In the April issue of Passagemaker was an article about a boat named
Dreamworld that made a costal trip from San Diego to Canada.

The author indicated that his preferred method of travel is using
only one of two engines for better fuel economy.

I like the idea of using either port or starboard engine
alternatively with the other available as back up and of course, both
engines if more thrust/speed required.

I do not recall reading anything in this use group about such
activity, but it has me thinking ... and having questions.

With the extra-unused engine creating extra drag, how much would fuel
efficiency drop off at trawlering speeds?

Would the rudders, autopilot, or drive shafts be damaged due to off
center thrust?

Would the same arguments hold up with outboards and I/O's?

I would welcome all thoughts on this subject.

Best Regards,
Jim Garner
jimgarner1@earthlink.net

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For eight years and 1400 engine hours, I have usually run our 65000 lb
trawler on only one of her Lehman 135 engines at a time.  Both engines are
used for maneuvering ( or being in a location where hard maneuvering might
be come necessary) and for those few occasions when extra speed was
necessary to catch the tide or be a  location by a specific time ( a no no).
Our Defever has Borg Warner Velvet Drive transmissions and the oil pump is
located on the drive shaft which turns with the propellor.  The slow speed
of the off engine propellor provides sufficient lubrication to prevent
damage to the transmission.  The transmission gets warm, but never gets as
hot as the operating transmission.
The rudder indicator shows a 3 degree offset required by the unbalanced
driving force, which causes additional drag.
Our single engine operating drives our trawler at 6 knots at 1700rpm which
is a speed loved by the engine.  Fuel consumption is less than 2 gal/hr as
measured by our Flowscans and confirmed by actual fuel usage.
At speeds over 6 knots with our boat, the fuel consumption/speed graph shows
that it is better to use both engines.  While both engines each show better
economy while running together, the total fuel usage is increased.  For
example, both engines running at 1700rpm produces 7.5kt at fuel usage of 4
gal/hr.  Both engines at 2400rpm produces 9.5kts at 14gal/hr.
Not many of us will cruise at 6 knots and be passed by everyone.
We leave for the Bahamas in a few days for a couple of months.  Unless we
top off over on the east coast of Florida, we will not need to buy fuel til
we return.  It is not likely that we will see a dock during this cruise
either.
Tom Little
Kalani, Defever 49PH

Actually, this has been discussed before. In order of importance:

1. The transmission may not like a freewheeling prop owing to not getting
   enough lubrication from a dead engine. Can you spell Vise-Grips? This is
   transmission brand and model dependent.
2. A locked prop may produce unacceptable drag.
   I do want to do this and was even thinking of feathering props, but their
   cost (around $4000 wholesale) would outweigh fuel savings even on the Great
   Loop.
   Wishfully,
   Ron Rogers

----- Original Message -----
From: "Jim Garner" jimgarner1@earthlink.net
|
| The author indicated that his preferred method of travel is using
| only one of two engines for better fuel economy.
|
| I like the idea of using either port or starboard engine
| alternatively with the other available as back up and of course, both
| engines if more thrust/speed required.
|
| I do not recall reading anything in this use group about such
| activity, but it has me thinking ... and having questions.

Somewhere back in time, I seem to recall reading that a freewheeling prop
creates more drag than a locked prop when single engine running on a twin
engine vessel.  I intend to test these things later this year, however, what
have the rest of you experienced?

Best regards,

Bob Lowe
www.MV-Dreamer.com
www.CruisingAndMaintainingYourBoat.com

Actually, this has been discussed before. In order of importance:

1. The transmission may not like a freewheeling prop owing to not getting
   enough lubrication from a dead engine. Can you spell Vise-Grips? This is
   transmission brand and model dependent.
2. A locked prop may produce unacceptable drag.
   I do want to do this and was even thinking of feathering props, but their
   cost (around $4000 wholesale) would outweigh fuel savings even on the Great
   Loop.
   Wishfully,
   Ron Rogers

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Jim Garner wrote:

I like the idea of using either port or starboard engine
alternatively with the other available as back up and of course, both
engines if more thrust/speed required.

I do not recall reading anything in this use group about such
activity, but it has me thinking ... and having questions.

REPLY

Good grief people!
We beat this topic to death a couple of times in the past. as well as having
several tries at the perennial discussion of twins versus singles.

What amazes me is the lengths  some people will go to in an attempt  to save on
fuel using some Rube Goldberg arrangement  but at the same time  will reject any
discussion at using  newer and better technology  to achieve the same result.

In addition, it has been my observation that many  subscribers to this list are
especially focused on  redundancy and back-up to the redundancy.
This pre-occupation goes beyond simply being a belt and suspenders approach.

Part of this concern with redundancy may be a result of age  and a concern for
personal safety.
However I suspect much of it also comes from our social culture.
We are constantly bombarded by admonitions to be safe this and practice safety
that by professional "safety" people who make a living selling safety to the
masses. These professionals range from traffic police who measure their
collective success in reduced road accidents and fatalities to insurance
companies who measure how much money they have to pay out in policy benefits
etc.

