A ship can be physically ready for the next stage and still be blocked by an incomplete class survey or missing certificate — here is how planners manage these approval gates.
A ship can be physically ready for the next stage and still be unable to move forward because a required classification survey, approval, or certificate is not complete. For a shipyard planner, this is one of the important differences between tracking physical production and managing the actual project schedule.
Classification milestones are not simply dates placed on a construction programme. They are points where the condition of the ship, the completed work, and the supporting documentation must satisfy requirements before the project can pass into its next stage.
The exact survey scope depends on the ship type, class notation, contract, flag, and applicable regulations. Classification societies such as DNV, ABS, Lloyd's Register, ClassNK, and Bureau Veritas have their own rules and procedures, while flag-state requirements and international conventions create another layer of statutory approval (see our article on Quality Assurance and Classification Society Surveys for how these surveys fit into overall quality control). The planner does not need to become a class surveyor, but does need to understand how these approval chains affect the schedule.
What a Classification Milestone Means in Practice
During newbuilding, several physical events have particular significance because they mark a change in the ship's construction status or operating condition. Common milestones include the start of block erection or keel-laying stage, launching (sometimes called float-out, depending on the yard and construction method), mooring or berthing trials, sea trials, and delivery.
The terminology can vary between projects. Some yards use keel laying as the formal milestone while others place more emphasis on the start of block erection. The important point for planning is not the name of the event but what approvals and surveys are required before the event can take place.
At the start of major hull construction, class involvement confirms that the construction is progressing in accordance with the approved design and applicable class requirements. As construction continues, surveys are performed at defined stages rather than only at the end of the project. This allows class to verify items such as hull structure, welding, machinery, piping, electrical systems, and other relevant systems while they are still accessible.
Launching introduces another important transition. The ship changes from a construction environment to a floating vessel, and the required inspections and tests need to support that transition. Depending on the vessel and project arrangement, class may need to verify relevant items before launching and attend specific examinations or tests associated with the launch and subsequent afloat construction.
Mooring and berthing trials, commissioning activities, and harbour tests then provide evidence that systems are functioning correctly before the vessel proceeds to sea. Sea trials are particularly important because the vessel is being tested under operating conditions. Propulsion, steering, navigation, safety, machinery, and other systems are tested according to the approved trial programme and applicable requirements (our article on Sea Trials and Delivery covers this stage in more depth).
Delivery is the final major project gate. At this point, the vessel needs more than a physically complete hull. The required surveys, tests, certificates, outstanding class items, and statutory documentation must be sufficiently complete for the vessel to enter service under the agreed delivery conditions.
For the planner, this means a classification milestone should be understood as a gate between activities, not simply another activity in the Gantt chart.
Classification and Flag-State Requirements Are Not the Same
Classification and statutory requirements often appear together in the project schedule, which can make them look like one approval process. They are related, but they are not identical.
A classification society assesses the ship against its own applicable classification rules and the agreed class notation. Its surveys and approvals cover areas such as structure, machinery, systems, materials, construction and testing.
Statutory requirements arise from the flag state and the international conventions that apply to the vessel. SOLAS, MARPOL and other international maritime requirements create obligations covering areas such as safety, lifesaving appliances, fire protection, navigation, pollution prevention and other aspects of the vessel's operation.
The flag administration may perform these statutory surveys itself or may authorize a Recognized Organization (RO), which in many cases is a classification society, to carry out some or all of the work on its behalf. This delegation is not informal practice; it is governed internationally by IMO's RO Code (Resolutions MSC.349(92) and MEPC.237(65)), which sets minimum authorization, competency and oversight requirements for organizations acting on a flag state's behalf. That formal arrangement is one reason class and statutory activities can appear closely connected in a shipyard programme.
From a planning perspective, however, it is safer to keep the approval chains visible. A class survey being complete does not automatically mean that every statutory certificate is complete. Conversely, completing a statutory inspection does not necessarily close every class requirement.
A master schedule should therefore distinguish between classification gates, statutory or flag-state gates, and the internal yard activities that support both.
Put Milestones in the Schedule as Gates
A common planning mistake is to create an activity called "Class Survey" with a duration of one or two days and link it to the surrounding construction activities. That gives the survey a visual position in the programme but does not necessarily represent the real constraint.
For important milestones, the better approach is to establish a clear chain: construction readiness → documentation readiness → surveyor attendance → inspection/test → acceptance or outstanding items → milestone release.
The actual survey may take only a short time. The preparation behind it can take much longer.
