Port Otago's newest tug, Arihi, has another week on the slipway as it undergoes its first maintenance programme, since its delivery from Turkey in August last year.
The tug will be on a slipway in Dunedin's upper harbour for about a fortnight in total for minor repairs and some painting touch-ups.
Port Otago general manager of marine and infrastructure Sean Bolt said slightly damaged paint, from Arihi's ship-board journey to Port Chalmers, would be repaired and also new anti-fouling applied, which would last for five years, as opposed to two and a-half years.
''We decided while she was out of the water we might as well anti-foul now,'' he said.
The 18.7m long and 300 tonne Arihi was still under warranty, but local contractors were doing the work, and if necessary, could talk to the Turkish builders, he said.
Included in the work programme is the welding of additional bolts to the outer casing of the twin ''azimuth stern drive'' units, so as to be able to bolt on sacrificial anodes, which could in the future be unbolted and replaced by divers, as opposed to having to put the vessel on a slipway to grind off the welded anodes.
Marine sacrificial anodes, usually in zinc or aluminium, are bolted or welded to metal hulls as the anodes attract corrosion, which would otherwise attack the boat hull, through an electrochemical reaction.
Azimuth stern drive units have been common on tugs since the mid-1980s. The units allow the base of the propeller unit, inset in the hull, to swivel the propellers 360 degrees, giving the tugs a high degree of manoeuvrability.
