The single arm boat davit handles only one boat, normally the lightweight rescue boat. It uses a special boat bail or sling to enable lifting at a single point. Hence, the relatively dangerous and time-consuming process of threading two hooks through bow and stem hoisting rings is eliminated. A typical single arm track- way boat davit arrangement is shown in figure 4-15. BOAT DAVIT TYPES AND CONFIGURATIONS There  are  seven  design  types  of  boat  davits currently in use for handling boats aboard Naval ships. Each of these design types comes in several different configurations.  Table  4-1  shows  a  list  of  the  design types  and  configurations. Overhead Suspended Boat Davits Overhead  suspended  boat  davits  consists  of  two sets of sheaves mounted beneath a sponson or other overhang. The boat falls are reeved through the sheaves and connected to a double drum boat winch for power hoisting.  The  boat  is  stowed  suspended  from  hooks directly over the water. The boat is lowered using only Table  4-1.–Boat  davit  and  configurations DAVIT DESIGN TYPE OVERHEAD SUSPENDED CONFIGURATION Double arm, fixed PIVOTED Single arm Double arm, span wire Double arm, strongback PIVOTED  LINK Double arm, span wire Double arm, strongback PIVOTED SHEATH Double arm, span wire SCREW RADIAL SLEWING Double  arm Single arm, standard Single  arm,  non-magnetic Single arm, overhead TRACKWAY Single arm Double arm, span wire Double arm, strongback the force of gravity and it is hoisted by the winch Overhead suspended boat davits are used mainly on aircraft carriers and amphibious helicopter landing ships. Pivoted  Boat  Davits Pivot boat davits can be either the single-arm con- figuration or the double-arm configuration. The arm(s) pivot(s) around a single axis to move inboard or out- board. Pivot single-arm boat davits handle one boat. Pivot double-arm boat davits may handle one or more boats, depending on the application. Depending on the configuration, one boat may be stowed gripped in against the arms, or two boats may be stowed one over the other between the arms. Depending on the model, the boat davit arms are connected by either a strongback or a span wire. The single-arm configuration and the double-arm  configuration  are  gravity  boat  davits. Pivoted  Link  Boat  Davits The pivoted link boat davits are double-arm boat davits designed to lower, to hoist, and to store one or more boats. Two davit frames, one forward and one aft, are mounted to the ship's deck. Each frame supports a davit arm. The arms are connected to the frames by pivoting links. The arms then pivot around the multiple axes of the links to move the boat(s) inboard and out- board (fig 4-14). Depending on the configuration, one boat may be stowed gripped in against the arms, or two boats may be stowed one over the other between the arms. Depending on the model, the boat davit arms are connected together by either a strongback or a span wire.  Pivoted  link  boat  davits  are  gravity  boat  davits. Slewing  Boat  Davits Slewing boat davits have a single arm mounted on a pedestal, which in turn is mounted to the ship. The arm slew rotates about the vertical axis of the pedestal to move the boat inboard and outboard. This boat davit design, commonly called a slewing arm davit (SLAD), is used to handle rigid inflatable boats (RIB). The boat or boats are stowed on the deck of the ship next to the pedestal.  The  slewing  boat  davit  is  electrically  powered and it is also a mechanical boat davit. Trackway  Boat  Davits A trackway boat davit can be either of single arm or double arm configuration. The trackway boat davits may  handle  one  or  more  boats  depending  on  its 4-15