What you witnessed on board the ship was a principle of Canadian Forces integration. There are certain occupations, such as those in the medical or logistics fields, that actually serve a common purpose throughout the Canadian Forces, regardless of the colour of the uniform. They can serve in any number of units in any organization, whether it's in the army, the navy, or the air force. We call them common support trades or common support occupations.
That's what you witnessed on board the ship. It wasn't a matter of sharing. Those individuals were actually trained in that particular occupation and could be posted anywhere.