There are two basic formulas that I have tryed to make work depending on what I am doing. Also it helps if you have a strong math background, which I don't. I am open for any suggestions.
Formula # 1
''For Time per Hour or Day''
New Consumption = New Speed 3
_____________ _________
Old Consumption Old Speed
Formula # 2
''For per mile''
New Consumption = New Speed 2 x New Distance
_____________ _____________________
Old Consumption Old Speed 2 x Old Distance
You have to be able to change the basic formula around to fit the question, just like Time, Speed and Distance or try to memorize the different formulas for each type of problem. Its complicated but once I did it a few times, I got of it. Also it helps to remember that you are always trying to find the NEW THINGS (NC, NS, or ND). New things are on top, and old things are on the bottom.
NC = NEW CONSUMPTION
NS = NEW SPEED
ND = NEW DISTANCE
OC = OLD CONSUMPTION
OS = OLD SPEED
OD = OLD DISTANCE
EXAMPLE 1
You are steaming at 15 kts, your vessel burns 326 bbls of fuel per day. What will your rate of fuel consumption if you decrease speed to 12.2 kts?
A. 175 bbls day
B. 215 bbls day
C. 277 bbls day
D. 300 bbls day
ANSWER ''A''
NC = NS3
___ ___
OC OS3
Change to
NS3 x OC
_______
OS3
NC = NS3 x OC
____________ NC = 12.2(3) x 326 bbls / 15 kts(3)
OS3
NC = 1815.848 x 326 / 3375 =175.4 bbls
In these problems I use a TI - 30XA calculator,Here is how I figured it out.
On my calculator I punch in 12.2, then hit 2nd, x3 keys, you should get1815.848, the same thing is true for the 15 kts punch in 15 then hit your 2nd, x3 keys, you should get 3375.
Punch in 1815.848 divide by 3375 x 326 = 175.68.
Hope this helps
