Just found a set of Murphy’s Laws in Colvin’s (1972) Coastwise and Offshore Cruising Wrinkles, a very entertaining book on cruising design. There are six in total:

MURPHY’S LAWS RELATING TO THE BEHAVIOR OF INANIMATE OBJECTS

• If anything can go wrong, it will go wrong.
• When left to themselves, things always go from bad to worse.
• If there is a possibility of several things going wrong, the one that will go wrong is the one that will do the most damage.
• Nature always sides with the Hidden Flaw.
• Mother Nature is a Bitch.
• If everything seems to be going well, you have obviously overlooked something.

From Thomas Colvin 1972. Coastwise and Offshore Cruising Wrinkles.