Running on one engine

[BuoyOBuoy]

Something I have never done before. Never owned a 2 engine boat.
I am about to put an offer in on a Sea Ray with dual Caterpillar 3116 engines.
My question is (1) What should I be looking for mostly?
(2) If I am just cruising around my home port on a Sunday afternoon is it OK to be just running on one engine.?

 

[psneeld]

Yes. Running on one is done all the time....not common, but I've heard and seen plenty of examples.

It's usually not done for any particular reason other than the other one or other part of it's running gear is inoperable.

Arguably it doesn't save fuel
It possibly makes boat handling more difficult
It does save hours on engines which could mean savings on longevity and maintenance but most motors aren't run enough in their recreational lifetimes
There are other pros and cons but none that prevent it and a few weak ones that say it's the way to go.
Plus other pros and cons that others may chime in with....

Usually the type of packing glands for prop shafts need to be determined if they need modification, the transmissions need to be determined if they can be freewheeled or locked, the boat handling in a crisis should be evaluated, charging system needs to be evaluated as well as other systems that need an engine running and I am sure some posters may add others

 

[SplashFl]

Something I have never done before. Never owned a 2 engine boat.
I am about to put an offer in on a Sea Ray with dual Caterpillar 3116 engines.
My question is (1) What should I be looking for mostly?
(2) If I am just cruising around my home port on a Sunday afternoon is it OK to be just running on one engine.?

Once had a small 30 ft. Sea Ray. IMO their mass produced mediocre boats that look better then they actually perform. If your set on that boat you'll want the contract to read "subject to survey & sea trial." You want a top survey company for the boat plus another for the Cat's & generator. Running on one will only be ok in wide open areas. You'll find she wants to turn in the opposite direction of that engine and unless you have enough speed, impossible to turn in the other direction. Several months ago I had to shut one down due to an over heat warning. NOT FUN, especially when going under 2 ICW bridges.

 

[psneeld]

I was a captain for Sea Ray dealership and ran every model of theirs for tears in the early 2000s. Also a pro captain that has run hundreds of different kind boats.

The Sea Ray diesel boats handled fine (compared to all kinds of boats) on one engiine, their only model I disliked for one engine ops was the 38 foot gasser. Small props and rudders plus the long narrow hull made it a monster to handle on one engine when docking.... but wasn't bad at speed.

As far as Sea Ray boats, can't say for every boat, every model and every year. But I did run older Sea Rays and Newer ones up to about 2006 and like all manufacturers they had good and bad models. Some construction, some systems, layouts, etc...but overall they were a decent boat at a decent price with excellent support from the company. It might all have changed as many manufacturers were know to be great, got bought out and turned to trash.

So just do your homework as most boaters experiences with a broad spectrum of boats, models and years is pretty limited unless in the marine business for a lot of years.

 

[ranger58sb]

Something I have never done before. Never owned a 2 engine boat.
I am about to put an offer in on a Sea Ray with dual Caterpillar 3116 engines.
My question is (1) What should I be looking for mostly?
(2) If I am just cruising around my home port on a Sunday afternoon is it OK to be just running on one engine.?

1) Surveyors will be your friend. You might ask about that specific model on clubsearay.com. I dunno about 3116s; used to be boatdiesel.com was a go-to place for engine info, but maybe there's some other internet source for Cat info now...

2) Yes, OK... but I'd say don't bother. There are several threads about it here -- @psneeld summarized -- and you could read more about it with some searching. Bottom line, not much gain, if any, and it might come with risks.

Once had a small 30 ft. Sea Ray. IMO their mass produced mediocre boats that look better then they actually perform.

Geez, Splash, cut us a break!

Yes, mass-produced Chevies. Styling eventually went way far "European" -- not my favorite -- but then again Sabres and so forth are in the "arm and leg" category for many. Near as I can tell from reading, the "Chevy" era lasted all the way up 'til the L-Series intro circa 2014-2015 (?) or so. OK, not a tank like an older Hatt or your era Bert -- but also not a latter era Bertie with al the issue those came with.

-Chris

 

[O C Diver]

Was out to lunch with a group about a week ago. Senior men who were former cruisers. A fuel filter can on the port engine failed. After moving the fuel back to the tank and determining the cause, we headed home on one engine.

Steering with one engine on a planing hull in displacement mode was poor. On this particular boat Sea Ray recommends not using the autopilot as you basically half to over steer. Most of us took a turn at the wheel. One of the things I would caution you on is steering in a narrower channel in a cross current. The course correction was probably better than 25 degrees. Regularly glancing at a moving map chart plotter confirms you're staying centered in the channel when the boat is pointing out of the channel. As mentioned by others, best to use single engine in open areas and avoid cross winds and currents.

