Work is nearly completed on the boom of the world's biggest single-masted superyacht now docked in Auckland.

Dave Ridley, Hall Spars & Rigging NZ's operations manager, said the carbon fibre boom of M5 was at the Silverdale factory where work was nearing completion.

M5, estimated to be worth US$50m is moored at Silo Dock in the Wynyard Quarter for repairs. Its boom is set to be fitted back onto the vessel next month.

Ridley estimated that boom weighed about 5 tonne, "equivalent to above five cars".


"It's 28m long - about as big as a standard mast but very big for a boom," Ridley said, telling how it was trucked from the Wynyard Quarter where the yacht is alongside Orams Marine Village on Beaumont St.

The 78m yacht is the largest sloop or single-masted yacht built.

"At 92ft or 28m long and 6.5ft or 2m wide, the boom dwarfs everything else in the workshop," Ridley said.

In early August, that boom will be trucked from Silverdale to Babcock (NZ) at Devonport. M5 will be sailed across the harbour and moored at the end of Queens Parade ready to have the boom re-fitted.

"That will be around August 10. That's the only place where the boat can get close enough to the wharf for a crane to reach it," Ridley said.

"It's exciting for the team to have gear of this size here. Having the experience, facilities, and capacity to work on any rig is key in our philosophy of providing world class customer service for any client.

Asked why the boat was being repaired here, Ridley said the owner liked the South Pacific.

M5 is owned by Texas oil billionaire Rodney Lewis.

"By having it in the shop, we've got the best scenario possible with all facilities in place and the tools and personnel on hand to carry out the job efficiently with no travel time," Ridley said.

Four staff have been working full time on the boom with support from engineers at Gurit to carry out a full ultrasound on the boom.

Upgrades have been made to the boom's structural areas, with some parts of it replaced.

In the Wynyard Quarter, repairs have also been carried out to M5's fibreglass diesel tanks which have been tested for any leaks or faults.

Workers at the dock said an epoxy resin coating was applied to those tanks.