OPTIMOOR is an easy-to-use mooring analysis computer program for use by vessel and terminal personnel as well as by port designers and naval architects. It is based on the OCIMF recommendations and procedures and includes OCIMF wind and current coefficients for tanker moorings.
OPTIMOOR can be used to plan a vessel's mooring arrangement and to assess the adequacy of a terminal's mooring facilities. It can be used to manage the mooring while at the berth. It can be used to train personnel in how to tend ship moorings and to react to situations.
At terminals, OPTIMOOR can be used to assess the adequacy of vessel mooring equipment for the terminal mooring arrangement. The need for and effectiveness of auxiliary mooring lines can be judged. Wind or current limitations can otherwise be imposed. Tide tables can be input in advance and then used to anticipate line tending requirements.
On vessel, OPTIMOOR can be used to plan mooring arrangements in advance. Time will then be saved in deploying lines to the proper mooring points. At the mooring, OPTIMOOR can be used in real- or fast-time mode to anticipate line tending requirements.
Vessel owners and operators can use OPTIMOOR to check the adequacy of vessel mooring equipment placement on new and existing vessels. It can help determine if vessels can be safely moored at various terminals, and if special limitations are necessary.
Vessel and terminal personnel can train on OPTIMOOR to learn proper techniques of arranging and tending mooring lines. Advantages and problems of various mooring arrangements can be demonstrated. The time-forward feature with tide, draft and trim changes will illustrate how to anticipate line tending and what is the best tending action.
The Oil Companies International Marine Forum (OCIMF) Mooring Equipment Guidelines, 1992 states:
"The mooring equipment guidelines promulgated by OCIMF are based firmly on the following criteria.
"Ships ... shall have outfits able to restrain them alongside berths in winds of 60 knots from any direction simultaneously with either: 3 knots current from ahead or astern, or 2 knots current from 10 degrees off bow or stern quarter, or 0.75 knots current from the direction of maximum beam current loading"
"Where the environmental conditions at any particular berth are likely to exceed the criteria, it is incumbent upon the berth operator to provide the additional restraint required."
"Forces in the moorings due to changes in ship elevation from either tidal fluctuations or loading or discharging operations must be compensated by proper line tending."
Hand calculation of the various applied and resulting forces, using methods described in several OCIMF documents, is difficult and time consuming. And the results of such hand calculations are only approximations. Computer simulation has in the past been the work of specialists, and was time consuming and expensive. OPTIMOOR is a simple program, employing the methods and formulae recommended by OCIMF, in a manner that can be run even by non-technical personnel.
Within OPTIMOOR, descriptions of the vessel mooring gear and arrangement and the placement of terminal mooring points are prepared on simple "spread sheets". Another "spread sheet" is then used to describe the mooring line arrangement of that vessel at that berth. The wind and current velocities and directions are then input to analyze that mooring system, by calculating mooring line loads and vessel motion. These calculations are carried out instantaneously when ever input data is changed.
Lines that are loaded more than 55% of RBS are highlighted in red. A plan view of the mooring, shown above, can be viewed to check the mooring line arrangement. The mooring load analysis can be printed for records and later study.
Functions and commands are intentionally simple in OPTIMOOR. One key command brings the case back to its initial conditions and resets target pre-tensions. Another brings all lines up to the tension that provides the least vessel movement. The user may then alter tensions in mooring lines by a simple process analogous to tending the mooring winch to bring the mooring line load distribution into better balance. A key command sweeps the wind through 360 degrees to determine the "worst-case" loading on each line.
OPTIMOOR has provision for input of initial and final draft and trim conditions and times. It also has provision for tide tables and local correction factors and even for tidal currents. Line tending requirements can then be anticipated by stepping forward in time by minute or hour intervals. Also, one key command "fast-forwards" and displays the times at which various lines will be overloaded.
OPTIMOOR minimizes the need for the user to gather, calculate, and input other data, relating to wind and current forces and mooring line strengths and elasticities.
A data base of wind and current coefficients includes (under license) the OCIMF wind and current data. OPTIMOOR calculates vessel windage areas based on the vessel size and the present draft and trim. It then calculates the forces and moments applied by the specified wind and current. Other forces, for example tugs, ice, passing ship can also be applied.
OPTIMOOR includes the approximate new breaking strength and load-extension characteristics for mooring lines. Data are provided for wire, aramid/HMPE, nylon double braid, nylon plaited and stranded, polyester, and polypropylene. Both new and broken-in characteristics for the synthetic ropes are provided, based on TTI and OCIMF test data. Synthetic tails on the ends of mooring wires are also included.
OPTIMOOR considers the on-deck length and vertical angle of mooring lines in its calculations. It calculates effects of fairlead and bollard elevations relative to vessel and pier decks. Where applicable, winch brake limits can be set and if exceeded will pay out rope.
OPTIMOOR is now available in two versions: "Standard" which analyzes moorings at piers and sea islands, and "Plus" which also analyzes moorings at offshore spread moorings utilizing buoys and catenaries.
OPTIMOOR is now availabe as a Windows program. It runs under recent versions of Windows.