It is clear that the protagonist has experience sailing, but I would like the opinion of any seasoned sailors here who've seen this film: was this man a good sailor?
Do you know how to navigate old school (sextant, stars, etc.)?
Do you always wear a life vest and have emergency provisions at the ready?
Etc...
I am a professional mariner, and have extensive knowledge of celestial navigation, including the use od a sextant.
The biggest mistake in this movie, and a common misconception, with regards to the sextant is that you obtain a position fix from one observation. In reality, you only obtain a so-called "line of position" i.e. a line on which any point could be your location. To obtain a fix you need at least two simultaneous observations or at least one previous observation in combination with your new observation. In order to use a previous observation though you would need a precise speed log (or a very qualified guess of your speed), so for our hero in this movie, the only option would be two simultaneous observations. At broad daylight that can be done by observing the sun and the moon (if visible), but that is no easy job!
"Gentlemen, you can't fight in here! This is the War Room!"