A Tale of Two Tachometers.*

[oldgit]

One of the Tachos on the Flybridge has been playing up since boat purchase and the method of encouraging it to work has gone from gentle light tap to a real well annoyed thump failing to get it to move.
Dismantled twice and lubricated twice which resulted in a short term fix.
Decided to finally sort it.

1. Repair old unit + P&P and how long gone ? £125.00 +
2. New single "Genuine" Yanmar unit. £500.00
2. Unused but new single boxed "Yanmar" unit Ebay. £260.00.
3. 2 x KUS tachos from well known aftermarket supplier £140.00 + P&P
or
4. Solution 2 x KUS tachos via Ebay, arrived 2.5 days after ordering. Total cost £70.00.
Needed to run 2 x wires from alternators to fly for signal to new tachos.
Downstairs Tachos still running using gearbox sender units.
Sorted.
*with apologies to Mr C Dickens.
The Yanmar oil pressure gauges are basically old rubbish as well.

 

[Rocksteadee]

I had similar, replace pair on fly with aftermarket only to find out that the 2 saloon ones were reading higher.
It turns out that all 4 Volvo tachometers had a fiddle factor to overread 3.5%. This was presumably the engines did not reach max revs on commissioning. This was something Volvo would never do and Princess would never do. Later model of same boat had option of 1” less pitched props.

 

[oldgit]

All up and working, bit of fiddle calibrating new units to agree with existing tachos..

 

[mil1194]

All up and working, bit of fiddle calibrating new units to agree with existing tachos..

But how do you know the existing ones were correct…?