Row Conditioning 
3x 12 minutes as follows:

3:00 @ r19 

1:00 @ r22

3:00 @ r19

1:00 @ r22

3:00 @ r19

1:00 @ r22

2:00 rest between sets

You'll alternate between 3:00 @ r19 steady with 1:00 @ r22 at least 5 seconds faster than the steady-state pace. Try to push the speed to an uncomfortable pace during the one-minute blocks before settling back to your steady-state rhythm for another block of three minutes. Used ErgZone app to program this workout -- recommended splits were 2:16.5 (3:00) and 2:09.5 (1:00). I wasn't able to maintain the target pace during the 3:00 minute blocks.