As a rower for the past 5 years, I can say with certainty that height is definitely a factor in rowing. This does not mean that because you are shorter that you are unable to compete with taller individuals, but it will be harder. If you're not into serious competition, it won't hinder your ability to row, it's just that at high levels of competition it shows. Why is this? Rowing is all about your stroke. People who are taller, or have longer limbs, are able to take longer strokes, which propel the shell further and faster. At 5'11 I wasn't the tallest rower, but with a wingspan of 76 inches, (I have really long arms) I was able to compete well.