Shipbucket

I have never read Friedman's book on RN Destroyers. Does
anyone know why the Royal Navy did not have enclosed turrets
(and enclosed bridges) on their destroyers until 1942-43? The
Japanese started this trend in 1928 with the Fubuki class, and
the USN followed suit by 1936. Given the RN's far-flung areas
of operations (North Sea, North Atlantic, Pacific, etc.) it seems
odd to expose gun crews and bridge personnel to the elements
- and to possible fragments from enemy fire.
Having said that, the RN destroyers from the Tribal class on
are very good looking ships, and this illustration of the JKN class
is wonderful.

re the open bridges, IIRC most navies kept at least open lookout positions until even postwar. the pilothouse was enclosed on the destroyers, so the actual steering happened below.

the open gun mounts were IIRC because of the larger weight of closed mountings.

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Drawings are credited with J.Scholtens
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Enclosed bridges: these were introduced for cruisers in the early 1930s but during the war the roof was removed as being able to see what was happening in an air attack outweighed the extra protection from bullets and splinters. So far as destroyers were concerned, the A to I group lasted as a standard design almost until the outbreak of war. IIRC a roofed bridge was advocated (by Mountbatten) and perhaps installed in some ships, but even more with destroyers, being able to see aircraft and manoeuvre to meet the threats outweighed protection.

Enclosed mounts: Again A to I standard kept the open single 4.7in in use until the J class, and single mounts were reintroduced (4", 4.7", 4.5") for the war standard O to C classes, for gun production and availability reasons. The J,K,N had open-backed twins. The L, M had enclosed weatherproof mounts. The Battles had proper DP twin 4.5in turrets.
Here the reason was weight, but weight resulted from turret design. It's not just that the mountings were heavier. A heavier mount results in a larger ship, especially if the number of guns is increased, so that top weight is increased. The open singles, and the J-type twins were central pivot mounts. They had no mechanism below deck, and the shield was kept light for rapid training. The twins did have power training, but might not have had if the weight had not increased markedly during design (aided by the motors to turn them of course.) It was initially hoped to put three twin mounts on a destroyer under 1500tons (treaty limit) but the Js came out at 1670tons, Ls 1920tons, Battles 2300tons with only two turrets but extra light AA.
Ammunition was fed to ready use racks behind the open shields (which had to be open for that reason also.) The enclosed mounts on L,M class were so partly to be weatherproof, and partly because of the elevation increased to 55 degrees. Being enclosed, ammunition had to be fed inside the shield, but there was still no rotating shell feed mechanism below deck so that shells had to be fed in the centre of the mount, which accounted for the wide spacing of the guns and so a large shield. The Battle class had proper turrets (derived from those fitted to battleships and carriers, but feeding shell and charge separately). The ammunition feeds below deck rotated with the turret above deck. This was a much heavier mount than the 4.7" open twin.
[Single 4.7" 9 to 11 tons approx, depending on Mark and elevation. Single 4.5" 11tons; with remote power control 15tons
Twin 4.7", J 25tons; L,M rotating weight 38tons, 58tons including turret base and below-deck hoists; Battle 4.5" twin turret 46tons.]

Very nice work

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