[AncientMariner]

During the "sea trials" it was noted that both tachs on the 40000 I am buying are off 50-100 RPM.

Have you encountered the same and if so what have you done about it?

It was also recommended that I replace the tachs with Aetna tachs which are digital and guaranteed to be +/- 1rpm.

Thanks,
Paul

[jmk]

Very common and not a Tiara specific issue. If you use a photo tach to calibrate the difference you can just adjust mentally. Where it matters is those engines should hit 100-150 RPM above rated WOT. It really matters and accuracy of your tach is crucial. For Cummins that would be 2700+ RPM.

[AncientMariner]

Many thanks JMK

[RobS]

I installed Aetna tach on my prior boat and loved it. Some don't like the look of the digital display, I did. As mentioned above, once you photo tach you can make a note of the delta, even make up an index card chart of gauge vs actual..

[AncientMariner]

I just ordered a photo tach, much cheaper than $400 plus for a pair of Aetnas. At least for now

[RobS]

Good move on the photo-tach. That's what I did on my prior boat and just made note of the true vs. gauge delta. But then a couple years later I built a custom dash with all new instrumentation so bit the bullet and installed an Aetna. Single screw so half the cost..