Thread: Maybe this one?
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Old 03-24-2013, 10:12 PM   #210
westwinds
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City: Wisconsin
Join Date: Feb 2013
Posts: 96
Quote:
Originally Posted by westwinds View Post
...

I used a water line length of 68 feet since the bow of this trawler goes almost straight down and a weight of 140,000. I used two speeds.

At 9.9 knots, 2000 RPM engine speed and 100 propeller horsepower for each engine, the fuel burn is 5.2 gallons per hour for each engine, which gives .95 miles per gallon. For those that are curious, the speed length ratio is 1.2,


At 8.24 knots, 1666 RPM, and 58 propeller horsepower for each engine, the fuel burn is 3.1 gallons per hour for each engine, which gives 1.33 miles per gallon. The speed length ratio is 1.0...
I made an error. Somehow I changed the length of the boat to 70 feet rather than 60 feet. Substitute the following for the above:

I used a water line length of 58 feet since the bow of this trawler goes almost straight down and a weight of 140,000. I used two speeds.

At 9.14 knots, 2000 RPM engine speed and 100 propeller horsepower for each engine, the fuel burn is 5.2 gallons per hour for each engine, which gives .88 miles per gallon. For those that are curious, the speed length ratio is 1.2,

At 7.62 knots, 1666 RPM, and 58 propeller horsepower for each engine, the fuel burn is 3.1 gallons per hour for each engine, which gives 1.23 miles per gallon. The speed length ratio is 1.0.

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