Mooring Analysis and Wave Loads

Mooring analysis is the engineering calculation of the forces a cage system must resist and how the anchor, rope, and bridle layout distributes them, using site data on significant wave height, peak wave period, current speed versus depth, wind, and water depth. Loads scale with exposed net and collar area: a 120 m circumference cage in 2 m significant waves with a 0.5 m/s current can see total horizontal loads in the tens of tonnes, rising sharply as fouling grows. Analysis outputs include anchor holding capacity (typically 5 to 20 tonnes per anchor depending on seabed), line pre-tension, maximum excursion, and safety factors, usually 1.5 to 3 on ultimate loads depending on certification scheme. For the operator, the payoff is storm survivability and fish welfare: a well-analysed mooring keeps the net cylindrical under load so fish retain swimming volume and oxygen flow; a poorly analysed one lets adjacent cages collide or nets collapse during extreme events. Related concepts include HDPE cage design, biofouling drag, and offshore site licensing, which increasingly requires documented mooring analysis as a permit condition.