Originally made from wood, shells are now almost always made from a composite material (usually a double skin of carbon-fibre reinforced plastic with a sandwich of honeycomb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.
The coxswain (or simply the cox) is the member who sits in the boat facing the bow, steers the boat, and coordinates the power and rhythm of the rowers - by communicating to the crew through a device called a cox box and speakers. They usually sit in the stern of the boat, except in bowloaders where the coxswain lies in the bow. Bowloader are usually seen as the coxed four and coxed pair type of boat.
With the smaller boats, specialist versions of the shells for sculling can be made lighter. The riggers in sculling apply the forces symmetrically to each side of the boat, whereas in sweep oared racing these forces are staggered alternately along the boat. The sweep oared boat has to be stiffer to handle these unmatched forces, so consequently requires more bracing and is usually heavier – a pair (2-) is usually a more robust boat than a double scull (2x) for example, and being heavier is also slower when used as a double scull. In theory this could also apply to the 4x and 8x, but most rowing clubs cannot afford to have a dedicated large hull which might be rarely used and instead generally opt for versatility in their fleet by using stronger shells which can be rigged for either sweep rowing or sculling. The symmetrical forces also make sculling more efficient than rowing: the double scull is faster than the coxless pair, and the quadruple scull is faster than the coxless four.
Outside of resistance type, we found the number-one arbiter of ride feel to be cord quality. Water ergometers tend to employ nylon cords, while air ergometers feature metal chains — a durability factor we anticipated would result in our favoring air. But while all three water rowers aced our expectation of smooth, high-tension strokes, perfecting the chain seems to be more difficult: Some tug with just a slight rumble, others feature bouncy, grinding chains that are incredibly loud, something akin to angry snoring. As for nylon, the best wind and unwind like elastic silk — no slack, no sound, no catching, just perfectly even tension throughout the stroke.