How to handle one engine failing?

[Airnet]

If you have 2 motors and have an engine failure, what do you do?

Controlling the boat isn't a big deal but what do you do with the dead engine. I've read something about securing the shaft so the prop doesn't keep spinning the transmission. I'll admit, I don't know how to stop the shaft from spinning.

Anyone have theories on how to handle a failed engine when you have many hours till you reach your destination?

Thanks,
Curt

 

[Comodave]

The first thing I would do is check and see what the manufacturer of the transmissions say about free wheeling. It may not be an issue. Trying to stop a shaft from spinning may be tough to do or it may be as simple as putting a chain wrench on it and blocking the wrench so it doesn’t spin, but that may or may not work.

 

[psneeld]

Not only the transmission, but also how the stuffing boxes are set up to free wheel.

Other than what those two manufacturers recommend......

Running on a single engine is pretty common from everything like emergency shutdown to fishing or cruising on one....the engine generally is out of the picture unless there is some issue with sea strainers and speed forcing water up through the saltwater cooling system and possibly flooding the engine..... you can always just shut off that seacock.

As far as keeping the shaft from spinning if you have to....there are shaft brakes available for purchase, pipe wrenches, straps, wiring shaft couple bolts to something, etc, etc...a google search may turn up plenty more solutions.

 

[jgwinks]

Can be as simple as dropping a pipe wrench on the shaft, so that it stops the shaft turning when moving forward. You can block it in place or more likely it will ride against the hull or other structure on it's own. A strip of rubber between the wrench and shaft will prevent any marring. If the end of the wrench rides on the hull, pad that as well.

 

[Steppe]

I bought a 12 inch vice grip with a pipe jaw. Attach it to the shaft and let the handle ride against the bilge or floor.

Sent from my SM-T220 using Trawler Forum mobile app

 

[jgwinks]

And keep in mind when you arrive at your destination, maneuvering to the dock on one wheel might not be fun.

 

[psneeld]

Maneuvering on one should be practiced often if the vessel is difficult on one.

 

[hmason]

The one time I needed to secure the shaft I simply wrapped a line around it and secured the bitter end to an engine room upright. Just be sure to wrap the line in the correct direction so that when the shaft tries to turn the line gets tighter. My method will not score the shaft and is simple to remove.

 

[sunchaser]

Our Hurth transmissions freewheel just fine both by the book and in reality. PSS seals no overheat and ditto gears.

Yes, we found all this out a decade ago while running on one engine for about 40 hours. As mentioned, just shut an engine down and cruise for awhile provided your gear book is ok with it.

 

[psneeld]

Our Hurth transmissions freewheel just fine both by the book and in reality. PSS seals no overheat and ditto gears.

Yes, we found all this out a decade ago while running on one engine for about 40 hours. As mentioned, just shut an engine down and cruise for awhile provided your gear book is ok with it.

I would agree but depending on your operation, your speed might be critical to a PSS seal if not fed by some flowing water and you exceed whatever the manual says for the PSS.

On the Sea Rays I used to run, before they started cross flowing between engines and seals...we used to pop the water feed off the dead shaft seal and just let the ocean backfeed into the bilge. the bilge pumps kept up no problem, but you do want to keep an eye on the water level....

Of course interconnecting the feeds is even better if you get around to it....

 

[cafesport]

Never use metal to metal as a shaft brake, notch a pair of 2x4’s and use a pair of hose clamps to prevent rotation.

 

[Flatswing]

I would agree but depending on your operation, your speed might be critical to a PSS seal if not fed by some flowing water and you exceed whatever the manual says :

Agree: Practically speaking, at displacement speeds, the PSS will not get even warm if no crossover feeds. I have run many times on one engine with the other freewheeling (ok per my ZF transmission manual) checked the PSS temps regularly, never more than 5 degrees above sea water temp. I have no experience @ planing speeds at much higher shaft rpm’s (but it is quite impressive how fast the freewheeling shaft turns)!

