Rev counter discrepencies.

[ianainge]

My flybridge rev counters decided to go on the blink yesterday or one of them did, on tick over and at speed my starboard counter was recording 120 revs less than the port one when throttles matched, went downstairs and those two were perfectly matched at the higher reading . tried turning the engine of and on a few times but to no avail. Got back to the Marina left them for couple of hours re-started and all back to normal. any clues to cause and remedy please. Volvo 63p,s.

 

[jfm]

Dunno for sure but t seems like your fault has to be in the guage. If the other pair of tachos read ok it cannot be anything at the engine end.

The volvo gauges that came with 63ps were possibly a bit unreliable. We had to get a new tacho when our previous 63p-ed boat was couple of years old and I recall others on here have mentioned needing new gauges.

 

[hlb]

In two boats, I have never seen all four rev counters agree. Makes me wonder if car rev counters are anything like accurate. But then there is not another one to check it with!

 

[Vagabond]

The rev counters are driven off the alternator and are adjusted when the boat is first sea trialed ... if you are lucky! There is an adjusting screw on the back of them.