Vetus Fiberglass Stern Thruster Tunnel 7-9/32" Diameter. Combining a VETUS stern thruster with a VETUS bow thruster will provide even greater maneuverability of your boat in locks or harbors. By placing a side-directional thruster in the bow and another one at the transom, everything from docking and sailing away to finding a spot in the lock or marina becomes child's play! Even the effects of wind and current can be effectively countered. Installation of a VETUS stern thruster is simple, the electric motor and other electric components are fitted internally to the transom of the boat. The stern thruster tunnel and the propeller are installed externally on the transom.