Case studies reveal learning points for suppliers and owners, as growing numbers of BWMSs are fitted
The inherent similarities which usually exist between sister ships can be exploited to save time and money when retrofitting ballast water management systems (BWMS). For example, Argo Navis Marine Consulting & Engineering co-founder Andreas Zontanos explained recently in a case study for Marine Propulsion’s sister publication Tanker Shipping & Trade, that: “I usually recommend owners do not scan all the sister ships, as long as the technical staff is allowed to carry out basic checks on each vessel to verify locations set aside for the system installation.”
Mr Zontanos was referring to the company’s work as the integration engineer for retrofitting an Ecochlor BWMS on a 115,849 dwt tanker this year, following three installations on similar ships from the same fleet in 2017.
Although the projects might be similar, a series allows improvements to be made, he indicated. For example, the fourth tanker in the series benefited from improvements learned from retrofittiung the first three vessels: piping was rerouted due to placement difficulties that occurred during the first retrofit and the Ecochlor generator’s location was moved to improve accessibility. The compressed air lines were also upgraded to allow for better water draining prior to use.
For Techcross, its experience of about 1,000 BWMS installations on newbuildings and as retrofits has helped it identify the best situation in which to fit them: ideally, during a drydocking period or, if that is not possible, during a voyage.
So when it proposed that a retrofit installation on a 4,800 dwt tanker would be carried out during a voyage, it was already targeting a less-than-perfect option. But then the ship’s operating schedule was suddenly changed, making even the voyage-based option impossible.
In a case study published in Marine Propulsion’s Ballast Water Treatment Technology guide, the company explained that the work to fit one of its ECS300B (Electro-Cleen System) BWMSs was actually conducted in the outer port of Yeosu in South Korea.
This change of plan meant that its installers had to overcome the difficulties of an unstable working environment, with no change from the original timeframe. In particular, they needed a tug with a crane and a means of transporting and lifting supplies from the port’s berths to the vessel.
They also had to adapt as the work progressed. They found that the ECS system’s total residual oxidant sampling pipe and neutralising agent dosing pipe would partially block the vessel passageway, so they modified the design drawings and reinstalled the lines to resolve the inconvenience.
They made additional modifications so they could manage their working time to meet the ship’s operating schedule. For example, they removed fittings that needed adjusting so that the main welding work could continue.
In an unusual installation, one shipowner took a do-it-yourself approach. Using ship staff and selected subcontractors “is a lot cheaper” than other installation options, according to Seatruck Ferries fleet director Ben Coppack. Installation was very straightforward, Mr Coppack said. “It’s just filters, pipes and pumps,” he pointed out. For the electrical work, he paid tribute to the SeaKing Group, which provided an electrical technician to travel with the ship to connect all the components. Wärtsilä SAM Electronics provided the control systems.
For an average of about £175,000 (US$246,000) per ship, the Irish Sea operator installed an Optimarin Ballast System (OBS) on each of five roro freight ferries. Installations began in November 2016 onboard the 5,300 dwt Seatruck Progress and continued until September 2017.
For four of the ships, the system was delivered as a set of components and the crew used Optimarin’s manuals to assemble them. For the other ship, Seatruck bought a skid-mounted system that Optimarin had available from stock and broke it down to get it into the vessel.
Mr Coppack chose a UV treatment system because of the limited space available and because it did not use any chemicals, which would add to its operating cost. Although the ships do not load much ballast compared with large ocean-going ships – about 100-150 m3 – they do this twice each day; much more frequently than other ship types, so the total volume, and thus the amount of chemical that would be needed for some systems, is large.