Head races are time trial / processional races that take place from autumn (fall) to early spring (depending on local conditions). Boats begin with a rolling start at intervals of 10 – 20 seconds, and are timed over a set distance. Head courses usually vary in length from 2,000 metres (1.24 mi) to 12,000 metres (7.46 mi), though there are longer races such as the Boston Rowing Marathon and shorter such as Pairs Head.
A bumps race is a multi-day race beginning with crews lined up along the river at set intervals. They start simultaneously and all pursue the boat ahead while avoiding being bumped by a boat from behind. If a crew overtakes or makes physical contact with the crew ahead, a bump is awarded. As a result, damage to boats and equipment is common during bumps racing. To avoid damage the cox of the crew being bumped may concede the bump before contact is actually made. The next day, the bumping crew will start ahead of any crews that have been bumped. The positions at the end of the last race are used to set the positions on the first day of the races the next year. Oxford and Cambridge Universities hold bumps races for their respective colleges twice a year, and there are also Town Bumps races in both cities, open to non-university crews. Oxford's races are organised by City of Oxford Rowing Club and Cambridge's are organised by the Cambridgeshire Rowing Association.
At the collegiate level (in the United States), the lightweight weight requirements can be different depending on competitive season. For fall regattas (typically head races), the lightweight cutoff for men is 165.0 lb. and 135.0 lb. for women. In the spring season (typically sprint races), the lightweight cutoff for men is 160.0 lb., with a boat average of 155.0 lb. for the crew; for women, the lightweight cutoff is 130.0 lb.
If the machine is to be housed on a wooden floor you will need a mat beneath to reduce vibration and also noise. If space is tight, the hydraulic options are usually the smallest. It's also worth checking your floor can take the weight if you're going for one of the bigger, heavier models. For most, this shouldn't be a problem, if you have any doubts get a surveyor to check as it could be a very expensive mistake!
I kayak (ocean and flat water, not river), so I was drawn to the WaterRower over a flywheel type rower (which I have used in gyms) because I wanted to hear the sound of the water, which I miss hearing against the hull of the boat during the winter when I can't get out on the lake. I also like the way the paddles engage in the water; it's a very smooth pull and release, and moving the mass of the water instead of a dialed down tension feels more natural. As someone else also commented, the seat (at least on the wood version) is incredibly smooth and solid; no wobbling at all. I generally listen to music on my Nordic Track ski machine, but with the WaterRower I am content to listen to the sound of the water; working out on this is somehow both energizing and calmingly meditative at the same time. In the event that you want to use it while watching tv (this is one use to which I wanted to put it), it is quiet enough to hear the tv without having to turn it up.
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.