Monday, 27 February 2012

Boat gear: Cruz Pro RH-60 engine tachometer

we give the RH-60 a "thumbs up"!

Ever since we purchased Pelagia, we've intended to put a tachometer (engine RPM) in the cockpit -- Pelagia has her engine instruments at the inside steering station.

This "need" became more acute after an engine breakdown (off Cape Beale, Barkley Sound... thankfully we're a SAIL boat!) in 2009 sheared off the tach sensor, and we no longer had an engine tachometer.

Enter the Cruz Pro RH-60 engine tachometer/engine hours gauge.

The manual for the RH-60 (which is available on line, so we were able to review before purchasing) indicated hooking this little gauge (Cruz-Pro has RPM gauges with larger numbers -- we didn't need larger) should be quite simple.

Amazingly, getting it to work was indeed simple! (Even easier with a smart regulator such as our Balmar ARS-5.) 

First time running the engine showed RPM perhaps a little low -- calibration is carried-out by (i) determining actual RPM (such as with a timing light) then simply (ii) adjusting the RH-60 so it matches the actual RPM.
RH-60 installed in Pelagia's cockpit coaming

We now have an engine tachometer in the cockpit. (And, because it outputs RPM via NMEA 0183, we could also have a tach readout at the inside steering station.)

Boat things are not usually so easy to install...!

UPDATE: June/July 2012. I finally got around to checking the calibration of the RH-60 using a timing light/laser. The actual RPM was about 70% higher than the Cruz Pro was reading. No problem, I followed the directions to re-set/calibrate the RH-60 to the actual RPM. However, I made the mistake of calibrating at a relatively low RPM. Thus, when running at (actual) RPM of 2500, I got a readout of over 4000 RPM. (In doing so, I discovered the factory default "max RPM" alarm -- a piercing noise.) 

So, I learned that I had to calibrate the RH-60 with the engine running at a fairly high RPM. All seems correct now.  It was easy to adjust the RH-60 calibration.

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