The water flywheel is comprised of two paddles encased in an enclosed tank of water. As you pull the cable, the paddles move through the water creating resistance. The beauty of this machine is it uses the mass/density of water. The paddles create the drag, so the harder you pull, the more resistance increases. Think about moving your hands through water. The faster you go, the more dense water feels. The slower you go, the less you feel the resistance. And this type of resistance is excellent for your joints. Click here to read the full review.
The most commonly damaged piece of rowing equipment is the skeg, which is a metal or plastic fin that comes out of the bottom of the boat to help maintain stability, and to assist in steering. Since the skeg sticks out below the hull of the boat it is the most vulnerable to damage, however it is relatively easy to replace skegs by gluing a new one on. Hull damage is also a significant concern both for maintaining equipment, and for rower safety. Hull damage can be caused by submerged logs, poor strapping to trailers, and collisions with other boats, docks, rocks, etc.
Outside of resistance type, we found the number-one arbiter of ride feel to be cord quality. Water ergometers tend to employ nylon cords, while air ergometers feature metal chains — a durability factor we anticipated would result in our favoring air. But while all three water rowers aced our expectation of smooth, high-tension strokes, perfecting the chain seems to be more difficult: Some tug with just a slight rumble, others feature bouncy, grinding chains that are incredibly loud, something akin to angry snoring. As for nylon, the best wind and unwind like elastic silk — no slack, no sound, no catching, just perfectly even tension throughout the stroke.