Ted

 

[rslifkin]

Handling issues like Ted mentions above really vary between boats. How widely the engines are spaced, the size of the rudders, and whether or not the props are in tunnels can all make a big difference. A faster planing hull with small rudders will often handle poorly on one engine and may be very short on rudder authority at lower speeds on one engine. Other boats with bigger rudders will steer a bit worse than with both engines running, but not particularly poorly.

Locally, a lot of the charter fishing guys troll for some fairly slow fish, so most of them with twin engine boats troll with one engine shut down to get the boat slower (and burn less fuel compared to adding more drag in the water to slow down). Many of them have retrofitted larger rudders to their boats to get acceptable rudder authority and autopilot behavior when trolling (they're often doing ~1.5 kts with 1 engine idling in gear and added drag in the water).

 

[BuoyOBuoy]

Look. You guys are amazing. Your opinions /replies are exactly what I was looking for.
I definitely will be getting a survey and sea trial from recommended and qualified experts.
Too much money to purchase then have to throw money at it. Best to pay it up front then I know what I'm getting. Many thanks

 

[Ephemeral]

Something I have never done before. Never owned a 2 engine boat.
I am about to put an offer in on a Sea Ray with dual Caterpillar 3116 engines.
My question is (1) What should I be looking for mostly?
(2) If I am just cruising around my home port on a Sunday afternoon is it OK to be just running on one engine.?

Some transmissions are not supposed to be freewheeled, as the get cooling water only running. ( TwinDisc, for example). Check with the transmission manufacturer guidelines before running on one engine. You can solve that by locking the shaft.

 

[Mac2]

Some transmissions are not supposed to be freewheeled, as the get cooling water only running. ( TwinDisc, for example). Check with the transmission manufacturer guidelines before running on one engine. You can solve that by locking the shaft.

Interesting. I was advised twin disc could be freewheeled. I’m talking around 7-8 knots. Oil is getting thrown around the inside of the transmission, keeping them cooled off. The only reason I see for running one engine on purpose is to keep it in the optimal rpm range. I don’t want to under load the engines. I have a crossover from one shaft seal to the other to keep the non running engine shaft seal cool.

 

[Ephemeral]

Interesting. I was advised twin disc could be freewheeled. I’m talking around 7-8 knots. Oil is getting thrown around the inside of the transmission, keeping them cooled off. The only reason I see for running one engine on purpose is to keep it in the optimal rpm range. I don’t want to under load the engines. I have a crossover from one shaft seal to the other to keep the non running engine shaft seal cool.

My TwinDisc Manual says not to freewheel. Manual is available online still. I had shaft stoppers machined. Others will say to put a pipe wrench on the shaft to stop it from spinning. However, a pipe wrench will gall a very expensive Aquamet Shaft. No thank you.

 

[Mac2]

My TwinDisc Manual says not to freewheel. Manual is available online still. I had shaft stoppers machined. Others will say to put a pipe wrench on the shaft to stop it from spinning. However, a pipe wrench will gall a very expensive Aquamet Shaft. No thank you.

Mine are MG-5061. Installed in 1998. Doesn’t state anything in the manual and twin disc either didn’t know, or I never got a call back. I will look again at an online manual. I would be interested to see some pics of your shaft stoppers.

 

[Mako]

That SeaRay probably has V-drives. I doubt they would have an issue with free-wheeling, but check it as well as the gear for that ability.

The engines of course need all the usual mechanic-inspections. Has that boat been run mostly in fresh or salt water?

 

[psneeld]

My Twin Discs on my sportfish with 3208s could be freewheeled. Did it all the time trolling offshore.

Also the Twin Discs on some of the Sea Rays I ran, both a 40 and a 54 footer with diesels could be free wheeled. Some Twin Disc models did recommend starting the engine and idling for a few minutes every so many hours of freewheeling to keep the lube cool and in the gears.

 

[mvweebles]

Topic comes up from time to time and it's always a head-scratcher to me. If you want to run on just one engine, why not buy a boat with one engine? Reduce engine hours? Hardly - diesels don't die of old age, they are murdered through neglect.

Here's a concept: buy a boat that matches how you'll use it. Buyers frequently talk about wanting to run at displacement speeds but want a fast boat just in case they might want to go fast. So they buy a boat for the 1%-2% of the time they're running. Why not get the right boat for the 98% of the time and adapt themselves for the 2%? Something like making a cup of coffee while waiting for a bridge?

That said, I waited 20-minutes for a bridge the other day. Got old quickly.....

Peter

 

[psneeld]

I can see if you run your boat closer to 50/50 why one would buy a boat with twins yet run on one for various reasons that are found in the numerous threads on the subject.

