Animating the boat
It is said that an animator is an actor with a pencil. The point remains true even though you are using Blender instead of a pencil. A good animator is also a good actor. This is true even for something as simple as rowing the boat.
Think about rowing the boat. Basically, you dip the oars into the water, move the blades backwards with respect to the boat until the stroke is done, then lift up the oars and move them back to the starting position. So, how long is this motion going to take?
Rowing is not just a mechanical action. People will row differently depending on their purpose and attitude.
All animators should own a stopwatch. You can get an inexpensive one online or at a local store. If you don't have one, you can use a clock or an online stopwatch that you might find at sites such as http://www.online-stopwatch.com/. However, none are as convenient or as accurate as a real stopwatch.