 

[Portage_Bay]

Agree: Practically speaking, at displacement speeds, the PSS will not get even warm if no crossover feeds. I have run many times on one engine with the other freewheeling (ok per my ZF transmission manual) checked the PSS temps regularly, never more than 5 degrees above sea water temp. I have no experience @ planing speeds at much higher shaft rpm’s (but it is quite impressive how fast the freewheeling shaft turns)!

I recommend keeping an eye on a PSS without water feed. Their documentation says no feed needed at displacement speeds. But I had a water feed blockage and kept checking during a 3 hr run at 7.5 kts. It was hot to the touch. A longer run may have been a problem.

 

[rgano]

I would agree but depending on your operation, your speed might be critical to a PSS seal if not fed by some flowing water and you exceed whatever the manual says for the PSS.

On the Sea Rays I used to run, before they started cross flowing between engines and seals...we used to pop the water feed off the dead shaft seal and just let the ocean backfeed into the bilge. the bilge pumps kept up no problem, but you do want to keep an eye on the water level....

Of course interconnecting the feeds is even better if you get around to it....

Do you not need to be mindful of backfeeding water into the dead engine from this shaft seal cooling cross-connect? Seems a valve might be in order or simply pinching a hose with a vice grip.

 

[psneeld]

Do you not need to be mindful of backfeeding water into the dead engine from this shaft seal cooling cross-connect? Seems a valve might be in order or simply pinching a hose with a vice grip.

True, I forget how Sea Ray got around backfeeding, I am sure some Youtube or other could show the safe way.

 

[PM]

You already know that you need to replace the bad engine so I won't get into that.

if you are determined to continue to use your boat with only one engine you really need to remove the prop from the bad engine. Although it is not easy, it can be done while the boat is in the water, otherwise a lift might be in order, still not a big deal.

pete

 

[ABfish]

I'll ditto the need to do some practice runs with one engine. You may find that the boat is not controllable with one engine.

I briefly lost an engine on my boat. It has hydraulic power steering that runs off of the starboard engine and of course, that's the engine that conked out. I could center the rudder manually, but that's about it. And as soon as I put the port engine in gear, the boat turned right.

There's no way I could have run or docked the boat on the port engine alone.

 

[rslifkin]

It definitely depends a lot on the boat. On my boat, we're restricted to somewhere in the 6 - 7 kts on one engine, but at that speed, shaft freewheeling isn't an issue for our transmissions or the stuffing boxes (they don't have water feeds anyway). Maneuvering takes some planning, mostly due to reverse being of limited use (it'll always turn the boat towards the dead engine). Steering in forward is a non issue. The boat turns tighter towards the dead engine than the live one, but will still turn pretty tightly toward the live engine. Boats with particularly small rudders may have more trouble.

 

[Mambo42]

Maneuvering on one should be practiced often if the vessel is difficult on one.

Agree with you on this one. It is always a good idea to practice emergency situations on a regular basis. Practicing gives you the peace of mind that you know you can do it when push comes to shove. The moment you end up with one engine, e.g. in 25 kts cross wind, is not the time to find out how you should handle the boat on one engine.
Same goes for MOB procedure. Just practice it once every month and you will see that it becomes second nature.

 

[High Wire]

Don’t put a pipe wrench or vice grips on the shaft! Put it on the coupling.

 

[DennisB1]

Have you considered using a diver to remove the prop on the failed engine. You need access to a hub prop puller, proper wrenches, a big hammer and lines to secure the prop when it comes off. I have and spare props onboard but never have used them. If you have a long distance to cover the removal solves the worries of a spinning prop. Key is finding a diver and having the tools. Just a thought if it could be easily accomplishedo.

 

[ssurabus]

When I first started reading this thread, I felt good that I had a crossover to the dripless seals added years ago. This was on the recommendation of my yard after a discussion on running on one engine. Then I saw the comment about the possibility of back-feeding. I never thought of the issue of the raw water working its way back into the dead engine through that crossover connection. The seal's cooling water comes from a take-off on the transmission cooler (Mainship 40T, twin Yanmars). Does anyone have a setup with the crossover that has actually done something to prevent the possibility of the live engine forcing water into the dead engine?

