Software
/ Spill
Tools / Using
Spill Tools / Step 3
Step 3. The Mechanical Equipment
Calculator
In this step, you'll estimate how
much of the spilled oil you could skim off the sea surface during the time remaining
before the oil is predicted to reach the sensitive site. You have on hand a
single, small skimmer vessel, a Sandpiper (skimmers are boats and other devices
that can remove oil from the sea surface before it reaches sensitive areas along
a coastline). Here's how to use the Calculator to make the necessary calculations:
1. Create and name
a new scenario. To do this, click New Scenario, type in the name of your
scenario, then click OK.
2. Assign the Sandpiper
platform to your scenario. To do this, click Go to Platform, click on
the Sandpiper in the list of skimmers, then click OK. You will see information
about the characteristics of the Sandpiper. Next, click Scenario Assignments,
click on the name of your scenario, click >>Move>>, then click OK.
The Calculator shows you information
about the Sandpiper obtained from the manufacturer or estimated by oil spill response
experts, including its Service Type (the mechanism it uses to skim oil) and Operating
Environment (the environment it is designed to function in). Note in particular
the Nameplate Pump Rate, shown in the lower left corner of the window. This is
the maximum rate at which the Sandpiper can skim fluid from the water surface,
under ideal conditions (in real life, consider reducing this value if you are
attempting a skimming operation in rough seas). When using the Calculator for
a real response, adjust Offload, Transit, and Utilization Times to match your
situation. These are the times taken (a) to offload collected fluids from the
skimmer and (b) to complete a one-way transit to the transfer point, and (c) the
time available to collect and recover fluids, transit to and from backup storage,
and offload recovered fluids. For more details about the information you see on
your screen, click ?.
Change Utilization
Time to 10 hours, since you have an estimated 10 hours before the oil
slick reaches the sensitive site.

3. Return to your
scenario: from the Scenario menu, choose the name of your scenario, then
click Go to Scenario.
The Calculator will add the Sandpiper
to its list of skimmers used for this scenario, and its UT, Utilization Time.
4. Fill out the
boxes in the Calculator to describe your spill scenario, as shown below.
- Under Operational Period, to indicate
when the skimmer can start working and when it will stop working, type in
Start and End dates and times. You have just 10 hours to skim oil from the
slick before it is predicted to reach the sensitive site, so type in a Start
date/time and End date/time that are 10 hours apart (as in the example below).
Note that the Calculator uses the 24-hour time system, in which time of day
is indicated by four digits, the first two indicating the hour (00 to 23)
and the last two indicating the number of minutes past that hour (00 to 59).
Each day begins at midnight, 0000, and the last minute of each day is 2359.
- Type in the Volume and Area of
the slick, and choose units (the Calculator then will automatically estimate
Thickness).

5. Click Calculate. The Calculator will use the information
you entered to predict
- Area Covered - the area of the
slick that the Sandpiper can skim during your 10-hour operational period.
- Fluid Recovered - the total amount
of oil and water the Sandpiper can collect in 10 hours.
- Fluid Retained - the total amount
of fluid the Sandpiper will retain in its hold after 10 hours (some skimmers
can decant water as they skim; the Sandpiper cannot).
- Oil/Emulsion Recovered - out of
the total fluid recovered, the amount that is either oil or emulsion (a frothy
mixture of oil and water, often called mousse).
- Free Water Recovered - out of
the total fluid recovered, the amount that is free water (water that is not
emulsified with oil).
- Free Water Retained - the amount
of water the Sandpiper will retain in its hold after 10 hours
- Free Water Decanted - the amount
of water the Sandpiper will decant as it skims (this value will be zero, since
the Sandpiper does not decant water)
- Time to Fill - The time taken
by the Sandpiper to fill its hold with fluid (once the hold is full, the Sandpiper
must transit to a location where it can offload the fluid it has collected).
- Number of Fills - The number of
times the Sandpiper can fill its hold with recovered fluids during the Utilization
Time.
(Cost per Barrel [Cost/bbl], the
cost in U.S. dollars per recovered barrel of oil, would be estimated if you
had entered the hourly cost of operating the Sandpiper.)
Questions
- About how much oil could the Sandpiper
recover during the operational period? ____ barrels
- What percentage of the total volume
of the slick is this? ___%
- Is skimming with the Sandpiper
a realistic option, given the time you have available?
- The Sandpiper is a relatively
small skimmer. What if you also had available the ACRU2, a larger skimmer?
(the ACRU2 is the name of a particular skimmer in the Recovery 1 class). How
much oil could the two platforms recover during the operational period? ____
barrels (Hints: (a) be sure to reduce the Utilization Time for this skimmer
to 10 hours, and (b) once you've added this platform to your scenario, press
Calculate again.)
- About what percentage of that
oil would be skimmed by the ACRU2? ___ %
Check Your Answers
Revised: April 16,
2001
Office of Response and Restoration, National Ocean Service, National Oceanic
and Atmospheric Administration