Certification is the threshold, not the decision
By the time a candidate reaches an owner the tickets have been checked. Everyone still in the running can do the job on paper, so the certificate stops being a differentiator and something else decides it.
Discretion
The quality owners mention most, and the hardest to assess. Crew see a family at close range over long periods. Owners are choosing people who will not discuss what they see, on board or ashore, and whose social media does not become a liability.
Consistency
Not peak performance — reliability. A crew member who is very good most weeks and poor when tired is harder to manage than one who is consistently good. On a long season, consistency is worth more than brilliance.
Fit with the crew already on board
The most underrated factor. A yacht is a small closed environment for months at a time. Someone who is technically excellent but abrasive costs more than they contribute, because the people around them start looking elsewhere.
This is why an honest brief matters. If a previous hire failed, the reason is usually the most useful piece of information available.
Longevity, with a caveat
Owners value crew who stay, and short stints on a CV invite questions. But length of service is not automatically a positive signal: someone who stayed three years on a yacht that never left the dock has less experience than someone who did two demanding seasons.
The question is what happened during the time, not how long it was.
Presentation
Not a superficial concern in this context. Crew are visible to guests constantly, and standards of presentation are part of what an owner is paying for. It is assessed at interview, and it is one reason a photograph is standard on a yachting CV.