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.
Sometimes, slides are placed underneath the erg to try to simulate the movement of being on the water. It allows the machine to move back and forth smoothly as if there is water beneath you. The slides can be connected in rows or columns so that rowers are forced to move together on the ergometer, similar to how they would match up their rhythm in a boat.
Water machines are generally quieter than air rowers - you can still hear the water moving in the tank, but users tend to find this a pleasant ambient noise. Water rowers also tend to require little maintenance. Because there's a tank full of water involved, however, these can be very heavy, and larger than most other rowers: if you have a smaller home, a less-than-permanent workout space, or you move frequently, these might not be best for you. And because they're so high-performing, they do come at a high cost.
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.
In general, multi-boat competitions are organized in a series of rounds, with the fastest boats in each heat qualifying for the next round. The losing boats from each heat may be given a second chance to qualify through a repechage. The World Rowing Championships offers multi-lane racing in heats, finals and repechages. At Henley Royal Regatta two crews compete side by side in each round, in a straightforward knock-out format, with no repechages.
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.