[n40487171]

I believe those use a hydraulic accumulator system rather than compressed air.

[KennyBlanken]

Guess what's on the other side of the membrane or piston in a hydraulic accumulator?

[n40487171]

I would guess that it would be a metal spring of some sort that doesn't lose energy to thermal side effects of compressing and decompressing gas, for a higher round trip power efficiency. Or else it could be a relatively large gas reservoir so that it doesn't heat or cool the gas too much.

[gotts]

I'm far from foiling boats would you mind explaining why are these compressors human powered and not gas/battery powered? Is it something from racing code?

[BrentOzar]

Racing code - America's Cup races prohibit stored energy aboard the boat, for example. Exceptions are made for certain springs, valves, and batteries for electronics.