Driving on a single engine

[QBhoy]

So my thoughts…I know that our princess 385 with her twin 61a’s, has shaft stern gland cooling fed from the engine. Yours likely has too. Often wondered around if this should be considered when running on one engine. Or if the non running engine should be locked in gear to stop the shaft turning.

 

[fred247]

no gains,
disadvantages- manoeuvrability severally effected, running and berthing.
hot water port engine, start battery charging stb engine
spend most time running on rivers ( both engines )

 

[scottie]

Jus be aware that it has been known for water to make its way to they exhaust system in the non running engine in longer trips!

 

[jointventureII]

Offset rudders are usually so the shaft can be drawn out without removing rudders.
I reckon a broker is talking b@llocks.

Yes precisely. We are doing the RINA renewal survey on a San Lorenzo 118 (shafts out) and it's made a lot easier because of this. The Sunseeker 28m didn't so rudders out, nightmare.

In terms of the original problem, I don't know if there are gearbox oil temp sensors but if there are, then just keep an eye on that.

When we lost an engine on the Sunseeker 28m, the gearbox oil temp on the out-of-action engine went up about 5 degrees and on the Pershing 108 (triple engine, surface drives) roughly the same when running 2 engines rather than all 3, both times running at about 10-11 knots.

 

[volvopaul]

I have just bought an Atlantic 42 with twin Volvo Penta TAMD63P diesels (2 x 370HP). The engines are mounted close together apparently to facilitate running on a single engine whilst in harbour or on rivers, canals. The rudder offset only being 5 degrees to keep in a straight line. This all sounded good in terms of more economic running whilst limited to 8Kts (local speed limit) but what is this doing to the idle engine gearbox? Hopefully, the gearbox is designed to be spun by the idle prop but could it be doing some damage? Anyone else been in this situation?

Did you call me on Monday to discuss this ?

 

[Greg2]

Atlantics are very nice boats - congrats!

If memory serves the engines being mounted lower was about reducing the angle of the shafts and running on one engine was said to be a benefit but a few extra degrees of rudder don’t really make much difference.

We had a Broom 41 and the gearboxes were okay for running on one engine i.e. prop free wheeling when the engine wasn’t running. I checked the manual for the gearboxes to confirm and to avoid the stern glands getting too warm (water cooled from the raw water system on the engine) we used to run a half hour or so each side - in reality they would do much longer. We ran on one engine when on inland waters with speed limits.

Our current Hardy 36 also has gearboxes that are okay with shafts turning when the engine isn’t running (again it is mentioned in the manual) and we have PSS seals so no lubrication required below 12 knots. We still tend to alternate engines so that we have hot water - we have a split charging system so whichever engine is running will charge all batteries. Again, we run on one when on rivers but would also consider it on a lazy coastal passage.

Benefit’s of running on one engine are putting less hours on the engines (quite a big plus if doing a lot of inland cruising), easier to keep to river speed limits, running one a bit harder with more load and possibly a little less fuel.

No real downsides if we alternate as there will be hot water and the batteries get charged. If manoeuvrability is likely to be an issue (e.g. going into a berth or lock) then we simply start the other engine.
.

 

[oldgit]

On club outings and travelling in convoy with other craft at low speeds , some boats ie. Turbo 36 or Princess 360 really have difficulty in holding a course at low speeds.
This results in them having to use a single engine to hold position with the accompanying loss of steering control or constantly dropping back and then surging forward again.
Most skippers then use alternate engines to make some sort of controlled progress.

 

[oldharry]

Yotty props are freewheeling all the time they are using their sails unless locked off. There is some argument as to whether a stalled prop creates more drag than one allowed to freewheel, and of course the output shaft bearings are subject to wear all the time it is rotating. The general view is that a locked prop causes less drag, but that turns on the prop design and blade area ratio. The heat in a gearbox comes from the friction caused by the presssure on the cog teeth as each gearwheel meshes under heavy load. That will be virtually non existent with the power produced by a freewheeling prop. Heat in hydraulic boxes is caused by the compression of the fluid.

The manufacturers recommendation overrides though. Few yachts have KAD's in them!

 

[PilotWolf]

On club outings and travelling in convoy with other craft at low speeds , some boats ie. Turbo 36 or Princess 360 really have difficulty in holding a course at low speeds.
This results in them having to use a single engine to hold position with the accompanying loss of steering control or constantly dropping back and then surging forward again.
Most skippers then use alternate engines to make some sort of controlled progress.

I seem to remember there being issues around the 9/11 times with fighters not being able to fly slow enough to formate on the wings of some 'targets'.

Photos of incredible angles of attack were common.

W.

 

[Greg2]

On club outings and travelling in convoy with other craft at low speeds , some boats ie. Turbo 36 or Princess 360 really have difficulty in holding a course at low speeds.
This results in them having to use a single engine to hold position with the accompanying loss of steering control or constantly dropping back and then surging forward again.
Most skippers then use alternate engines to make some sort of controlled progress.

Yes, I think that with planing hulls it is less of an option to run on one engine. I should have said that our Broom 41 had a skeg keel, which made it possible and our Hardy is semi-displacement with a chuffing great keel so holds a course well with one donkey doing the work.

 

[Sneds]

Sorry I have no input regarding your 1 engine question but I know Bowhunter, moors next to our Sealine F36 and is a lovely boat.
Congrats on the purchase.