Catenary calculator
Catenary mooring system
A catenary mooring system is the most common mooring system in shallow waters. Through gravity the catenaries, between the floating unit and the seabed, will show the typical shape of a free hanging line. The catenaries are hanging horizontally at the seabed. Consequently the catenary lengths have to be larger than the water depth and the anchor points in a catenary mooring system are subjected to horizontal forces. The catenary configuration provides a restoring force on ship motions mostly through the weight of the catenaries.
A catenary mooring system is the most common mooring system in shallow waters. Through gravity the catenaries, between the floating unit and the seabed, will show the typical shape of a free hanging line. The catenaries are hanging horizontally at the seabed. Consequently the catenary lengths have to be larger than the water depth and the anchor points in a catenary mooring system are subjected to horizontal forces. The catenary configuration provides a restoring force on ship motions mostly through the weight of the catenaries.
A catenary mooring line will have a part which is laying on the seafloor and a part of the mooring line suspended in the seawater. The part that is uspended in the seawater will take on a catenary shape. Depending on the waterdepth, the weight of the mooring line and the force applied to the mooring line at the fairlead, the length of the suspended mooring line S in [m] can be calculated with:
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In the Figure above a catenary mooring line is shown. The angle is the angle between the mooring line at the fairlead and the horizontal shown as angle j. The force applied to the mooring line at the fairlead is given as F.
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The waterdepth plus the distance between sealevel and the fairlead in [m] is d in this equation. w is the unit weight of the mooring line in water in [t/m].
The horizontal distance X in [m] between the fairlead and the touchdown point of the mooring line on the seabed can be calculated with:
The weight of the suspended chain V in [t] is given by:
De shape of a catenary mooring line is given by the function:
The shape of the catenary line is uniquely determined by parameter b given by:
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