How often to start the engines?

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Boatboy0110

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Jan 16, 2024
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I'm a liveaboard in Florida. Just went from a 31" sail to a 36 Prairie Boatworks 36" trawler with twin Perkins 4's.
I don't have a lot of desire to cruise on the weekends. The boat is my home and my office and I see something going wrong out there that tends to keep me at the dock (sad ... I agree). My question is how often should I start my engines and let them run for a while? I started the sailboat (Yanmar) once a month and let it run for 15 minutes, brought it up to full throttle a few times and used the recommended shut down procedure from Yanmar.
Any feedback would be appreciated. These engines have sat for over two years but they started immediately and purr. Trainees are tight. I also cycle these when I run the engine. Thanks! Bob in Punta Gorda, FL.
 
Engines need to be used. Sitting for a couple weeks between uses isn't a big deal, but only ever getting run at the dock with no load on the engines isn't good for them at all. If you want to keep them healthy, you need to periodically take the boat out and get it some exercise.
 
IMO, take the boat out once a month for an hour. It's more about getting the engine, transmission, and engine room up to operating temperature and baking the moisture out of the oils. If you can't do that, then do it every other month. Running the engine for 15 minutes in the slip every month isn't as beneficial as going every other month for an hour cruise.

Ted
 
O C Diver said:
IMO, take the boat out once a month for an hour. It's more about getting the engine, transmission, and engine room up to operating temperature and baking the moisture out of the oils. If you can't do that, then do it every other month. Running the engine for 15 minutes in the slip every month isn't as beneficial as going every other month for an hour cruise.

Ted
Click to expand...
Absolutely!
 
The underlying question is how long does it take for all the lube oil to drain from the bearings. My guess is probably only a day or two.
The owners manual does not say anything about periodic operation. It does say to start at full throttle which I could never bring myself to do. Counterintuitively it probably makes sense to hit the engine with full oil pressure and the injector pump with full fuel pressure asap then back down but my cringe factor goes up with the rpms.
Off season I try, as you noted for your yanmar, to run to operating temp monthly preferably by cruising but I suspect this is only a "feel good" practice. Moving fuel through the filters,keeping some water in the pumps and cutlass bearings is probably just as beneficial.
 
I agree, take the boat out for a ride and have fun!

If where you are is like where I am, the crazies are mostly out on the weekends, especially 3 day weekends. In the middle of the week it's much calmer, so we do that mostly - :)
 
I take mine out 1-2 times per week for a minimum of 2 hr cruise even though its a 45 minute drive each way to get to my slip. It's worth it and it keeps me on top of anything that may need attention.
 
Get an unlimited Sea Tow or BoatUS towing policy and do once a month “barnacle run”.
 
DNT99611 said:
There are thousands of gillnet boats here in Alaska that sit on the hard for ten months out of the year. Does not seem to hurt their engines much.
Click to expand...
Point well taken.

I think boaters over-think the whole routine of running engines monthly. Won't hurt the engine of course, but by far the most beneficial result of a monthly engine exercise is the manly experience of communing with an engine. It's a guy thing I suppose - part of adolescence that we never escape.

My wife has a theory that males hit puberty and don’t really mature past 14 or so. We sharpen our game and smooth out the rough edges, but our core being is a barely pubescent boy with all the attendant motivations and priorities. As youngsters, men built forts and tree-houses. Now? We escape to our boat. Running the diesel displaces putting baseball cards in the spokes of a bike. Some things change…….but not really.
 
Yup.

Had 4 motorcycles at one time, now down to 2 and soon to 1. Triumph Bonneville.

Never going to sell my Bonnie. Sometimes I just hop on in the garage and dream of a winding road - :)
 
It's hard to get an engine up to operating temperature without putting a load on it. That's hard to do in the slip. I've often wondered if just running the engine in the slip and not getting it hot is worse than not running it. Seems to me you're just asking to get condensation in it.
The comment about gillnetters is interesting. A Bristol Bay boat sits for 10 months out of the year, then they run the crap out of them for 2 months then back in storage in a less than kind environment.
 
My diesel engines do just fine sitting idle for 6 months at a time. My gas engines do much better if they get a run cycle on them at least once every two months.
 
My diesels do just fine sitting for 6 months in the barn over the winter. They start immediately when we launch. I do not like running them at the dock without getting underway to actually heat them up.
 
According to the marine diesel industry, most engine problems begin in the fuel tank. This is because water intrusion is more present on the seas than it is on land. Still, according to BP, “Under normal storage conditions, diesel fuel can be expected to stay in a usable condition for 12 months or longer at an ambient of 68 degrees Fahrenheit.” Yet the lifespan of diesel drops to, “6 to 12 months at an ambient temperature higher than 86 degrees Fahrenheit.” As diesel fuel ages, BP points out that, “fine sediment and gum forms in the diesel brought about by the reaction of diesel components with oxygen from the air. The fine sediment and gum will block fuel filters, leading to fuel starvation and the engine stopping. Frequent filter changes are then required to keep the engine going. The gums and sediments do not burn in the engine very well and can lead to carbon and soot deposits on injectors and other combustion surfaces.”

