I got the boat before I got him. Also, when I encountered Elbow he had the "negate all damage divisible by 3" but when I won the fight and recruited him, that perk did not come with him. I think that might be by design, though?
Elbow is an enemy Navi, they have the negate all damage divisible by 3 ability. However, when they join your team, it becomes a "good" Navi, which has the ability to give extra directions when navigating. Another example is Cap, enemy Pirate, who has a chance to intimidate you. However, your good Pirate grants you free deals from pirates. These and a few others(like Dandy, Mate, Boy) crew members' ability changes when they change sides.