What are the little wings on the rear of a battleship turret?

I recently got back into scale modelling and I find battleships fascinating, so I have finished a model of HMS PRince of Wales, and am mostly done Yamato.

Both ships have main gun turrets that have - and I don’t know what to call them because I don’t know what they are - these odd little wings on the back of each main turret. If you look at pictures of other battleships they do too; it’s not country-specific. They are plainly evident on drawings of Bismarck:

Oddly if you look at this photo of USS Wisconsin, it has the little wings on Turret 2 but not Turret 1:

France’s battleship Richelieu has them too though they’re small:

What are those things?

I can’t find a decent link offhand, but they constitute a range finder for local use in the event that central fire control breaks down.

And as for why the Wisconsin doesn’t have the rangefinder on Turret 1, Iowa class battleships initially had a different type, but that was later considered redundant with other methods on board. From here:

As built, all three turrets on the Iowa class had 25 power, 46 foot (14 m) rangefinders, with Stereoscopic Mark 52 used in Turrets II and III and Coincidence Mark 53 in Turret I. The Mark 52 weighs 10,500 lbs. (4,763 kg) and cost about $100,000 US during World War II. Near focus for the Mark 52 is 5,000 yards (4,570 m) and the maximum range is 45,000 yards (41,150 m). Mark 53 was a coincidence type with a special astigmatic lens which allowed it to range in on a single point source, such as a searchlight. In the 1950s, the Mark 53 rangefinder was removed from all four Iowa class battleships as weight compensation for growth in other areas. This rangefinder was selected as the increasing sophistication of fire control radar made its special capability redundant. The lower height of Turret I above the water also meant that this mounting had a shorter distance to the horizon capability. The openings in Turret I were then armor-plated over, as can be seen in the photographs below.

I just want to say I love The Dope.

They are the prisms for the optical range finder. Think of them as two periscopes but mounted sideways in the turret. You look through the rangefinder and you use an adjustment knob to adjust the images until they match. At that point, you had the range to your target. The further apart the two mirrors are, the finer your range calculation can be. Until the advent of radar, it was was the only way to figure out how far you were shooting.

Here’s the short version:

For a deeper dive, and if you have an hour, check out Drachinifel’s take on the topic: Range-finding and Fire Control - Plotting Your Demise - YouTube

Here is a view of the rangefinder on USS Iowa showing just how prominent they are.

As ODF said, they’re for local fire control in case the central one gets knocked out.

Obviously, I’ve been beaten to this answer by almost a day. But if you’d like to know a lot more about how those things work, there’s this hour-ish long narrated slideshow about their history:

That video was fascinating @scabpicker, thanks for that. I was in fire direction control for 155mm artillery and wondered how naval gunnery worked. I just watched the whole thing and it was all well explained. And I thought our gunnery solution was complex! It pales in comparison.

I remember reading how almost always the first thing destroyed/damaged if a battleship actually got into a surface fight was RADAR controlled fire, thus the optical local control was always implemented even in post-war battleship designs.

The German pocket battleship Scharnhorst had its radar destroyed by the first salvo it took in the Battle of the North Cape and was effectively crippled for the rest of the battle. HMS Duke of York had working radar and as a result could blast away accurately and hit Scharnhorst at least a dozen times, doing massive damage and leaving her open to being torpedoed by destroyers.

I would only add that Scharnhorst’s optical fire control was still working, but the battle occurred at night, so her accuracy was poor. Also, the German fire control radar wasn’t all that good. Had it been working, I doubt it would be much better than her optical systems. What really handicapped Scharnhorst was the damage to her search radar. This left her blind forward, so she blundered into close range with a British battleship.

Nitpicking: there are endless online arguments between ship dorks like me about whether the Scharnhorst class were battlecruisers or battleships, but only the much smaller Deutschland class were called pocket battleships.

You’re right, that was applied to the Deutschland class. My error.

Scharnhorst and Gneisenau were unlike any other ship ever built. They are their own thing. You can’t really call them battlecruisers - they’re sort of the opposite of battlecruisers. Battlecruisers, like Hood, or the Kongo class, sacrificed a bit of armor for speed (at least initially; after WWII they tried armoring them up.) Scharnhorst and Gneisenau sacrificed the size of their primary weapons. They were nearly as large and as heavily armored as the King George V class of battleships but their primary weapons were much smaller.

Most battlecruisers had less armor and firepower, compared to contemporary battleships, and cruiser-ish speed. This made their fighting power below that of battleships. The Scharnhorst class was no exception. Their armor was better than most battlecruisers, but their armament was well below that of any contemporary BB. So battlecruisers.

Hood, as built, had armor and armament comparable to the best battleships of her time. So she was a battleship. A fast one, but fully capable of being alongside a QE-class battleship in a 1920s battle line. You wouldn’t want to put HMS Tiger in that line.

When I was a kid I built a plastic model of the Scharnhorst. I always thought that was a cool name. Thanks for the info about it, good to know, ignorance fought.

At least when you’re firing your howitzer it isn’t moving.

In the Battle of Denmark Strait, Bismarck’s forward radar fire control was knocked out by the shock of her own guns firing.

Exactly — no speed, and also no roll and no pitch.

Man, you would have thought that’s the sort of thing QA would catch.

Eventually. As planned, and as originally they built her, she was underarmored - but Jutland, where British battlecruisers showed an unnerving propensity for exploding, suggested remodeling was in order. Even then though at most points her armor wasn’t as thick as battleships were - close, perhaps, in some areas, but not quite, and tellingly she had much thinner deck armor.

Granted, Hood, too, is kind of unique (and of course literally so, they never built any more in the class.)

I love battleships. They were such colossal testaments to waste and hubris.

With vacuum tube technology, the radar was always likely to vulnerable to blast damage.