America’s Cup hydraulic foiling system hits 3sec benchmark

The 2021 America’s Cup AC75 foiling monohull will use a high-performance hydraulic cant system to drop its foils in the water in as little as three seconds, the team defending the trophy series has revealed.

Emirates Team New Zealand has released a video showing how the AC75’s massive foils will drop into the waters around the Auckland-based race course to provide lift, and retract when not needed.

It uses a main valve block, which Emirates Team NZ project manager Peter Thomas said also doubled as a storage tank for hydraulic fluid in between movements. The storage system, which is pressurised on one side, can take oil from the main cylinders and prime it in the valve block within 15sec, ready for another tack or gybe.

The whole battery operated, electric motor-based system is controlled by a programmable computer.

“The motor and pump are not powerful enough to give us the pressure that we need,” Thomas said. “So we pre-charge the accumulator, and that allowed us to move the arm in the rapid movement in about 3sec.”

The 2021 America’s Cup contenders will drop a leeward foil in the water while working, and drop both the starboard and port foils for maximum stability, including potentially before a race starts.

Under the rules of engagement, the teams expected to vie for the America’s Cup will be able to build two boats to run their campaign.

The Cup campaign is already courting controversy among teams. Complaints so far include restrictions on the amount of signage that teams can use on their onshore hangars where the boats will be stored, and the amount of glass they the building use that will allow opposing teams to spy on each others’ boats – the requirement has been cut from 60 per cent in early planning to just 33 per cent for all teams bar Luna Rossa, which will only have a 30 per cent opportunity for “passive surveillance”.

Cup contender Ineos Team UK has already tested the foiling monohull in a scaled-down 28-foot boat (pictured, above), with early signs showing the design is stable at speed – something with which the previous Cup’s foiling catamarans struggled.