ASCE MOP 129
Mooring of Ships to Piers and Wharves
|Publication Date:||1 January 2014|
PURPOSE AND SCOPE
The purpose of this manual is to provide general guidance to determine forces acting upon piers, wharves, and other fixed structures such as berthing and mooring dolphins due to berthed vessels and to provide background for safe and efficient fixed mooring design practice. The ultimate goal is to provide vessels with a "safe berth" with adequate and sound mooring structures and arrangements. This manual is not, however, intended to be a complete, standalone mooring analysis and pier design document, because the subject matter is too complex and the variety of vessel and facility types with specific requirements is too wide. The reader is directed to the various important documents that cover these areas as introduced in the last section of this chapter and referred to throughout this manual.
Ships were once much smaller than they are today. Ports provided mooring accessories on wharves and piers based on a local standard, which proved adequate through many years of experience. Ship captains and pilots could direct the line handlers to tie up a ship in accordance with years of experience as mariners and based on tradition. However, ships built today are increasingly larger and more complex such as tankers, container ships, roll on-roll off (RO-RO), ships, bulk carriers, cruise ships, military vessels, etc. These ships typically have a larger area exposed to wind and deeper draft hulls exposed to current and passing ship effects. Old standards and methods are often inadequate, and analytical methods have been developed to determine mooring forces and optimize the arrangement of mooring lines. Safe mooring also includes limiting the movement of the ship in berth. Preventing parted lines and ship breakaways is another goal of performing a mooring analysis.
This Manual of Practice provides guidelines to determine safe mooring practices for vessels in ports and harbors. These guidelines include design criteria, analysis methodologies, and other relevant information. Although more comprehensive and detailed publications are available, this manual provides an overview of the subject and guides the reader to the use of important design standards and other sources. This manual is primarily concerned with large ocean-going vessels at somewhat protected locations, although many of the basic principles presented are applicable to small craft and at more exposed locations as well. Dynamic analysis is introduced to familiarize the reader with the procedures and provide an understanding of when it is a necessity. The manual does not attempt to provide a rigorous, comprehensive coverage of this topic however. Offshore, single-point, and spread moorings are not addressed herein. In addition, this manual does not deal with the design and/or selection of fender systems for the berthing of vessels. This topic is well covered elsewhere, such as in basic texts dealing with port and harbor engineering and the fender manufacturer's product literature. However, as fenders do constitute an important part of the vessel-mooring system, discussion of fender systems in relation to the moored vessel is included.