Run your boat to keep it in top condition...
 
Yes, run it but not necessarily idle it at the dock.
 
There are some boats in my marina that haven't moved in years and probably haven't been started either. They do however have people cleaning them weekly.
 
My experience...run it to get the oil back in the cylinders (oil pressure up to max) for a minute or so, or run it hard.

Running it for a 1/2 hour or so without a major load and getting the oil temp above 165 or so (not just coolant) isn't any netter and will probably add more moisture/contaminates than the minute run.

Better to just perform the long term store it steps but if that borderline of 3-4 months no use.... hard to say what's best/easiest.

Another topic easy to overthink....
 
Just got back from my abbreviated "at least once weekly" 2 hr cruise. Had to get back in the slip since the diver was coming for my 5 week bottom cleaning and going to replace a couple zincs. It may be a bit anal, but I feel that I must take it out at least once a week.
 
SS shafts are known to pit due to lack of oxygen in the shaft logs after lack of water movement due to not running the boat. This came from my neighbor who works in the local boat yard. I'm not sure of how often he starts the engine and puts it in gear, but I know he has been rebuilding his wood boat for years and has never left the dock.
 
My engine sits for 7 months a year never getting turned over.

If you don't go out for months at a time, why both owning a boat at all? Why not get a houseboat built on a barge??

What is "something going wrong out there that tends to keep me at the dock"
 
So, the boat is really just a home on the water. If the motivation to live so is mostly a financial consideration, then I would guess from the tenor of the first post that the routine underwater hull (cleaning and hauling) and engine maintenance we all consider vital to preserving the operational capability and value of our boats is likely NOT much of a consideration, and that after a few years of occupancy the boat will be worth less than it was at purchase. OR, it was possibly acquired cheaply making the above motivations re: operability and value moot. I'm trying not to be negative about the PO, just trying to assess what is really going on in the brain pan. The poster did come to us with a seemingly well-motivated query albeit with an apparent lack of knowledge/motivation about many things nautical. Hopefully, that vessel will be getting some underway time.
 
Imo, there's a significant difference between sitting on the hard for 7 months and the boat sitting in saltwater for 7 months. I would guess the humidity in the engine room with some water in the bilge would be higher than a boat 100 yards away on the hard with a dry bilge.

Ted
 
While I am sure that the externals of any unused and untended engine subject to possibly higher humidity are in more jeopardy of developing "issues," I do not think that the internals, which are what the OP seemed to be addressing, are going to see any real difference in the "short" term of season-to-season storage differences. However, tending to the engine in minimal ways like an occasional misting of WD40 and a minimum of heat like incandescent lights and/or a bilge heater or two can have the most positive effects on an engine's environment saving all the down sides of dry winter storage.
 
rgano said:
While I am sure that the externals of any unused and untended engine subject to possibly higher humidity are in more jeopardy of developing "issues," I do not think that the internals, which are what the OP seemed to be addressing, are going to see any real difference in the "short" term of season-to-season storage differences. However, tending to the engine in minimal ways like an occasional misting of WD40 and a minimum of heat like incandescent lights and/or a bilge heater or two can have the most positive effects on an engine's environment saving all the down sides of dry winter storage.
Click to expand...
Our boat rests in the water 5 months over winter in the PNW. Before we put it to bed for the winter we run it up to temp, then throw it in to gear for 5 minutes at idle, then shut it down. Proceed to change oil and filter, remove tranny fluid and replace with fresh, run up engine again. Then do a fresh water rinse, followed with 4 gallons of RV antifreeze. Also topping off fuel tanks and through a cover over her. Has worked well for 10 years
 
Make sure the boat is well fastened to the pier, and run it in gear to apply adequate load to bring it up to operational temperature. Running it at idle has dubious benefits, and may do more harm than good.
The comparison to the Alaska fish boats idle periods is not a good comparison to idle pleasure boats.
Those guys must take great pains to insure that their motors are in top shape for the brutal fishing season, and most of them spend significant time and money to insure that.
 
We have seasonal construction equipment that sits for 6 months at a time. I start it on our yard and run it for five minutes every couple of months. Battery condition, bird nests in exhausts, tires low on air, even missing batteries due to theft- you need to check this stuff or you'll be disappointed when you mobilize the equipment.

Lots of benefits and no negatives. People that run diesels every day check the oil and water, take a look at all sight gauges, walk around the machine, and go to work. Five minute warmup unless it's really cold.

Same with the boat every 3 or 4 weeks. Crank the engines, crank the gen, engage fwd and rev on the engines. Load up the gen by cutting off the shore power. Run the bow thruster back and forth.

Generator gets to operating speed, engines do not though they will warm up substantially.

Diver says spin the thruster every week or two to help keep it clean. Prop shop says spin the shafts regularly to prevent crevice corrosion.

I had a generator impeller fail during a dockside test. Easy fix at the dock, not so much fun away from the dock.

I'd like to see a real study about the negative effects of idling, given that most heavy equipment spends thousands of hours idling during its lifetime. Modern engines don't load up and smoke after lots of idling.
 
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