if you have other ways of leveling your gunners faster, sure, having gunners 10 levels higher would make the grind easier.

but if this is your first BB line, I'd say you are fine where you are.  Having near ship-level gunners is a good way to learn careful BB play. 

Just remember that when your BO gets to lvl 89 and get the Iowa, your gunners would need to be at lvl 91 to use the proper guns. 

Thx for the info am going to use this event to lvl up my Gunners at +10 from my BO.

Ive been USN befor but back on the old NY server so i kinda know what i'm doing just come back to NF after 4 years away its all new again :(

The old NY server got merged into Bismarck server, which was later merged into Kaiser server. So you should still have your stuff from back then.

It doesn't really matter how far your gunners are ahead of your BO. Normally you should concentrate on your supports. If you have only 1 BO and 1 set of gunners, then they will get a few million XP ahead of the supports in the process. That helps for accuracy and reload. But don't get tempted and switch to higher tiers before your supports are leveled high enough.