Today’s session was 10K with a target pace of 2:16.7/500m which is about 137 Watts. It wasn’t possible to keep the heart rate graph flat/horizontal at any particular rate because it kept increasing throughout the 137 Watt session. Perhaps it would have leveled out if the session was longer than 10K?
A screen recording will eventually be available for rowing-along-with on YouTube at: Indoor Rowing 10K at 137 Watts 07072018 but it is uploading very slowly and might take a few hours at the current rate of upload.
Happy rowing to you.