The Ship Model Forum

Interesting puzzle!

I wonder if "Atlanta was launched with 3-bladed props but were changed to 4- bladed due to vibration" actually means Atlanta and Juneau had 3-blade screws but subsequent ships had 4-blade screws?

Because of the profile angle of the photos posted I can't be sure how many blades the screws had.

Changing screws would have been a much larger problem than just switching from the 3-blade screws designed for the ship to 4-blade screws that were designed for another vessel. New screws would have to be designed to match the propulsion plant and then fabricated. It would have required a shipyard period and significant delay in sending the vessels to the Pacific theater.

Does anyone have copies of the monthly War Diaries that were submitted to the Commander in Chief US Fleet? I got them from the National Archives for the USS Oklahoma City CL-91 and they are pretty detailed. These give a day-to-day account of the ship's activities, including yard periods. For example they record when the Oklahoma City lost the starboard anchor and 125 fathoms of chain. They might mention the vibration and screw changes (if it happened) on the Atlanta/Juneau.

The twisted shafts and shaft supports that were ripped out of the hull really show the force of the blast that blew off the stern.

Phil

_________________
A collision at sea will ruin your entire day. Aristotle

Phil,

War Diaries are a mix bag. Some have a lot of detail, many don't say much unless it directly relates to battle action. The most memorable War Diary I have encountered, was for USS STEVENS (DD479), particularly during her evaluation of the "Aircraft-Handling" function. It read like a journal, was easy to read, and gave a lot of details about aircraft handling launches and recovery evaluations warts and all. Likely the worst War Diary I looked at, was for USS SAN DIEGO (CL-53) in 1942. All they wrote was "In Port" or "At Sea" for days. Nothing on what Task Force/Group/Unit they were assigned to or where they were at. They violated every rule for War Diaries. However, when they were involved in a Battle, they simply inserted the ship's After Action Report.

Deck Logs many times will have more details on day-to-day activities. But, if one hopes to find when a ship was painted. Forget it. Painting was so routine that less than 1% of the time is it mentioned.

Along with many other ship modelers, I was very excited about the recent release of the Very Fire 1/350 USS ATLANTA. It is a kit we’ve all been desiring for quite some time.

However, I am faced with a conundrum. I wish to model an early war USS SAN JUAN, specifically how she appeared on 7 August 1942. I understand that the released ATLANTA shows her at the time of her sinking, which is near that date and she had not been extensively modified. But I also know that the ATLANTA/JUNEAU twins were different than the SAN DIEGO/SAN JUAN twins in some ways.

Also, some mention was made that Very Fire would be releasing a SAN DIEGO some time in the future. If they follow the usual pattern of other manufacturers, it would be a late war version of the ship. (The VEE Hobbies 1/700 USS SAN DIEGO, for example.)

My question for all the ATLANTA Class experts out there is this: what would have to be done to the Very Fire ATLANTA to make an early war SAN JUAN? Or, conversely, what would I have to do to a late war SAN DIEGO to make an early war SAN JUAN? Which mash-up would be easier?

There is a personal reason behind this inquiry. The USS SAN JUAN was one of three ships that gave fire support to my father’s unit, the 1st Marine Parachute Battalion, when they landed on Gavutu-Tanambogo on 7 August 1942 as part of the assault on Guadalcanal. I have 1/350 kits of the USS MONSSEN and the USS BUCHANAN, and I wanted to properly complete the trio.

Thanks in advance for your help.
Fred Sirois

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Fred Sirois
Tace et Exemplar Aedifica

Fred, I'm certainly NOT the Atlanta class expert that you're looking for. Nevertheless, here are some things I've found regarding San Diego/San Juan.

1) Glenn R. Arnold's Warships Perspectives Atlanta Class Cruisers in World War Two: "San Diego . . . was the first of the Atlantas to have her open bridge area over the main bridge designed as part of the ship during its building and the first to be built with the aft mounted 40mm AA gun tub . . . additional minor changes made to San Diego and all subsequent Atlantas was the installation of more splinter shielding, the installation of external ladders from the Bridge and Battle II, and changes in gun directors and radar that varied from ship to ship."

2) Timmy C's 30NOV2022 entry on the preceding p17 of this CASF.

3) Dick J's 07DEC2022 entry on SteelNavy.

4) Matt@krakenhobbies.com 10JAN2023. A few days ago I asked him about the San Diego mod that he's working on. ". . . the San Diego is not complete yet but is near done. Since Very Fire has claimed a follow up to the Atlanta will be a San Diego, I have dialed back scope of this conversion to include-
Modified Bridge wings
Pilot House Roof
Raised 20mm Tub and 20mm clipping room in front of the Bridge
Stern 40mm Quad tub
Additional 20mm platform around Funnel #2
Structure where the Boat Crane Machinery was removed
Searchlight Platform on #2Funnel
These are just the major changes I have noted . . . "

Please share your discoveries.

