Pilot ladder

A pilot ladder is a highly specialized form of rope ladder, typically used on board cargo vessels for the purposes of embarking and disembarking pilots. The design and construction of the ladders is tightly specified
by international regulation under the SOLAS regime.
Construction.
The ladders are made by threading and fixing a series of hardwood, machined steps, each not more than , onto two pairs of minimum diameter manila ropes, and binding each step to the ropes at (+- ) intervals. At a maximum interval of eight steps, the standard step is replaced by a "spreader", which is an elongated version of the standard machined step, with a minimum length of . The spreader's function is to prevent the ladder from twisting in the prevailing weather conditions when in use. 
The lowest four steps of the ladder are normally made from a synthetic or composite resin, which is more resistant than hardwood, to the interaction between the host vessel and the pilot boat coming alongside.
Because the decks of most commercial ships are far above the waterline, pilots and others who need to come aboard at sea can usually only do so if a pilot ladder is put out. When not being used, the ladder is stowed away (usually rolled up) rather than left hanging.