That's the great thing about being the captain. A boat is not a democracy. The captain is king. He can search his crew, which might upset them, but ultimately if they are cleared, they still have a job if they want it.
The clients, will be happy that their money was found. And when it's found, they'll be happy that the captain found it. Sure, they'll be pissed at getting searched, but they'll blame the culprit for that. And you'll have the culprit in hand.
Of course this doesn't work in normal society, but a boat at sea isn't "normal society". I'm guessing only ONE person would strenuously object to the search, and that's where I'd start the search.
The clients, will be happy that their money was found. And when it's found, they'll be happy that the captain found it. Sure, they'll be pissed at getting searched, but they'll blame the culprit for that. And you'll have the culprit in hand.
Of course this doesn't work in normal society, but a boat at sea isn't "normal society". I'm guessing only ONE person would strenuously object to the search, and that's where I'd start the search.