How engine hours are count?

[New_sailor_in_marina]

I'm curious about how engine hours are count.
Is it just the time between starting and stopping the engine?
Or does it dependent on RPM, meaning running at higher RPM engine hours are shorter/pass quicker, and running at lower RPM let engine hours last longer.
If dependent on RPM, does anyone have information how hours are count for Volvo Penta?

 

[VicS]

Usually the number of hours the engine is switched on. Turn the key to the run position or press the power on button and the timer will start running and run until you switch off again. It is not even limited to the time the engine is actually running.

 

[Tranona]

I'm curious about how engine hours are count.
Is it just the time between starting and stopping the engine?
Or does it dependent on RPM, meaning running at higher RPM engine hours are shorter/pass quicker, and running at lower RPM let engine hours last longer.
If dependent on RPM, does anyone have information how hours are count for Volvo Penta?

Welcome to the forum

Literally the number of hours the engine is running, irrespective of revs or whether in gear or not. Actual point of start/stop varies according to whether it is when the switch is on or the engine starts/stops but makes no real difference.

The life of the engine depends in part on how it is used. Engines rarely die from wearing out mechanically. The Perkins engines in the current small Volvo range are used in industrial and agricultural machinery and mechanically have typical life of 8-10K hours. However to achieve these hours they are usually run at the optimum speed/power output for long periods. The working rev range is 2-2800rpm on something like a D1 30. Running slower and under lighter loads generally reduces life so most boats are fitted with a propeller that give a comfortable cruising speed at +/-2200rpm which is approx 50% power, maximum torque and lowest specific fuel consumption. Engines prefer constant running under load so starts followed by short runs are bad as is light load running for example to charge batteries and leads to build up of deposits such as unburned fuel and oil which clogs exhaust elbows. Most makers recommend periodically running at high rpm for short periods to burn off such deposits

I used to own a Volvo MD2030 which was in a charter boat in the Med. It did 350-400 hours a year (3 or 4 times as much as the typical UK private boat). Operating speed was 2400rpm and most runs for 3-5 hours at a time. Totally reliable, oil changed every 150 hours and when I sold it at 10 years and 3500 hours there was no indications of wear or loss of performance.

 

[LittleSister]

VicS has it, as usual.

Usually, any time the engine is switched on but not running is minimal and can be ignored for practical purposes.

The hours counted are unaffected by RPM.

 

[penberth3]

VicS has it, as usual.

Usually, any time the engine is switched on but not running is minimal and can be ignored for practical purposes.

The hours counted are unaffected by RPM.

Not always. Hour meters, engine mounted or on the older mechanical tachometers, were simply geared to the drive. "One hour" was an hour running at a specified RPM, double that RPM and it showed two hours running per hour of time. Probably a better indication of how much work the engine had done.

 

[rogerthebodger]

On my setup I have a water flow switch that feeds 12 vdc to my engine hours meter as well as and inverting transistor switching an indicator light off when water is flowing.

This makes it that only when the engine is actually running and cooling water is flowing does the engine hours count

The oil pressure light could also be used with an inverter transistor to drive the engine hours meter

 

[MontyMariner]

Not always.

Yes, that thought crossed my mind.

 

[Tranona]

Not always. Hour meters, engine mounted or on the older mechanical tachometers, were simply geared to the drive. "One hour" was an hour running at a specified RPM, double that RPM and it showed two hours running per hour of time. Probably a better indication of how much work the engine had done.

That does not apply to the Volvo Penta engines the OP is asking about where the hour counter starts and stops electrically .

With diesel engines life is more related to the volume of fuel burned than the number of times the crankshaft revolves, although in yacht auxiliary use engines tend to die from lack of (proper) use rather than excessive use.

 

[rogerthebodger]

Boat engines are newer loaded due to the fluid drive of the propeller unlike a car / truck engine that can be overloaded by driving in too a higher gear

 

[jbweston]

Inevitably things have changed over the years. 50 years ago my parents had a boat with Perkins T6.354s. They had no hour meters so we added one that was mechanical, fixed to one of the engines and was powered by engine vibration and shakes, rather like those old motion-powered self winding clockwork watches.

