What to check on a Gravity Davit.
A gravity davit launches a lifeboat by letting the boat's own weight do the work: once the securing gripes are released, the boat rolls or slides down a track or on rollers until the arms swing out fully over the ship's side, after which the crew lowers it on wire falls controlled by a brake. This differs from a luffing (radial) davit, which swings the boat out using a powered winch through an arc, and from a free-fall davit, where the boat drops directly into the water without a controlled…
What makes this type
A gravity davit launches a lifeboat by letting the boat's own weight do the work: once the securing gripes are released, the boat rolls or slides down a track or on rollers until the arms swing out fully over the ship's side, after which the crew lowers it on wire falls controlled by a brake. This differs from a luffing (radial) davit, which swings the boat out using a powered winch through an arc, and from a free-fall davit, where the boat drops directly into the water without a controlled lowering phase. Gravity davits remain common on cargo ships and tankers because the mechanism needs no electrical power to launch, only to recover.
Main components
Davit arms and track
Curved or straight tracks along which the boat cradle travels outboard under gravity, stopping at the fully swung-out position where the falls take over.
Winch and wire falls
A drum winch pays out the falls under control of a centrifugal brake during lowering, and hauls the boat back up after recovery using a motor or hand crank as backup.
Centrifugal brake
Limits lowering speed regardless of load, the single part that keeps the boat descending at a controlled rate instead of in free fall.
Limit switches and hydrostatic release
Stop the winch at the top and bottom of travel and, on the lifeboat's painter, provide a hydrostatic release so the boat floats free if the ship sinks before launching.
Selection / Sizing
- Safe working load, set well above the fully loaded lifeboat weight including all persons and equipment.
- Outreach needed to clear the ship's side at the relevant freeboard and any flare in the hull.
- Lowering speed, kept within the range the brake is designed to hold under full and light load.
- Number of falls and drum arrangement, matched to the boat's weight and the required recovery speed.
Regulations / Class
Gravity davits fall under SOLAS Chapter III and the LSA Code, which set requirements for launching arrangements, load testing, and periodic operational testing including lowering the boat fully loaded or with an equivalent test weight. Class and flag administration surveys check the winch brake, wire falls, and hydrostatic release on the same schedule as the lifeboat itself, and davit winches are subject to a defined wire rope renewal interval based on age and condition rather than a single fixed number across all types.
Typical faults
| Fault | Consequence |
|---|---|
| Corroded or slack wire falls | Uneven lowering, boat hangs off level or a fall parts under load |
| Seized or worn track rollers | Boat does not swing out fully, davit arms jam mid-travel |
| Brake lining wear | Lowering speed exceeds the safe rate, risk of uncontrolled descent |
| Neglected hydrostatic release servicing | Release fails to activate or fires prematurely |
What to look for in a supplier
- Load test certification for the specific davit and winch combination, not a generic type approval alone.
- Spare parts availability for the brake and winch, since these are the components that wear fastest.
- Compatibility confirmed with the ship's existing lifeboat weight and outreach requirement before ordering a replacement unit.
A gravity davit that has never been load tested with the actual boat aboard is unproven; a paper certificate for the davit alone does not confirm the full system works together.