Apparently, sail boats---the big ones that cost a lot of money---can be stolen. Some one sneaks into a marina in the dead of night sails it away. This is what Ingram, an experienced sailor, is accused of doing when police arrest him at the beginning of Aground by Charles Williams.
Ingram comes up with an alibi and is promptly hired by the owner of the stolen boat to help her find it. Not surprisingly for this genre, she is young and beautiful. Eventually, they find the boat has run aground, as the title suggests.
So we have two people failing in love on a sailboat, miles from shore, unable to move, and there is a dangerous man aboard. Williams generates considerable suspense from this seemingly impossible situation just as effectively as in another of his nautical thrillers, Dead Calm.
Of the two, I like this one better. The principal couple are more dynamic, the villain who makes their lives miserable is easier to understand, and the structure and pacing are flawless.
Also as in Dead Calm, Williams use correct nautical terms to describe Ingram's ingenious and heroic efforts to float the boat off a sand bar. I understand few of those terms, but that didn't stop me from following the action.