Keep in mind that the concept of 'gentleman' in this quote isn't just the courtesy like we use it today. Rather, it's actually talking about the social class of people who probably would have had land and possibly a title. The Royal Navy, due to the very technical nature of running a ship, frowned on the concept of the scion of nobility coming in and purchasing his commission. Rather, they wanted people who actually knew how to sail to become officers. Because of this more meritocratic approach, the gentlemanly aspects of commission that existed in the Army didn't exist in the Navy, and Naval officers were often not, in the strict definition, gentlemen. But they were still important and special to the Empire.

Source: BBC Making History