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Old 09-08-2015, 06:49 AM   #41
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"I turn the power on at the helm station with the ignition key the hour meter runs even if I don't start the engine."

This is the normal KISS installation.

For better accuracy you could use an oil pressure switch that would only run the clock only with the engine on.

But with the short time the "key" is on before the engine is operated , almost no one bothers with added complexity.
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Old 09-08-2015, 10:37 AM   #42
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I just confirmed that my VDO tachometer is under reading by about 30%. I checked my logs and it's been consistent since I got the boat in March. I also consistently run it at about 70% of full RPM. Could it be that my hour meter is scaled by RPM?

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Old 09-08-2015, 11:11 AM   #43
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...Could it be that my hour meter is scaled by RPM?

Richard
Most VDO tachs with hour meters for our vintage boats have a DC driven hour meter. An easy way to check is to turn the key on and watch. You should see some movement. Our hour meter is powered by the same 12 VDC that is for the tach illumination.
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Old 09-08-2015, 11:14 AM   #44
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Most VDO tachs with hour meters for our vintage boats have a DC driven hour meter. An easy way to check is to turn the key on and watch. You should see some movement. Our hour meter is powered by the same 12 VDC that is for the tach illumination.
Thanks - I'll try that. If so then I guess my meter is faulty. I wonder how long that's been true - the engine hours could be up to 40% higher than recorded.

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Old 09-08-2015, 11:18 AM   #45
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Is it your engine hours or tachometer that is reading low? You can check the tach. It should have an adjustment on the back.

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Old 09-08-2015, 11:44 AM   #46
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Larry's advice worked for me. There is a thread that I started last spring called"Tachometer Adjustment" that covers the process. I set the engine at cruise RPM's with the laser tachometer then matched the tachometer on the Pilothouse helm with the set screw at the back of the tach. The tach now matches the laser tach at most RPM settings.


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Old 09-08-2015, 11:52 AM   #47
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Is it your engine hours or tachometer that is reading low? You can check the tach. It should have an adjustment on the back.

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Sorry - I re-read my post - it wasn't clear. It's the engine hours on my VDO tach that are reading 30% low and not the RPMs. They seem fine (though I've not checked).

Thanks

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Old 09-08-2015, 12:51 PM   #48
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I use my HM on the VDO tach to do fuel calcs in my log. Run time and dipstick readings used to figure GPH, range, fuel buys, etc. I have not checked the HM against a clock. Will do next run. If it is off I'm going to be pissed.
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Old 09-08-2015, 12:52 PM   #49
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Most VDO tachs with hour meters for our vintage boats have a DC driven hour meter. An easy way to check is to turn the key on and watch. You should see some movement. Our hour meter is powered by the same 12 VDC that is for the tach illumination.
I checked this morning. The hour meter only moves when the engine is running and not when everything is powered up with the engine stopped. I sat there for quite a few minutes with the oil warning alarm sounding just to find out!

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Old 09-08-2015, 12:55 PM   #50
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My VDO will not clock the HM with ign on, engine off. Only starts clocking when tach gets an AC signal from the running engine.
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Old 09-08-2015, 01:23 PM   #51
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Most stand alone hour meters do not operate as an electric clock would.

Power on it runs , power off it doesnt.

Many have a tiny motor that winds the clock for a few min of operation.

Usually it is 2 winds for a 1/10 of an hour.
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Old 09-08-2015, 01:35 PM   #52
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Sorry - I re-read my post - it wasn't clear. It's the engine hours on my VDO tach that are reading 30% low and not the RPMs. They seem fine (though I've not checked).

Thanks

Richard
Richard, I have a portable digital laser tach onboard FW. I'd be happy to loan it to you next time we get together.

Sounds like your tach's hourmeter might run like airplane tach time runs...as a percentage of Redline/WOT.
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Old 09-08-2015, 02:45 PM   #53
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Here are a couple of shops that work on VDO gauges in CA. Maybe it's a simple fix such as changing a gear to get them accurate. We rebuilt both our VDO hour meters and it was important on the number of teeth that the mechanical counter has.

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Old 09-08-2015, 03:18 PM   #54
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Richard, I have a portable digital laser tach onboard FW. I'd be happy to loan it to you next time we get together.

Sounds like your tach's hourmeter might run like airplane tach time runs...as a percentage of Redline/WOT.
Al,

Thanks - I'll take you up on that offer.

I'm going to do some experiments at the dock to see if the hours meter is affected by RPM. I'll report back.

Thanks

Richard
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Old 09-08-2015, 09:30 PM   #55
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jdud, does your boat have oil pressure/overheat alarms that sound when the key is turned on?
the alarms don't come on when I turn on the ignition key on but they will sound when I shut down the engine and don't turn off the key. My electronics only work when the key is on. When I was learning to use the GPS and sonar I had the key on and ran the hour meter up. I am at least the third owner and just bought the boat this season. I have no idea what the other owners did so I can't be sure of the hour meter.

This is my first boat and it is quite a learning experience.
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Old 09-08-2015, 11:32 PM   #56
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This is my first boat and it is quite a learning experience.
Don't be so hard on the hourmeter. If yours was 100% spot on (the very best possible accuracy) and mine was a barely-believable 30% off, the mean would be 15% inaccuracy.

If you've got an average HM, you're within 15% of the extremes of practical accuracy.

If your engines surveyed well, are running well and the externals are in good shape, no worries! Relax and enjoy.
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Old 09-09-2015, 01:51 AM   #57
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In the old days (1970's) The tach / hour meter was based on the engine running at 1800 RPM. Faster = faster hour meter. That's something to check.
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Old 09-09-2015, 08:04 AM   #58
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In the old days (1970's) The tach / hour meter was based on the engine running at 1800 RPM. Faster = faster hour meter. That's something to check.
We had a 26' 1966 Chris Craft, a Chevy gasser. The tach was mechanical and the hour meter ran faster or slower based on our RPM's. We put a lot of hours on the engine trolling for salmon so who knew what the hours on the meter really meant. The hours never were questioned by the different surveyors and the new owner who we stayed in contact with for several years never mentioned it. Maybe because it was pre-internet.
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Old 09-10-2015, 07:16 AM   #59
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An inaccurate hour meter is still fine for oil changes and other PM.
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Old 09-13-2015, 11:57 PM   #60
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An inaccurate hour meter is still fine for oil changes and other PM.


I agree, just as long as it still actually runs reliably.
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