What do I do with the halyard?

Hint 1 of 15:

First you have to get it.  See "How do I get the halyard?"

Hint 2 of 15:

Try pulling on it.

Hint 3 of 15:

You hear a noise from behind the back wall.

Hint 4 of 15:

What's back there?

Hint 5 of 15:

The porthole is there, but it's still closed.