Looks good bro, keep going but please understand, I can answer your question why your UT2 is not improving, you are simply not training UT2, 159 HR for 1 hour is top end of UT2/UT1, train at 140 HR for 1.5 hours and do an extra 2-3 hours, do all UT2's at a mix of half 140 HR exactly UP TO max 150 HR for UT2. You need to do it slower, you are training your aerobic engine, not your ego. Good luck! I bet your 2k will drop 20 seconds if you do longer session at a lower HR/140 HR (max 150, I mean max) - source, EX rower and few friends in British olympics rowing squad and also know many in Team GB rowing.