Empirical data has already shown that a single screw vessel is more economical
than a twin. Smaller engines burn  less fuel than larger engines.
There is a whole body of information dealing with the relative merits of two ,
three four and even five bladed propellers in terms of efficiency, thrust and so
forth.
A separate body of  data  deals with position and placement of propellers struts
relative to hull including tunnels, cutaways,  kort nozzles etc.

Despite all this information there doesn't't seem to be a consensus as to what
solution is the best.
However, when I read of suggestions of  diving over the side to change props
from one side to the other as part of a fuel management program, I can only
shake my head in wonder.

What point is there in saving fuel if you risk injury or worse diving overboard
in mid ocean  to dink around with changing props?

If saving fuel is the primary concern then select a vessel designed to optimize
this aspect and accept the downside this means in other respects.
If ultimate safety is more of a concern, then  load down the vessel with dual
everything and hang the cost.

But  why dink around with make shift arrangements  which are neither good from
one perspective or the other?
That way you end up with the worst of both approaches and none of the good.

regards
Arild

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(snip)
Fishing trawlers almost invariably run with a single diesel and no backup
powerplant.  If anyone had the incentive to protect a multi-M investment, I
would think you would find him there.
(endsnip)

Forgive me this . . . no insult intended, but I think that view is
hopelessly optimistic. Fishing is a business, and a strapped, tight margin
one. There are exceptions of course, but generally in tight margin industry,
corners are caught to the very limit. If it works, it goes. If it runs,
another season is risked.

They gamble, and not always willingly. Engine needs rebuilt? Maybe, but that
$20,000 may be all that is left for fuel for the next run. Maybe if we make
it big on that run.....whoops, price was down and permit fees (Taxes) were
up . . . maybe we can rebuild her next year.

I've seen fishing boats go out with equipment I wouldn't have bothered to
scrap. (this coming from a guy whose boat resembles a colander at the
moment)

(of course there are fishing boats with equipment I could never hope to
afford to balance that out)

I work in industry (not fishing). Have all my life. From farming to heavy
equipment to electrical work to computers.

Safety and redundancy are never at the top of the list. Really. It takes an
incident, or a regulation (and those are always short-sighted and
reactionary) to even get marginal attention focused there . . . particularly
in redundancy. It is horrendously expensive.

Industry = Money. Always.

Maintenance is seldom on the top of the list either . . . if it runs, it is
run. It costs money to shut it down . . . to maintain it. It costs capacity
to have a preventative maintenance schedule AND there is no calculatable
benefit to the accountant types . . . it is only an expense and not easy to
justify until something breaks itself. Even to protect multimillion dollar
installations . . . they are run to capacity, then fixed when they break . .
. or replaced...or sold. Or run some more.

To the worker-bee, "make it happen or you will be replaced" ...the ingenuity
displayed is amazing sometimes.

To the independent, it can be their next meal. They will make it work, till
it absolutely cannot.  (seen the same thing in farming, I have).

As I said, there are exceptions, but do not look to the fishing fleets for
how to run or setup your boat. Their priorities do not resemble yours. Their
assumptions are different from yours. Their pressures are different than
yours.

CUAgain,
Daniel Meyer
http://cuagain.manilasites.com

I'm saving this one.  I know you didn't mean it to be funny, but I laughed
out loud.  --FrankB

-----Original Message-----
From: trawler-world-list-bounces@lists.samurai.com
[mailto:trawler-world-list-bounces@lists.samurai.com]On Behalf Of Arild
Jensen

Good grief people!
We beat this topic to death a couple of times in the past. as well as having
several tries at the perennial discussion of twins versus singles.

What amazes me is the lengths  some people will go to in an attempt  to save
on
fuel using some Rube Goldberg arrangement  but at the same time  will reject
any
discussion at using  newer and better technology  to achieve the same
result.

In addition, it has been my observation that many  subscribers to this list
are
especially focused on  redundancy and back-up to the redundancy.
This pre-occupation goes beyond simply being a belt and suspenders approach.

Part of this concern with redundancy may be a result of age  and a concern
for
personal safety.
However I suspect much of it also comes from our social culture.
We are constantly bombarded by admonitions to be safe this and practice
safety
that by professional "safety" people who make a living selling safety to the
masses. These professionals range from traffic police who measure their
collective success in reduced road accidents and fatalities to insurance
companies who measure how much money they have to pay out in policy benefits
etc.

Empirical data has already shown that a single screw vessel is more
economical
than a twin. Smaller engines burn  less fuel than larger engines.
There is a whole body of information dealing with the relative merits of two
,
three four and even five bladed propellers in terms of efficiency, thrust
and so
forth.
A separate body of  data  deals with position and placement of propellers
struts
relative to hull including tunnels, cutaways,  kort nozzles etc.

Despite all this information there doesn't't seem to be a consensus as to
what
solution is the best.
However, when I read of suggestions of  diving over the side to change props
from one side to the other as part of a fuel management program, I can only
shake my head in wonder.

What point is there in saving fuel if you risk injury or worse diving
overboard
in mid ocean  to dink around with changing props?

If saving fuel is the primary concern then select a vessel designed to
optimize
this aspect and accept the downside this means in other respects.
If ultimate safety is more of a concern, then  load down the vessel with
dual
everything and hang the cost.

But  why dink around with make shift arrangements  which are neither good
from
one perspective or the other?
That way you end up with the worst of both approaches and none of the good.