Condition Assessment Programme (CAP) Thickness Measurement and Condition Assessment Inspection

What a Condition Assessment Programme is

CAP is a voluntary service that an owner requests from a classification society. It is not a statutory survey and it is not needed to keep a ship in class, which the annual, intermediate and renewal surveys do. What CAP adds is a graded statement of the ship's actual condition at the time of inspection, prepared to a published procedure. Each society runs its own scheme with its own procedures and report format, and some describe CAP as a service separate from classification itself, carried out independently of the class survey even when the same society classes the ship.

Most schemes are split into modules. The hull module, where thickness measurement sits, combines detailed visual and close-up survey with extensive gauging and an assessment of strength using the gauged thicknesses: hull girder longitudinal strength, buckling of deck and bottom panels and, in some schemes, fatigue. Machinery and cargo system modules rely on function tests, vibration and oil analysis and similar checks, and are outside the work of a thickness measurement firm.

Ratings are commonly given on a scale of 1 to 4, running from very good through good and satisfactory to poor, with the exact definitions set by each society. Oil majors and charterers normally look for a rating of 1 or 2.

How CAP thickness measurement and close-up survey feed the rating

The society's surveyors carry out the close-up survey, typically across most of the cargo and ballast tanks, recording coating condition, corrosion, pitting, grooving, cracking, buckling and deformation. The thickness measurement that accompanies it is normally more extensive than the class minimum for a renewal survey of the same ship: more transverse sections, more plate-by-plate coverage of the main hull girder, and more internal structure in more tanks. The gauging locations are set by the society's CAP procedure and its surveyor, and the measurement firm works to that plan.

The society uses the readings twice. First, each structural area is graded by comparing gauged thickness with the original and with the allowable margins, alongside the close-up findings. Second, the gauged thicknesses go into the strength assessment: the hull girder section is recalculated with actual rather than as-built scantlings, and deck and bottom panels are checked for buckling. A transverse section with gaps, or readings that cannot be tied to a specific longitudinal, forces the society either to make assumptions or to ask for more gauging. That is why CAP data has to be complete and exactly located, member by member.

Because the society carries out the CAP, it will normally expect the gauging firm to hold that society's approval under IACS UR Z17 and its own surveyor to attend, and some schemes add requirements of their own. Confirm the arrangement with the society, and give us the ship's class at the enquiry stage so the job can be scoped against it.

Pre-CAP condition gauging: knowing the likely result first

A disappointing rating is hard to undo once a charterer has seen it, so many owners want an indication before they commit. Pre-CAP gauging is the owner's own condition assessment inspection, carried out weeks or months before the CAP survey. Our team gauges a targeted sample: transverse sections amidships, critical structural areas, ballast tank structure where coatings have failed, deck and bottom plating in known suspect areas and, on bulk carriers, hold frames and their brackets. The readings are compared with the society's allowable margins to show where the ship sits in the substantial corrosion band or beyond it.

The result tells the owner whether to proceed, which steel to renew before the CAP survey and how much yard time to book. Pre-CAP gauging is not credited by the society and does not need class approval, but it follows the same method and reporting standard, so the numbers are directly comparable with what the CAP gauging will find. Much of it can be done during a port stay or lay-by period, with spaces entered under the ship's own permit system.

What the owner receives, and from whom

From us, the owner receives the thickness measurement report on the forms the society requires, with numbered sketches; the gauging data in a format the society's CAP team can use; a summary of readings in the substantial corrosion band and beyond allowable limits; records of pitting and grooving; photographs; and a list of any areas that could not be gauged, with the reason. For pre-CAP gauging, the same data comes with an outline of the steel renewal it implies.

From the society, the owner receives the CAP rating and its report or declaration, which is the document charterers and vetting departments read. We do not issue or influence the rating, and a pre-CAP gauging indicates where the steel stands, not what the society will conclude. Keeping that line clear protects the owner as well: a CAP rating is worth something to a charterer precisely because the society that gives it is independent of the people who measured the ship.

Frequently asked questions