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We present a challenge on language leaks.

Our navigator was recently rereading a book on sailing-ship seamanship, a topic in which he maintains an interest even though his hands-on experience in that type of vessel is minimal.  This time he noticed (as pointed out by the author) that many nautical expressions have leaked into landlubber use.  This is in spite of the fact that most nautical sentences from the sailing-ship era are quite opaque to the modern English-speaker.  In fact he was able to draw up quite a list of leakers, and here we present his challenge.  Only one of the following phrases was not derived from a technical seagoing expression.  Which is it?

1. change tack
2. make headway
3. by and large
4. taken aback
5. chock-a-block
6. without a clue
7. give some leeway
8. overhaul
9. bear down
10. stand aloof

Answers next week.