Bollard Pull Mooring

MARITIME – ANCHORING & MOORING CALCULATOR Bollard Pull Mooring A precise tool.
📖
What is the Bollard Pull Mooring & How does it work?

When a vessel is moored in a flowing current, the mooring system must resist the hydrodynamic force generated by the water. This force is primarily a function of the current speed, the vessel’s projected area normal to the flow, and the water’s density. If the resisting force – supplied by the ship’s bollard pull – is insufficient, the vessel can drift, increasing the risk of line failure or collision.

The drag force exerted by the current can be estimated with the classic drag equation. By treating the vessel’s side‑on projection as a flat plate, the force is calculated as:

F_c = frac{1}{2} rho C_d A V^{2}
F_c = current‑induced force (N), rho = water density (kg·m⁻³), C_d = drag coefficient, A = projected area (m²), V = current speed (m·s⁻¹)

The total required bollard pull is obtained by distributing this force among the mooring lines, accounting for the line angle to the vessel and applying a safety factor. The resulting pull is the value that the vessel’s winches must be capable of delivering to keep the vessel securely moored under the given current conditions.

⚙️
Parameters
Result —
❓
Frequently Asked Questions
What is bollard pull in maritime navigation?
Bollard pull is the maximum tension that can be exerted on a ship’s anchor line or mooring system, used to resist the forces acting on the vessel.
How does current speed affect the bollard pull calculation?
Current speed increases the hydrodynamic force on the vessel, requiring a higher bollard pull to maintain mooring stability.
What is the role of water density in bollard pull calculations?
Water density affects the drag force exerted by the current; denser water increases the force needed for bollard pull.
How do you estimate the drag force on a moored vessel?
The drag force is estimated using the classic drag equation, considering factors like current speed, projected area of the vessel, and water density.
Why is it important to calculate bollard pull for a moored vessel?
Calculating bollard pull ensures that the mooring system can resist hydrodynamic forces, preventing drifting and reducing the risk of line failure or collision.
What factors should be considered when using this calculator?
When using this calculator, consider accurate measurements of current speed, vessel dimensions, water density, and environmental conditions to ensure reliable results.
How can insufficient bollard pull affect a moored vessel?
Insufficient bollard pull can lead to vessel drifting, increased stress on the mooring lines, potential line failure, and higher risk of collision with other vessels or structures.

Results are for informational purposes only and do not constitute professional advice.