Reply #67: Tankers don't even have the equipment to do that.

[Merchant Marine]

The way a tanker's manifolds and pumps are set up, the ship can only pump cargo between the ship and a shore facility. Tankers don't have any setup for "vacuuming" oil and seawater, or for separating the mixture once its on board.

Ships do have a seawater intake system to feed water to the water purifiers and fire pumps, as well as the engine heat exchangers for cooling, but that system could not be used to remove oil. (This was the reason behind the Iraq War spills, Saddam was hoping that the oil would foul the intakes on the US Fleet, disabling them.)