I seem to recall driving an old diesel tractor in the 1970s that actually had a notice on the hour meter that it was measuring hours run at a specified RPM, so running faster for an hour added more than one hour, and at reduced revs less than an hour - as Penberth3 says above.

Nowadays measuring the hours from on to off makes more sense and is easy to do with modern electrics.

 

[mattonthesea]

Until I realised how easy it is to install an hour meter I would note the hours by checking my watch at engine on and off times. An easy, if slightly inaccurate, calculation would follow.

 

[Daydream believer]

My volvo D1-30 has the Volvo standard instrument panel with hours shown in the rev counter. Because that failed on my MD 2020, I had a counter wired to the alternator. In the new engine, as it was already installed in a handy position, I wired it in to the new engine alternator. It will only work when the alternator is producing a current.
It matches the hours on the instrument dial. So the answer - as far as the D1 30 is concerned- would be that the hours refer to running hours, not switched on hours.

 

[Daydream believer]

VicS has it, as usual.

Usually, any time the engine is switched on but not running is minimal and can be ignored for practical purposes.

The hours counted are unaffected by RPM.

So with due respect I would dispute your comment- In my case, at least
Crossing the shipping lanes in the Dover Strait (for example) my engine is normally switched on, but not running.
I think that is recommended
That can be 4 hours in some conditions. I do it because being SH I can reach down to the control & use the engine if needed, without going below to turn on first
The same applies in any area where my engine may be needed,

 

[Rappey]

I would note the hours by checking my watch at engine on and off times.

Wow. Thats dedication..
There seems to be some overly complicated methods of triggering the hour meter?
I just connected mine to the wiring going to the ignition switch so turn the key to on, hr meter counts. A few hrs out means oil change a few hrs early ?
Cant see the need for minute accuracy. My engine is so old that the hr meter is more for novelty factor and working out how many litres per hr over a tank full of fuel.

 

[rogerthebodger]

So with due respect I would dispute your comment- In my case, at least
Crossing the shipping lanes in the Dover Strait (for example) my engine is normally switched on, but not running.
I think that is recommended
That can be 4 hours in some conditions. I do it because being SH I can reach down to the control & use the engine if needed, without going below to turn on first
The same applies in any area where my engine may be needed,

So your engine is not running so you can start your engine from the helm position then engage gears.

Using the alternator to drive the engine hours meter is the same s using either a water flow or oil pressure switch to drive the engine hours meter is in my view correct as you are measuring the time the engine is actually running

In y case when the engine is on tick over the alternator is not generating which is why I used the water flow witch

 

[Rappey]

my engine is normally switched on

Does that mean power to the engine control panel but key in off position , or key turned ? Key in the run position is when the hr meter should run rather than when there is live to ignition but off.

 

[Daydream believer]

I was never confused. But I am now

 

[Daydream believer]

So your engine is not running so you can start your engine from the helm position then engage gears.
In y case when the engine is on tick over the alternator is not generating which is why I used the water flow witch

Yes
Generates on tickover, as can be seen on the BM1
I did not have a key
But to each his own

 

[Tranona]

So with due respect I would dispute your comment- In my case, at least
Crossing the shipping lanes in the Dover Strait (for example) my engine is normally switched on, but not running.
I think that is recommended
That can be 4 hours in some conditions. I do it because being SH I can reach down to the control & use the engine if needed, without going below to turn on first
The same applies in any area where my engine may be needed,

Do you not have the engine control panel in the cockpit? Never seen the point in having it in the cabin, particularly as you can get a reasonably waterproof panel with all buttons.

 

[MikeBz]

Our hours meter (Perkins Prima M50) is driven off the tacho drive from the alternator, which makes me wonder if it is revs dependent. As an aside I still haven’t worked why they are intermittent - works fine when at the pontoon, in gear under load for some time, but stops or becomes intermittent within minutes of casting off!