Buy a map.
“The distance from Portsmouth to the Normandy beaches is approximately 90 miles.”
https://travelasker.com/how-far-is-it-from-portsmouth-to-the-normandy-beaches/#google_vignette
Have you ever posted something without being a jerk? You always have to add that snark.
And 40 miles in open, shallow seas is not a little off.