A ship's ladder is a specific style of stairway initially used on ships. Since ships have limited deck space, ship builders had to design stairs with unusually steep slopes. These stairs became known as ship's stairs or ship's ladders. The Occupational Safety and Health Administration calls these stairs ship's ladders. In 2003 OSHA modified their regulations to include safety specifications for ship's ladders.
When a ship's ladder extends farther than 6 feet, all employees who will be working on that ladder must receive training in how to inspect and use the stairs properly. On a ship's ladder that is used to climb from one level to another, the side rails must extend at least 3 feet above the level or be equipped with a grab rail to allow for easier access.
A ship's ladder must be able to support at least two loads of 250 pounds (115 Kg)each on any two treads. The ladder must also be able to support additional weight due to ice buildup, rigging and impact. The center of each individual tread must support a single concentrated load of 250 pounds (115 kg).
The rungs of a ship's ladder must be uniformly spaced and parallel. The rungs must be at least 6 inches and not more than 12 inches apart. The ladder must be at least 16 inches wide between the side rails.
A ship's ladder must have toe clearance of 7 inches unless the nature of the work requires a lesser clearance; 4.5 inches is the absolute minimum allowed. The distance between the ship's ladder and any obstacle on the climbing side must be at least 30 inches. If an obstacle is unavoidable, the clearance must be at least 24 inches, and a device to deflect climbers around the obstacle must be used.
Every ship's ladder must be equipped with a cage or well to provide fall protection when the ladder length extends beyond 24 feet. The cage must be easy to access and must direct a falling employee toward the lower level. A personal fall protection system may also be used instead of a cage or well.
Rest and Landing Platforms
A ship's ladder that has a well or cage as fall protection may have a continuous climb of 50 feet or less. If the ladder has a personal fall protection system, the continuous climb may be longer than 50 feet. If the ship's ladder will extend beyond 150 feet, a rest platform at least 18 inches by 24 inches must be provided at least every 150 feet. When two ladders are used to reach a work area, the ladders must be separated by a landing platform at least 24 inches by 30 inches.