15/2/2023
M/S Silja Serenade was maintenance painted with Jotun coatings in January. The dry docking lasted 16 days, during which the ship’s underwater hull, topside and part of the tanks were painted. The prevailing weather conditions imposed their own restrictions on outdoor docking.
M/S Silja Serenade is a cruise ship owned by the Estonian Tallink Grupp, which operates under the Silja Line brand on the Helsinki-Mariehamn-Stockholm route. The ship was built in 1990 at the Masa-Yards Turku shipyard. The ship accommodates 2,852 passengers and 450 cars.
M/S Silja Serenade was maintenance painted at the Turku Repair Yard in January. Dry docking lasted 16 days, during which the ship’s underwater hull, topside and part of the tanks were pretreated and painted. Maintenance painting was performed with Jotun products supplied by Nor-Maali.
Outdoor docking is significantly different from new construction, where a large part of the painting is done indoors during the block phase. In the outfitting phase, the new building is mostly covered and heated.
In outdoor dockings, the weather forecast needs to be followed very closely and one must react quickly to changes in temperature and humidity. Environmental conditions determine the schedule and scope of the repair. In the worst case, the planned work has to be cancelled.
During the dry docking of Silja Serenade, the environmental conditions were quite challenging. The temperature varied between -2 °C and +3 °C. There was no cover on Silja Serenade during the maintenance. Heavy rains were avoided, but the cold temperature and the wind blowing from the sea created challenging conditions for maintenance painting.
Interior paintings were easier to be carried out, but also in some interior spaces, the temperature of the steel was very low (+7- +8 °C), because they were located at the ship’s outside shell facing cold air on the other side of the plate. Heaters were used during painting biotanks, but ballast tanks, for example, were not heated during surface treatment. The conditions in them were practically the same as outside the ship.
Image: AS Tallink Grupp
Before the painting, the areas to be painted were high-pressure washed (approx. 300 bar) in order to remove water-soluble salts and other impurities. In this maintenance, washing was possible because the temperature was above 0 °C at the moment. If the temperature had been below 0 °C, water washing would not have been done.
After washing with water, the damaged areas were blastcleaned to Sa 2½. In addition, edges of existing paint were feathered in order to have the best possible corrosion protection at the overlap of old and new paint.
Silja Serenade’s underwater hull and topside were maintenance painted with Jotacote Universal N10 and Hardtop AX. The underwater hull was touch up painted, i.e. only the damaged areas were treated. After pretreatment, the bottom was painted with two layers of Jotacote Universal N10 epoxy coating. The boottop got a full coat. In addition to the repairs made with epoxy, the topside was painted with Hardtop AX polyurethane topcoat. Before the topcoat, the topside was washed to remove impurities.
The painting had to be done in a really fast schedule, so a product that works in the cold and can be quickly overcoated was chosen as the touch up paint. The first choice for such conditions was Jotacote Universal N10, which can be used down to -10 °C. Under the prevailing conditions, the product could be overcoated after just 15 hours. This fit into the schedule, where overcoating had to be done the next day from the previous paint layer. Jotacote Universal N10 cures quickly and the curing continues also in water, which enables early launching of the ship. This is especially useful in cold weather.
The short overcoating interval and the cold weather brought their own challenges to measuring the paint film thickness. In some cases, film thicknesses could not be measured, but had to be estimated according to the wet film comb and the paint consumption.
Maintenance painting in winter – Silja Serenade in dry dock. Nor-Maali´s Coating Advisor Sara Grundsten-Lyapova measures the film thickness of Jotacote Universal N10.
Jotacote Universal N10 is a polyamine cured pure epoxy coating. It is a fast drying, high solids and high build, abrasion resistant product. It is specially designed as a universal, all round, all year, new building and maintenance coating where fast dry to handle is required. It can be applied at sub-zero surface temperatures.
Typical uses in marine for Jotacote Universal N10 are exterior and interior areas, including outside hulls, superstructures, decks, cargo holds and water ballast tanks. This product has very high flexibility making it especially suitable for the temperature variation experienced in crude oil, chemical and shuttle tankers. Approved for PSPC cross over testing with a wide range of shop primers.
Hardtop AX is aliphatic acrylic polyurethane coating. It has a high gloss finish with very good gloss retention, so it well suited for topsides, decks and superstructures. It has good chemical resistance. Hardtop AX is also an easy-to-apply product, which is important in such a demanding location.
Dry docking was done in Naantali at Turku Repair Yard. Turku Repair Yard Ltd is the largest dry dock in Northern Europe, established in 1989. The shipyard employs around 100 employees and in addition 250–300 subcontractors. The shipyard repairs, among other things, car ferries and tankers, but also smaller fishing and warships. Every year, 80–100 vessels are repaired at the shipyard. In addition to repairs, Shipyard makes ship modifications, such as extensions and painting.
The dry dock is 265 m long, 70 m wide and 7.9 m deep. The company has also a 101 m long and 21.6 m wide floating dock. Turku Repair Yard is a part of Estonian BLRT Grupp.
Image: AS Tallink Grupp
Tonnage: 58,376 GT
Length: 203.03 m
Beam: 31.93 m
Decks: 13
Passengers: 2,852
Ice class: 1 A Super
Speed: 23 kn
