Originally made from wood, shells are now almost always made from a composite material (usually a double skin of carbon-fibre reinforced plastic with a sandwich of honeycomb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 WaterRower Classic is handcrafted from solid American Black Walnut wood, finished with danish oil. The WaterRower's patented WaterFlywheel has been specifically designed to emulate the dynamics of a boat moving though water and is unsurpassed in its simulation of the physical and physiological benefits of rowing. WaterRower will not provide support or documentation for any product transported outside of the original country of purchase
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.
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.