The importance of knowing what’s normal…

by Adrian on July 9, 2014

Since we departed the UK a week ago we’ve been making a special effort to try out and test everything onboard that we’re going to rely on from now on. This has meant living off grid as much as possible, charging batteries from renewables and the generator, making all our own water and generally relying on the systems I’ve installed and prepared over the last couple of years.

The importance of knowing what is normal is advice I’d encourage every boat owner to consider.

A few days back we had an issue with the generator cutting out after a few minutes use. To cut a long story (and lots of head scratching) short, the problem was small threads of fine seaweed (from Portsmouth harbour I think) blocking the boat’s water inlet port used to supply cooling water. Water was getting through, but not enough and the genny was clever enough to shut itself down before overheating.

Why was this hard to diagnose? Because I could see water coming through the strainer, but it obviously wasn’t enough and I didn’t know what was normal.

Also, the temperature at various points on the generator should have been a clue – if I knew what was normal.

So, I’ve started a new list with descriptions of what is normal when things are working correctly.


Generator Heat Spots:
G1 Cylinder head 43.8°C
G2 Exhaust lower 24°C
G3 Windings 49°C
G4 Exhaust upper 52-65°C
G5 Temp sensor 34°C

(These are measured with a Laser thermometer – a very useful piece of kit 20140709-175213-64333224.jpg
Water flow : vigorous enough to hit the lid of the strainer – I now have a video of it – thrilling viewing, but it may be useful!

Charge separator
Feed from alternator 14.14V
Output 1, 2 & 3 14.14V

Fuel supply pressure from vacuum gauge: 2.1 hg 20140709-175512-64512798.jpg

Coolant level when running: above the max line, just above the vessel sealing ridge.

I also know that I should be able to blow down a water intake hose and force air out under the boat – very useful for diagnosing blocked seacocks and water ports.

{ 1 comment… read it below or add one }

Kathie Guthrie July 15, 2014 at 16:33

………..and remember Jackie to make sure the water overflow pipe is not blocked up with Salt or it will blow your freshwater tanks if you fill too quickly without an air escape!!!!!!!!!!!!!!

Not relevant to a generator but certainly useful when filling water tanks eh??


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