The Boating Forum - Running with one engine off

I have heard that trolling or running on only one engine is bad. I guess the other prop windmills and may cause issues.....can anyone shed any light on this? What kind of damage might it cause?

hogwash...been doing it for years....

ditto above for outboards

inboard application can be bad depending on how the shaft is set up

Right.. No problem in an outboard, it's water cooled outside plus it ratchets so the gears aren't spinning on that one anyway. In an inboard you usually need to block the shaft so it won't spin because the cooler isn't working if the motor's off.

x4 no problems ever....no load on the engine at such a low speed

That's how you do it, when trolling. Troll one and then the other...

Two comments: first, put the dead engine in gear to drag the prop for extra brake...it will knock 1.5 to 2 mph off the trolling speed. Second, don't back down hard on the dead engine or you will drive water up the exhaust and into the head.
MDT

Two comments: first, put the dead engine in gear to drag the prop for extra brake...it will knock 1.5 to 2 mph off the trolling speed. Second, don't back down hard on the dead engine or you will drive water up the exhaust and into the head.
MDT

x2. Also, don't if you have a large following sea that "might" could drive water up the exhaust. Not likely but can happen.

Also - go back and forth between the engines and try to keep the hours on each about the same.

When were sail fishing on theses in board boats u really only need 1 engine in gear but we always still leave the other one running that when if u need to run a fish down just pop it in gear and back down.

I troll with one engine on occasion, but I have a policy of NEVER turning off either of my engines while I'm offshore. They burn no gas idling, and although I've NEVER had a problem with them, I don't want to discovery a problem while I'm offshore. It may cause my engine hours to go up prematurely, but it's worth it to me.

I troll with one engine on occasion, but I have a policy of NEVER turning off either of my engines while I'm offshore. They burn no gas idling, and although I've NEVER had a problem with them, I don't want to discovery a problem while I'm offshore. It may cause my engine hours to go up prematurely, but it's worth it to me.

The first time I was thirty miles out, anchored up in my single powered boat, I also really really did not want to turn the motor off. But, after you do it a few times you get used to it.

On inboards whether you can do it or not is very application specific. It all depends on how the transmission is lubricated. You need to check your specific transmission down to the model number. Some can free wheel without any damage but on others the bearings won't get lubricated. There are usually rpm and time limits even if it can free wheel. Mine are 8 hours at no more than 50% of max rpm.

Twin I/Os only have one power steering pump, so that can become a chore if using the other engine.

This thread applies to me as well. I have my first inboard boat and have heard all my life that you cannot run on only one motor without strapping the shaft. This summer I had 2 mechanics tell me it's fine to run and let the second prop free wheel. Just to confirm, if I want to run around 7 or 8 knots, I should have no problems with one engine off? I had to do it this summer for a 2 hour run back to the marina and I was really uncomfortable doing it. Should I relax?

This thread applies to me as well. I have my first inboard boat and have heard all my life that you cannot run on only one motor without strapping the shaft. This summer I had 2 mechanics tell me it's fine to run and let the second prop free wheel. Just to confirm, if I want to run around 7 or 8 knots, I should have no problems with one engine off? I had to do it this summer for a 2 hour run back to the marina and I was really uncomfortable doing it. Should I relax?


It depends. On most all the ZF's, freewheeling at 1,500 rpms or less for up to 6 hours at a time is just fine - its in the manual. On most of the Twin Discs, freewheeling is a no-no - not saying you can't do it at idle speed for short periods of time, but it is not reccomended.

On my ZF's we do it all the time trolling for Striped Bass, and even when drifting for Fluke, we generally alternate an hour on each at a time.

The first time I was thirty miles out, anchored up in my single powered boat, I also really really did not want to turn the motor off. But, after you do it a few times you get used to it.

Ha. I don't want to get used to it. I want to get home. :thumbsup:

Leaving a engine idle when you don't need to, esp a new engine in tune is not necessary - I don't think any one here is going to change your mind, so have at it. But you are unnecessarily adding carbon to your engine, and gettign the oil dirty much quicker. Not to mention racking up hours that will cost you big time at resale. Start changing the oil every 50 and run ring free every tank if you are going to fuel your paranoia.....

Ha. I don't want to get used to it. I want to get home. :thumbsup:

you have to understand and trust your engine. no need to keep it idling at anchor for hours on end :roll

I shut off the engines in the middle of the gulfstream sometimes to go snorkeling among the weed lines on the way to the Bahamas. This tends to stress out my wife, but I won't go in the water with engines running. I met a guy in the Bahamas whose young son was chopped up really bad while snorkeling when the shifter was bumped on a boat with running engines. I know the thread is about fishing but I am bored and it's a good lesson.

Inboards...Check with the manufacturer of your marine gears...year and make is important.

most, not all marine gears use the input shaft to drive the lube oil pump for the marine gear...freewheelin these MG's for even a short period of time can toast the bearings because there is no lubrication.

Others will operate safely under certain conditions.

The dripless shaft seals on my vee drive requires pressurized lubrication.

On my boat I have a crossover hose, so only one engine is required to be running.

Another option would be to remove the supply hose and permit seawater intrusion through the small hole, assuming the bilge pumps would keep the level in-check.

I run my twin Yamaha F-150's single all the time. My only question has been if you can leave the starboard ignition on so the Yamaha fuel management system still keeps track of everything? I know the engine hours aren't affected when the engine is not running but I’m not sure if it effects anything else.

i dont get how this is a problem at all

I cooked a ZF tranny this way a few years back. Port motor broke an alternator belt. Shut it off and drove home 3 hours on starboard motor (inboards).....Fixed belt the next day but now tranny was stuck in forward no matter where the controls were. Mechanic pulled the tranny and said I cooked it by not tying the shaft to prevent it from spinning the whole ride in with the motor not running. Cost me 1800 bucks!