Tacho intermittent open circuit

[Crystal_RPAYC]

The Tacho on my 2007 309 has just started to intermittently drop to zero whilst the motor is running. It usually returns to the operating speed after a few seconds. Any suggestions on what could be the cause. Thanks

 

[Stu Jackson]

I recommend that you check the connections, starting at the back of the alternator, then at the cockpit panel.

 

[Maine Sail]

This can happen when the batteries are full. Do you also have solar?

 

[Stu Jackson]

Or if you're still "plugged in."

 

[tahomathundr]

Check the connections at the panel because moisture can get in. I have the opposite problem, my tach will max out at 4000rpm then fall back within 30 sec to cruising rpm and we have traced it to moisture condensation. My boat is in the water all year with a canvas pedestal cover which may be part of the problem. Rain is not a problem this year as we have been dry almost 2 months, and this is Seattle area, so we are looking at condensation. Good luck tracing the problem down.

 

[Pompadi]

Ours did the the same thing, ended up replacing the tacho.
Got the new one from Catarina direct for about $120 , local supplier in Australia wanted $400..!!

 

[Crystal_RPAYC]

Looks like it was the new solar panel. I now switch it off when the motor is running and have not had the problem since. Thanks Maine Sail and Stu Jackson.

 

[peter_ms]

Aren't electronics amazing?
We were running wing on wing surfing 8-10kts towards Scotch Bonnet, an ugly seagull & cormorant crap covered rock in the east end of Lake Ontario when the depth sounder popped from 150' to 20!!!
I jumped on the chart and we shouldn't have been anywhere near that shallow. This had happened earlier for about 20 min then went back to normal.
Skip asked what I had just done below and I replied "just plugged in my cellphone charger in the cigarette lighter". Unplugged it and the depth went back to normal...