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post #8 of Old 07-10-2012
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Re: Diesel consumption.

Originally Posted by flyingwelshman View Post
My New-To-Me Hunter 30' had a fuel gauge.

The fuel gauge was located on top of the fuel tank.

The fuel tank is conveniently located under the cockpit, between two lockers.

To read (or rather: "attempt to read") the gauge one had to empty a locker, invert one's self (with someone holding one's ankles). In this way one could see the gauge, but not read the fuel level on it.

I spoke to a bunch of people about fuel consumption and most of the responses involved keeping track of hours run (and RPM's) and diesel added. In that way the consumption rate could be established.

Well, Dammit Jim! I'm a cook not a mathematician (or 'electrician' - more on that later).

I decided to install a new gauge attached to a sending unit.

I replaced the old gauge and float with a new float and sending unit and wired it all to a switch and shiny gauge that I inserted into my cockpit coaming.

The damned thing didn't work.

I didn't have time to play around with it as I was heading out for a week and a half with my wife. I was convinced that I was running low on diesel at one point so I reverted to the tried and true technique of inserting a wooden spoon handle into the tank. Worked a treat!

A good friend of mine is an electrical engineer. I asked him to take a look at the new gauge's wiring , determine why it wasn't working.

He was very impressed by my work and said that the installation was perfect except for three 'minor' mistakes.
  1. The connections were not secure - who knew that ring connectors are rated by wire gauge as well as the size of the hole?
  2. The wires were connected to the wrong terminals.
  3. And the polarity was backwards.

Other than that he said I did an expert job.

The gauge seems to be working now.

While the gauge was not working I decided to track the engine hours and try to ascertain fuel consumption rates.

I came up with this engine log. Please let me know if you think it would be useful and if you believe it should have more information.


Looks fine, except there's nowhere to record how many gallons you're using. Geez what's the use of it without that!

I think you could also just go by the old rule of 18HP/Gal/HR. Look at your engine manual and see how many HP you're using at your chosen RPM (assuming correctly sized prop) and you'll be really close.

See also this thread:
fuel consumption gas vs diesel


I have a sauna on my boat, therefore I win.
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