Vessel Laytime Calculator
User Guide — How to calculate laytime, demurrage & despatch
Version 1.0 — March 20261. Overview
The TheCharterBox Vessel Laytime Calculator is a professional tool for calculating laytime, demurrage, and despatch for voyage charters. Designed for ship owners, charterers, brokers, and operators who need accurate, auditable calculations.
The calculator runs entirely in your browser — results update instantly as you type. No software installation required.
Multiple Ports
Unlimited loading and discharging ports, each with independent settings, holidays, and rates.
60+ Country Holidays
Pre-loaded public holidays with automatic weekly rest day detection for every region.
Reversible Laytime
Combined or independent port calculations with per-port standalone comparison.
Weather Working Days
Full WWD support with all SHEX, FSHEX, SSHEX combinations.
Charter Party Presets
GENCON, ASBATANKVOY, SHELLVOY, BPVOY, NYPE, BALTIME — one-click setup.
PDF & Excel Export
Professional branded documents ready for demurrage claims.
2. Getting Started
Access the Calculator
Visit www.thecharterbox.com/vessel-laytime-calculator/. No login required to use the calculator and see results.
Account Benefits
| Feature | Without Account | With Free Account |
|---|---|---|
| Use calculator & see results | ✅ | ✅ |
| Print calculation | ✅ | ✅ |
| Auto-save (browser) | ✅ | ✅ |
| Save to account | — | ✅ |
| Export PDF & Excel | — | ✅ |
| Report issues | — | ✅ |
Register free at www.thecharterbox.com/register/
The Three-Tab Layout
Work left to right: set up voyage and port terms, enter SOF events, then review calculated results.
3. Charter Terms Tab
Define the entire voyage — vessel details, ports, and commercial terms at each port.
Voyage Details
- Enter the Vessel Name (required).
- Enter the Voyage Number (required).
- Optionally select a Charter Party Preset to auto-fill port defaults.
Charter Party Presets
| Preset | Type | Default Terms |
|---|---|---|
| GENCON 1994 | Dry bulk | SHEX UU, Clause 6 commencement |
| ASBATANKVOY | Tanker | SHEX UU, 6 hrs NOR notice |
| SHELLVOY 6 | Shell tanker | SHINC, reversible laytime |
| BPVOY 5 | BP tanker | SHINC, reversible laytime |
| NYPE 2015 | Time charter | Off-hire calculations |
| BALTIME 1939 | Time charter | BIMCO time charter |
| Custom | — | All fields blank |
Global Options
Reversible Laytime — time saved at one port offsets time exceeded at another. Auto-adds a second port when enabled.
Once on Demurrage, Always on Demurrage — once laytime expires, all subsequent time counts regardless of holidays, weekends, or weather.
Adding & Configuring Ports
Click “+ Add Port” to add loading or discharging ports. Each port is a collapsible card with fully independent settings.
Laytime Type
| Group | Options | Used In |
|---|---|---|
| Sunday rest | SHINC, SHEX, SHEX UU, SHEX EIU | Traditional terms |
| Friday rest | FHINC, FHEX, FHEX UU, FHEX EIU | Middle East |
| Fri + Sat rest | FSHEX, FSHEX UU, FSHEX EIU | Gulf (UAE, Saudi, etc.) |
| Sat + Sun rest | SSHEX, SSHEX UU, SSHEX EIU | Most countries |
| Weather Working Day | WWD + all above combinations | When weather matters |
Holidays
Weekly off days auto-set from country. Public holidays load automatically — uncheck any that don’t apply, or add custom local holidays.
NOR Rules
| Setting | Description |
|---|---|
| NOR Notice Hours | Hours between NOR acceptance and laytime start (0, 6, 12, 24) |
| NOR Validity | ATDN (any time), Office Hours Only, or Custom Hours |
| Commencement Rule | Immediately, Fixed hours, Next working period, GENCON Clause 6, On berthing, Berthing or notice, Custom |
Laytime Allowed
Direct Entry — days and hours. Rate-Based — cargo quantity (MT) ÷ daily rate (MT/day) = auto-calculated.
Financial Terms (Per Port)
| Field | Description |
|---|---|
| Demurrage Rate | Daily rate when laytime exceeded (required) |
| Currency | USD, EUR, GBP, etc. |
| Despatch Rate | Daily rate for early completion, or “Half of Demurrage” |
| Despatch Basis | All Time Saved or Working Time Saved |
Mandatory Fields
Fields marked * must be completed: Vessel Name, Voyage Number, and per port — Port Name, Country, Laytime Type, Allowed Laytime, Demurrage Rate, Despatch Rate.
4. Statement of Facts Tab
Record the timeline of events at each port.
Switching Ports
Port tabs at the top — click to switch. ✓ = valid data, ⚠ = errors to fix.
Adding Events
Click “+ Add Event”. Events auto-sort by date/time — earliest at top.
Standard Events
| # | Event | Description |
|---|---|---|
| 1 | NOR Tendered | Master notifies readiness |
| 2 | NOR Accepted | Charterer/agent accepts notice |
| 3 | Laytime Commenced | Laytime officially starts |
| 4 | Vessel Berthed | Vessel arrives at berth |
| 5 | Hoses Connected | Tankers — hoses connected |
| 6 | Commenced Loading/Disch | Cargo operations begin |
| 7 | Weather Delay | Start/end of weather stoppage |
| 8 | Shifting | Vessel moves between berths |
| 9 | Completed Loading/Disch | All cargo handled |
| 10 | Hoses Disconnected | Tankers — hoses removed |
| 11 | Vessel Sailed | Vessel departs |
Validation
- Chronological — events within each port must be in time order.
- Logical sequence — NOR before Accepted, Commenced before Completed. All violations shown.
- Cross-port — loading dates must precede discharging dates. Error shows on the port with wrong dates.
Weather Log
Appears when WWD laytime type is selected. Record weather delays with type and times.
5. Results Tab
Results calculate automatically in real-time. Validation errors show instead of results until fixed.
Per-Port Results
Each port shows allowed, used, saved/exceeded, and “If standalone” demurrage or despatch — what the result would be independently.
Combined (Reversible)
Total allowed, total used, net result, and one combined demurrage or despatch amount.
Colour-Coded Breakdown
A red “LAYTIME EXPIRED” divider marks where demurrage begins. Visual timeline bar below gives an instant overview.
6. Save & Load
Saving (Logged-In Only)
- Complete calculation — all mandatory fields filled, no SOF errors.
- Click “Save” — title auto-generated with vessel, voyage, and timestamp.
- For existing: choose “Update” or “Save as New”.
Loading
Click “Load” to see saved calculations. Click to fully restore all settings, ports, events, weather, holidays.
Auto-Save
Browser auto-saves every 30 seconds — even without an account. Kept for 7 days. Restore prompt on return.
7. Export (PDF, Excel, Print)
PDF Export
Professional branded document: voyage details, port table, per-port SOF, summary, colour-coded breakdown. Ready for demurrage claims.
File: Laytime_[Vessel]_[Voyage]_[Date].pdf
Excel Export
| Sheet | Contents |
|---|---|
| Summary | Voyage details, port details, results |
| Statement of Facts | SOF events per port |
| Detailed Breakdown | Period-by-period with status and totals |
File: Laytime_[Vessel]_[Voyage]_[Date].xlsx
Click “Print” or Ctrl+P. Enable “Background graphics” for colours.
8. Reporting Issues
Click “Report Issue” (logged-in only). Name and email pre-filled from your profile. Select type (Bug, Feature Request, Other) and describe the issue.
Reports go to [email protected].