It's time once again for our regular open thread. Talk about whatever you want, so long as it isn't culture war.
Reminder that we're doing a virtual meetup in the discord (link in the sidebar) tomorrow at 1 PM Central (GMT-6).
Overhauls are Rangefinding, The Newport Conference and the US Dreadnought, Signalling Part 1, Coastal Defenses Part 8, and for 2022, Coastal Defenses Part 9 and my review of Jeremiah O'Brien and Pampanito.
Comments
When did a state-of-the-art battleship become entirely immune to the fire of elderly coastal guns? That is, if you fire an old black-powder gun, presumably the (relatively) low-powered roundshot just bounces off the armour of, e.g., HMS Dreadnought. But what if you hit the superstructure, or something outside the armoured box? Is it possible to achieve a mission kill with a sufficiently golden BB? And what if we use somewhat older ships - is Warrior likewise immune, to go to the other extreme? What about destroyers or cruisers, presumably much less armoured than capital ships?
It's going to be very hard to get a mission kill with a single golden BB. Battleships are designed to make it so you can't really do that. But it depends on how elderly and how immune. If we're talking, say, a 32 pdr, then even leaving range aside, there's not much one could do to Iowa. If you managed enough hits, you could theoretically take out the directors and all the optics, but that's extremely unlikely. But frankly you were at that point for practical purposes by the 1880s or so, even leaving aside the issues of range and fire control. And if we're talking anything bigger, then it's definitely going to able to take out unarmored stuff like directors. Probably the best example of superstructure damage is South Dakota at Guadalcanal, where she suffered quite badly despite not seeing any armor penetrated.
The early ironclads that actually faced such coastal guns seem to have been successful enough that planning to use them for coastal attack was considered reasonable. (Until the defences improved.)
Though winning isn't the same thing as immunity - 1940s destroyers are probably not immune to 32pdrs if they get hit, but still trivially win by having enough range/accuracy to not get hit.
Rough estimates suggest that 32pdr roundshot penetrates ~3" of iron or ~2" of steel at very close range, and half that at ~1km range. Which suggests that even an early ironclad's or a cruiser's main armor may well be enough (for what it covers), and that if you're close enough to penetrate an Iowa's director (1.5"), you're close enough that this won't save you because she doesn't need it at that range. (And possibly prefers to use local control at such short range. Director-based systems had a minimum accurate range, 1500 yards for the Mk37, because the parallax/dip corrections overflow.)
This scales roughly linearly with the caliber (not the weight), so the 1860s giant smoothbores would probably penetrate a contemporary ironclad but not the main belt of a steel battleship.
Right, but I was thinking of such use cases as forcing the Dardanelles, or a Norwegian fiord, where you can't use your standoff range and have to come to close quarters. I'm trying to figure out when warships become unsinkable (not the same as invulnerable, since there's presumably some amount of superstructure damage that puts them out of action) to black-powder muzzle loaders. After that, there's also a question of which generations of armour provide such invulnerability to which of guns. Does cutting-edge 1880s armour protect against an 1870s rifled gun using smokeless powder and presumably not roundshot? And so on for other pairs of decades.
I'm not sure if close-range immunity was ever reached against the first (c.1890) long (= high-velocity, enabled by slower-burning (but still black-ish) powder and breech-loading) heavy guns. My usual estimate says the 13.5" at close range can pierce a treaty ship and the 16.25" maybe even a Yamato, but that doesn't allow for those being uncapped shells, which are likely to shatter on impact.
Note that a narrow channel by itself doesn't force a short-range engagement, as the ship can try to destroy the fort from long range before approaching. However, a fort is effectively a smaller target (it can't sink and can deeply bury its magazines etc, leaving only the guns and observation positions exposed) and can have better accuracy than a ship (from not having to deal with roll and pitch). Hence, a ship attempting this from very long range may not have enough ammunition to fully disable the fort, while a ship attempting it from a range the fort can fire at (but can't penetrate the ship's main armor) may take many hits outside the armor, including a serious risk of hits to small vulnerable spots such as directors.
It's also theoretically possible to force a short-range engagement with a fort in a steep-sided non-straight channel, or a well-hidden (possibly mobile) gun, but opportunities for those might be rare.
The fort can also use mines or torpedoes, though later battleships did try to protect against those.
Apropros of current events, would the Ottawa treaty and CCM have been better off as no-first-use treaties?
Yeah, maybe structuring the CCM treaty that way makes sense, but then you're sacrificing a lot of the moral high ground and have to either keep spending money on cluster munitions or not have them even if the treaty says you're allowed to use them now.
The Ottowa Treaty was stupid from day 1. Land mines used properly are pretty safe and entirely deescalatory.
Not in general, but in the particular fiord I have in mind because I lived next to it as a child, you can make a fairly large mountain mask the batteries, and force hostile ships to come around the bend before they can engage. The steep-sided mountain would block even very high-angle fire, I believe.
I should maybe have specified that that's maybe never reached by surface ships. Submarines operating reasonably deep are immune to kinetic impact projectiles (even the 18" diving shell was only effective for ~50-100m after it entered the water, and that's measured along its trajectory not vertically), and while they are theoretically not immune to blast, even a battleship HC shell has less explosive than a real depth charge. They were sometimes used to run past forts, but this risked running aground or hitting mines or nets.