I think that your biggest problem is going to be that most people are completely at a loss for what to do when given 4-5 days with nothing to do but confined to a ship. Watching the water go by will be great for about twenty minutes! (g)
I would ensure that you have a decent library on board with a wide selection of books. Many find that reading at sea is both the ultimate sea passage pastime but also the ultimate reading time. Request them to bring books as well but know that they will run out of things to read if not supplemented by your library. I'd also pick some of the longer fiction and non-fiction for stocking; your basic 175 page novel is done in a few hours when at sea.
Also I'd bring at least a half dozen decks of cards, a cribbage board, a copy of Hoyle on card games, a chess/checker board and pieces, and maybe a board game. DVD's and the like are fine but I wouldn't take much more than a dozen or so. They are inadequate entertainment long term-the truly unimaginitive and bored passenger will watch all of them back to back in a day, and then where are you?
Another idea involves one pastime of older seamen. Bring either some manila, some small stuff, and/or some small cordage and a good book on decorative knot-tieing. Some may find squareknotting of interest and while away hours on it. Others may find that they just want to try a simple eye-splice. Have the materials around to pacify their interest.
And you should have a good extra supply of writing materials for them. You'll be amazed at how many times they'll need either a sheet of paper or a pen or pencil. You'll not want to put the navigator's supplies at risk in meeting their need.
You can also get them fishing. Even people who think they hate fishing, like me, love it when they catch something. And it entertains all on board when they do tie into something of size.
I hope this has been of some help.
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