For example, a sea trial should not be treated as an isolated activity that starts on a particular date simply because the vessel is mechanically complete. Before the trial, the planner may need to coordinate commissioning, harbour testing, outstanding punch items, trial documentation, approved procedures, crew availability, owner's representatives, class attendance, and statutory requirements.
The same principle applies to launching. The launch date may be fixed months in advance, but the ability to achieve that date depends on a series of technical and approval conditions being closed beforehand.
In the master schedule, these milestones are best represented as gates or hard constraints with predecessor conditions, while the supporting activities remain normal schedule activities. Where the scheduling software permits it, milestones can also be connected to readiness checklists, document registers, or separate approval schedules.
Surveyor Attendance Needs Planning
Class attendance is a resource that needs to be coordinated, not assumed.
The yard should normally give the classification society sufficient advance notice of required attendance, particularly for major events such as launching-related inspections, significant tests, and sea trials. The exact notice period depends on the class society, location, survey scope, vessel and local arrangements, so a planner should use the agreed project procedure rather than applying an arbitrary number of days to every survey.
The practical lesson is simple: do not wait until the activity is nearly ready before contacting class.
A planner should monitor the expected survey date early and confirm that the required surveyor or survey team can attend. This becomes especially important when several vessels are being constructed simultaneously or when the yard is working around weekends, holidays, port restrictions, or limited local surveyor availability.
A change of only a few days in surveyor attendance can have a much larger effect if the next activity is launching, undocking, sea trial departure, or delivery.
The Documentation Problem
Many schedule delays that appear to be "class delays" actually originate earlier in the project.
Drawings may have been submitted late. Comments may remain open. A revised drawing may not have reached production. Test procedures may not have received the necessary approval. Certificates for materials or equipment may be missing. Commissioning records may not have been completed. Outstanding survey items may not have been closed.
The physical work can therefore look complete while the approval package is not ready.
This is where the planner has a useful coordination role. The class-related schedule should be linked to the activities that generate the evidence required for acceptance. Drawing approval, material certification, equipment testing, commissioning records, inspection requests, test reports and punch-list closure should not exist as completely separate worlds from the milestone programme.
For major gates, a planner should ask a straightforward question: "What must be complete and available on the day the surveyor arrives?"
The answer should then become a set of schedule predecessors or readiness checkpoints.
Where Yard, Owner and Class Coordination Breaks Down
The most common problems occur at the interfaces.
The yard may plan a test for a particular date without confirming class or owner attendance. The owner may expect a trial to proceed while important documentation is still under review. Class may arrive as planned but find that the equipment or system is not ready for inspection. A flag-state requirement may remain open even though the corresponding class activity has been completed.
These issues are rarely solved by adding more float after the problem occurs. They are better managed through early visibility.
For major milestones, the planner should maintain one agreed target date and make the readiness conditions visible to the relevant parties. Changes to the milestone should trigger coordination with production, commissioning, quality, owner representatives, class and, where applicable, the flag-state or authorized organization.
It is also useful to distinguish between planned completion and accepted completion. A system being marked 100% complete in a production report does not necessarily mean that its class survey, test record, documentation, or punch items are closed. That distinction becomes particularly important near delivery.
Treat the Milestone as a Hard Gate
A physical activity can often move by a day or two without immediately stopping the project. A classification or statutory gate can be different.
If a required survey has not been completed, or the necessary approval has not been obtained, the vessel may not be able to proceed to the next contractual or operational stage. The schedule consequence can therefore be much greater than the duration of the missed survey itself.
A planner should resist the temptation to make a class milestone "flexible" simply because the Gantt chart needs to accommodate a production delay. If the vessel cannot legally or contractually proceed without the relevant acceptance, moving the milestone in the schedule does not solve the problem. It only hides the risk.
This is why major classification and regulatory milestones should be treated as schedule gates with explicit predecessors, rather than dates that are adjusted whenever production changes.
Classification Milestones and Overall Delivery Risk
Classification activities sit at the intersection of engineering, procurement, production, commissioning, quality, documentation and regulatory compliance. A delay in any of these areas can eventually reach the same gate.
If a required drawing is approved late, the associated construction may be late. If construction is late, testing may be late. If testing is late, class attendance may need to move. If the surveyor cannot attend the revised date, sea trials may move. Once sea trials move, delivery can move as well.
That is why classification and regulatory milestones deserve a visible position in the master schedule. They are not administrative dates added to the programme after construction planning is finished. They are control points that determine whether the vessel is actually allowed to move from one stage of the project to the next.
For a shipyard planner, the objective is not to manage the class rules. It is to make sure the project schedule reflects the reality of those rules, the required attendance, the documentation, and the acceptance process before the vessel reaches each critical gate.
