Some of the ships, like 3 set BB's, and CVs in general, would benefit quite a lot from allowing friends to control the same vessle.

Imagine having it so the owner operates and controls the main guns, but passengers would control other aspects, like S-Guns, Depth Charges, and torpedoes. Carriers would benefit even more so from multiple players, each one being able to micromanage a few squadrons to split the overall workload.

Obviously you would want to do this with people you trust, and plan ahead of time who will be controlling what.

On a different game we've done a similar thing, and it worked out fantastically. This would provide a unique draw to the game, being able to fight at sea with you and your friends, something that I've not seen done... ever, except on Warbirds, but that game kinda sucked and cost subscription.