Maritime Propulsion

 

The New Zealand ferry operator’s new 34.9m (114.5 ft.) catamaran Korora, delivered from the Q-West shipyard in December, features a water lubricated propeller shaft arrangement based around a Henley Integrated Propulsion System.

 

Auckland-headquartered Henley Group, an approved Thordon distributor, with a history dating to 1917, secured the contract to design and supply Korora’s complete drivetrain, following the company’s involvement with the first vessel in the series, the 2014-delivered Te Kotuku.

 

Mark Power, Managing Director, Henley Group, explained: “Our brief was to design and supply the entire driveline, which included the TG100 seal and our Integrated Propulsion System (IPS). At the start of any project we designate Thordon Bearings equipment with Henley components as we find they offer cost and performance advantages when used in conjunction with our glass-reinforced “Easi Flow sterntube and ruddertube systems.”

 

For first-of-class Te Kotuku, however, the owner opted for a different transmission and sealing arrangement to the one Henley had originally specified; but “after some issues with the first vessel we were asked to supply our complete IPS package, which included Thordon’s TG100 forward shaft seal,” said Power.

 

In addition to the TG100, Thordon’s scope of supply included SXL tail shaft, strut and rudder bearings along with its ThorPlas-Blue bearing, which was used as an “isolator” between the bronze seal’s housing and the aluminum hull. This arrangement was considered the optimum solution for preventing corrosion.

 

Henley’s IPS typically consists of various custom drive line components from engine mounts to rudder. This package includes Tiger propellers, together with Thordon bearings and seals, Twin Disc transmission and engine controls and Vulkan couplings.

 

Thordon Bearings introduced the TG100 mechanical seal in 2013. Suitable for propeller shaft diameters of 100mm (4”) to 305mm (12”), the seal combines hard wearing silicon carbide seal faces with Thordon’s proprietary elastomeric polymer bellows.

 

A unique feature of the TG100 is the emergency seal that permits stand-alone operation to allow the vessel to safely return to the nearest port, preventing permanent seal damage. The unique omega “O” shape of the proprietary elastomeric bellows minimizes torsional vibration and maintains the required spring force throughout the allowable range of axial shaft movement. This elastomeric bellows has no shelf life and no scheduled replacement.

 

Korora, the sistership to the 2014-delileverd Te Kotuku, has now commenced operations ferrying up to 400 passengers on Fullers’ Waiheke Island service.

 

A second vessel, again built to an Incat Crowther design by Wanganui-based Q-West and based on the same Henley/Thordon drive train, is schedule for delivery in June. Options are available for an additional two of the same, as part of Fuller Group’s extensive fleet renewal program.