Would opening command to engineers and Marines improve selection?

Would allowing engineers and Royal Marines to seek executive command give the Navy a useful extra pool of candidates?

Yes, but if captain vacancies stayed fixed, the wider and potentially stronger pool would also reduce existing executive officers' promotion chances.

A viewer suggests that engineers and Marines qualified for executive command would provide a useful pool of officers. Volunteers crossing branches would probably be highly motivated and could raise the quality of the candidates. The numerical example holds five captain vacancies constant while the eligible pool grows from ten commanders to eleven, reducing each officer's chance from five in ten to five in eleven. The model explains why a reform that benefited the service could still face rational opposition from executive officers near the promotion cutoff.