Cruising On One Engine Only

Reasons why I will run one engine:

#1) Waiting for the stupid Oshkosh CN railroad bridge to open. This is the worst bridge in our area. I’ll shut down one engine then hold position in current and wind.

#2) Sometimes our very young guests want to be pulled on a tube or similar play toy very slow. Shut down one engine and keep the other in the slowest possible position.

#3) During long slow no wake areas. My reason is to reduce engine hours and I think its saving fuel but I have no proof of the second.

In all three cases I run the blower.
 
carterchapman said:
John,

I haven't received my boat yet, but did all 2005 340's have the cross-over water feed line for the shaft seals?
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I would imagine so, but no guessing required. Open the engine hatch. Lean in and look straight down or a little forward, back toward the bow. If a thin (1/2" OD at most) black line snakes out from under the front of one engine, up over the stringer, back down across the bilge, up over the second stringer and under the front of the second engine, you have it.

If you climb down there, when you look at where the shaft goes through the bottom of the hull, you'll see two of these lines. One comes from the raw water cooling system on the engine, the other crosses over to the other side as described.

If you plan to use this method, you may want to check to make sure that the crossover is not blocked. You could take both ends off and blow through, but I just asked my dealer to check. I replaced my shaft seals (Strong) when I bought the boat, and they are unconditionally warranted for two years, so I wasn't too worried myself.
 
Four Suns said:
I stand corrected... (I did it myself). John's boat does not have a hydraulic pump on the engine. It uses hydraulics but is off the turning of the steering wheel only... PM me your address and I'll send you a beer.

Man... what a wiener of a boat. ;-)
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Cyber beer - isn't that fattening?
 
Presentation said:
On our boat, you must have the keys on and the ignition switch at the helm on. The engine does not need to be running.
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This discussion came up before. I tested this on my 240 and my 270 and had a friend try it on his Chap. All 3 cases, key in on position and engine off = hour meter not running. Key in on position and engine running = hour meter running. I have to have my key on to listen to the radio. If the hour meter ran that whole time I would have about 300 hours on my boat in one season, but I only have 57.

FWIW, which isn't very much.
 
Four Suns said:
There is no free lunch... On top of the increased drag from either an unpowered prop or stationary prop and deflected rudders, you probably have one hydraulic pump for your steering so you'll only be able to run a particular engine and not either/or.


Also, I'm not convinced you save money running a gas boat designed for plane speeds at displacement speeds. Let's say you want to travel 1000 miles down the ICW. You are putting 3-4 times the hours on the engine and running it at a low RPM for extended periods. At the end of the day, you are going to have to account for increased oil changes (and other issues that may arise) that are based on the hour meter. The big kick will be how does this affect depreciation as well. Is the savings you get by running a gas engine in a boat at displacement speed going to counter the fact one or two engines have 3-4 times the hours on them? I really doubt it.... Yeah... tell people "the high hours are at displacement speed" when you sell it and their eyes will glass over. It's like telling someone the reason a car has 300,000 miles is because it was on the highway... no one cares. They'll go buy the boat with lower hours.

Once you factor in the additional depreciation and the increased frequency of maintenance, I bet you are better off running the boat as it was designed... The biggest cost on your boat is depreciation (not fuel) and, unfortunately, running a boat around at displacement speeds to save fuel cost increases the depreciation costs on a gas boat. People will say "that's not real money"... All money is real in my world.

For example... let's say there are 20 1997 330 DA's on the market when you go to sell yours. They are all $50K and have 500 hours on their gas engines. Your boat, however, has 1500 hours on the gas engines. Cost of new engines is about $40K installed... What's your boat worth? Zero.

My 2 cents
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Might this explain why, after having an emergency shutdown on port engine this summer, I had virtually no control of steering with just starboard engine running? When putting starboard gear in forward, boat wanted to veer hard to the left. Luckily I was only 1/4 mile from the dock, but what a pain in the arse getting back on the lift.


I never considered it could be related to one engine being down.....and may not be after all, but hearing about all of you that CAN and DO run with only one motor, and still have control, makes me wonder if my steering pump is only run by port motor.
 
I have never had any issues with steering with just one engine other than not being able to use the other engine for docking.
 
even in my narrow 280, one engine tweaks the boat enough to make it inefficient.
 
highslice said:
This discussion came up before. I tested this on my 240 and my 270 and had a friend try it on his Chap. All 3 cases, key in on position and engine off = hour meter not running. Key in on position and engine running = hour meter running. I have to have my key on to listen to the radio. If the hour meter ran that whole time I would have about 300 hours on my boat in one season, but I only have 57.

FWIW, which isn't very much.
Click to expand...

I have wondered about this since buying my boat. Previous owner stated that hours would be adding up as long as keys and ignition breakers were on, regardles of engines actually running. this would be a very poor engineering design flaw to say the least. Since I am new to the boat, I am not sure and have yet to test it.

Certainly an inconvience to turn off keys and ignition breakers everytime you float or anchor just to save hours on the meter.

b
 
Hampton said:
I would imagine so, but no guessing required. Open the engine hatch. Lean in and look straight down or a little forward, back toward the bow. If a thin (1/2" OD at most) black line snakes out from under the front of one engine, up over the stringer, back down across the bilge, up over the second stringer and under the front of the second engine, you have it.

