I have seen something on vacuum anchors (but I can't think what it was for). I suspect CWE would use screw piles or some other sort of friction piles, once they're in they're in and it is unlikely they would ever need checking for movement. One of CWE's approaches is to use off the shelf products where possible. I think a 10 or 15m long screw pile would have the same same design in all sites in a job location, only the cut length would change. Whereas if a vacuum caisson (?) would have to be specifically moulded for each anchor location and not off the shelf. It would require very detailed bathymetry and then fairly hefty engineering too - I don't see that as feasible. thoughts?