Source: International Convention for the Safety of Life at Sea (SOLAS), Chapter III (Life-saving Appliances and Arrangements), Part B (Requirements for ships and life-saving appliances), Regulation 11.
Reference: imorules.com – Regulation 11
The Administration may permit embarkation ladders to be replaced by approved devices, provided that there shall be at least:
Refer to Regulation 11 of SOLAS Chapter III.