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Sea Time Calculator UK

Enter your values below to get the result first, then scroll for the full explanation and guidance.

Step 1 • Add values

Use the calculator

Enter your values below to generate an instant result. You can update the inputs at any time to compare different scenarios.

Example calculated from the inputs and method shown below.

Results refresh instantly as values change.

Estimated logged sea-service days

26 days31 calendar days before exclusions

Estimated logged sea-service days: 26 days (31 calendar days before exclusions)

Count whole UTC calendar days in the entered period, include the end date only when selected, then subtract days that should not be logged.

Voyage-log estimate

Count whole UTC calendar days in the entered period, include the end date only when selected, then subtract days that should not be logged.

Result snapshot

A quick visual read of the values behind this result.

Calendar days in period31
Excluded days5

Recommended next checks

  • →Check the inclusive-date convention used by the relevant log or application.
  • →Retain the underlying voyage and discharge evidence for any formal sea-service claim.
Calendar days in period
31
Excluded days
5

This is a calendar-day log estimate, not certification of qualifying sea service for tax, watchkeeping, visa, employment or maritime-authority purposes.

Try different values to compare results.

Estimate days in a voyage log from start and end dates, with an explicit end-date convention and excluded days.

Fast to use

Built for comparison

Clear result output

Table of Contents

6

About Sea Time Calculator UK

Sea Time Calculator UK helps you work through the main numbers for this topic quickly with a simple input flow and an instant result.

Use the calculator result as a practical starting point, then review the explanation and assumptions on the page if you want more context.

Calculation method

Logged days = whole calendar days between entered dates + 1 when the end date is included - entered excluded days.

Calendar-day voyage-log estimate only. This does not certify tax, watchkeeping, visa, employment or maritime-authority sea service.

Formula explained

Calculation flow

This calculator is structured for fast UK-focused estimates with clear inputs, repeatable logic, and instant results.

Formula

Input values -> calculation engine -> instant result

How the result is built

1Enter the values requested in the form.
2The calculator applies the configured formula logic.
3The result updates instantly with a breakdown.
4Use the output to compare scenarios quickly.

Example

Example calculated from the inputs and method shown below.

Assumptions

  • Calendar-day voyage-log estimate only. This does not certify tax, watchkeeping, visa, employment or maritime-authority sea service.

Source basis

  • UK-focused calculator flow
  • Structured input validation
  • Instant result breakdowns

FAQ

Common questions

Calendar-day voyage-log estimate only. This does not certify tax, watchkeeping, visa, employment or maritime-authority sea service.

Trust and notes

Assumptions and important notes

This calculator is designed to give a fast estimate using the method shown on the page. Results are most useful when your inputs are accurate and the tool matches your situation.

Use the result as guidance rather than a final diagnosis or professional decision. If the result could affect health, legal, financial, or compliance decisions, verify it with a qualified source where appropriate.

  • Calendar-day voyage-log estimate only. This does not certify tax, watchkeeping, visa, employment or maritime-authority sea service.

Method

UK calculator guidance

Last reviewed

April 17, 2026