The only problem with water displacement, which I originally thought was a terrific idea as well, is how accurately you could really measure them. You would have to have a very large tank, which would mean that to the average Jow, it would be very difficult to measure any better than 1ml, which is equal to 1 cubic centimeter. That isn't very accurate really. Plus, how could your average hunter who just wants to see for fun what his rack scores measure it at all. Another point is how do you measure the rack for displacement at all? Part of the skull would have to be submerged, which would obviously affect everything, unless you dunked 1 side at a time. If you did that, then you would have to split the skull, thus disqualifying it for P&Y or B&C. These are only a few of the problems I ran in to when first thinking this over.