I'm not a sea player, but this is what I can offer from my own experience, maybe someone will find it useful.

The first boss will miss at around 650 dodge.

On the second boss I had 800 accuracy and around 1500 cannons and it was not enough to sink him in the designated time. I was hitting on hull, but some players with around the same stats and higher sailor damage can sink him by hitting on sailors. So it should be possible with higher sailor damage, not sure how high though.

LOL I hit the guy but someone already had told me don't use hull so I did sailors with around 650 blazing flame things and fire ammo I have plus old boxes of the good grape shot , was a small slice from a KO on him but time ran out -BTW - I have less than 650 dodge and maybe 700 acc ~ possible my welkin crap I wear at sea gives me more than normal chance as I use all buffs I can find , from old and new gear and pots~ . The fire crap was almost same as anything  else as it seems they figured we will try it and just gave it fire resist so high it is like spit balz , so that is why I started busting out refined boxes I carry for like 5 years.
 Going in I figured I last a minute at most , so I am certain most players with any investment in sea skillz and ships will be able to do this eventually . Luck in game really is needed now , because I hit for some CRITS , that was CRUCIAL or he will be at half life and not a sliver left of health .

 First boss ..then bye bye for me anyway and I am a gimp . BTW you lose cannon it seems , WTG IGG another IM sink .