TWL: Single engine performance of twin engine boats
I'm of the mind that a good engine will run forever given the proper
care and feeding so I've started looking for a single engine trawler,
40-50', and, not being willing to die for my beliefs, would like some
kind of get home engine. When I talked to a broker about this he
suggested I still wanted a twin engine boat and that I could run it on
one engine for efficiency. Other than the obvious inefficiency of a
freewheeling prop and having to keep the rudder turned to one side while
trying to keep a straight course, I was wondering if this was a feasible
alternative to a single engine. I know that Navy ships do this to save
fuel while sacrificing top end speed. Autopilot would probably handle
most of the difficulty in steering. Engine use would be rotated to keep
the hours even. What's the downside and would there be any appreciable
difference in fuel savings?
Just doesn't seem right to me but I've only had fast boats. Trawlers,
I'm learning, are a whole 'nother breed.
Steve Kress
Not a trawler owner - yet
Your biggest risk operating on one engine is the condition of the gears.
They will be operating without active lubrication or cooling (the lube pump
is engine driven). Some gears are okay, some are not.
Personally, I do not take the risk...gears are real expensive!
Bob
R C Smith Jr
M/V MARY KATHRYN
Hatteras 58 LRC
Currently lying Annapolis
At 10:48 PM 10/16/02 -0700, you wrote:
I'm of the mind that a good engine will run forever given the proper
care and feeding so I've started looking for a single engine trawler,
40-50', and, not being willing to die for my beliefs, would like some
kind of get home engine. When I talked to a broker about this he
suggested I still wanted a twin engine boat and that I could run it on
one engine for efficiency. Other than the obvious inefficiency of a
freewheeling prop and having to keep the rudder turned to one side while
trying to keep a straight course
Just one observation from personal experience experimenting with running
with one engine on a twin engine boat.
The autopilot had a very difficult time satisfactorily steering to overcome
the obvious tendency of the boat to steer itself off course, toward the
direction away from the side of the engine being used. This could simply
reflect the rudder size, autopilot power, etc. The final result was that
the boat had to be hand steered much of the time, particularly when wave
action tended to steer the same direction as the engine being used. On our
particular boat I don't see it ever being a practical option, except for
emergency use in case of an engine failure.
Dan Stone
M/V Slow Dance
Albin 43
St. Petersburg, FL
<I'm of the mind that a good engine will run forever given the proper
care and feeding so I've started looking for a single engine trawler,
40-50', and, not being willing to die for my beliefs, would like some
kind of get home engine. When I talked to a broker about this he
suggested I still wanted a twin engine boat and that I could run it on
one engine for efficiency. Other than the obvious inefficiency of a
freewheeling prop and having to keep the rudder turned to one side while
trying to keep a straight course, I was wondering if this was a feasible
alternative to a single engine. I know that Navy ships do this to save
fuel while sacrificing top end speed. Autopilot would probably handle
most of the difficulty in steering. Engine use would be rotated to keep
the hours even. What's the downside and would there be any appreciable
difference in fuel savings?>
Steve,
A few thoughts on this:
-
I'm not sure that you'll experience a significant fuel savings by
running on one engine, unless of course you run slower. I believe there
was a list discussion on this subject a year or so back and most people
didn't report dramatic savings. -
If the fuel savings aren't there, then your next reason to consider
is a get-home engine, which has been discussed ad nauseum on the list.
In short, unless you're doing extensive offshore running, a dedicated
backup engine may not be needed. Your dinghy or some other method (or a
tow company) may be a suitable choice for the rare times you need it. -
Since you already are convinced that an engine will run forever
given good maintenance, there would be no lifespan advantages to having
a second engine since the first engine will run forever anyway. -
With twin engines you have double the maintenance (almost), and two
engines crammed into the space where one would sit. -
With twin engines you have exposed running gear, which is probably
more at risk of damage than your engine is of failure. -
If you really want a twin engine boat, then I'd recommend looking at
a trawler catamaran. You'll get far better fuel economy, as well as
better speed. Both sets of running gear are protected behind a keel.
And all reports are that they run and handle well on one engine. -
And finally, I'm guessing that your broker has a whole bunch of twin
engine boats he'd love to sell you, but doesn't have many single engine
boats.
In summary, I think getting a twin engine boat with the intention to run
it on one engine is kind of the worst of both worlds.
Bob Deering
Juneau, Alaska
Alaska Pacific Yacht Charters
www.AlaskaPacificYachts.com
Not to mention that two engines cost twice as much as one to begin with.
- And finally, I'm guessing that your broker has a whole bunch of twin
engine boats he'd love to sell you, but doesn't have many single engine
boats.
In summary, I think getting a twin engine boat with the intention to run
it on one engine is kind of the worst of both worlds.
--
Keith
There is nothing new I can teach the sea.