There would have been a huge number of applicants for only a handful of positions, so a week is nothing to wait!
They will be looking for people who have the appropriate technical skills, qualifications and experience in electrical, electronic and hydraulic engineering. HNC, City & Guilds etc, but i would say you also do need to have experience using these skills.
Not people who can design things, people who can and have got their hands dirty and can repair and maintain the equipment. They are not looking for people who know how to fly ROVs – you cannot learn to fly and ROV until after you get the job, hence the look for technical qualifications and experience.