Transport water returned to the bay is contaminated with varying amounts of fish blood, solids and naturally occurring fish oils. This material is highly viscous and adhesive, and possesses the foul odor usually associated with decomposing fish. Grasa slicks are very persistent, with deposits several centimeters thick evident at the waterline of structures and vessels in the harbor. This pollution problem is exacerbated by the continual presence of other man-made and organic flotsam. The Filterbelt operates on the principal of a sorbent lifting belt skimmer.
Oil adheres to the upwardly moving conveyor, while water passes through.
Grasa behaves very similarly to heavy oil spilled on water. Consequently, recovery effectiveness and efficiency are expected to be very high. It represents the 68th Harbor 28 delivered since the model was introducted in 1991. The all-aluminum Harbor 28 continues to be the most popular oil response vessel in the world.