Stanza 3 Summary

Get out the microscope, because we’re going through this poem line-by-line.

My Captain does not answer, his lips are pale and still;
My father does not feel my arm, he has no pulse nor will;

The dead captain, unsurprisingly, doesn’t respond to the sailor’s cries. With another synecdoche, the speaker focuses on the captain’s lips to represent his general state of death.
Again, the captain is referred to as the speaker’s father, underscoring their bond.
Sadly, the color has left the captain’s face and he has no pulse. Here, “will” means the ability to do something, like move.

The ship is anchor’d safe and sound, its voyage closed and done;
From fearful trip, the victor ship, comes in with object won;

The ship finally arrives safely in the harbor and drops its anchor. Its trip is done.
The speaker reminds us that the trip was difficult and dangerous, but the mission was a success.
“Victor ship” here means the victorious ship, not a ship named Victor.
Why is it victorious? Well, it’s won its object, met its goal. Hurray!

Exult, O shores, and ring, O bells!
But I, with mournful tread,
Walk the deck my Captain lies,
Fallen cold and dead.

And now that the speaker is in the harbor, he calls out to the shores and the bells to party down. Since neither shores nor bells are actually alive, this appeal to inanimate objects represents more apostrophes by our speaker.
Why would just the speaker just be interested in the shores, though? Even though, on a boat, the shore would be the closest part of land, here the speaker means for the whole country to celebrate.
Using a part of the land to represent the whole is again (you guessed it) synecdoche.
Really, though, the speaker uses the shores as a symbol to represent the crowds of people standing there. He wants them to keep cheering and celebrating the homecoming of the ship and the success of the mission.
While the crowd celebrates, the sailor remains on the ship, pacing sadly next to his dead captain.