Education
Ship-to-Ship (STS) Transfer
Operations in West Africa
A complete guide to STS operations: how they work, where they happen, IMO regulations, safety requirements, and commercial aspects in Nigerian and West African waters.
Overview
What is a Ship-to-Ship Transfer?
Ship-to-Ship (STS) transfer is the process of transferring cargo, primarily crude oil, refined petroleum products, chemicals, LNG, or LPG, from one vessel to another while at sea or at anchorage, without the cargo touching shore infrastructure.
Two vessels moor alongside each other (usually bow-to-stern offset), with large pneumatic fenders placed between the hulls to absorb impact and maintain standoff distance. Cargo is pumped through hoses connecting the manifold connections of both vessels.
STS operations are critical in West Africa because most ports in the region cannot accommodate fully-laden VLCCs (200,000+ DWT), making offshore lightering and cargo aggregation essential for economical crude exports and product distribution.
How STS Works: Step by Step
Pre-Transfer Planning
Cargo compatibility assessment, fender sizing calculations, mooring plan, and safety checklists completed. 48-hour notification to NIMASA for Nigerian waters.
Vessel Approach & Mooring
Manoeuvring Ship (MS) approaches Constant Heading Ship (CHS). Fenders positioned. Head lines, breast lines, spring lines, and stern lines secured.
Cargo Operations
Cargo hoses connected. Pre-transfer conference held. Cargo pumped from discharging vessel to receiving vessel under POAC oversight. Gas detection and fire watches maintained.
Completion & Departure
Hoses disconnected, cargo survey completed, Statement of Facts signed. Mooring lines released. Vessels depart. STS records retained for 3 years.
Nigerian STS Zones
Designated STS Areas in Nigerian Waters
Lagos Bar / Outer Anchorage
Product & Crude STS
Most commercially active STS zone in Nigeria
Bonny Offshore Anchorage
Crude STS
Shell-operated terminal; ~13M barrels storage
Forcados Offshore Anchorage
Crude STS
400,000 b/d nameplate capacity
Escravos Offshore
Crude STS
Chevron-operated; 3.6M barrel storage
Qua Iboe Offshore
Crude STS
ExxonMobil-operated; ~320,000 b/d
NIMASA must be notified at least 48 hours before STS operations in any of these zones. Operations outside designated zones require specific approval.
Vessel Classes
Vessel Types Involved in STS Operations
| Vessel Class | DWT Range | Role in STS |
|---|---|---|
| VLCC | 200,000-320,000 MT | Primary accumulator; receives multiple smaller parcels via STS |
| Suezmax | 120,000-200,000 MT | Intermediate carriers; load at terminals, transfer to VLCCs offshore |
| Aframax | 80,000-120,000 MT | Regional transport; feed smaller parcels to larger vessels |
| MR Product | 35,000-55,000 MT | Most common for lightering and inland delivery after STS |
| LR1/LR2 | 55,000-120,000 MT | Long-range product distribution |
Regulatory Framework
IMO Regulations & Nigerian Compliance
MARPOL Annex I, Chapter 8
Applies to oil tankers of 150 GT and above. Requires approved STS Operations Plan, coastal state notification 48 hours before operations, and STS records retained for 3 years.
2025 STS Transfer Guide
Published by CDI/ICS/OCIMF/SIGTTO, the most significant update in 50 years. New terminology (CHS/MS instead of Mother/Daughter Ship), human factors chapter, digital fender sensors, and updated safety checklists aligned with ISGOTT v6.
NIMASA Designated Zones
Nigerian Maritime Administration and Safety Agency designates specific offshore areas where STS operations are permitted. Operators must not conduct STS outside these zones without specific approval.
Flag State & Port State
Flag State administration approval of STS Operations Plan required. Port State Control inspections verify STS documentation. ISPS Code compliance mandatory. Additional P&I and H&M coverage required.
Safety Requirements
STS Safety Equipment & Procedures
STS operations require extensive safety equipment and procedures to prevent cargo spills, fires, and environmental damage. Both vessels must have tested fire main, water spray systems, gas detection, and emergency shutdown systems (ESDS) linked between vessels.
A qualified Person in Overall Advisory Control (POAC) oversees the operation, with STS superintendents and mooring masters from the service provider managing the physical connection and cargo transfer.
Mandatory Safety Equipment
Primary pneumatic fenders (ISO 17357 compliant)
Secondary "baby" fenders above waterline
Cargo hoses with third-party pressure testing
Quick-release hooks with strain gages
Fire main tested and under pressure
Water spray system tested and ready
Manifold water curtain operational
Gas detection systems operational
Emergency Shutdown System (ESDS) linked
Ship separation detection and trip system
Emergency Release Coupling (ERC)
Oil spill response equipment (booms, skimmers)
Need STS Support?
Calmwaters Provides STS Coordination Services
Our port agency team coordinates STS operations at Lagos, Bonny, Forcados, and Escravos offshore anchorage. We handle NIMASA notifications, terminal coordination, and documentation.
Written by Pius Nobei, MBA
CEO, Calmwaters Shipping Ltd
Pius Nobei is the CEO and Founder of Calmwaters Shipping Ltd, an NPA Licensed vessel charter broker based in Lagos, Nigeria. With over 15 years of experience in West African maritime trade, Pius specializes in tanker chartering, offshore vessel coordination, and Nigerian port compliance.
Published: January 2026
Updated: August 2026
Reviewed by: Calmwaters Maritime Advisory Team
Frequently Asked Questions
STS Transfer FAQ
What is a Ship-to-Ship (STS) transfer?
Ship-to-Ship (STS) transfer is the process of transferring cargo, such as crude oil, refined petroleum products, chemicals, LNG, or LPG, from one vessel to another while at sea or at anchorage. Two vessels moor alongside each other with fenders between the hulls, and cargo is pumped through hoses connecting the manifolds of both vessels.
Where do STS transfers happen in Nigeria?
NIMASA has designated specific offshore STS zones in Nigerian waters including Lagos Bar/Lagos Outer Anchorage, Bonny Offshore Anchorage, Forcados Offshore Anchorage, Escravos Offshore, and Qua Iboe Offshore. Operators must conduct STS within these approved zones and notify NIMASA at least 48 hours before operations.
Why are STS transfers common in West Africa?
STS transfers are common in West Africa due to infrastructure constraints (most ports cannot accommodate fully-laden VLCCs), economic drivers (VLCC per-barrel freight is significantly lower), the region's status as a major crude exporting hub, and Dangote Refinery's impact creating new product distribution networks across the region.
What are the IMO regulations for STS transfers?
MARPOL Annex I Chapter 8 applies to oil tankers of 150 GT and above engaged in STS operations. Tankers must have an approved STS Operations Plan, notify the coastal state 48 hours before operations, and retain STS records for 3 years. The 2025 STS Transfer Guide (2nd Edition) introduced updated terminology, human factors guidance, and digital technology standards.
How much does an STS transfer cost?
STS costs include service provider fees (equipment, LSV, superintendent), fender rental, cargo hose costs, mooring personnel, support vessel charter, NIMASA/port authority fees, additional insurance, and demurrage during operations (typically 12-48 hours). Total costs vary by vessel size, cargo type, and location.