OA 510 Classico transmissions

[Hornloaded]

In my quest to find my next boat I am looking at a 2000 OA 510 Classico that is stabilized and could be bought at a good price.
While we will use this boat local (Channel Islands, CA) for several years, long term we want to do Alaska to Mexico.
I have read many posts of owners, here and on boatdiesel.com, that regularly use a single engine at trawler speeds(7kt) to do LRC.
My question is, can anyone tell me what transmissions this boat would most likely have and can they be left in neutral or locked in gear when off?
This boat has Cat 3126TA engines.
Also, if anyone has one, can you tell me what the engines RPM is at 7kts?

 

[Insequent]

I can't help you regarding transmission brands, but it may not have been a standard spec. Read the name plate when you are on board!

What I and others have found however is that running a twin-engined boat on one engine more likely than not will use slightly more fuel. See attached graph. The issue running on one engine is that I needed 7° of rudder to go in a straight line. That, coupled with drag from the free-wheeling prop more than offset the gains from avoiding the parasitic loads for the second engine. So little to no gain, or more likely a slight loss in fuel economy.

But, I see one advantage of running a twin engined boat on one engine, And that is, with just running one engine to get to the same speed it will be at greater rpm and load, and with a better load-factor. Indeed, at slow speeds neither of the twins are likely to be loaded and warm enough for extended hours of operation. Some engines are more tolerant of low loads than others, usually the newer electronic controlled one are superior in this regard.

I would only run on one engine if I needed extreme range, and was running below 7kn, say 6kn or so. I've never needed to do it, and don't envision ever doing it either.

 

[Ken E.]

Most Twin Disc transmissions can be freewheeled without damage. The TD website has a pdf file with a list of the models that can or cannot be freewheeled. Other gear brands and models cannot be freewheeled at all and the shaft must be locked down to prevent damage, for example the Allison M20s that I had in a previous boat. You can check with the other gear makers for their specifics.

On the topic of running on one engine, I've done quite a bit of that between here and Alaska. The main attraction to me is to increase the loading on the 'On' engine, although I do burn less fuel even with the rudder deflection mentioned above. As I read in superyacht magazines, it is common for the big guys to shut one off to save fuel when crossing, for example, the Atlantic from the east coast of the US to Europe.

 

[Brisyboy]

Don`t for get the other issue of free wheeling a prop - if the stern gland is cooled/lubricated by water under pressure from its running engine - there won`t be any! There are ways around this but it takes a bit of plumbing