Development of a Mooring Calculation Model for Pontoons: Preliminary Dimensioning of Mooring Chains and Concrete Anchors

Abstract

Floating concrete pontoons require reliable mooring systems to limit movement and transfer environmental and operational loads to the seabed. In practice, anchoring solutions must also remain cost-effective, installable and compatible with available chain and anchor dimensions. The aim of this thesis was to develop a calculation prototype for preliminary dimensioning of mooring chains and concrete deadweight anchors for SF Marina’s floating pontoon systems. The prototype was developed in Python and combines analytical models for chain geometry, mooring loads and anchor capacity to evaluate feasible chain and anchor configurations under given environmental conditions. The chain model is based on static equilibrium and submerged chain weight, while the anchor capacity model uses capacity tables derived from a simplified Pearl Harbor type anchor formulation. The program evaluates discrete chain dimensions and anchor weights, allowing the selected solution to correspond to practical component alternatives rather than idealized continuous sizes. The prototype was evaluated using a reference case and a comparison between analytical anchor capacity tables and PLAXIS 2D simulations. The results were consistent with SF Marina’s proposed anchoring solution and showed that the chain strength margin was large, while the anchor capacity was more sensitive to seabed assumptions and anchor penetration depth. The developed prototype is considered suitable as an internal early-stage design support tool. It can help compare mooring alternatives, identify governing parameters and document preliminary chain and anchor selections. However, the results should be interpreted with caution where seabed conditions, penetration depth or dynamic loading effects are uncertain.