An 'oar' is often referred to as a blade in the case of sweep oar rowing and as a scull in the case of sculling. A sculling oar is shorter and has a smaller blade area than the equivalent sweep oar. The combined blade area of a pair of sculls is however greater than that of a single sweep oar, so the oarsman when sculling is working against more water than when rowing sweep-oared. He is able to do this because the body action in sculling is more anatomically efficient (due to the symmetry).
Water rowers feature a tank that is actually filled with water as a means for resistance. As you increase the pace of rowing, the resistance naturally increases as well. This means that you can set your own pace and resistance in a single motion. The same is true for air rowers. Air rowers use a fan or flywheel to create resistance, and you have control over the intensity of the workout due to the fact that the air resistance depends on your pace. Most water and air rowers come equipped with -- or at least have as an option -- monitors that track various functions such as distance, strokes, strokes per minute and calories burned.
On a rowing machine, you don’t want to be wearing clothes that are too baggy as the fabric can get caught between the seat and the beam it slides on.  It’s not a disaster if that happens, but it can get annoying if your shorts keep getting caught there while you’re trying to get a serious workout.   It’s better to wear shorter, tighter-fitting shorts (nothing ridiculous), but just enough to ensure it doesn’t the material doesn’t hang down.
The table on the left gives the speed of waves of different wave lengths in deep water. “Deep” in this context is not an absolute value, but is relative to wave length. The simple relationship starts to to breakdown when the depth of the water is less than 1/4 th the wave length. At that depth the bottom exerts sufficient drag on the wave to slow its motion and thus decrease the wavelength [equations and more about wave speed].
 The amount of water in the tank simulates the weight of the boat and crew, the more water in the tank the heavier the boat and crew. The standard Calibration Level is Level 17. If the user is lighter in weight, Level 15-16 can be used. If the user is heavier in weight, level 18-19 can be used. The maximum level to fill the tank is Level 19. DO NOT fill above the maximum level – this could void the warranty.

This rower has been designed to ensure stroke consistency and utilises a triple blade impeller system. Perfect for smaller houses or apartments, this model includes the easy tilt feature for fast fold-up and storing. Assembly is a one man job that will take twenty to thirty minutes to complete. A step by step illustrated instruction manual has been included, in addition to all of the tools needed for this process.

This affordable rowing machine is streamlined, simple to use, built well, has a comfy seat with a realistic rowing movement, and especially good for a newbie. Because the cost of this machine is less than $150, it is popular on the net. As it has a hydraulic rower, resistance is provided by just one piston under the main key column. Along with a comfy cushioned seat, LCD screen, this machine provides 12 hydraulic cylinder resistances.