40 minutes steady state; The breakdown as follows

10 min x 2: 4,3, 2, 1 @18, 20, 22, 24

then
10 min of 10 strokes ON (5k pace), 10 strokes OFF (easy good paddle)

10 minutes: 4,3,2,1 @ 20, 22, 24, 26

cool down paddle for 3-5 min