Differences between The Container for A Davit-launched Liferaft And Other Type of Liferaft Containers

Davit-launched liferaft container vs Throw-overboard container

1. Presence of Lifting Points/Lugs (Key Distinction)

• The canister features integrated, pre-embedded high-strength lifting lugs and mounting bases, specifically designed to interface with the hooks of a liferaft davit system and automatic release mechanisms.

• This allows the entire assembly—canister and the liferaft contained within—to be hoisted by a crane and swung outboard.

In contrast, a "throw-over" (toss-overboard) type canister lacks built-in lifting lugs; it is not designed for being lowered while fully loaded and must instead be deployed by being thrown or dropped directly into the water.

2. Differing Structural Load Standards: Designed for Hoisting, Not Primarily for Impact Resistance

For a "throw-over" type canister, the core requirement is an 18-meter drop-impact test, ensuring the unit remains intact when dropped from a height directly onto the sea surface.

For a "davit-launchable" (hoistable) canister, the focus is on static and dynamic suspension loads—specifically, the ability to withstand the sustained tension of the combined weight of the liferaft and its full complement of occupants. Its drop-test requirements are less stringent, as it is not intended for high-altitude free-fall deployment (though it can, in an emergency, be deployed by being thrown overboard).

3. Internal Lashing and Separation Mechanism

Davit-launched liferafts feature a specialized internal lashing/separation system: once the raft inflates, the canister—initially attached to the underside of the raft—is released when the separation line breaks, allowing the canister to detach and float away.

In contrast, throw-over (toss-over) liferafts are designed for the entire canister to be thrown directly into the water. Upon hitting the water, the painter line triggers inflation, causing the canister to open and the raft to deploy; these lack the controlled separation mechanism found in davit-launched versions.

4. Shape and Dimensions

For a given passenger capacity, a davit-launched liferaft canister is generally longer and has a slightly larger diameter; it also includes designated slots or recesses to align with the davit cradle. These canisters are often elongated-oval or octagonal in cross-section to facilitate secure positioning within the cradle.

Throw-over liferaft canisters are typically standard cylinders—a simple, streamlined shape designed for manual deployment (throwing) overboard.

5. Hydrostatic Release Unit (HRU) Installation

For davit-launched rafts, the positioning of the HRU and the routing of the associated lines are configured to accommodate the operation of the launching cradle.

For throw-over rafts, the HRU is positioned specifically to ensure the raft automatically detaches and floats free should the vessel sink.