Well, I'm a 132 level Corsair with 5.4k hp. My battleship got something like 58k. (I'm getting 4k per SP [Got 8 SP's atm] and 2k per level on it, so therefore: 12 [levels since 4th job] * 2 = 24k 4 * 8 = 34k 34 + 24 = 58k) I don't know if it will mess up my battleship, so I don't wanna take a risk. Annie \ David? xD
The more you wash, the more damage your ship will take when you are hit by 1/1 attacks (think Zakum, HT, Manon, Griffey, Papulatus, Pianus, Grandpa...) so overwashing is definitely bad, especially if/when Battleship cooldown is implemented. Personally, I'm not the most attentive person when grinding sometimes, so I have enough HP to tank Anego's gun (5400) in case I zone out and hit attack cap. 5400 is also enough HP to take on Horntail and Black Crow with HB, so it's the highest I personally recommend washing, if you really want to. A careful Corsair is a good Corsair; like David said, you've got enough HP without washing to do anything important so long as you're careful. If and when the time comes that Horntail becomes a thing, then you can consider washing the few points you might need extra to have enough HP for that. As it is, you shouldn't need to, it's only a comfort thing.
The server currently does not have a cooldown on Battleship, however GMS (and every official server) does have a cooldown for Battleship, and it will likely be implemented in the near future.
I believe that the 3rd job's skills have a higher priority than this, right? I maxed Battleship, should I max Rapid Fire now? thanks for the help ^^