This can dramatically reduce the cross-sectional area of a thruster system resulting in reduced drag and reduced weight and increased bouyancy. Smaller tunnels improve the structural integrity of the hull by reducing the amount of hull that needs to be removed during installation. A specific instance where this becomes a critical factor is in a vessel that is built with structural frames placed close together. In most cases, Shipwrights' tunnels are the only tunnels small enough to fit between these frames maintaining the original structural integrity and yet providing sufficient HP to provide adequate side thrust. This occurs frequently in vessels of aluminum, steel, and wood construction.
Smaller tunnels allow vessels of shallow draft to benefit from bow and stern thruster installations.
Furthermore, many lightweight, modern, motor and sail vessels have minimal submerged hull in the bow section, allowing only enough space for a small tunnel. Catamaran motor and sail vessels are severely disadvantaged by having to install a large tunnel in order to have enough power to provide functional side thrust. Many commercial river vessels and house boats are severely limited in draft and can only use small, high-powered tunnels of the type Shipwrights manufactures.