THL: Stay a safe distance from vertical surfaces if there are significant waves present in the area. A passing boat or ship may generate big waves that escape your attention until there is no time to escape. An example is the North anchorage of the Golden Gate Bridge (but there are special cases, e.g. rough water classes or the OWRC regatta, when there is a fast flood coming through the Golden Gate, and it is useful to be close to the wall since the current is slower there).
When waves run into water moving in the opposite direction, they are slowed, just as if they were approaching a beach. Wave length becomes shorter, wave height higher, and they may break. A good (bad) example of this is an ebb current flowing out of Raccoon Strait into waves coming in from the Golden Gate. Good rough water training, if that’s what you want.
According to Men’s Total Fitness, rowing machines are not only great for aerobic workouts, but they also work all of your body's major muscle groups. What’s more, you don’t have to go to the gym to work out on a rowing machine, as many manufacturers make high-quality rowing machines -- and even rowing machines that fold up for easy storage -- that are suitable for home use. Two popular types of rowing machines are the water rower and the air rower.
The rowing machine itself is unlike any other on the market with its patented water filled flywheel. It is hard to exactly copy the action of a scull on the water, but the mechanics of the flywheel spinning in water comes in a close second on dry land. The fact that the water is 800 times denser than air means that there is no need for any extra resistance or dampening that you will find in normal air rowers. The faster you pull, the more resistance is generated giving it infinite variability. However, if you want to be able to practice rowing with a faster stroke, you will have to reduce the amount of water in the tank unlike an air rower where you just have to adjust the baffle.