Charginging batteries with twin screws

[zinbaad]

I was wondering if there are two alternator/generators on twin screw vessels? If so do they both charge up the system?
While on the dock the other day a sailbot guy came up inquiring & admiring the Albin 31 then suggested only running one engine while underway for fuel economy? He said he knew others who would run & rotate each motor to match the hour meters. Anyone out there ever do this??

[Tuxedo]

Can't reply to the battery charging question, but you could figure it out with a experimentation and a volt meter.

The bigger issue is that if you don't lock your shaft, you can ruin the transmission.

[jleonard]

Many of the twin screw trawler guys alternate engines as you suggest. Depending on your tranny you may or may not be ok. Freewheeling a BorgWarner at trawler speeds for example will not hurt it.

[TD]

I like two engines running since most of my boating is out in the Pacific. For 1-2 gallons/hour to idle an engine is well worth the saftey/reliability for me. When I am inside the ocean I have trolled with only one engine running and one off. If I put my battery switches to "all" it will charge all batteries including the house battery which runs my electronics. In summary though it just doesn't make sense to me to turn off an engine when out in the ocean. I have not checked my flow meter fuel useage on cruising with one engine but, if you are above idle it doesn't make sense because one prop not rotating is a drag and is going to reduce efficiency. I would bet you will burn more fuel than if both engines are running.

[RobS]

You have to check which type of shaft seal you have. The dripless type require cooling water which is taken off the raw water side of the cooling system, Thus the engine must be running to supply the shaft seal cooling water if the shaft is turning or the seal will be damaged.

[jcollins]

Just curious. When you talk about locking the shaft are you just putting it in gear or is there another procedure?

[Maid Marian]

On my 2002 31 TE the house battery was jumped to the port engine battery. I didn't like this configuration because it loaded the port alternator more than the stb. I have since disconnected the jumper and now have the option of switching the house to the port or stb engine. Keep in mind you have to put the house selector switch in both and the engine you wish to charge from in both.