Row Intervals
20:00 as 4x5 mins at varying stroke rates
1: 2 mins @ r16/ 1 min @ 24 / 2 mins @ 16
1: 2 mins @ r18/ 1 min @ 26 / 2 mins @ 18
1: 2 mins @ r20/ 1 min @ 28 / 2 mins @ 20
1: 2 mins @ r22/ 1 min @ 30 / 2 mins @ 22

The lower rate work should not be an excuse to take it easy. Try and hold around 75% pressure on these intervals and sprint the minute intervals. Use the two minute interval after each sprint as recovery time. But intentional recovery, not fall apart slouch kind of recovery - keep that same 75% pressure.