Accurate outboard hour meter

Barnacle_Bill

Admiral
Joined
Feb 8, 2004
Messages
6,469
I got this idea from a retired electronics instructor friend of mine but haven't tried it yet. Get a hot tub pressure switch and using a T adaptor connect it to the tell tale line. Run power for the meter thru the normally open contacts on the micro switch. The gauge could be mounted under the cowling. Or if you have a water pressure gauge you could tap into that and mount the hour meter on the dash. These pressure switches can be bought with adjustable pressure of 1-5 PSI. Can anyone think of any reason this wouldn't work? Silvertip?
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
Re: Accurate outboard hour meter

If the switch works reliably at 1 - 5 PSI and is marine rated (as in ignition protected) it should. It should be waterproof since it is used with a hot tub, but it may not be explosion protected although that is less of an issue with an outboard than an I/O but nevertheless a potential problem if you have a fuel leak. I question the need for this since the only time the meter would run is when the key is on if you wired it to switched 12V. If you are in the habit of leaving the key on with the engine off, AND it is absolutely essential to know exact run time, do what you want to do. Regardless how you wire the thing, nobody but you is going to know whether displayed hours is "real" or not -- especially on an outboard that is not brand new.

And be aware that, depending on the outboard, there may not be enough pressure in the telltale to trigger the switch. Some engines have very low water pressure at idle.
 

Barnacle_Bill

Admiral
Joined
Feb 8, 2004
Messages
6,469
Re: Accurate outboard hour meter

Personally I have no real need for one but the subject does come up once in a while. I thought about idle pressure as an old 83 merc 150 I had usually just spit and sputtered at idle. 1 psi isn't much but I have no idea what the pressure was on that motor.
 

Star

Chief Petty Officer
Joined
Sep 21, 2010
Messages
481
Re: Accurate outboard hour meter

Why would you cobble this all together? Northern Tool has a tach /hour meter for $33. on sale this week. It does add .1 of an hour every time you start your motor but who cares!!! Runs for 3 to 4 years on internal battery.
 
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