If you climb down there, when you look at where the shaft goes through the bottom of the hull, you'll see two of these lines. One comes from the raw water cooling system on the engine, the other crosses over to the other side as described.

If you plan to use this method, you may want to check to make sure that the crossover is not blocked. You could take both ends off and blow through, but I just asked my dealer to check. I replaced my shaft seals (Strong) when I bought the boat, and they are unconditionally warranted for two years, so I wasn't too worried myself.
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Couldn't find anything in my manuals, so I'll look when it is delivered - two weeks.

Thanks
 
I am guessing here but I would think steering with one outdrive vs. 2 compared to steering with one shaft (inboards) would be different. My guess is the one outdrive case would be more difficult.
 
I had asked this question one mechanic from MM and he told me that later models (he wasn't sure when they had started)have some module that watches RPMs. This allows engine to run at idle speed without cumulating hours. Sinse he gave me no specifics on the models and years this still needs to be confirmed.
 
During the winterizing (when I had my boat on blocks) I could clearly see that as soon as I start one (any) engine water comes out from both shafts. I guess, it's safe to assume that my boat has crossover cables and I can run with one engine down without damaging shaft seals on the other.
 
A note on engine hours. We purchased a 2000 Maxum 2400 SCR 4 years ago, kept it for a year and then sold it. It only had 90 hours on it when we purchased it, or so we thought.

We met the original owner a few months after we sold it. Turns out he installed the hour meter 2+ years after he purchased the boat new. The boat did not come with one from the dealer. Turns out it really had 200+ hours on it when we purchased it.

Our port tach on Mrs Robinson was replaced 2 years ago. Hour meter reads 70+ hours right now, starboard one reads 700+. I kept the old port tach for documentation purposes. I document all of our hours in a log, but that is as good as me remembering to do so and as trusting as a potential buyer trusts me/the log.
 
Thanks for all the great points. Really got me to thinking. Here in North Carolina from the Nuese River to blue water and southbound we have a lot of voluntary no-wake areas and areas of the ICW that you want to take at displacement speeds. I thought if I could save some fuel by operating on one engine (I have twin gas 7.4s with V drives) then I'd go for it. Not so sure anymore after reading the posts. According to test reports, I should get about 1.19 miles per gallon at 8 MPH vice .93 miles per gallon at 29 MPH operating on both engines. Not a big savings, but a savings of about 50 miles per tank. Significant for a long trip.
 
I went through this process a while back and decided to always run both engines for peace of mind. I only run one engine when I am forced to, like you know, when an oil line bursts, or a log jumps out of the water and hits a prop, or the depth of the water suddenly changes and you hit bottom....
 
BTW, slightly OT, we have 4 bladed 17 X 16 cupped props on ours. I had to run the 3 bladed spares for a while, waiting for new 4 bladed props, after that log hit us. The 4 bladed props make a huge difference on this boat.
 
New owner reopening this discussion.

I’m a pilot so I get the asymmetric thrust/crab/sideslip if running one engine. Also in aircraft it is a general rule you lose 70% - 90% of performance when you lose an engine due to the inefficiency. My goal for the purpose of this thread here has nothing about increasing efficiency or care of lack of performance since I have no destination half of the time. Just idling up the river between beaches and anchor points.

I’m not too bright on my systems yet...
With twin Merc 5.0 MPI I/O with Bravo III do I have to worry about the idea of a free turning prop on the shut down engine? Gear issues etc? Seems to me that the I/O would not have this issue? What about power steering issues? Any reason not to idle on one engine when entertaining at idle?

One of my engines has 10 hours less than the other. I was thinking of evening it up over the next year for OCD reasons, but also curious about saving fuel and engine time while idling around.

Easy on the flames please.
 
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LUnaCY said:
New owner reopening this discussion.

I’m a pilot so I get the asymmetric thrust/crab/sideslip if running one engine. Also in aircraft it is a general rule you lose 70% - 90% of performance when you lose an engine due to the inefficiency. My goal for the purpose of this thread here has nothing about increasing efficiency or care of lack of performance since I have no destination half of the time. Just idling up the river between beaches and anchor points.

I’m not too bright on my systems yet...
With twin Merc 5.0 MPI I/O with Bravo III do I have to worry about the idea of a free turning prop on the shut down engine? Gear issues etc? Seems to me that the I/O would not have this issue? What about power steering issues? Any reason not to idle on one engine when entertaining at idle?

One of my engines has 10 hours less than the other. I was thinking of evening it up over the next year for OCD reasons, but also curious about saving fuel and engine time while idling around.

Easy on the flames please.
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Had an alternator fail on one of the engines in my 2000 340 Dancer. Had to run about 30 miles to get home. Worst cruise of my life. Virtually impossible to go straight... without an autopilot. I was exhausted when we got back. Didn't try to dock. SImply threw lines and pulled her into the slip.
 
This discussion always centers and for the most part only considers fuel efficiency and seal lubrication. An overlooked problem with single engine operation of a twin engine boat is the distance between the shafts. When the shafts are a minimum distance apart, the boat is still controllable, but on larger boats where there is a greater distance between the shafts, the boat can become almost unmanageable as speed increases because the rudders must be deflected toward the powered side to offset the off-centered thrust. That negatively impacts efficiency and speed and makes docking a serious challenge if the reason you are running on one is mechanical or physical damage to running gear.
 
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