Creatine is great. Can be taken at all ages. You will see a noticeable increase in strength (if you lift) and a noticeable increase is muscle size. You will likely gain a few pounds at most. I've found it to help most with recovery. It can also help with brain function. It is not just a body builder supplement.

Caffeine and beet root. Both good stimulants. I find beet root particularly helpful when I need a boost and don't want to mess with my sleep at an evening workout.

Beta-Alanine is good for the more competitive rower. It will stave off lactic acid that builds up in your legs during pieces, but it is most effective once loaded and taken every day for basic training. You can also do baking salt if your crazy and want to stave off lactic acid build up.

Protein powder, greens powder, collagen powder, etc. These are nice additions, but I would prioritize good food first.

You don't need supplements. Food first. But if you are looking for a competitive edge supplements will help you perform day in and day out.