I don't have Arnold's book on the ATLANTA class, but some of his "stated/quoted" facts are wrong.

None of the first four ATLANTA's had 40-mm mounts installed as completed. At least USS ATLANTA and SAN DIEGO were initially completed without a quad 1.1-in mount on the fantail. The fantail mount was added during Post-Shakedown yard period. SAN JUAN had Mk 51 directors installed for her quad 1.1-in mounts at PHNY after her hang fire repairs in 51 mount, replacing the Mk 44 directors.



USS ATLANTA and USS JUNEAU were lost before any significant mods were made to them. USS SAN DIEGO and USS SAN JUAN had their quad 1.1-in mounts replaced with 40-mm mounts in 1943 overhauls. Dick already provided radar location differences.

Fred,

Here are a couple of images of SAN JUAN just before and after the Guadalcanal Invasion.

Repost of my response on the Steelnavy site:

The main structural difference between the first pair (Atlanta & Juneau) and the second pair (San Diego & San Juan) in late 1942 was the open bridge above the pilot house. The second pair had more extensive wind baffling. So the 1942 rig ship (Atlanta) would be your best starting point. The other major difference was radar. The first ship of each pair (Atlanta and San Diego) had an SC air search set of the foremast and no SG surface search set. Juneau and San Juan had their SC set moved to the mainmast to allow an SG to be mounted atop the foremast. The late war config of both San Diego and San Juan had a totally different open bridge above the pilothouse, and so that would have to be completely redone, along with redoing all of the AA, in order to back fit a late war San Diego into the '42 config.

It looks like Very Fire included the wrong 5"/38 mounts for their new Atlanta kit in 1/350 scale, a very easy mistake to make. The kit looks like Mk.32s were included. But photos of the real ship indicate that Atlanta and other early ships of the class were fit with mounts that had a gunhouse with the same shape as the Mk.28s fit to fast battleships.

Can anyone confirm or deny?

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Have fun, Monkey around.™

-Steve L.

Complete catalog: - https://www.model-monkey.com/
Follow Model Monkey® on Facebook: - https://www.facebook.com/modelmonkeybookandhobby

Confirm or deny the kit's parts or the real thing? If the kit's parts, Martin's review of the kit indicates they're the same 5" turrets as the ones provided in their Cleveland kit: http://www.modelwarships.com/reviews/sh ... tlanta.htm

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De quoi s'agit-il?

Both the kit and the real thing, actually. For many modelers, the difference will probably not be bothersome. But for others, aftermarket to the rescue.

In any case, the Very Fire kit appears to be very nicely done.

_________________
Have fun, Monkey around.™

-Steve L.

Complete catalog: - https://www.model-monkey.com/
Follow Model Monkey® on Facebook: - https://www.facebook.com/modelmonkeybookandhobby

I looked through the OP 805 (page 548) for the dual 5"/38 mount shields, and the mounts used on battleships (Iowas, etc.) had 2" thick shields. The battleship shields would be much too heavy (65,000 pounds for the shield only) for light cruisers.

The Mk 32 mounts on the Clevelands had the Mk 31 shield (31,400 pounds) with much thinner armor (3/4" and 1/2") and destroyers had something like 1/4" thick shields (14,500 pounds).

Note: shield Mark numbers are not the same as the gun mount Mark numbers. Each mount Mark number had an associate shield Mark number that was usually not the same as the mount Mark number.

Phil

_________________
A collision at sea will ruin your entire day. Aristotle

Regarding the Juneau sublcass (CLAA-119) did they had wood planking on the decks or was it full metal cover?

Yes, which is why the mounts on early Atlanta class ships may be Mk.28 Mod.1 mounts which had a shield thickness of 1.25 inches and were intended specifically for light cruisers according to the gun catalog. This is the mount David suggested and he may be right. Link: http://archive.hnsa.org/doc/guncat/cat-0250.htm

The shape of the mounts on the early Atlanta class cruisers does not match the shape of Mk.32 mount gunhouses. So with respect to the Very Fire kit, the shape of the mounts included with the Very Fire Atlanta kit does not match photos of the mounts on the actual ships.

Compare the photos below of the 5" mounts on Atlanta and San Diego with the mounts fit to Cleveland-class ship USS Biloxi. Pay particular attention to the height of the vertical glacis plate (frontal armor plate). The Atlanta-class gunhouses are noticeably differently shaped than those of the Cleveland-class ship. The Atlanta-class 5" mounts' vertical glacis is much taller than the vertical glacis of the Mk.32 mounts fit to the Clevelands. The tall Atlanta vertical glacis looks to be the same height we see on Mk.28 mounts fit to fast battleships. I am not suggesting that the Atlantas were fit with the same mount as fast battleships. I am saying that the shape is the same or nearly the same.

