-Low Chance (less than 10% and perhaps less than 5% - aka once every 20 battles) to lower a level of the enemy ship (even sinking it) with permanent effects (effect remains after battle, ships will be able to level up again normally after this)
I do not think this is a good idea - It can make Ship Raids near impossible without, draining the target which is a lot harder to do in active guilds.
10 Ambush = 20 Attacks. And lets say, the tail is unsinkable and has a Low Chance ability. It will kill off sinking the tail to quickly disperse the targets remaining purse. Again - Will not stop Ship Raids, but will make them 50% harder if not more.
Unless I have a wrong end of the stick here or perhaps if a Ship has Immunity to Call Levs, it can not have this feature (And vice verser) or... the whole idea be scrapped/remodel (Lowering the every X battles to 5, for example)
Admittadly chances of the person gaining these 2 attributes, are as possible as me growing a pair of tits overnight. Chances are it won't happen... But I can see people running fleets with Sloops that can not be sunk through Call Levs or PvP battles. Hell, I can see myself doing it! Three Frigates which are immune to Call Levs, and Sloop Tails which can not be sunk nor sunk via cast upon! Or a 4 Ship of the Line fleet, all with the immunity to Call Levs + The Sloop Tail sharing 2 Ship Traits Immunity + Low Chance! Which would lead to pirate activity, go on a downtrend and make it much less profitable - For one to even consider, going to the merchant side?...
All other Ship Traits I am fine with; I said so myself its far to easy to sink a 60 attribute Ship of the Line and my victims, are aware of such