Initial findings from SailGP’s technical review into the high-speed collision during the ITM New Zealand Sail Grand Prix in Auckland reveals complex loss-of-control sequence but no evidence of system malfunction.
The incident occurred at the start of Race 3 on the opening day of the event, when the New Zealand Black Foils F50 lost control approaching Mark 1 at speed before sliding sharply into the path of the French DS Automobiles F50 catamaran.
Both boats sustained significant damage and two athletes were injured in the crash.
Following the incident, SailGP engineering teams conducted a detailed review using high-rate performance data, onboard telemetry, simulator recreations and video analysis to understand precisely what occurred.
Data analysis reveals complex loss-of-control sequence but no evidence of system malfunction.
The Data analysis shows that the New Zealand F50 was sailing towards mark one at 90 km/h, when it encountered a gust during the first reach of the race.
That sudden increase in wind speed caused the boat to accelerate rapidly, increasing lift on the hydrofoils and raising the ride height of the boat. As the boat rose, the leeward foil pierced the surface of the water, triggering a side slip and a rapid increase in leeway.
SailGP Director of Performance Engineering Alex Reid said the combination of speed, gust conditions and foil ventilation created a highly dynamic sequence which developed within seconds.
“The data shows the boat accelerated quickly and rose high on its foils,” Reid said. “Once the leeward foil pierced the surface, the boat entered a side slip where the foil began generating unwanted lift through leeway rather than via rake.”
“At that point the dynamics of the boat changed very quickly. Control inputs from the flight controller were still being applied, but we believe the physics of the slide meant the boat could not be brought down in time.”
As the side slip developed, the rudder angle increased significantly as the crew attempted to regain control while avoiding nearby boats. The rudder briefly lost effective flow before re-attaching along with the windward bow immersing, causing the boat to round up sharply into the wind and decelerate rapidly.
With the French F50 sailing close astern at speed, there was insufficient time or distance to avoid contact once the sequence began.
No evidence of system malfunction
Analysis of high-rate performance data and onboard systems shows no abnormal system behavior or structural failure prior to the incident. Instead, findings concluded the collision stemmed from a rapid hydrodynamic loss-of-control sequence triggered by foil ventilation during high-speed foiling in gusty conditions.
“There is no evidence of a mechanical or software failure in the systems leading up to the incident,” Reid said. “What we see in the data is a very fast chain of aerodynamic and hydrodynamic events that pushed the boat beyond its controllable envelope at that moment.”
As part of its ongoing review process, SailGP engineers are assessing mitigations which could help crew better manage similar scenarios in future – with solutions being explored alongside SailGP athletes ahead of this weekend’s KPMG Australia Sail Grand Prix and further afield.
Ongoing review and learning
The collision occurred just 15 seconds after the start of Race 3, with New Zealand traveling approximately 48 knots (90 km/h) and France close behind at roughly 46.4 knots (86 km/h).
A penalty review hearing has since upheld the original decision that New Zealand broke Rule 14 (avoid contact), resulting in an eight event point penalty, while France was found to have had no reasonable opportunity to avoid the collision.
New Zealand and France teams to miss upcoming Sydney Sail Grand Prix
SailGP confirmed earlier that both the New Zealand and France teams will miss the upcoming KPMG Sydney Sail Grand Prix this weekend as repairs continue, with work underway to return both teams to racing as soon as possible.
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