http://response.restoration.noaa.gov...2_OilatSea.pdf

Read it. And get this part:
"Other factors that make this technique unreliable are the
on-scene weather and difficulties inherent in estimating area of coverage. Waves will
increase natural dispersion during the early parts of the spill, break the surface tension
that causes the oil to look "slick," and mix some of the oil into the surface layer temporarily.
"Under calm sea conditions, an observer will probably view most of the floating oil. A few
hours later, if the wind has increased and breaking waves have developed," stop for a minute

How can that be? Breaking waves developing in an oil slick? Ha ha ha. You boys need to listen
to this dumb blonde. ;-) resume again

"it is not unusual for an observer to report significantly
less oil due to overwashing of the oil by waves even though the amount of floating oil probably
has not changed. Observers should note that as the wind speed increases, the observers'
ability to detect the oil decreases (Ministry of Transport 1992)."

Thank me.

Cheers,
Ellen