Every classed vessel runs on a five-year cycle. Annual surveys check that the vessel still meets its class conditions. The intermediate survey at year two and a half does a deeper review. The Special Survey at year five renews the class certificate, with structural, machinery and equipment scope that goes far beyond annual checks. For the owner, this is the single largest planned cost block in the vessel's lifetime, often eight to fifteen percent of asset value depending on age and condition.
What the Special Survey covers
The Special Survey examines the vessel's structural condition (hull plating, framing, internal members), machinery (main engine, generators, shaft, propeller), safety equipment (lifeboats, fire systems, navigation), tank inspections including ballast and cargo tanks, and the documentation chain back to the previous Special Survey. It is performed by the classification society surveyor with the owner and yard team in attendance.
In-water vs dry-dock survey
Many class regimes allow in-water surveys for hull underwater inspection between dry-dockings, performed by certified divers under surveyor supervision with video documentation. This reduces dry-dock requirements from once every two and a half years to once every five years on qualifying vessels. The choice affects total yard time and cost materially. Eligibility depends on coating condition, vessel age, type and prior survey results.
The owner's preparation
- Trends in thickness gauging from prior surveys to anticipate steel-renewal scope
- Equipment certificates, recalibration logs, maintenance records assembled before yard arrival
- Survey scope agreed with the class surveyor in a pre-survey meeting
- Long-lead items (specific spares, coating systems, replacement equipment) ordered weeks in advance
- A yard slot booked with realistic time allowance for unforeseen scope, not the optimistic estimate
Where Special Surveys overrun
The most common cause of an overrun is discovered scope. A thickness gauge reveals plate below the renewal threshold. A tank inspection shows pitting that needs treatment. An engine bearing measurement reads outside tolerance. Each finding adds work, material lead time and surveyor re-attendance. Owners who go in with a realistic discovery contingency in the budget come out in line. Owners who plan to the surveyor's minimum expected scope tend to overrun.
Documentation handover
A Special Survey is not complete until the documentation file is signed. Every weld, every replaced component, every recalibration goes into the file. The class society retains the file, the owner gets a copy, and the next surveyor in two and a half years starts from this baseline. A clean, complete file shortens the next intermediate survey. A messy file lengthens it.
How RS Marine handles it
We work Special Survey scopes alongside the owner's superintendent and the attending class surveyor, with the yard providing the facility. Steel renewal, structural repairs, machinery scope and documentation discipline are all part of our delivery. Our preferred approach is the pre-survey meeting (us, owner, surveyor, yard QA) to agree the scope before mobilisation. Surprises during the survey are then real surprises, not avoidable miscommunication.
RS Marine Sp. z o.o. delivers hull construction, refit and repair, industrial HVAC and electrical installations from Gdynia, Poland. Operating since 2018 with IACS-affiliated welders and a team of over 100 specialists.