These positions are more like optional positions, as a ship can easily survive with out them, or another member of the crew can have abilities that branch into this area, rendering the crew with no need for the official position. Few pirates are willing to be compared to the Marines by sailing metal ships. But a pirate ship can still be made of metal, it's just a bit rare. Generally, only marine ships are made of metal. Adam Wood is insanely rare and impossibly expensive. The type of the ship needs to suit the crew. When a ship is cared for, loved dearly, and treated like a nakama, it can develop it's own sense of self. The ship is just as much a member of the crew as the people on board, as evidenced with the Going Merry. Originally, Usopp unofficially filled this position by fixing the Going Merry with his carpentry skills, but the position was officially taken up by Franky later in the story. The Shipwright fixes and maintains the ship. Usopp fills this position on the Straw Hats as the ship's sniper. He or she must be an expert marksman and usually wields a gun or some type of projectile-based weapon. The Gunner mans and maintains the cannons. Tony Tony Chopper is the Doctor of the Straw Hats. The Doctor treats everyone's injuries and handles the sick. The Cook prepares the crew's meals and makes sure the kitchen is stocked. The Navigator charts the ships path and keeps it on course. Despite never being stated as such in the story, Roronoa Zoro is unofficially thought of as the First Mate of the Straw Hats. He or she usually oversees the work of the other crew members, and answers only to the Captain. The First Mate is the second-in-command of the pirate crew. This position in the Straw Hats is filled by Monkey D. In the world of One Piece, he or she is usually the strongest member of the crew. The Captain commands the entire crew as its leader. Almost all of them are filled by characters of the Straw Hat crew. I think that if ever Luffy’s ambition came in the way of Zoro’s than Zoro would leave the crew.These positions are almost essential to have on a pirate ship. The distinction is subtly made clear as well – for instance Luffy likes food vs Zoro likes booze, or Luffy’s playful energy vs Zoro who is always either sleeping or training. The reason I think it’s possible is because Luffy and Zoro are the only two strong personalities in the Strawhat crew – everyone else’s personality is too tied up with their identity as a Strawhat pirate under captain Luffy especially because Luffy offered most of them an escape from painful circumstances (Zoro, Sanji, Usopp, and Franky are the exceptions to this, but Franky will never leave because it’s his ship and Sanji is too busy with the ladies who are indebted to Luffy big time, Usopp already left once, so that just leaves Zoro). It (Zoro leaving the crew) could happen but probably not in the way you have imagined. *Theory by Vandenreich Luffy luffy vs bellamy luffy vs usopp luffy vs zoro nakama One Piece Theory roronoa zoro will leave the straw hat crew sanji zou In the meantime, Luffy’s experience with Zoro will cause him to become more serious and when Kaidou is beaten, both will have a heartfelt reunion and apology. Not saying Zoro will beat Kaidou, but Zoro will save Wano from his forces and will become Wano’s gratest hero. In Japan, the only crrature that can stand equally with the dragon is the tiger. Kaidou is a dragon zoan and Zoro is represented by the tiger. In the meantime, Zoro will decide to go after Kaidou by himself. Zoro will become a SHs again of course but that won’t be until after Kaidou is beaten. No matter how close you are to someone, there are some things you should NEVER do or say. The closer you are to someone, the more likely you are to hurt them. Zoro is the SH who is closest to Luffy and that is exactly why he left.
Tired of Luffy’s carelessness, Zoro will leave the crew and of course, everyone else will be devastated. What Luffy just said is unforgivable and he just destroyed some of his own repsect and dignity. For me, I think Luffy may spit on Zoro’s dignity and pride by saying something like “What have you sacrificed!? What have you lost!!” Zoro sacrificed his pride, self respect and dignity but bowing his head and begging his greatest enemy for power all for Luffy’s sake. As things get heated up, Luffy may say something unforgivable. In Zou, Luffy may get sentimental at Ace’s grave and Zoro may something that Luffy misinterpts as insensitive and gets pissed off. What can we conclude with everything I’ve said so far? That not only is Luffy naive and careless, when emotional, he says anything and everything and is prone to getting violent. His seemingly uncaring nature makes him come off as insensitive or harsh. Of course its not like Zoro’s any better with emotion. The reason I bring up Luffy’s naivety and carelessness is because that might be brought up in their dispute.