Special Survey Thickness Measurement · Gdańsk, Poland
Renewal and Intermediate Survey Gauging in Gdańsk: Sequencing Tankers, Ferries and Dock Days
A renewal survey in Gdańsk is rarely a single event. A tanker may discharge at Naftoport, wait in the Gulf, then enter a Remontowa floating dock, and each stage opens different tanks to measurement. We mobilise a team from India to the ship and sequence the thickness gauging across those stages, so cargo tanks are measured when they are gas-free, bottom plating when the ship is dry, and every reading lands in time to steer the steel order. The plan is built backwards from the dock slot and the discharge programme.
Gauging sequenced across three stages
Discharge, anchorage wait and dock each open different spaces. We assign tanks and plating to the stage where they are accessible, so nothing is measured twice and nothing is left until the last day of the stay.
Tanker programmes under the ESP rules
Oil tanker renewal gauging widens at every survey and follows a survey programme agreed with the class. We prepare the measurement plan by tank and transverse section before the ship arrives, with the previous report as the baseline.
Ready for a cold working season
Baltic winters change how thickness gauging is done: couplant thickens, steel is cold and daylight is short. Our plan allows for warm-up time, suitable couplant and sheltered work so readings remain reliable.
How does a renewal survey unfold for a tanker calling at Gdańsk?
A crude tanker due its renewal survey typically spends time in three places. At Naftoport she discharges, which takes the ship's own pumping capacity and the terminal's schedule. If the berth is occupied or the cargo plan changes, she may wait at the anchorage in the Gulf of Gdańsk. Then, after tank cleaning and gas-freeing, she moves to a floating dock at Remontowa for the survey itself, with the hull dry and the yard's staging in place.
Each stage allows different measurements. At the terminal, deck structure, pipelines and pump room can be gauged as soon as permits allow. At anchor, ballast tanks and sometimes cleaned cargo tanks offer an uninterrupted spell. In dock, the bottom, side shell and double bottom become accessible, and the class surveyor attends. Treating the three as one programme avoids the common mistake of leaving all gauging to the dock, where it competes with blasting, painting and steel work for access.
In what order should cargo and ballast tanks be gauged at Gdańsk?
The order follows tank readiness rather than tank number. Segregated ballast tanks are usually available first, since they do not need washing after discharge, and they are often the spaces where coating breakdown is worst, so they come early in the plan. Cargo tanks follow as they are washed, ventilated and certified gas-free; the plan lists them in the order the ship's crew or the yard expects to release them.
Within each tank, readings begin with the members the previous survey flagged as close to the renewal limit, then continue through the survey programme's mandatory extents: transverse sections, deck and bottom plating, longitudinals and their end connections, and bulkheads. Where the ship has been in service long enough for the extents to widen under the ESP rules, we confirm with the class what is required before the team travels, so tank access is requested correctly.
What does gauging in a Remontowa floating dock involve?
In a floating dock the ship is lifted clear of the water and the hull can be blasted and examined from below. The yard prepares access to the shell and bottom, while the ship's tanks are cleaned. The most valuable gauging is the first pass, done as soon as plating is exposed, because the yard's steel list is formed from it. Readings taken late in the stay lead to rushed decisions and change orders.
We plan to arrive when the ship is docked or the day before, and to measure each area as the yard releases it. Daily results are passed to the superintendent and the attending surveyor, with readings beyond limits flagged, so renewal decisions are made area by area rather than at the end. Ferries, tankers and offshore units differ in how they are staged, so the plan is adjusted to the vessel type and to the yard's project manager's sequence.
How are ro-pax ferries and bulk carriers handled differently?
A ro-pax ferry on a scheduled Baltic route has a fixed dock period and limited room for delay, so thickness measurement is sequenced tightly with the yard's programme. The structure that dominates the gauging is vehicle decks, ramps, ballast tanks under the decks and the shell at the waterline. Plating beneath car decks wears from moisture trapped under coatings, and steel at the ice belt of a ferry running in winter can lose thickness faster than the rest of the side shell.
A bulk carrier loading coal or grain in the Northern Port is measured differently. Holds are gauged between loading stages or after discharge, covering hold frames, hopper and topside tank plating, tank tops and corrugated bulkheads. Ships due a renewal survey often arrive with cargo remaining, so the plan identifies which holds will be empty and when, then adds ballast tanks and deck structure to fill the available time.
How does a Baltic winter affect thickness measurement in Gdańsk?