 

[MaDehn]

If you need to just get home, lock the shaft by one of the ways noted. A spinning prop creates a ton more drag than a stationary one If you have a long distance to go, do a quick haul and remove the prop. Makes you a lot more fuel efficient and removes worries about tranny , shaft seal, and engine.

 

[rslifkin]

A spinning prop creates a ton more drag than a stationary one

If the trans can handle freewheeling, test it both ways and find out how the boat in question behaves. Some prop designs may produce less drag when locked, but many will produce less drag when freewheeling. Exact results depend on blade shape and area as well as prop pitch.

 

[MaDehn]

If the trans can handle freewheeling, test it both ways and find out how the boat in question behaves. Some prop designs may produce less drag when locked, but many will produce less drag when freewheeling. Exact results depend on blade shape and area as well as prop pitch.

my experience as a pilot says that this is not true- is that based upon engineering or hunch? There is a huge difference between a windmilling prop and one stopped in an airplane- is there some difference in marine props? seems like the same principles would apply. just curious what the above is based on? Thanks

 

[rslifkin]

my experience as a pilot says that this is not true- is that based upon engineering or hunch? There is a huge difference between a windmilling prop and one stopped in an airplane- is there some difference in marine props? seems like the same principles would apply. just curious what the above is based on? Thanks

Typically in an airplane when you shut down an engine with a variable pitch prop (which is most multi engine prop planes from my understanding), you feather the prop, which greatly reduces the blade drag by aligning them with the passing air. Sailboats often use folding or feathering props for the same reason. But typical powerboat props are fixed pitch. With a higher blade area prop, having it stopped can be as bad drag wise as dragging along a bucket as large as the diameter of the prop.

Basically, the ideal state of feathered blades isn't available in this application, so it's a question of windmilling vs locked with the full blade surface still exposed to the passing flow.

In the case of a sailboat with a 2 blade fixed prop of low blade area, locked may be better than windmilling, particularly if you can get the blades aligned vertically so they're in the disturbed water flow behind the keel. But as you increase the blade count and surface area, that can change the game.

 

[psneeld]

my experience as a pilot says that this is not true- is that based upon engineering or hunch? There is a huge difference between a windmilling prop and one stopped in an airplane- is there some difference in marine props? seems like the same principles would apply. just curious what the above is based on? Thanks

Yes, there seems to be a big difference in a marine engine out..... especially if you can't feather the prop. I do have aviation experience

I have heard both ways as being more efficient....freewheeling or locked...I traveled on a USCG Icebreaker with a prop locked from south of Iceland to near the North Pole all the way back through Sweden, Denmark then on to North Carolina. The ship's engineer explained the advantage on that ship in great detail...we did have the time to discuss it....

I think there are a lot of variables that cause this such as speeds travelled, props in general, drag form driveline, etc...etc....

Small boats have reported across the board results from their own real world trials and I would tend to agree that there is no one right answer. Every boat is a little different.

So few things in life are yes or no, black or white, better one way or another...so it just falls into that realm of "it all depends".....

 

[rslifkin]

I just did a bit of searching and found this test: https://forums.sailboatowners.com/threads/fixed-vs-free-wheeling-prop-updated.107118/

That shows a locked prop on a test jig as producing about 3 times the drag of the same prop freewheeling on the same test jig. And the prop used doesn't appear to be drastically different in design to what many of the boats on this forum would use.

 

[psneeld]

I just did a bit of searching and found this test: https://forums.sailboatowners.com/threads/fixed-vs-free-wheeling-prop-updated.107118/

That shows a locked prop on a test jig as producing about 3 times the drag of the same prop freewheeling on the same test jig. And the prop used doesn't appear to be drastically different in design to what many of the boats on this forum would use.

Sure seems like a lot of studies show freewheeling to be less drag than stopping the rotation.

I wonder why all the tid bits here and there why some studies or theories have it reversed.

 

[rslifkin]

Sure seems like a lot of studies show freewheeling to be less drag than stopping the rotation.

I wonder why all the tid bits here and there why some studies or theories have it reversed.

It may be that in some cases of high driveline friction (where rotational speed is significantly restricted when freewheeling) that freewheeling proves worse than locking the prop (this was mentioned in some of the research I did).