Northern European countries, with many months of frozen water, have discovered that if their oarsmen use the proper rowing motion on the ergs, their technique in boats, when the thaw comes, is far advanced compared to the rowers who just trained on the ergs as we all do,--sloppily.
Use the erg as a mind training machine as well as an instrument of torture. If we can think about and train our minds and muscles to go through the correct motions on the erg, we will be less likely to drag the blade on the water during recovery, lunge into the catch and drive the catch in.
When using the erg, the following points may help the people who want to improve their catches.
Row normally and observe the consistent height of the chain when pulling. It should be completely horizontal, no bumps, and the same for each stroke. Mark the vertical height of the chain on the frame with tape (or chewing gum if desperate!).
Now, when you are approx 12 inches away from the catch on the way forward, you will gently allow your hands to bring the chain up to the mark.
When you drive off the stretcher the chain height does not change in any way whatsoever. In other words you have got the blade to the correct height on the recovery forward, not on the drive, so you have utilised your length, utilised the entire compression, stopped driving the boat backwards before the blade is fully covered and stopped your bum shove.
At the finish of the erg stroke, train yourself to have a circular finish, carry your chain below the mark until the last 12 inches of travel then gently rise into the catch position whilst on the way forward. In other words you have taught yourself to have a clean finish so that the boat can run, avoided skidding along the water which leads you into a lunge at the catch which leads you into a high catch which gives you a short stroke which was late anyway because you were high. Early squaring is the secret to fast precise catches which is one of the secrets of good bladework.
When you feel confident that your technique is satisfactory on the erg you should start to row with your feet out of the straps. It will help you to develop a longer, smoother, accelerated finish and it will prevent "snatching"; pulling your body onto the handle. Makes you appreciate the importance of having "pressure on the foot plate" all the time. Until you have gained some experience don't do it for high rate work. Good to try it on the water as well. Rowing "square blade" on the water is also character building, good crews can "square blade" all day on good water, including racing. Start off with a small manageable number of strokes and build up.
Now, line up all two brain cells and think of each and every stroke. Despite what some of you may fondly think, your brain is the most important organ of your body. When you are rowing on the water, exaggerate your good technique, using full motions, it will fall back into place on power.