DL 105 Marine Survival Davits BT Elliott 2011
Davits A system to move a lifeboat from the stowed position, outboard for launching and recovery Davits A system to move a lifeboat from the stowed position, outboard for launching and recovery Radial Obsolete Mechanical Obsolete Gravity
Radial Davits Manually swung out, first one then the other, manila falls, two person operation
Mechanical Davit Hand cranked out, manila falls, 2 man op.
Gravity Davits Industry Standard One man operation Wire rope falls No power needed to launch Brake controlled lowering speed Electric winch for hoisting Manual cranking gear with safety device Launch able with vessel listing and trimming
Types of Gravity Davits Roller Gravity Single Pivot Multi-Pivot Free-Fall Fixed
Roller Gravity
Single Pivoting
Multi-Pivoting
Multi-Pivoting Used when height is restricted, deck above
Free Fall
Fixed Drill rigs, no concerns about listing and trimming
Training Ship Lifeboats 1, 2, 3, 4 use Roller Gravity Davits Lifeboats 5, 6 use Single Pivot Gravity Davits
Roller Gravity Davit Lifeboats #1, 2, 3, 4
Pivoting Davit Lifeboats # 5, 6
Roller Gravity Davits Most common on TSGB Style of Davit that the USCG is basing their testing on
Main Components Track way and Davit Arm
Track Way Each supports and guides an arm Transfers weight and forces to ship Provides mounting surfaces accessories such as winches, grips, locking bar and limit switch
Davit Arm Moving part of system using rollers Cradles lifeboat Attachment point for wire sheaves, span wire and tricing pendent
Electric Winches Not needed to launch Track way or Deck Mount Closed gearing 2 Drums Centrifugal Brake 120 ft/minute maximum Dead Man brake Overhauling Wheel Emergency cutoff switch Operating Controls on Rail
Drums Sized for 6x19 wire, Fleet Angle ≤ 8۠
Davits 1, 2, 3, 4 Centrifugal Brake Dead man Brake Manual Cranking with Safety device Overhaul Wheel
Emergency Cutoff Operating Controls
Gripes Secures lifeboat to Davit Arm in stowed position
Tricing Pendent: brings boat alongside for loading Frapping Line: replaces tricing and controls boat while lowering
Limit Switch Cuts power to winch before final Securing