Originally made from wood, shells are now almost always made from a composite material (usually a double skin of carbon-fibre reinforced plastic with a sandwich of honeycomb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.
One downside of the Waterrower for me are the footrests. Whilst they are perfectly adequate if you want to row in shoes, rowing barefoot, which is something I like to do, is impossible. The plastic is completely square at the bottom and has sharp edges that cut into your heels. I also found that my shoes get caught when trying to put them in and out of the holders, which is a bit irritating.
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.
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 benefit of a water resistance rower is that it most closely simulates a boat moving through water. Rowing resistance comes from the effect of fluid drag acting on the boat; in other words, resistance increases according to stroke rate. The patented WaterFlywheel emulates this naturally self-paced benefit of rowing. This is a workout with immediate benefits, regardless of your level of experience! Please also note that you can adjust the workout intensity by changing the amount of water in the tank. The more water, the higher the effort level required.
At the junior level (in the United States), regattas require each rower to weigh in at least two hours before their race; they are sometimes given two chances to make weight at smaller regattas, with the exception of older more prestigious regattas, which allow only one opportunity to make weight. For juniors in the United States, the lightweight cutoff for men is 150.0 lb.; for women, it is 130.0 lb. In the fall the weight limits are increased for women, with the cutoff being 135 lb.
The WaterRower Club is hand crafted in solid Ash and stained for color. The WaterRower Club has been designed for High Traffic Areas such as Commercial Gyms, Studios, Rehabilitation Clinics, etc. Its Black Rails have been styled to prevent scuffing, other wooden components are finished in an attractive rosewood which is more resistant to soiling than the Natural model. 

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.