22 Dec 2021

Major refit for NIWA’s deep-water research vessel, ‘Tangaroa’

A significant contract undertaken by Diverse Engineering in 2021 was the refit of NIWA’s RV Tangaroa, New Zealand’s only ice strengthened deep-water research vessel. The company’s facilities, experienced staff, Class approvals, qualifications and teamwork approach all contributed to NIWA’s decision to bring its flagship vessel to Nelson for refit.

In addition to general maintenance and repair, the client had two major requirements: upgrading the deck crane and removing and replacing worn deck plates. The turnaround was tight with just 22 days in which to complete the job, as a voyage at the end of that timeframe could not be delayed.

Although the existing deck crane was still in good condition, its lift capacity and reach were insufficient. When Tangaroa is docked to port, the crane, positioned on the starboard side, is limited in lifting capacity due to extended reach, meaning the ship must use shore cranes. NIWA purchased a new, Italian-made Effer crane from Australia. Diverse Engineering was commissioned to remove the old crane, which had a lift capability of 16 tons, and replace it with the new one which was tested to 24.5 tons and has a considerably improved reach.

Tackling the job began with removing the original crane and cropping off the base. Modifications had to be made to the pedestals and these were designed by Marine Industrial Design (recently opened in Nelson), which undertakes the majority of NIWA’s marine design work. Diverse Fabrication completed X-ray welding to an exceptionally high standard for the fitting of the new bases; ultrasonic welding passed 100% visual, 100% X-ray and 100% mag-particle testing showing no flaws.

The Effer, weighing around 10.5 tons, was positioned on the pedestal by Lift N Shift Nelson before Diverse fitters took over the install. With authorisation from the manufacturer, Diverse Hydraulics was responsible for changing all piping, positioning the new systems and performing load testing. Diverse Hydraulics is licensed to commission and load-test Palfinger cranes, so was considered by Effer to have the capability for this.

As well as the new crane installation, major work had to be completed on the vessel’s main deck. Diverse undertook removal of all existing wear strips (which were reaching minimum allowances and tolerances under Class rules) and fitting of new wear strips. Approximately 200-220m2 of plating was fitted requiring around 3,000 lineal metres of weld, completed using arc-air to remove the plates and MIG welding. As the ship was without an operable crane at the time, Diverse brought its portable, specially designed flat rack mounted Hiab on board to dispense with the need for shore cranes.

Diverse Engineering commissioned painters from Intergroup Nelson and NIWA also brought in painters, so extensive scaffolding was required, erected by contractors. Diverse staff were deployed throughout the ship completing a range of other projects including engine maintenance, the building and fitting of new bilge water tank, installation of pipework and repair of the ship’s Hiab cranes. Diverse provided all facilities, including air compressors.

The job was finished on schedule, the evening before Tangaroa had to sail back to Wellington where a sub-sea exploration crew was waiting to board her. Tangaroa will not require another refit for at least two years and NIWA was delighted with both the quality of work and timely completion of the contract, something that had concerned them at the outset due to the extent of work involved. Tangaroa’s smaller sister ship, RV Kaharoa, is scheduled for a refit at Diverse Engineering in 2022.

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