"Low: High"  
8 x 2 mins 
Spend the first minute at a lower rate and then step up to a higher rate for the second minute
1: r20-->r24
1: r22-->r26
1: r24-->r28
1: r26-->r30
1: r22-->r26
1: r24-->r28
1: r26-->r30
1: r28-->r32
1 minute rest between rounds

Followed along with DH rowing vid from Rowvember 2021. Came out too conservative on the first two rounds. A low rate does not mean 'go slow' - you just need to shift your ratio to a strong drive and slower recovery to keep a good split. As the stroke rate goes up accelerate back with the leg push taking the resistance with you.