Why do twin engine boats never have the same amount of hours?

[b_mac]

Hey, been noticing on twin engine cruisers, when I look at the engine hour meter, one engine always has more hours? Why is this? Why would one engine be favored over another?

[Mnbear]

I think because one has been used more than th other

[markpierce]

I've a single engine, so have nothing invested. How much variation in hours are you speaking?

[roetter]

Not on my boat - a 45' cat. At least right now. Less than one hour difference.

But, quite often the port one does sneaks ahead, when we are just doing short run times - in an out of anchorages with sailing in-between. The port engine heats the warm water tank so we run that to be able to have a shower when we are anchored and do the dishes when underway. It takes a longer run because of lack of wind for the starboard engine to pick up.

[clownfishsydney]

The last post has one of the main reasons why engines may have different hours. In our case, I try to run the port engine towards the end of a passage as that is the one heating our shower water. Also, I try to make sure the hours are balanced out as close as possible, even if it means making it up the next day.

However, our boat actually has a huge discrepency in hours on the meters. Why? The starboard one was replaced about 120 hours ago as it was faulty. Another reason can be accidentally leaving the ignition on (not sure if this turns over the meters on ours, but it does on my outboard powered cat that we use for scuba diving - I know, I left one on for a few days once).

[ranger58sb]

Originally Posted by b_mac

Hey, been noticing on twin engine cruisers, when I look at the engine hour meter, one engine always has more hours? Why is this? Why would one engine be favored over another?

Some boats used for trolling are run on one engine for extended periods. If the skipper doesn't "equalize" over time, they'll show different hours.

Sometimes the hour meter is incorporated into another gauge, e.g., the tachometer. Anything that causes the tach to be rebuilt or replaced generally loses engine hours (the clock gets reset to zero).

An engine overhaul often resets the hour meter. A new engine on one side would do the same.

Others mentioned the hot water issue. Could also be about battery charging, for those using alternators on one engine or the other.

-Chris

[belizesailor]

Another water heater variation here....water heater is plumbed to starboard engine.

Also starboard engine is further away from our cabin and the SSB so if I need just a little extra battery juice, like to drive the SSB, I can fire up starboard with less ambient noise.

[Sand crab]

Sometimes one engine will have a bigger alternator so it gets used more for charging and peak electrical usage, etc.

[Floridakeyz]

Originally Posted by b_mac

Hey, been noticing on twin engine cruisers, when I look at the engine hour meter, one engine always has more hours? Why is this? Why would one engine be favored over another?

Starting one engine always first, one engine breaks, other gets you home senerio

[Triumphant]

The Moorings Leopards cats require the port engine running to operate the anchor windlass

[svfraidknot]

on my 42 solaris the port motor seems to have a little less vibration in it and if i need to run it to charge batteries which late at night if watching ttv internet or whatever i might do ,,, it will charge at an idle an idle where as my starboard side needs tro run about 1100 rpms to charge ,, who know why it works . but for that reason my starboard side had 200 more hours ,, but my port motor was the one with only 700 hours on it the injector pump swarmed on me ,, and another good reason my port side tank holds more fuel .. there is that ..

[JPA Cate]

...and then, there's always some variation in the actual engine hours meters themselves.

[rwidman]

My boat has a single engine but two tachs, one for each helm. When I bought it several years ago, the upper tach worked but the hours display was blank. I got around to having fixed a couple months ago. The hours counter was operating, just the display was blank.

Now it shows about 11 hours less than the other tach. I can only attribute this to an inherent inaccuracy. 11 hours error out of 3,600 hours is pretty close I think.

[Zoid]

Some prefer to keep a difference in hours between the engines to space out the maintenance required. Easier to service one engine at a time rather than have both to do at the same time.

[Goosebumps]

Originally Posted by Zoid

Some prefer to keep a difference in hours between the engines to space out the maintenance required. Easier to service one engine at a time rather than have both to do at the same time.

Very good point. Also catamarans power or sail should be operated under one engine when calm seas, little current or head wind. Often speed difference under these circumstances between using 1 or 2 engines is only 1 or 2 knots, but fuel consumption will be double with 2. Displacement trawlers can operate under 1 engine power but at lower speed as the autopilot wouldnt be able to cope with high power from either port or starboard. On catamarans autopilot copes better.