Why can't we design more efficient containment booms?

One of the problems I am noticing in the oil spill, is that the containment booms don’t seem to do a very good job of containing the oil. Some oil is stopped by them, but there is invariably a lot of leakage. Seems like a better design, one that reaches deeper under the surface, and higher above it, could go a long way towards better mitigation. Oil floats on water, so why is it so hard to construct a boom that is a more effective barrier?

light oil floats.

when oil gets emulsified it can get mixed with the water to some depth. chemicals and agitation through waves can cause an emulsion to form. chemicals were injected at the well head something that was new and untested for its effect.

oil plumes from this current spill are hundreds of feet deep, a surface boom wouldn’t have effect on those. booms or berms near the shore might help some if the depth is shallow.

Waves are also a problem. I don’t see how any boom could work in rough seas (such as we had in the weeks immediately after the accident).