On page 25 of the SoB book, the rules for rope are given as to how far you travel and what happens of you don't make it across to your intended target (ie: a ship).

Could a player use a rope to swing across open water, not to land on a ship, but to cross the gap of deep water to get closer to the shoreline of the island levels?

Um, good question. I guess that would depend on "how" they are swinging. Between boats, aren't they throwing a rope to the other boat and swinging that way? Course, here I am trying to apply logic to Descent

-shnar

I'd say yes. the line about them being used to swing to other ships doesn't seem to be intended as an all-inclusive statement. Also, it avoids the issue of being able to swing towards a ship that's way too far for you to reach, but not towards an empty space that's way too far.

Of course you can, that's what they're for. We've had four ship battles and in none of them were the ships close enough for a single rope swing. But it's faster than swimming (usually). You may also use them on the island assaults. Again, faster than swimming.

Also, logic-wise, no you don't throw ropes to the other ship. Well, you do, but they're grappling hooks to tether the boats together. You swing on ropes that are attached to your own mast. That's why it just kinda goes out into the water and you drop.