Free wheeling

[Rocket09]

Hello all, I have read my transmission manual and I can use only one engine, but I can not see the advantages of using only one engine while running. Will I really save on gas ? What would be the advantages? Anyone done it ?

Merci

[tomschauer]

if you run on only one engine, you will save some fuel if you are happy running about 4 knots and constantly steering your boat. Much faster, fire up the other one.

[bobeast]

You know when you have a sprained ankle you try to run? Yeah its kind of like that. You can do it, but you won't enjoy it.

[jcoll]

If you have dripless shaft seals it's my understanding you'll need to secure the non-running motor's propshaft so as not to damage the seal. Water from the exhaust manifold supplies the seal as a cooling lubricant. While running through the water the prop will spin on the dead motor and cause damage. I suppose you could idle the one motor but the question becomes...... Is it worth it?

[Viper]

Source of the post If you have dripless shaft seals it's my understanding you'll need to secure the non-running motor's propshaft so as not to damage the seal. Water from the exhaust manifold supplies the seal as a cooling lubricant. While running through the water the prop will spin on the dead motor and cause damage. I suppose you could idle the one motor but the question becomes...... Is it worth it?

+1
Don't know at what speed that becomes a problem and you probably wouldn't be going fast enough on one engine but it's something else you'd need to worry about. Also, if you have the type of dripless that are fed off a manifold from both engines and both dripless logs are plumbed together, there have been cases where water from one log goes through the other log and up to the static engine's manifold. Because there is no exhaust pressure, under the right conditions, the engine can ingest water trying to exit from the elbow. Because of this, Mercury issued a recommendation years ago to do away with the connection between the two logs in case one engine fails while underway so it doesn't ingest water.

[jcoll]

Viper, that makes sense and if anyone should know about water ingestion problems it would be Mercury! They had their fair share of those issues. LOL!

[Rocket09]

Thanks for all your reply, I guess I wil continue with 2 engines.

[km1125]

I've read articles before where they actually tested this and provided data. In some cases it was a pretty minor savings but in others it made sense. Probably depends on the hull a lot and the prop sizes. There was also a difference of opinion on whether it was more efficient to lock the non-running prop or let it freewheel. I don't remember now how that concluded.