Thanks for the info. The Wikipedia article mentions that “Pre-production photography took place in January 2018 at sea on board HMCS Montreal, a frigate of the Royal Canadian Navy”, which is a bit perplexing because the current vessel of that name (FFH 336) is a 1990s-vintage Halifax-class frigate whose exterior (and, presumably, its interior as well) is far too modern to convincingly represent a WWII warship. (The original HMCS Montreal (K319), a River-class frigate dating from 1943, would have been perfect for the role, but it was scrapped in 1947.)
Anyway, I’m hoping they’ll do a good job of adapting Forester’s novel. If you’re planning to see the film when it comes out, two movies along the same lines that you might want to watch between now and then are the American film Action in the North Atlantic (1943), with Humphrey Bogart, and the British film The Cruel Sea (1953), with Jack Hawkins. Both deal with convoy warfare, though they’re very different in style and tone. Action in the North Atlantic is a wartime morale-raiser that celebrates (deservedly so) the merchant mariners who kept the Allied oceanic supply lines open, and many of whom found themselves on the receiving end of U-boat torpedoes in the process. It’s not very realistic, either in terms of production values (it was shot mostly in a studio) or its depiction of naval warfare (for instance there’s a wolf-pack attack in which a ridiculously large number of freighters and of U-boats are sunk in the course of about five minutes), but it’s entertaining and dramatic and it has some nice contemplative character-focused moments. The Cruel Sea, based on a novel by Nicholas Monsarrat, almost comes across as a documentary in its tone and realism: it’s gritty and sober and at times downright grim, and much of it was shot on two real WWII-era warships (a corvette and a frigate).