Interesting, I did not realize the nautical context of some of these phrases :)

Could you explain 'letting the cat out of the bag' in this context? I'm asking because I've read a different legend: Apparently on markets a few centuries ago, young pigs were frequently sold in bags. Sometimes people tried to sell captured cats as farrows in the hope the buyer would not open the bags before the deal was made and the seller far enough away. IIRC they chose cats because they sounded similar to farrows. Lacking farrows I cannot confirm that :)