Tourist - I feel your pain. I didn't know the Royal Navy had ready-use tins of worked-up ship and system specific personnel in sufficient numbers with the necessary ranks, SQs (Specialist Qualifications), expertise and liability for sea service available to be swapped around and take over its largest vessels mid-operation either. Apart from the odd bod from the ERP (Emergency Relief Pool) à la Topmast, it couldn't even do this in my time and I know even more billets are gapped these days.
The pool of offshore workers available 'on tap' is relatively inexhaustible by comparison. Subject to contract, they are 'hired and fired' as required.