Originally Posted by simonmd

Oh sure, you can go on just one engine, of couse. What i'm saying is that it's not a 'normal' thing to do. The main point of the question was whether it would be worth doing to save fuel, etc. With one engine it will have to work harder and you'll have more drag in the water due to the rudder being almost hard over to keep in the straight line so i can't see any advantage.

After all, most twin engine aircraft can safely fly with one engine. But they would never do so by choice for the same reasons. With the price of fuel these days if it was worth it, they'd all be doing it!

You are right. It's not normal to run on one engine in a boat with twins, but I hear that it's not an uncommon practice. How much fuel is saved that way? Will it hurt the tranny or the shaft bearings?
John

[simonmd]

I can't imagine that there would be anything to worry about tranny or bearing wise on the engine but like I said, can't see the fuel saving to be worth the bother once the extra drag and the fact it will have to work harder has been taken into account.

Best way to save fuel? Throttle down, simple. For example, a boat capable of 20kts will use a third of the fuel at 10-12kts. As you're obviously not going to be going that fast on one engine, you may as well have two of them running light than use one running hard.

[Talefin]

Running a twin powerboat with one engine shut down can be dangerous if you don't secure the shaft of the other engine. The transmission and drippless shaft seals are both cooled by the engines raw water pump and you may be damaging both, not usually a smart thing to do.

[DeepFrz]

If you have dripless shaft seals you may damage the one on the shutdown engine unless the shaft is prevented from turning. A normal stuffing box will not be damaged.