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1. Introduction to Marine Accommodation Ladders

A marine accommodation ladder is a safety access facility connecting a ship to the outside world. Specifically, it is a movable ladder facility installed on both sides of a ship for personnel to board and disembark. Generally, it is arranged at the edge of the deck of the lowest side passage on both sides of the ship that is not enclosed by the ship's outer plate. Its main function is to serve as a safe passage for relevant personnel to board or leave the ship. When not in use, the accommodation ladder is hoisted, folded and stored at the edge of the deck; when in use, it is lowered and suspended alongside the ship's hull.

 

2. Basic Structure of Marine Accommodation Ladders

The marine accommodation ladder mainly consists of two parts: the ladder body, the lifting, flipping and fixing device for the ladder, and their auxiliary facilities. It is available in two material types: steel and aluminum.

The ladder body includes components such as the ladder frame, steps, step transmission rod, upper platform, lower platform, handrails, protective wood, side rollers, lower rollers and pins.The lifting, flipping and fixing device of the accommodation ladder is composed of slings, rollers, crossbeams, lifting arms, transmission pipes, supports, eye plates, as well as related pins, shackles, tightening hooks and other parts.

 

3. Requirements for Installation of Marine Accommodation Ladders

As a connecting passage between a ship and the outside, accommodation ladders are mandatory for large passenger ships; they should also be installed on other types of large and medium-sized ships, while small ships generally do not require accommodation ladders.

Arrangement Position: Accommodation ladders are usually installed at the edge of the deck of the lowest side passage on both sides of the ship that is not enclosed by the ship's outer plate.

Quantity: Depending on the ship's size and usage requirements, one accommodation ladder is typically installed on each side of the ship.

Orientation and Fixing: The accommodation ladder shall be oriented towards the bow. When in use, a device for securing the lower platform to the ship's side must be provided to ensure that the end of the accommodation ladder and the lower platform are firmly abutted against the ship's hull within the range parallel to the ship's length. Preferably, this position should be within the middle half of the ship's length, and all drainage holes must be avoided.

4. Classification of Marine Accommodation Ladders

 

4.1 Classification by Material

Marine accommodation ladders are normally classified into three types based on material: steel accommodation ladders, aluminum accommodation ladders, and steel-aluminum accommodation ladders.

 

Material Type	Characteristics	Application Status
Steel Type	Heavy in weight and prone to rust and corrosion. After hot-dip galvanizing treatment, its rust and corrosion resistance is significantly improved, but its surface finish is difficult to enhance, which affects the appearance.	Rarely selected by shipowners currently.
Aluminum Type	Made of aluminum-magnesium alloy, it is lightweight with good strength and rigidity. After anodizing treatment, it has excellent rust and corrosion resistance, and features high surface finish and good appearance.	Preferred by both domestic and international shipowners at present.
Steel-Aluminum Type	The ladder frame and steps are made of different materials (one is steel, the other is aluminum). It is cumbersome to manufacture and affects the appearance.	Seldom used.

 

The main materials of the accommodation ladder shall be steel or aluminum alloy as specified in Table 1; other materials with physical and chemical properties higher than those specified in Table 1 may also be used.

 

4.2 Classification by Number of Sections

Based on the height of the deck entrance above the water surface and the limitations on the maximum elevation angle of the accommodation ladder, it can be divided into single-section accommodation ladders and multi-section accommodation ladders.

Single-section Type: There is only one section between the upper platform and the lower platform of the accommodation ladder.

Multi-section Type: Two or more sections are arranged between the upper platform and the lower platform, with intermediate transition platforms set between adjacent sections.

 

4.3 Classification by Step Type

It can be divided into two types according to the step structure: accommodation ladders with movable steps and accommodation ladders with fixed steps.

Step Type Structural Features

Movable Steps Steps are hinged to the ladder frame. A transmission rod is installed in the middle below the steps to connect the upper platform, lower platform and all steps. When the angle between the accommodation ladder and the horizontal plane changes, the steps and the lower platform remain horizontal at all times under the drive of the transmission rod.

Fixed Steps    Steps are fixed to the ladder frame by welding, using arc-shaped curved profiles.

The upper platform of the accommodation ladder is available in two types: rotary and fixed. Currently, the rotary platform is more commonly used.

4.4 Classification by Platform Type

 

4.4.1 Rotary Platform Type

The structure of single-section, multi-section or telescopic accommodation ladders is hinged to the upper rotary platform, which allows changing the direction and inclination angle between the ship and the boarding surface. The accommodation ladder can be suspended by steel wire ropes or chains from lower (respective) suspension points, or supported by rollers fixed at the bottom of the ladder.

 

4.4.2 Fixed Platform Type

The structure of single-section, multi-section or telescopic accommodation ladders is hinged to the upper fixed platform, which allows changing the inclination angle between the ship and the boarding surface. The accommodation ladder is suspended by steel wire ropes or chains from lower (respective) suspension points. The independently used pilot accommodation ladders adopt this fixed-platform type.