# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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Re: Barrels was DR thread from Nov-Dec '04
From: Bill B
Date: 2005 Jan 28, 17:37 -0500

```Doug

George posted a plausible explanation of the cube method, but I have not
seen your posting on how a merchant marine would solve the problem.

Any hope I will see another way to skin the cat from you?

Bill

> As for Bill's question about turns and fuel consumption the easiest way for
> me to show how much fuel these larger,laden vessels consume would be to take
> a question out of the C.G. exam for 3rd mate,unlimited as an example.
>
> Q: The speed necessary for reaching a point at the designated time is 18.0
> kt.The pitch of the prop is 23.9 ft.How many rpm will the shaft have to turn
> with a - 2 % slip to reach the point in the given time?
> My calculated rpm = 77 rpm
>
> If the fuel consumption at the above shaft rpm is 215 barrels/day what will
> be the fuel consumption if the vessel's speed is reduced to 14.0 kt.?
> My calculated consumption = 102.3 BBLS/day
> The correct answer = 101 BBLS/day
>
> Close enough to pick the correct answer out of the supplied answers but my
> calculated rpm is apperantly high as shown by the 102.3 barrels instead of
> 101 barrels.So,in real life, you can see that a fair amount of money would
> be lost if calculated incorrectly.

```
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