I used to play game where one of the "features" that I really liked was that it didn't matter if you had been playing for 10 years or 6 months. A pvp game where if you got killed most probably would have lost all your gear because another player had looted you.
So you could literally spend 2 months being succesfull in aquiring really hardcore set of gear only to loose it in 30 seconds. Sounds horrible?, maybe.. but on the otherhand you could be on for 30 seconds and aquire gear that someone spent alot of time to get.
So kind of works both ways, and people got hooked.
In naval action, it's almost the same, you can spend millions of dubloons on a single ship with upgrades and such and loose it in 10 mins if your unlucky. I like that!.
Easy come easy go.
However.. books.. books can take along time to aquire and you never loose the knowledge, that is giving people who the upper hand without ever loosing that upper hand.
You might argue that, players who have been around and played alot should have some sort of upper hand compared to new players,
Yes they should, and they already do.. skillwise.
Skill is the best upper hand you can have towards another, no need for more.
People need something to grind for?
Just add more stuff.. more really rare maybe even unique really good stuff that can give you the upper hand (but only temporary, til you loose it)... but things that also are lost with your ship.
Rare paintjob, rare flags!, rare mods!, maybe even hidden reinforcements that you can use once and then it's gone, giving you ai reinforcements during a battle. Totally unexpected.
Also unique drops (only 1 in the game at the same time drops) needs to be used within for example 24 hours or you loose it and becomes a potential drop for someone else.