Level cap on cannons and sailing?

[searage]

I've gotten both of these to level 6, but now no matter how many more ships I sink, the reputation bars won't move. It says I'm still getting reputation points, but it's not getting any higher.

Anyone else seen this? Is there a level cap? My cutlass is at 6 and still climbing...

Finally, has anyone been able to shoot any cannon shot besides the normal cannon balls and grappling hook?