Cold conditions are a practical challenge, not a reason to stop. Ultrasonic couplant stiffens and may freeze at low steel temperatures, so we carry couplant suited to the conditions and warm probes and cables before use. Cold steel and short daylight reduce the time available on deck, and wind off the Gulf makes open decks uncomfortable for careful work.
Inside tanks, temperature is moderated by the ship, but lighting and ventilation become more important, and cold plates may carry condensation that hides scale. Staging in a dock may be exposed, so the yard's shelter arrangements matter. We build extra time into winter jobs and ask the agent for the ship's expected location and schedule early. Ice in the Gulf does not often close the port to ocean-going ships, but its effect on tug and launch availability is considered in the plan.
What should the superintendent send for a Gdańsk renewal survey job?
The most useful package is the previous renewal survey report, the survey programme for this one, the class and the docking dates, plus the current tank status and the discharge programme at Naftoport. With those, we can set the gauging plan by tank and by stage, confirm which areas will be done afloat and which in dock, and state in advance which readings the class will want repeated by its own approved firm.
Readings are issued on the class formats with sketches and point numbers carried forward from the earlier survey, so the surveyor can compare directly. Where something at Gdańsk is gauged before the dock for planning only, the report says it is owner's information. Poland is a Schengen state, so travel for the team is arranged once the dates are fixed, and the earlier we hear of a slot change, the easier the visa window is to protect.
Where special survey thickness measurement sits in the survey cycle
Class rules set the survey cycle, and the cycle sets how much gauging a ship needs. A superintendent planning a call at Gdańsk usually knows which survey is due; the table shows what the thickness measurement for each one typically involves. The exact extent comes from the class rules for the ship type and the surveyor attending, so the thickness measurement programme is agreed with the class before work starts.
| Survey | When it falls | What the thickness measurement usually covers |
|---|---|---|
| Annual survey | Every year, within three months of the anniversary date | General examination. Gauging where the surveyor finds suspect areas or where substantial corrosion was recorded at an earlier survey. |
| Intermediate survey | In place of the second or third annual survey | Suspect areas, and on older ships and ESP ships selected ballast and cargo spaces with close-up survey; the extent grows with age. |
| Renewal survey No. 1 | Around 5 years | The first full baseline: suspect areas and selected plating and stiffeners, usually with modest steel renewal. |
| Renewal survey No. 2 | Around 10 years | Wider gauging of deck, bottom and side plating, transverse sections across the cargo area on ESP ships, and more close-up survey. |
| Renewal survey No. 3 | Around 15 years | Extensive gauging of cargo and ballast tank structure and more transverse sections. The survey most likely to turn up steel renewal. |
| Renewal survey No. 4 and later | Around 20 and 25 years | Gauging extended to most structural members in cargo and ballast spaces. Charterers often add a Condition Assessment Programme. |
| Docking survey | Twice in each five-year period | Bottom and side shell, sea chests, rudder and stern area while the hull is dry; suspect bottom plating gauged. |
How the job runs at Gdańsk
The sequence for a thickness measurement job at Gdańsk is short and written down, so the yard, the surveyor and the superintendent know who arranges what.
- Send the vessel name or IMO number, ship type, class society, the survey due (annual, intermediate, renewal survey number, CAP or owner's condition survey), the port and dates, and the scope you expect.
- We confirm the scope against the class rules for that survey, prepare the thickness measurement plan with frame and section references, and say whether the measurement will be credited to a class survey.
- Mobilisation is planned around visa lead times and the vessel's schedule; the ship's agent arranges port access, and the yard or ship arranges staging, lighting, ventilation and gas-free certificates.
- Gauging with calibrated ultrasonic thickness gauges: through sound coatings only where the gauge's through-coating mode has been verified on a coated reference, otherwise on cleaned bare steel, with every reading tied to its frame, strake and location on the sketch.
- Readings are compared with original thicknesses as work proceeds; substantial and excessive corrosion and any cracks are reported to the attending surveyor and the superintendent the same day.
- The final report is issued on the class thickness-measurement formats with sketches, a summary of locations exceeding the allowable margins, piping tables where piping was in scope, and the gauge calibration and technician certificates.
Who does the work, and when class approval applies
We send the team from India to the ship for each job rather than keeping staff at the port, and plan the mobilisation around visas and the vessel's itinerary. The work is planned and supervised by the founder, our Responsible NDT Level III (ASNT NDT Level III in UT, RT, MT, PT and VT, with more than eleven years of international field experience). Technicians hold certification under the company's written practice to ASNT SNT-TC-1A; Atlantis is ISO 9001 and ISO 14001 certified.
