MarineLog has a video of the T/V A Whale in action.
The problem with capturing oil from the sea is that the surface of the sea is uneven and constantly changing. The slots cut into the hull of the A Whale on the other hand are fixed.
The other issue it the nature of the movement of the oil. Here is: Why is oil spill hard to predict? Look to the clouds.
According to the Coast Guard the A Whale managed to recover 1100 barrels of oil in 24 hours. The report from CNN here. That is much lower then the hype from the owner who claimed (NOLA.com A Whale' oil skimmer testing extended a week)
A Whale can process 21 million gallons oily water a day. That's about 75 percent of the total collected in two and a half months by 500 smaller skimmers working to clean up the massive BP spill.In other words the claim was that A Whale would be about 28,000 times more effective then the skimmers already working the spill.
The media has been conflating the terms "oily water" and "oil" which makes the comparisons confusing. In any case these numbers are not a meaningful measure of how effective the T/V A Whale is at reducing the adverse environmental and economic impacts of the oil spill.