Why the First Sea Lord could not command the board like a fleet

Could a First Sea Lord act as an authoritarian leader?

Only to a limited degree. Other board members had independent duties and political leverage, so effective First Sea Lords had to manage relationships and persuade rather than simply issue orders.

The First Sea Lord was the senior service officer, but the other Sea Lords held defined responsibilities and could resign in protest, turning personal conflict into a political crisis. Fisher could exercise unusual influence through political skill, yet even he had to persuade colleagues. The board's earlier ability to force the Duke of Clarence, the future William IV, out of the Lord High Admiral's office demonstrated the strength of collective authority. The transition from absolute command at sea to collective Admiralty governance made authoritarian habits, exemplified by St Vincent, especially hazardous.