ETNZ nose dive

Emirates Team New Zealand suffered damage to the bow of their AC40 after an early start testing on Auckland’s Hauraki Gulf in some top end conditions.

It was a day when the awesome power and speed of the AC40 (now in full LEQ12 mode) was on display, putting over a mile on the chase boat which was travelling at 36 knots in lumpy seas, before a deep nose-dive caused structural damage to the bow area with a nasty carbon crack emanating from the forestay and down along the starboard side stopping just short of the internal bulkhead in the crash-zone area of the boat.

In recent weeks the Emirates Team New Zealand AC40 has been taken out of its one design configuration and testing stepped up in its development and data collection towards the design of its AC75.

The team were testing under manual flight control to the north of Waiheke Island in around 15-20 knots of windspeed and large waves. While sailing downwind at over 40 knots of boat speed, the crew onboard lost control of the ride height which caused the rudder and elevator to come out of the water. This resulted in a high-speed uncontrolled gybe and simultaneous deep nosedive followed by a capsize.

The resulting impact of the water pressure collapsed the foredeck at the bow of the AC40. Significantly the watertight bulkhead aft of where the damage occurred maintained its structural integrity, successfully serving the purpose of controlling water ingress so the boat could be righted and towed back to base.

Within moments of the incident, the team on the water and design and build team back at the base were well into a program to assess the damage and repair timeline but also importantly understand the precise loads on the structures in the incident and lessons that can be learned and implemented going forward.

Emirates Team New Zealand CEO Grant Dalton said, “It appears that when the boat nose-dived, which was the best we have done, the high water pressure and side load collapsed the forward section of the deck causing the resulting bow damage. The designers are analysing the load cases of the incident and although it might be too soon to tell, it is likely that we will have some retrofit structure necessary to our boat and throughout the AC40’s fleet. But we will understand this further in the coming days.”

The LEQ12 was righted quickly by the experienced chase boat crew who were highly praised by the sailors, Dalton and the recon unit on the water for their calmness and professionalism in the situation and the boat was expertly towed back to the base on its foils. The design team and engineers will be looking closely at the damage and analysing the load profiles that the boat experienced in the nose-dive and as Dalton offered: “It could be that we need to put another ring frame in the bow area just to strengthen that whole area up…or we might need some longitudinals.”

The AC40 was towed back to base on its foils after the incident and is back in the shed being assessed for the repair job ahead.