CORRECTION
Ensure during the Rock Over phase your arms are straight (not
locked)and remain straight throughout the Recovery up the slide to the
Catch. At the Catch concentrate on keeping a strong torso, arms remain
straight and push away with the legs. We like to say 'think of hanging
off the handle as you push away'. You should feel a stretch in the
upper back and back of your shoulders as you push the legs.
The Catch Drill is a very good exercise to practise to help solve this
problem of bent arm rowing. Please see this link for information on
the Catch Drill
http://www.watercoach.com/home/technique_module/technique_drills_2.htm