Türkiye has transitioned into a main region for ship repair and retrofit activity and recently Gemak Shipyard, part of the Gemak Group, became the first shipyard to apply a silicone-based hull coating to a vessel in Europe.
The coating was applied as part of a decarbonisation upgrade repair and retrofit project. Gemak is also working on another means of reducing emissions – lengthening the hull. “One of the major retrofits for a vessel is lengthening, which is mostly applied to the parallel body,” said a yard representative. “Lengthening a vessel by keeping the existing propulsion arrangement has a positive effect on efficiency, which means transporting more cargo with the same power.”
Gemak has an innovative way to execute the lengthening process. The fabrication of the new block to be inserted is undertaken before the arrival of the vessel. The new block includes not just the hull, but all piping and outfitting. The section is coated and ready for insertion using gantry cranes, which have up to 570t lifting capacity. Gemak has designed and fabricated a skidding system with six degrees of freedom, which provides an accurate and quick fitting process with ±5mm tolerance.
The advantage of using such a system is that the hull surface is clean, with no welded attachments to hinder manoeuvring of the blocks.
“Lengthening a vessel by keeping the existing propulsion arrangement has a positive effect on efficiency”
Another method for lengthening a vessel is the bulbous bow, but these are designed at the newbuilding stage for the expected speed parameter of the vessel. A popular method of reducing emissions is to slow the vessel down, but this reduces the effectiveness of the bulbous bow. This is not so much of an issue for slower vessel types, like large tankers, but the removal of the bulbous bow has proved effective.
Such a major operation is performed during the periodic survey. Due to decarbonisation and the need to maintain a CII rating – or move up a rating level to satisfy a charterer’s requirements – the traditional five-year classification society Special Survey is morphing into a regular retrofit schedule.
This may include re-coating the hull with a low friction, high performance product. Gemak believes it is the first shipyard in Europe to apply such a product to a vessel. Other practical approaches to the decarbonisation process are energy-saving ducts; these reduce turbulence and support linear acceleration of the water flow to improve propeller thrust. Gemak is fabricating these constructions at the yard, reducing the need to transfer them from elsewhere, and thus reducing costs.
The propeller is an obvious means of improving a vessel’s efficiency, but an upgrade requires removal. Gemak has designed a lift trolley to speed up the removal process.
Looking ahead, a shipyard representative said the yard is now ready to conduct retrofit installations of wing sails, rotor sails, dual-fuel systems, and hull air-lubrication systems, all in an effort to further reduce the industry’s emissions.