What Is the Mooring Line Catenary Tension Calculator?
A catenary mooring line provides restoring compliance through the suspended self-weight of the line curving under gravity.
As the vessel drifts, more chain lifts off the seabed, smoothly increasing restoring force without rigid snubbing.
How Does the Mooring Line Catenary Tension Calculator Work?
Computes catenary scaling parameter a = TH / w.
Evaluates required suspended catenary arc length s to touch down horizontally on seabed.
Calculates maximum fairlead tension T_max = TH + w*h.
Determines grounded anchor chain length lying flat on seabed.
Mooring Line Catenary Tension Calculator Formula & Variables
The core mathematical equation utilized by this calculator is expressed as:
Inextensible catenary curve mechanics relating horizontal pretension, suspended line sag, and fairlead tension.
How to Use the Mooring Line Catenary Tension Calculator
- Enter water depth to fairlead in meters.
- Enter submerged linear chain weight in N/m (accounting for seawater buoyancy).
- Provide horizontal tension force in kN and total installed chain length.
Step-by-Step Example Calculation
Deepwater Floating Offshore Wind Platform
Input Values:
Understanding Your Result
Maximum tension occurs at the top fairlead where horizontal tension and suspended weight combine.
Grounded length must remain positive to ensure zero vertical uplift force at the seabed anchor.
Factors That Affect the Result
- Line weight: Heavier chains generate stiffer restoring forces at smaller horizontal platform offsets.
- Pretension: Increasing fairlead pretension lifts more chain, steepening line departure angle.
When Should You Use This Calculator?
- Station-keeping design for semi-submersibles, drillships, and floating wind platforms.
- Sizing winches, fairleads, and drag-embedment anchor holding capacity.
Assumptions & Limitations
- Assumes quasi-static, 2D planar, inelastic catenary without hydrodynamic drag or bending stiffness.
- Assumes flat, horizontal seabed.
Frequently Asked Questions
Calculation Accuracy & Reference Note
Closed-form exact solution to the classical Leibniz-Bernoulli catenary differential equation.