I have done it with one of my boats and would probably wind up doing it again if I ever get back in the big boat scenario.

 

[Ken E.]

Interesting. I was advised twin disc could be freewheeled. I’m talking around 7-8 knots. Oil is getting thrown around the inside of the transmission, keeping them cooled off. The only reason I see for running one engine on purpose is to keep it in the optimal rpm range. I don’t want to under load the engines. I have a crossover from one shaft seal to the other to keep the non running engine shaft seal cool.

Twin Disc's owners' manual gives all the models that can be free-wheeled and most can. There are rules that TD gives for doing this....number of hours, checking the temp, etc. My TD gears, model 5050, can be free-wheeled and I've done it numerous times.

 

[Mac2]

Wow! Finally found it! They call it windmilling or back driving. They list the models that can’t windmill. Not a big deal. You just need to run the engine for five minutes every 8 hours. Even though I can windmill, I will switch engines at the 8 hour mark if I decide to run one engine at a time.

 

[Mako]

I knew it @Mac2 you're a closet single-engine-dude!

 

[Mac2]

I knew it @Mac2 you're a closet single-engine-dude!

 

[ranger58sb]

My Twin Discs on my sportfish with 3208s could be freewheeled. Did it all the time trolling offshore.

Also the Twin Discs on some of the Sea Rays I ran, both a 40 and a 54 footer with diesels could be free wheeled. Some Twin Disc models did recommend starting the engine and idling for a few minutes every so many hours of freewheeling to keep the lube cool and in the gears.

We can freewheel our TwinDisc MG 5114A gears, but...

Our power steering only works off the starboard engine... so running on port engine only makes it a bear to steer.

For trolling with our previous convertible, we could alternate engines and over time keep the hours roughly the same. Not as easy, on this one. There was a glitch with our trolling valves when we got this boat anyway, and that actually took a couple years to figure out... so we haven't trolled much on this yet... and when we did, I kept the starboard engine running even if only port was in gear. Not much gain from all that...

-Chris

 

[rslifkin]

We can freewheel our TwinDisc MG 5114A gears, but...

Our power steering only works off the starboard engine... so running on port engine only makes it a bear to steer.

For trolling with our previous convertible, we could alternate engines and over time keep the hours roughly the same. Not as easy, on this one. There was a glitch with our trolling valves when we got this boat anyway, and that actually took a couple years to figure out... so we haven't trolled much on this yet... and when we did, I kept the starboard engine running even if only port was in gear. Not much gain from all that...

-Chris

That's one of those things boat builders do that drives me insane. Something like power steering should be powered from both engines. Leaving a boat in the situation of having a failure on the "wrong" engine causing significantly worse steering than if the other one had failed is poor / lazy / cheap design.

 

[ranger58sb]

That's one of those things boat builders do that drives me insane. Something like power steering should be powered from both engines. Leaving a boat in the situation of having a failure on the "wrong" engine causing significantly worse steering than if the other one had failed is poor / lazy / cheap design.

Yeah, seems perverse, to me...

-C

 

[Mako]

Same with hydraulic stabilizers. Usually driven off the starboard engine only

 

[rslifkin]

Same with hydraulic stabilizers. Usually driven off the starboard engine only

At least those sometimes have a hydro pump on the genset if there's only a pump on one of the mains, so you can still make the stabilizers available if needed with an engine shut down.

 

[jgwinks]

I don't think running on one engine to save fuel works. You'd have to run higher rpm's to get the same speed and there's the drag from the dead prop which is substantial. May well be a loss compared to running both. I've done it a few times but only because one engine was having a problem. Docking on one wheel is no fun, I'd start the other engine for that if possible. I had one engine shut down once due to an overheat, by the time we got back to the dock it had cooled enough to run it a few minutes.

 

[ronbo404]

Not looking to steal this thread, but doesn't running on one engine overload the motor?

 

[rslifkin]

Not looking to steal this thread, but doesn't running on one engine overload the motor?

It does put you above the intended prop curve. On a faster boat running slowly the engines are so lightly loaded at low speeds that the increased load isn't a concern. You wouldn't want to run the running engine hard with one shut down though. So for a boat that only does 8 kts at WOT with both running, shutting one down is likely impractical as you'd need to be going pretty slow. But for a boat that can do 15+ kts, running at 7 kts on one engine is fine load-wise.

 

[Comodave]

Not looking to steal this thread, but doesn't running on one engine overload the motor?

Probably not at trawler speeds.

 

[Mac2]

Not looking to steal this thread, but doesn't running on one engine overload the motor?

I was only looking at running on one engine due to speed restrictions where Im at. I was underloading my engines in these conditions.