Zen,

First and foremost, if you have a DR with a cluth/brake, set it so will back off if your ball is stuck. Many times just by doubling back the ball will come free. If you have two riggers in the water, throw in the engine in reverse. At least one should come free and then you an maneuver to free the other ball. Lastly, I absolutely avoid fishing heavy currents if at all possible... I have seen DRs ripped right off as well as part of the boat. One fish is not worth that amount of trouble...

Now this may sound painful, but have two sets of wire cutters handy. The tool Easy mentions is perfect for terminal work... You'll want to only use this for terminal work.
Heavy duty Craftsmans is the one that sits right next to my DR...

Downriggin'
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"If you are not scratchin bottom, you ain't fishing deep enough!" -DR

Puget Sound Anglers, Gig Harbor Chapter