[Basil Dreadflint]

One of my fully mastered pirates has the BB ready to go, but I don't want to complete it for zero rep.

I have taken him out solo a total of 11 times. ( If I'm bored, it's something fun to do.) My rule has been, if he makes it past the last (fourth) bridge, with at least high red health, it's a win. Then I let the Goliath sink me, so that I don't finish the BB.

Out of 11 attempts, I have 'won' the BB 6 times. 5 times, I have sunk at the last bridge. Here is how I do it.

Board the Pearl. Staff at the ready, wither, wither, wither. Tonic when your health is low in the red. Wither, wither, wither. If health gets to the red again, quick switch to doll and life drain. Back to staff and wither until the Navy soldiers are gone.

Now, go to the aft starboard cannon, the captains gun, and load Fury. Take the wheel and start moving straight toward the bridges. Don't sail all the way to them. Stay back as far as possible to get the ships to come to you. When the cutscene is over and the ships are on their way in, go to the aft starboard cannon. Sink the rear ship first, then the front ship. The two ships on port side will not fire at you while you do this. Use Fury on the first ship, then switch to Thunder for the second.

Move to the port side DECK gun and use iron shot to sink the two ships there. Don't try to use the Captains gun here, it can't hit the front ship. They will not fire back, cause you are solo.
When the fourth ships sinks, reload Fury before you go back to the wheel.

Turn the ship to the left, hit take cover, count to three, hit open fire, then fire one broadside. Run to the rear star cannon and take out the LEFT bridge first. Then the RIGHT bridge. Save the center for last, it doesn't have cannons. When the first bridge is gone, reload Thunder.

Back to the wheel, wait til all your skills have recharged. Sail through the RIGHT side gap, turn hard left and repeat the above for the second bridge set. Take cover and open fire before going to the cannon. Left bridge first, then right. From bridge to bridge, alternate between Fury and Thunder. Try to keep at least a few of each for the Goliath. Usually, by now, I'm still pretty well in the green health wise.

Wait for everything to recharge, and repeat the entire thing on the third bridge set. Again, LEFT bridge first. If one of the bridges doesn't fire back at you, (Sometimes this happens) make sure to switch to iron shot, don't waste your high power shot on a bridge that isn't shooting back at you.

Now, the last bridge set is the hard one. After the third bridge, I am usually in the yellow health, hopefully high in the yellow. (Only once did I get past ALL the bridges and still be in the green.) For the last bridge set, I do the same thing as the previous ones, but I shoot the RIGHT hillside first. It seems to be the one that does the most damage, so destroy it first. Don't forget to use your take cover and open fire before going to the cannon.

If you get the last bridge down and don't sink, technically it's a win. If you have yellow or high red health, you can run in the front of Goliath and slug it out from a distance. If you have very low red health, come out of the river, turn hard right, use ramming speed and full sail, and run far out into the ocean, and you will out run the Goliath till they give up. Either way, you win. I don't do either of these, because I want my BB to still be there, so I let the Goliath sink me.

One caution, When you sink the four ships, if the wheel won't let you grab it, back away and try again. I have noticed that sometimes you don't get the green circle. If you don't get ahold of the wheel fast, just let the bridges sink you. You won't have a chance anyway. No sense wasting time.