Thickness measurement that a classification society credits to a class survey has to be carried out by a firm approved by that society under IACS UR Z17. Atlantis is in the process of obtaining UR Z17 approval from DNV, Lloyd's Register and ABS. Until a certificate is issued, the readings we take are for the owner's own decisions, not for credit to a class survey, so tell us the vessel's class and the survey due when you enquire and we set the scope for the right purpose. Owner's and charterer's condition gauging, pre-docking steel estimates, pre-purchase and on-hire or off-hire gauging, and scrubber and piping condition checks between surveys do not need class approval.
Governing codes and standards
- IACS UR Z7 for hull surveys and the thickness measurement extents at each renewal survey
- IACS UR Z10.1 and Z10.4 for the enhanced survey of oil tankers and bulk carriers
- IACS UR Z17 on which firms may measure thickness for credit to a class survey
- SOLAS chapter XI-1, regulation 2, and the 2011 ESP Code
- ASTM E797 for manual pulse-echo ultrasonic thickness measurement
- ASNT SNT-TC-1A for the qualification of the technicians who take the readings
What you receive
- Measurement plan by tank and stage: terminal, anchorage and dock
- Thickness readings on the class formats with original thickness and allowable diminution
- Daily dock results with readings beyond limits flagged
- Sketches carrying forward point numbers from the previous renewal survey
- List of members for renewal, with location and dimensions, for the yard's steel order
- Gauge calibration records and technician certificates
Industries served
- Crude and product tankers
- Chemical tankers
- Ro-pax ferries on Baltic routes
- Bulk carriers loading coal and grain
- Ocean-going container ships
- Offshore support vessels
- Ro-ro and general cargo ships
Frequently asked questions
Can a tanker's renewal survey gauging be split between Naftoport and a Remontowa dock?
Yes, and it is usually sensible. Deck structure and gas-free tanks can be measured during or after discharge, while bottom plating and double-bottom structure need the dock. We assign each space to the stage where it is accessible. Readings taken before the dock are owner's information unless a firm approved by the class takes them as part of the survey.
How early should we gauge before a Gdańsk docking?
Early enough that the readings shape the yard's quotation, and close enough that the steel is still representative. Several weeks to a few months is typical. For a tanker, the best time is a gas-free spell after discharge, when cargo and ballast tanks can be entered and a team can arrive from India with visas in hand.
Does cold weather stop thickness gauging in Gdańsk?
It does not stop it, but it changes the plan. We use couplant suited to low temperatures, warm probes and cables before use, and allow extra time for access and lighting. Work inside tanks is moderated by the ship, while open-deck and dock staging work needs more shelter and a margin in the schedule.
What does a ro-pax ferry docking at Remontowa need from gauging?
Mostly vehicle decks, ramps, ballast tanks and the shell at the waterline, measured as the yard releases each area. Ferries have fixed dock periods, so we agree the sequence with the superintendent and the yard in advance and pass daily results, so renewal decisions are not held up at the end of the stay.
Will gauging in Gdańsk count towards the class renewal survey?
Only if taken by a firm approved by the ship's society as part of the survey. Atlantis is in the process of obtaining UR Z17 approval from DNV, Lloyd's Register and ABS, so for the moment our readings support the owner's decisions and steel planning, not class credit. Tell us the class when you enquire and we set the scope for the right purpose.
What do bulk carriers need from gauging when calling at the Northern Port?
Hold frames, hopper and topside tank plating, tank tops and corrugated bulkheads are the main targets, gauged between loading stages or after discharge. Because ships often arrive with cargo remaining, we ask which holds will be empty and when, and fill the remaining time with ballast tanks and deck structure.
Can special survey thickness measurement at Gdańsk be credited to a class survey?
Thickness measurement that a classification society credits to a class survey has to be carried out by a firm approved by that society under IACS UR Z17. Atlantis is in the process of obtaining UR Z17 approval from DNV, Lloyd's Register and ABS. Until a certificate is issued, the readings we take are for the owner's own decisions, not for credit to a class survey, so tell us the vessel's class and the survey due when you enquire and we set the scope for the right purpose. Owner's and charterer's condition gauging, pre-docking steel estimates, pre-purchase and on-hire or off-hire gauging, and scrubber and piping condition checks between surveys do not need class approval.
Planning a survey or a drydock?
Send the vessel name or IMO number, the class, the survey due and the port. We reply with the scope, the mobilisation plan and a quote for that vessel.
Request a QuoteRequest a ship gauging quote
Send the vessel name or IMO number, the class society, the survey due and the port. We reply with the scope, the mobilisation plan and a quote for that vessel.
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