Running engine tied up to dock harmful to engine?

JamesG161 · Jul 25, 2017

Take it out of gear and drink beer.
Jim...

PS: I never have Old Fuel or Old Beer.

Kermit · Jul 25, 2017

Normally I trust the experts. But how is that any different than running the engine with earmuffs? I've done it occasionally just to test how well my lines are holding and to exercise it if I haven't been out in a while.

uncledom · Jul 25, 2017

If you use up the suspect fuel by running it at the dock, how's the mechanic going to make any money?

MitchM · Jul 25, 2017

i cannot imagine that 'running the engine in gear while tied to a dock ' puts more stress and strain on the engine and the engine mounts than running in open waters in 4-6 foot seas. it might break a few dock lines though ----and then you'd have an untidy mess.

Davidasailor26 · Jul 25, 2017

Your engine should burn less than a gallon per hour even at cruise speed. That's a lot of running to keep the fuel fresh. Also, running at high RPM's in gear will put a lot of stress on the lines, cleats, etc.

Many people have problems like black exhaust smoke when running with a fouled bottom - running in gear at the dock would be the extreme of that. I don't know if that's really harmful to the engine or not.

Capt jgw · Jul 25, 2017

Running with the boat tied up would put slightly more stress on the engine and mounts, similar to running in a heavy head wind. I notice I can't get quite as high rpm tied up as when moving. That shouldn't hurt anything as long as you don't run full throttle. I'd be a lot more concerned about the lines and cleats. Also, running at the dock is going to make substantial currents in the marina which could really tick off your neighbors or even cause a collision.

Ted · Jul 25, 2017

I can't imagine that running your engine in gear would cause any problems. Diesel engines like to be run with a load and running it at the dock in gear would meet that requirement. It's much better for the engine than running it in neutral. I seriously doubt that you would put any more stress on your dock lines and cleats then they would experience in 25 knots of wind. I wouldn't hesitate to run it in gear at the dock.

plenny7 · Jul 25, 2017

Your engine can't tell if you are tied up at the dock. The prop is pushing water either way.

Stu Jackson · Jul 25, 2017

Capt jgw said:
Running with the boat tied up would put slightly more stress on the engine and mounts, similar to running in a heavy head wind.

Nope. Engine doesn't know or care.

Don S/V ILLusion · Jul 25, 2017

Wouldn't it be a lot quicker to simply remove the old fuel?

jssailem · Jul 25, 2017

While running at the dock to burn up "old fuel" makes no sense, the process will not impact the engine unduly. It is not as much fun as running the engine away from the dock. Running in gear is the proper way to test the engine. It needs to be run under a load. Not in neutral. With out a load it will stress the engine.
If you want to test the engines cooling system running at the dock is an excellent method of getting the engine up to temperature.
Be sure you have good lines, and secure dock and boat cleats. They will be tested. Double up your lines fore and aft. Tie on snug fore and aft spring lines.
Monitor your cooling water and temp gauge. There is more stuff in the marina then out on the briny deep that can clog your intake. Smile at the dock walkers. They will visit and want to know what your doing. Make up a good storyline.

jviss · Jul 25, 2017

I must say, this is one of the kookiest threads I have read on this forum in a long time. Forget the question the OP poses, about damage to the engine mounts, etc. Why on earth would you "use up old fuel" by running it rhough the single most expensive piece of gear on the boat? If it's not good to use, why run it through the engine? And, if it's O.K. to run through the engine, why intentionally use it up? Is it no good? What's "old" about it? Who said to use it up and get new fuel?

How much fuel? This could take as much as two hours per gallon. And, if it's crummy, it will dirty up your filters.

If the fuel is no good, pump it out and get rid of it! Or, "polish it," which is to pump it through filters.

Wow.

shemandr · Jul 25, 2017

It might also be illegal. As far as I know, and that isn't far, it is illegal to run an engine in gear in a slip to remove silt, sand, mud from the slip or, in effect, to dredge the slip. Most slips around here have depth problems at low tide. I would not like it if a neighbor was sending his silt over to my slip.

Benny17441 · Jul 25, 2017

Like everything, done in moderation will cause no harm beyond regular wear and tear.

Benny17441 · Jul 25, 2017

jssailem said:
If you want to test the engines cooling system running at the dock is an excellent method of getting the engine up to temperature. .

If you have ever overheated the engine trying to free yourself from a sandbar you will know that gunning the engine while tied to a dock will provide the same results. It is indeed "an excellent method of getting the engine up to temperature". The thing is it will not take much time or effort at WOT to get the temperature warning lamp and buzzer active. Perhaps a 15 minute run under load at mid throttle might be more indicative of the health of the cooling system.

SG · Jul 25, 2017

Guan:

I'm with JV and others.

How much fuel are you talking about wasting? Why trying to get rid of the fuel? What are you going to do, once you get rid of it -- leave the tank empty or refill-it or fix it or?

A lot of the supposition here involves assumptions. Please discuss the reasons that have led you to consider this wasting?

P.S. - Loading up the boat an engine at 1800 RPM is a lot different than at 2500 RPM. If you decided to do that for hours, I'm not sure your marina and/or dock mates would be so happy. Again, un natural acts have consequences.

SG · Jul 25, 2017

The ghosts of Sargent Preston and his dog are on the way over now ;^))))

Really, Guan.... How many gallons, what are you up to. Unless you really empty the tank, you can't clean it. Simply burning fuel leave enough crap in the bottom (below the pick-up tube and surfaces of the tanks). If it's just suspended growies, then polishing can do a lot, etc.

I've had to have my various tanks cleaned on one boat which was no fun. I think it was "bad" fuel that I just got "infected" with. It's something that can I hit you in a short time or can build over time.

Cycling the fuel is GOOD. Keeping it treated is essential. Having good filtration is also essential.

I'm curious. Can you explain?

jssailem · Jul 25, 2017

Benny, You are spot on. My first experience with this process, was when I bought my boat. Sea Trial showed an over heating issue. PO said he would have it fixed. On re inspection his captain was not available for another sea trial. No problem, will run the engine at the dock. Tied her up, Fired her up, an sat back to watch what happens for the next 45 minutes... Running in gear at 2K rpms we put a bit of a water stream behind the boat, but we got the engine up to 160 in about 10 minutes and it stayed there for the next 35 minutes. I called it good and bought the boat...