What is the extent of thickness measurement at Special Survey No.1 for a bulk carrier?
At the first special survey the systematic column holds one entry: suspect areas. Every transverse section, deck plate and wind-and-water strake belongs to a later survey. The measurement that does happen at five years travels with the close-up survey, not with the extent table.
The short answer
- Systematic measurement: suspect areas. That is the whole column.
- No transverse section, no deck plate, no wind-and-water strake, no bottom plate.
- The work that does happen travels with the close-up survey: a quarter of the forward hold's shell frames, one transverse web in each of two representative ballast tanks, and the members those cover.
- ClassNK asks for more: hatch covers and coamings, and the air and sounding pipes in the holds.
- Double-side skin reads the same: UR Z10.5 Table II carries one entry in this column too.
The systematic column is one line
Open UR Z10.2 at Table II and look down the column headed Special Survey No.1, age five years or less. It holds one numbered entry: suspect areas. Nothing is listed beneath it. UR Z10.2 R37
The 2011 ESP Code says the same thing in the same place, and so does every class rule the handbook holds for this ship type: BV, KR, CCS, INSB, LR, PRS Publication 39/P and ABS all print one entry in that column and leave the rest of it empty. This is the one survey in the cycle where the extent table asks for almost nothing. A.1049(27)
A suspect area is not a soft category. It is a location showing substantial corrosion, or one the surveyor judges prone to rapid wastage — either gate on its own is enough. On a five-year-old hull there may be none, and then the systematic column really does produce no readings at all.
What the close-up survey brings with it
The measurement that does happen at five years is not in the extent table. It follows the close-up survey, because the rule pairs the two: wherever close-up survey is required, the structure there is gauged at the same visit, for general assessment and to put the corrosion pattern on record.
At the first special survey the close-up minimum for a single-side-skin bulk carrier is: 25 % of the shell frames in the forward cargo hold, taken at positions that represent the hold, and selected frames in each remaining hold; one transverse web with its plating and longitudinals in each of two representative ballast tanks; and the transverse bulkhead and hatch-cover items the table names. UR Z10.2 R37
PRS words the pair selection tighter than most: its two representative water ballast tanks have to be of each type the ship has — one topside, one hopper side — rather than any two. PRS Pub 39/P
So the honest answer to a superintendent asking how many readings the first special survey needs is: as many as the close-up scope produces, plus whatever the suspect areas demand — and nothing that a transverse section would have added.
The two departures
ClassNK asks for more than the UR at this survey. Beside suspect areas its column adds the air pipes and sounding pipes inside the cargo holds in way of the tank top, and every cargo hold hatch coaming and hatch cover — plating and stiffeners in both cases. A programme built to the UR minimum and then surveyed under ClassNK is short by exactly those items. ClassNK Part B
DNV leaves the column blank, and that is not a gap. Every row of its table is empty against the first renewal survey — no transverse section, no deck plating, no strake. DNV states the suspect-areas obligation elsewhere in the same section rather than repeating it inside the grid. Read the blank as a drafting choice, not as a lower requirement. DNV Pt.7 Ch.1 Sec.4
Double-side skin: the same answer, a different UR
A double-side-skin bulk carrier is not covered by UR Z10.2. Its requirement is UR Z10.5, and the statutory counterpart is part B of annex A of the ESP Code rather than part A. At the first special survey the answer does not change: Table II's first column carries suspect areas and nothing else — no transverse section, no deck plate, no wind-and-water strake. UR Z10.5 R20
One thing does change, and it is worth knowing before the programme is written: an ore carrier reads the same column. Z10.5 runs one table across both sheets, so the ore carrier is not given a grid of its own at this survey. The ESP Code does the same — annex 2 serves the whole of part B.
What moves the answer
Two things, and both are conditions rather than dates.
A reading in the substantial corrosion band. Once a member is found substantially corroded the extent stops being the table's and becomes the escalation table's: UR Z10.2 sends it to Table VIII, the ESP Code to annex 10, DNV to its own Table 13. The widened readings are due before the survey can be credited. UR Z10.2 R37
Coating condition in the ballast tanks. A tank whose hard coating has fallen below GOOD and has not been made good — or which carries a soft or semi-hard coating, or never had a hard coating — goes onto examination at yearly intervals, and gauging follows the surveyor's judgement there. That obligation runs from this survey onward and is the usual reason a five-year-old ship starts collecting readings between special surveys.
Neither of these is discretion. Both are triggers written into the rule, and both are cheaper to plan for than to discover with the staging already down.
Sources
- UR Z10.2 Rev.37IACS — Hull surveys of bulk carriers, Feb 2023index entry →
- UR Z10.5 Rev.20IACS — Double-skin bulk carriers, Feb 2023official text ↗
- A.1049(27)IMO Res. A.1049(27) — 2011 ESP Codeofficial text ↗
- ClassNK Part BClassNK — Rules and Guidance for the Survey and Construction of Steel Ships, 2022official text ↗
- DNV Pt.7 Ch.1 Sec.4DNV — Rules for Classification: Ships, survey requirements, Jul 2022official text ↗
- PRS Pub 39/PPolish Register of Shipping — Hull Surveys of Bulk Carriers, Jul 2024official text ↗
Class-society and IMO documents are indexed and linked, never re-hosted. Where a class rule is stricter than the IACS baseline, the class rule governs.