Maritime superstitions

I've just finished watching Sky Ones new drama series Treasure Island, (I recorded it over the Christmas break on V+). I mention it as it was quite good and I recommend you all see it, (even if the ending is completely different to the book and nowhere near as good), but it's also the inspiration for todays post.
As you can imagine there was quite a lot of ships, sailing and sailors involved in the story and one of the sailors happened to mention some maritime superstitions he held.
It gave me the idea for todays post; I thought it might be fun if I put together a top ten list of some of the stranger maritime superstitions/customs that sailors/crew/passengers have held over the years.