Ultrasonic Thickness Gauging for Canal Traffic and Heavy-Lift Ships at Rendsburg

Rendsburg: the midpoint of the Kiel Canal

The Kiel Canal crosses Schleswig-Holstein from Brunsbüttel on the Elbe estuary to Kiel-Holtenau on the Baltic, and Rendsburg lies near its middle, where the canal meets the old course of the River Eider. The town grew up around that crossing. Today the canal passes south of the historic centre, under the railway high bridge, and the Obereider lake joins it beside the town. Canal pilots change over at Rüsterbergen, a short distance to the west, so most ships pass Rendsburg with a fresh pilot on the bridge and the second half of the transit still ahead of them. Because the town is well away from both lock complexes, a stop here divides the passage neatly in two, and ships that need a break in the transit for stores, crew or a cargo appointment often take it at Rendsburg.

The traffic is a cross-section of North European short-sea shipping. Feeder container ships shuttle between Hamburg or Bremerhaven and Baltic ports, coasters carry grain, fertiliser, timber and steel, small product and chemical tankers run between refineries and coastal depots, and ro-ro and heavy-lift ships use the canal to avoid the longer route round Denmark. Yachts and naval ships from the canal's own shipyards also pass on their way to sea trials. Container feeders keep to tight weekly rotations, whereas tramp coasters may learn their next cargo only a day ahead, and that difference decides how much warning we get before a job. Ships of every flag share a narrow channel with strict speed rules and passing places, so a stop has to be arranged with the canal's traffic control through the agent rather than improvised.

Two kinds of port activity bring ships alongside at Rendsburg. The heavy-cargo terminal at Osterrönfeld, on the south bank, handles project cargo, large machinery and energy components that arrive by road and are lifted aboard multipurpose and heavy-lift ships. Because those components travel on special road convoys booked well in advance, the ship's time alongside is one of the more predictable windows anywhere on the canal. The older town harbour off the Obereider serves smaller ships with bulk and general cargo, handled for businesses in the town and the farming country around it. Severe winters can bring ice to the canal and the Obereider; it rarely stops traffic, but an ice-class ship heading for the northern Baltic may well pass Rendsburg in January on her way to harder conditions.

Thickness measurement through the survey cycle at Rendsburg

Class rules set the survey cycle, and the cycle sets how much gauging a ship needs. A superintendent planning a call at Rendsburg 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.

Typical thickness gauging jobs at Rendsburg

Work at Rendsburg is short and opportunistic, built around a loading slot, a cargo delay or the canal transit itself. The superintendent usually sends the TM plan or the last survey report, flags the areas of concern and tells us how long the ship will be tied up. We then rank the spaces so the most important readings come first, and agree with the chief officer which tanks the crew will empty and ventilate ahead of arrival. Heavy-lift ships add crack detection to the list, because the fittings welded on and cut off for each voyage leave marks in the deck that need checking. Examples:

• A heavy-lift ship loading a transformer at Osterrönfeld: tank-top and tween-deck gauging under the cargo footprint, with magnetic particle testing where sea-fastenings from the last voyage were removed.
• A coaster discharging fertiliser in the town harbour: hold frames, lower brackets and tank-top plating gauged once the hold is swept, since corrosive residues attack bare steel quickly.
• A feeder container ship stopping at a canal berth for a crew change: scrubber wash-water and overboard lines measured with the system shut down.
• A product tanker transiting from the Elbe to the Baltic: engine-room sea water and fuel lines gauged by a riding team during the canal passage.
• Pre-purchase gauging of a general cargo ship lying idle at a canal berth: holds, ballast tanks and hatch coamings measured for the buyer.

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.

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