A classed vessel runs a repeating survey cycle — annual surveys, an intermediate survey, and a renewal or special survey on a multi-year period, with the underwater portion examined at required intervals. Every sensible maintenance plan is built on that calendar, because the calendar is not negotiable and the work is.
The structure of the cycle
| Survey | Character | Planning implication |
|---|---|---|
| Annual | General examination confirming the vessel remains in the condition class expects | Light; can usually be taken alongside |
| Intermediate | More detailed, falling between renewal surveys, with additional attention to structure and, depending on age and type, tanks | Often combined with a docking |
| Renewal / special | Comprehensive examination of structure, machinery and systems | The major expenditure event; plan two cycles ahead |
| Bottom / docking survey | Examination of the underwater hull, rudder, propeller, shafting and sea connections | Drives docking timing; sometimes possible in-water |
Machinery may sit under a continuous survey arrangement, where items are examined progressively rather than all at once, which spreads both cost and downtime. Whether that suits a particular operation depends on how the vessel trades.
Two documents govern everything
The survey status lists what is due and when. The conditions of class or recommendations list defects that must be rectified by a stated date. Together they define the mandatory portion of any docking scope; everything else is discretionary and can be phased. Any repair plan that does not start from these two documents is starting from opinion — a point we return to on our repair and refit page.
Planning around the cycle rather than against it
- Map the calendar two cycles ahead. Renewal surveys are visible years in advance; the expenditure should not be a surprise.
- Combine work with the docking that has to happen anyway. Discretionary steel, coating and shaft work costs far less when the vessel is already out of the water for a required survey.
- Protect the survey window. Book surveyor attendance before fixing the yard slot, not after. Surveyor availability is a critical-path resource.
- Front-load gauging. Thickness measurement completed before docking allows the repair scope to be tendered rather than negotiated on the hard.
- Do not let conditions of class run to their limit. A condition rectified at leisure costs little; the same condition rectified against a deadline does not.
In-water survey
Where permitted, examining the underwater hull afloat using an approved diving contractor can substitute for a docking in defined circumstances, depending on vessel type, age, class arrangement and the condition of the hull and coating. It is genuinely useful for vessels in continuous service, and it is not a universal option — availability is confirmed with class in advance for the specific vessel and the specific survey. Building a maintenance plan on an assumption of in-water survey that later proves unavailable produces an unplanned docking at short notice, which is the most expensive kind.
Consequences of letting the cycle slip
Overdue surveys can lead to suspension or withdrawal of class, which typically affects insurance cover and the vessel’s ability to trade or be chartered. Extensions may be available in defined circumstances but are granted at the society’s discretion against evidence, not assumed. Commercially, a vessel with a clean survey status and closed conditions of class is worth measurably more in a sale or charter negotiation than an identical vessel carrying open items — the paperwork is part of the asset.
Building the maintenance calendar
A workable calendar has three layers: the mandatory survey dates, the discretionary work grouped to coincide with them, and the operational commitments — charter seasons, contract periods, monsoon windows — that constrain when the vessel can be off-hire. Where those three conflict, the survey dates win, and the sensible response is to move the operational plan rather than to gamble on an extension. Seasonal and slot constraints in Indonesia are covered in our article on haul-out planning.
Support
This desk builds docking and survey calendars against the class status, tenders the scope to facilities that physically fit the vessel, and supervises the work. Contracts are issued by PT Komodo Galangan Nusantara; scopes are in USD. Contact sales@komodoluxury.com or +62 811-3823-875. See also class and compliance.
Aligning survey and commercial calendars
Vessels earn when they operate, and every survey is downtime. The practical craft is in stacking obligations so that one period out of service discharges several of them — bottom survey, thickness measurement, machinery items due within a reasonable window, and any outstanding conditions of class — rather than accumulating several short off-hire periods across a year.
That stacking has a limit: items surveyed too early may need repeating within the cycle, and pulling too much work forward inflates a single expenditure. The sensible approach is to build the calendar once, review it annually, and treat it as a planning document that the commercial team can see, rather than as a technical file that surfaces three weeks before a deadline.
Frequently asked questions
What is a special or renewal survey?
The most comprehensive periodic survey, carried out on a multi-year cycle, examining structure, machinery and systems in depth. It is the survey around which a vessel’s largest maintenance expenditure is normally planned.
Can bottom survey be done afloat?
In-water survey is permitted in defined circumstances depending on vessel type, age, class arrangement and hull condition, and requires an approved diving contractor. Whether it is available for a particular vessel and survey is confirmed with class in advance.
What happens if a survey is overdue?
Class can be suspended or withdrawn, which typically affects insurance cover and the vessel’s ability to trade. Extensions may be available in defined circumstances but are granted, not assumed.