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.
Assembly was challenging. One of the rails could not be attached because the embedded screw in the cross-beam was too crooked to fit into the hole on the rail. I had to place a nut on it to protect the screws and tap until it was true enough cap nut to be attached. The foot board is slightly wider than the top board. I will sand this to match when I reapply the finish. This will need to be done because the wood has a dry, ashy appearance. The wood is beautiful and mostly uniform. This rowing machine is a nice product, but the build quality of the unit I received was disappointing. I felt lucky that the gashes in the carton did not damage the product as the packaging was optimistic. The leading competitor I use at the gym seems to provide slightly more resistance. It is beautiful and useful, but with room for improvement.
From a fitness perspective, the WaterRower Natural works 84 percent of your muscle mass, helping tone and strengthen your muscles while burning far more calories than most other aerobic machines. The exercise is also low impact, as it removes all the body weight from the ankles, knees, and hips, but still moves the limbs and joints through a full range of motion--from completely extended to completely contracted.