🧭 Sea Service Calculator
Calculate your total sea service days for maritime certifications and renewals
⚓ Basic Information
📅 Voyage Details
| Joining Date | Sign-off Date | Exclude Days | Ship Type | Action |
|---|---|---|---|---|
🧮 Adjustment Options
📊 Your Sea Service Results
📋 Voyage Summary
📚 Complete Guide to Sea Service Calculation
🚢 What is Sea Service?
Sea service refers to the time spent working aboard commercial vessels, which is essential for obtaining and maintaining maritime certifications. It’s measured in days and must be properly documented to meet international standards set by the International Maritime Organization (IMO) and the Standards of Training, Certification and Watchkeeping for Seafarers (STCW) Convention.
📏 How Sea Time is Counted (IMO/STCW Rules)
According to STCW regulations, sea service is calculated based on actual days served aboard vessels engaged in commercial operations. The counting includes:
- Days from joining date to sign-off date
- Actual working days excluding leave periods
- Time spent on vessels over 500 GT for most certifications
- Service on vessels engaged in international or domestic trade
⛴️ Difference Between Actual & Effective Sea Service
Actual Sea Service: The total number of calendar days from joining to sign-off, including all days aboard the vessel.
Effective Sea Service: Actual sea service minus any non-qualifying periods such as:
- Shore leave exceeding 7 days
- Medical leave
- Disciplinary suspensions
- Time when vessel was laid up or not in commercial service
⚙️ How Adjustments Are Applied
Certain types of vessels and operations may qualify for enhanced sea service credit:
- Tanker Operations: Some jurisdictions allow 1.5x multiplier for chemical/gas tankers
- Dynamic Positioning (DP) Vessels: Enhanced credit for specialized operations
- Passenger Vessels: Additional requirements but standard counting
- Offshore Vessels: May qualify for enhanced credit depending on operations
📑 Documents Required to Prove Sea Time
To validate your sea service, you’ll need:
- Discharge Book (CDC) with proper endorsements
- Sea Service Testimonials from ship masters
- Company letters confirming service periods
- Ship’s articles or crew agreements
- Port clearance documents (if required)
🎓 Sea Time for COC Exams & Eligibility
Different certificates require specific sea service minimums:
- Officer of the Watch (Deck): 12 months sea service
- Chief Mate: 18 months as officer of the watch
- Master: 12 months as chief mate
- Engineer Officer: 12 months in engine department
- Chief Engineer: 18 months as second engineer
🧭 Country-wise Sea Time Rules
India (DG Shipping): Follows STCW minimums with additional requirements for Indian flag vessels.
United Kingdom (MCA): STCW compliant with specific requirements for UK endorsements.
United States (USCG): Has unique requirements including specific vessel tonnage and route restrictions.
European Union: Harmonized standards across member states following STCW Convention.
📋 Manual Calculation Examples
Example 1: Joined: Jan 1, 2023, Sign-off: Apr 1, 2023
Total days = 90 days, Exclude 5 days leave = 85 effective days
Example 2: Multiple voyages with overlap
Voyage 1: Jan 1 – Mar 31 (90 days), Voyage 2: Mar 15 – Jun 15 (92 days)
Without overlap adjustment: 182 days, With overlap adjustment: 166 days
🔗 Useful Links
For more information, visit these official resources:
- International Maritime Organization (IMO)
- Directorate General of Shipping, India
- STCW Convention – Wikipedia