Blog Post 03: Afloat Repairs — Operational Windows & Compliance
Title: Afloat Repairs: Operational Windows and Regulatory Compliance for Mid-Size Fleets
Target Audience: Technical Superintendents, Fleet Managers, DPA / Compliance, Operations Teams.
Core Keywords: Afloat Repair, Repair Afloat, In-Water Survey, IWS, Operational Window, Off-Hire Avoidance, IACS, Class Survey, Work Permit, Hot Work.
When You Do Not Need a Dry Dock
Every technical superintendent has faced the same decision: does this repair justify a dry dock, or can it be completed afloat?
The default answer has historically been "send it to dock" — partly because afloat repair was considered a temporary measure, partly because the documentation and compliance path was unclear. That has changed. IACS Unified Requirements and most major Class societies now recognise controlled afloat repair and in-water surveys (IWS) as valid alternatives to dry docking, provided they meet defined criteria.
For a mid-size shipowner, the ability to execute repairs afloat — in port, at anchorage, or at an operational location — translates directly into off-hour avoidance and schedule flexibility. The key is knowing when afloat repair is appropriate and how to execute it with the same rigour as a dry dock intervention.
What the Regulations Say
The regulatory basis for afloat repair rests on several instruments:
IACS UR Z10.2 (In-Water Survey). This Unified Requirement defines the conditions under which Class surveys can be conducted with the vessel afloat, including:
- The survey is carried out in sheltered water with acceptable weather conditions.
- The vessel is at a safe anchorage or alongside a berth with adequate clearance.
- The surveyor has access to all required areas, including means of transport to the survey site.
- The bottom condition is verified by a previous dry docking or is known to be in satisfactory condition.
IMO ISM Code, Section 9 (Non-conformities, Accidents and Hazardous Occurrences). The company must establish procedures to ensure that non-conformities are reported, analysed, and corrected. This applies whether the repair is carried out in dry dock or afloat. The documentation standard does not change with the location of the repair.
SOLAS Reg. II-1/3-1 (Structural Requirements). Any repair affecting the structural integrity of the vessel must be to the satisfaction of the Administration. When executed afloat, the repair method statement and associated calculations must be submitted to the Class society for acceptance.
Flag State and Port State requirements. Some flag states impose additional restrictions on afloat repairs involving hot work, structural welding, or underwater interventions. These must be verified before mobilisation.
The principle is consistent across all frameworks: afloat repair is permitted when it can be executed safely, with appropriate controls, and with documented evidence that meets the same standard as a dock-side repair.
Operational Windows: Choosing the Right Moment
The success of an afloat repair depends on selecting the right operational window. Three variables determine feasibility:
1. Weather and Sea State. Afloat repair — especially underwater intervention, side-shell welding, or shaft work — requires a stable platform. Typical thresholds:
- Wind: below 20 knots (Beaufort 4–5).
- Significant wave height: below 1.0 m for underwater work, below 0.5 m for precision welding.
- Current: below 2 knots for diver safety and work quality.
- Visibility: minimum 3 m underwater for inspection and ROV operations.
2. Vessel Operational Schedule. The repair window must align with:
- Port stay or anchorage period.
- Cargo operations (tank cleaning, gas-freeing for hot work).
- Crew availability for access, isolation, and safety watch.
- Charterer restrictions on operational changes.
3. Permit and Approval Timeline. Typical permits required for afloat repair include:
- Port authority work permit.
- Hot work permit (if welding or grinding).
- Confined space permit (if tank entry is required).
- Diving permit (if underwater intervention).
- Class surveyor attendance coordination (typically 48–72 hours' notice).
The technical superintendent who can integrate these three variables — weather, schedule, permits — into a single operational plan is the one who can turn a 14-day off-hire (dry dock transit + docking + undocking) into a 3-day intervention.
The Afloat Repair Workflow
A controlled afloat repair follows a defined sequence, regardless of the specific task:
1. Preliminary Assessment. The vessel's condition is assessed either by an on-site engineer or remotely via imagery and crew reports. The scope is defined: what needs to be repaired, what access is available, what risks exist. A preliminary method statement is drafted.
2. Technical Specification and Method Statement. The repair scope is translated into a technical document that includes:
- Description of the defect and proposed repair.
- Engineering calculations where structural strength is affected.
- Welding procedure specification (WPS) if hot work is involved.
- Access and staging plan.
- Risk assessment and mitigation measures.
- Quality and inspection criteria.
This document is submitted to Class for review when the repair affects structural integrity or statutory systems.
3. Permit Acquisition. The technical superintendent or the repair coordinator secures all required permits: port authority, hot work, confined space, diving, environmental (if underwater discharge or debris is possible).
4. Execution and Supervision. The repair is executed with continuous supervision:
- Work permit is active and visible at the work site.
- Safety watch is stationed for hot work or confined space.
- Diving operations follow IMCA or equivalent standards.
- Each work stage is photographed and witnessed by the supervisor.
- Repairs affecting Class-related items are witnessed by the attending surveyor.
5. Testing and Verification. After repair completion:
- Non-destructive testing (NDT) where specified: MPI, ultrasonic, dye penetrant.
- Pressure testing for sea valves, pipelines, or hydraulic systems.
- Operational test for machinery and equipment.
- Diver or ROV inspection for underwater repairs.
6. Documentation and Close-Out. The repair case is closed with:
- Completed work order with evidence (photos, test reports, NDT results).
- Class survey report (if applicable).
- Work permits closed and filed.
- Updated vessel maintenance history.
- Final report for the owner's technical file.
Common Afloat Repair Scenarios
Underwater hull repairs (IWS). Propeller polishing, anode replacement, sea chest cleaning, rudder inspection. Coordinated with Class for in-water survey credit. Typical duration: 1–2 days.
Side-shell welding (hot work afloat). Steel renewal on shell plating above or near the waterline. Requires cofferdam or caisson if below waterline. Method statement and NDT mandatory. Typical duration: 2–5 days.
Valve and sea chest repairs. Overhaul or replacement of sea inlet valves, overboard discharges, or cooling water system components. Requires box-up or cofferdam for access below waterline. Typical duration: 1–3 days.
Rudder and propeller work (afloat). Pin removal, bush replacement, blade fairing. Requires diver or ROV support and precision alignment. Typical duration: 2–4 days.
Pipework and system repairs. Replacement of corroded piping, flanges, or valves in machinery spaces or on deck. Requires isolation, drain-down, and hydrostatic test. Typical duration: 1–2 days.
Atlantech Marine's Afloat Repair Capability
We execute and coordinate afloat repairs across the Mediterranean and West Africa as an integrated part of the maintenance cycle, not as a standalone emergency service. Our approach:
- Pre-intervention assessment and method statement development.
- Permit coordination with port authorities and Class societies.
- Supervision by qualified marine engineers and Class-approved surveyors.
- IMCA-compliant diving operations where underwater intervention is required.
- Full documentation package delivered on completion: work order, evidence, test reports, Class documentation.
This capability means that a vessel operating between Gibraltar and Lagos can receive technical intervention at its operational location without deviating to a dry dock — provided the repair scope and conditions are appropriate.
Need an afloat repair assessed? Submit a service request or contact our operations team with the vessel location and defect description.
Atlantech Marine — Afloat repair, in-water surveys, and technical intervention for mid-size shipowners. Based in Malta. Operating across the Mediterranean and West Africa.
