Pig Dipper 6-30 is the last level in Pig Dipper.The objective of level 6-30 is to use the birds to defeat the boss. Get at least 42,000 points for 3 stars.
Like most boss levels, timing is the essential key.
3-stars score is fairly low, so it's easy for three stars.
Wait for the ship to near the top, then fire the Red Bird up into the bottom anchor, so as to push it into the gravitational field and on to the ship causing damage. Now fling the Black Bird up and around so he cuts the ropes holding up the boulders. Timing is key, as you want the bomb bird and the boulders to land on the ship. This should be enough to cause it to sink.