Calculator Inputs
Example Data Table
| Case | LOA (m) | Bow (m) | Stern (m) | Safety (m) | Fender (m) | Vessels | Inter-clear (m) | Env (%) | Mooring | Result (m) |
|---|---|---|---|---|---|---|---|---|---|---|
| Coastal tanker | 180 | 5 | 5 | 10 | 2 | 1 | 0 | 10 | 1.05 | ~212.0 |
| Container feeder | 140 | 4 | 4 | 8 | 2 | 2 | 15 | 12 | 1.06 | ~346.0 |
| Bulk carrier | 225 | 6 | 6 | 12 | 3 | 1 | 0 | 8 | 1.04 | ~275.0 |
Example results are illustrative. Apply local design criteria for final sizing.
Formula Used
The calculator estimates berth length from vessel length and allowances, then applies safety factors.
- Base length per vessel = LOA + Bow allowance + Stern allowance + Safety clearance + Fender allowance
- Effective length per vessel = Base length × (1 + Environmental factor/100) × Mooring factor
- Total berth length = (Number of vessels × Effective length) + (Number of vessels − 1) × Inter-vessel clearance
- Rounding = Round results to the selected increment, if provided
Use project specifications for allowances, factors, and rounding rules.
How to Use This Calculator
- Select your unit system and enter the vessel LOA.
- Set bow, stern, safety, and fender allowances.
- Enter the number of vessels and spacing if applicable.
- Apply an environmental factor and a mooring factor.
- Choose a rounding increment, then calculate and export.
Berth length drivers in preliminary planning
Berth length is governed by vessel overall length, end clearances, and operational safety space. Early layouts should also reserve length for fender projection, bow flare, and mooring hardware zones. Using consistent allowances across concept options helps compare quay wall lengths, dredge limits, and yard geometry before detailed marine structures are designed. Include future fleet scenarios so the berth remains serviceable during upgrades.
Allowances, clearances, and site constraints
Bow and stern allowances capture maneuvering, gangway placement, and end effects near dolphins or breasting piles. Safety clearance accounts for approach variability, pilot decisions, and daytime or night berthing tolerances. Fender allowance reflects fender thickness, compression, and the offset between hull and quay, so the effective occupied length matches the operational envelope. Check turning basins, berth pocket width, and apron uses that limit workable clearances.
Environmental and mooring factors for reliability
Waves, wind, and currents increase vessel motion and line loads, so designs apply an environmental factor as a percentage margin. Mooring factor represents mooring configuration efficiency and line angles, often higher where bollard spacing is constrained. Together, these multipliers convert geometric length into a more reliable operational requirement during variable weather windows. Use local metocean statistics and operational criteria to justify selected margins.
Multiple vessels alongside and spacing logic
When two or more vessels share a continuous berth, the controlling length is not only the sum of each effective vessel length. Inter‑vessel clearance must be added for safe line leads, tug access, and separation during cargo operations. This spacing is commonly defined by port rules and can dominate length when smaller vessels berth in pairs or trios. Consider emergency departure paths and fire breaks when defining shared-berth separations.
Rounding, reporting, and design communication
Construction planning benefits from rounded berth lengths that align with modular quay blocks, pile bay spacing, and fender panel repeats. A clear report should show inputs, factors, and a transparent breakdown to support review meetings. Exporting results enables quick comparisons across alternatives and provides traceable numbers for concept notes and tender documentation. Record assumptions, revisions, and approval dates to keep calculations auditable throughout delivery. This improves budgeting and schedule certainty.
FAQs
What does LOA mean in the inputs?
LOA is the vessel’s overall length from bow to stern. It is the primary geometric driver of berth length and should match the design vessel or the largest vessel expected in routine operations.
When should I increase the environmental factor?
Increase it when exposed swell, strong currents, or gusty winds create larger motions at the berth. Use metocean data and port operating limits to select a margin that reflects realistic downtime and safety needs.
How do bow and stern allowances differ from safety clearance?
Bow and stern allowances cover end effects such as gangway zones, dolphins, and maneuvering at each end. Safety clearance is an additional operational buffer along the berth to account for approach variability and working space.
Why is a mooring factor included?
Mooring factor accounts for the efficiency of the mooring arrangement, bollard spacing, and line angles. Poor line geometry can require more length to keep lines clear and operations stable during changing loads and tides.
How is inter-vessel clearance applied for multiple vessels?
It is added between adjacent vessels, so a two-vessel case adds one spacing segment and a three-vessel case adds two. Choose the spacing based on line leads, tug access, and port rules for simultaneous operations.
Should I round the result, and to what increment?
Round when your layout uses modular construction, standard fender panels, or pile bay spacing. Select an increment that matches your design grid, such as 0.5 m, 1 m, or 5 ft, and keep it consistent across options.