There is much to love about the WaterRower--and I do love it--but I would echo others' comments that although the seat rolls solidly and smoothly on the wood rails, the seat itself is very hard (I use a gel seat pad I bought for my hard fiberglass kayak seat), and the footpads are in need up rethinking and upgrading--the cheap plastic doesn't let you row in socks or barefoot and is not really worthy of a machine that is otherwise a stunning piece of engineering and a beautiful one as well. As one other person noted about his machine, my machine made a clicking noise on the return stroke, so I had to adjust the wheel underneath the top rail that connects to the footpad and pull it away gently from where it was rubbing against another component. Also, be warned: the instruction booklet is in the DVD case. I did not see the little sticker on the case telling me that, thinking I'd wait to watch the DVD until after I'd assembled it. But WaterRower has a copy of the assembly instructions on their website, along with a video (I found the written ones better and easier to follow), so I was able to assemble it with no difficulty.
Being able to easily store your rower is a huge plus. Make sure you investigate how well the machine stores, if it folds up or comes apart easily to be able to put it in your closet, or in other storage areas. As an example, the Concept2 Model D rowing machine folds up nicely by a simple pull pin located in the middle of the rower. Wheels on the bottom allow for easy moving.
Tank: The tank of the WaterRower M1 LoRise is made from polycarbonate, one of the strongest plastics available. It is virtually indestructible. The tank is sealed and can be filled with municipal water via a small opening closed by a stopper. This water typically contains enough chlorine to remain clear for some time. After exposure to light, the chlorine will degrade and the chlorine tablets included free with the WaterRower M1 LoRise should be added periodically.
Originally made from wood, shells are now almost always made from a composite material (usually a double skin of carbon-fibre reinforced plastic with a sandwich of honeycomb material) for strength and weight advantages. FISA rules specify minimum weights for each class of boat so that no individual team will gain a great advantage from the use of expensive materials or technology.

In sweep or sweep-oar rowing, each rower has one oar, held with both hands. This is generally done in pairs, fours, and eights. In some regions of the world, each rower in a sweep boat is referred to either as port or starboard, depending on which side of the boat the rower's oar extends to. In other regions, the port side is referred to as stroke side, and the starboard side as bow side; this applies even if the stroke oarsman is rowing on bow side and/or the bow oarsman on stroke side.