Other possibilities are that you are losing the leg drive by not transmitting it to the handle. 3 common newbie errors:gkucera wrote: the first 1/2 of the leg drive has almost zero resistance; it feels like I am pulling slack until I am half extended with my legs, then I get some pulling action. This induces bad form since I want to take up the slack with my back and arms to maximize stroke pull. I will keep working on it.
dropping hands to feet at the catch, so first part of drive is bringing hands up to be in line with the chain. get your body forward before the knees are broken and hold the position, this can get worse when going for length due to tendency to reach forward and down when coming to catch.
not straightening arms at the catch and so arms straighten while legs drive and handle doesn't move as fast - keep arms straight until legs are straight.
back rolls forward at start of catch - sit up straight with a strong not slumped back.
Just some other thoughts. James's stroke length is effective stroke length, if a significant part of the stroke does not move the chain appreciably faster than the flywheel, this will not significantly increase the stroke length at the force assumed.
One final point, rowing is an unusual action in that there is a long time between the major muscular efforts. As a result, unlike other exercises it is a major muscular effort more akin to a squat than normal aerobic exercise followed by a rest. The drive should be quicker than the slide back in most training despite only the drive being against a resistance. I have come across people who have an intrinsic idea that aerobic exercise doesn't involve the level of force required for rowing. Much of the force in rowing is produced anaerobically, but between strokes the metabolic products are reconstituted or metabolised aerobically so that there is little NET lactate production. As a result aerobic capacity predominates and the exercise is classed as aerobic, but not in the way that cycling is.
If you don't find that the above helps, you could try, after warming up thoroughly, pulling as hard as you can for 100m and see how fast a pace you can develop. You might also try as an exercise at much higher drag. This will mean that the flywheel slows down more between drives and you will feel the power coming on earlier as you are engaging the power at a slower speed. Then at lower drags you need to recreate this with an explosive catch from a powerful position to get the power down earlier.
Hope some of this helps to continue your improvement.
- Iain