I would start by avoiding dragging the lure under the boat, like if you are on the upwind side of the boat. If you do that you need a much heavier jig, so to avoid having to pay out a ton of line to find the bottom. Rubbing on the boat's bottom or hanging on the running gear will certainly be a strong possibility when you are fishing like that. If at all possible, when on the uptide side of the drifting boat, try casting up into the drift and jig your rig back to the boat. A bit of a PITA, but it IS a deadly effective method, when faced with the less-than-ideal alternative of fishing under the boat.
Also, continually snagging on the rubble bottom when on the down-tide side probably indicates that you are fishing with too much scope. The angle of your line is very important. Straight up and down is the ideal, but isn't often attainable. Again, more lure weight is called for. Carry a few 6oz jigs with you, if you want to stick with a bucktail. Otherwise, use a heavy sinker on a B/S, Chicken or Grand Banks rig, with a big GULP! 6" jigging grub on the hook.
This usually works wonders on those "difficult" days. And don't be afraid to pile the lead on - on some particularly bad days I've had to fish with as much as 14oz of lead, and slammed the fish, while others stubbornly stuck with a 4oz bucktail that never came near the bottom. They never got a bite - and some wondered why. Admittedly this is an extreme example, but I am not a fluke jigging elitist - I just want to catch fish and will do whatever it takes to make that possible.