Very Fire included Cleveland-class Mk.32s with their Atlanta kit, probably the very same models included in their very nicely done Cleveland class kit. But photos indicate that the early Atlantas did not have Mk.32s installed. The early Atlanta class had something else. What that something else is, I do not know. The shape of the mounts fit to the early Atlantas most closely matches the shape of a Mk.28 mount. My guess is that the Atlanta-class 5 inch mount may be a Mk.28 Mod.1 mount, which had thinner shields and was therefore lighter than the fast battleship Mod 0 mounts. Whatever was actually fit to early Atlanta class ships, it is certainly not a Mk.32 like the Clevelands had.

As you pointed out, fast battleships were fit with Mk.28 Mod 0, which had a 2" thick shield. We are in complete agreement that the Mk.28 Mod 0 mount was likely far too heavy for an Atlanta class ship. But perhaps the lighter-weight, thinner-shield, Mk.28 Mod 1 mount is correct for early Atlanta-class ships. The Mod 1 shape matches photos of early Atlanta-class mounts, the gun catalog states that the Mod 1 mount was explicitly intended for light cruisers, and the Mod 1 mount is significantly lighter than the Mod 0 mount fit to fast battleships.

Having said all that, later Atlantas, more properly known as Oakland class ships, are different. The Oaklands do indeed have what looks like Mk.32s, same as Clevelands. Reports indicate that the early Atlantas were dangerously top heavy which would account for lighter weight Mk.32 mounts being installed on the follow-on Oaklands, which also had two fewer 5" mounts than early Atlantas.

If true, the Very Fire kit has an Atlanta-class hull and superstructure with Oakland/Cleveland-class 5" mounts. This is an error, and an easy error to make, because these different mounts are so similar. If the real ships were fit with Mk.28 mounts, this is an easy error to correct with aftermarket Mk.28 mounts.

Trumpeter made a similar error with their 1/200 scale Iowa class ships. Their Iowa class kits have Mk.32 mounts. The real Iowa class ships had Mk.28s. And the difference is noticeable.

_________________
Have fun, Monkey around.™

-Steve L.

Complete catalog: - https://www.model-monkey.com/
Follow Model Monkey® on Facebook: - https://www.facebook.com/modelmonkeybookandhobby

I agree with Steve. The mounts on the Atlanta look like the Mk 28, and certainly would have had the lighter shell.

Phil

_________________
A collision at sea will ruin your entire day. Aristotle

From USS JUNEAU's Wreck, her portside 5-in mount showing damage (I suspect from the battle). You can get an idea of the shell thickness.

Interesting observation on the turrets! So for CL51-54 you will need MK28 5/38's but for CL95-98 the included MK32's will work, good to know.
I am looking for some information on the the CL95 class, particularly the transition between the bridge wings down to the 20mm tub in front of the bridge. The Floating Dry Dock and Profile Morskie USS Oakland plans both show it unclear as if its open between them or not. Seems plausible if there was a short set of stairs linking them as it seems like a steep angle, but again I have no good images looking down into that area. On Navsource (https://www.navsource.org/archives/04/095/0409521.jpg) there is a very good shot of the Oakland showing me the area in question, but it was before the bridge wing and Venturi wrapped down and around the 20mm tub. This earlier image would say that they are not connected, however I am not sure of the reason to extend the splinter shield and wind baffles to connect them if there wasn't going to be any passage between the two. Navsource has an image dated 10/27/43(https://www.navsource.org/archives/04/095/0409513.jpg) with the 20mm enclosure circled and we see the modification has occurred, but it's from too low of an angle to see if they joined the two deck levels. Small snips of the Profile Morskie plans to help illustrate



Matt

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In the yards right now:
USS Utah AG-16
On Hold
1/350 USS Portland CA-33 1942
1/350 Trumpeter Texas with a twist

When Oakland first commissioned, the lower tub forward of the bridge was separate from the the bridge wings.
https://www.navsource.org/archives/04/095/0409521.jpg
But this was altered post shakedown, at which time the guns forward of the bridge were also raised slightly. Note that this was one of the alterations circled on the following photo.
https://www.navsource.org/archives/04/095/0409513.jpg
The three later sisters completed to the revised arrangement.

Over the weekend I began sizing up the hull and deck of the Veryfire kit. I
have the plan set drawn by Alan Raven which came bound into my Warship
Perspective book. The plan is 1/192 (1/16 in to 1 ft.)scale. I made some
calculations by measuring the plan, converting the dimensions to 1/350 by
multiplying by 0.55 (192/350=0.548)

I found the following dimensions to be as near correct as my technique could
determine:
-total main deck length
-main deck from bow to front of 1st barbette
-stern to rear of aft barbette
-between fore and aft barbettes
-beam as measured at:
-first barbette centerline
-across front of 2nd deckhouse (thru "tunnel" between stacks)
-centerline of wing barbettes
-centerline of aft barbette
So Far-So Good

Moving to the profile view:

-Bilge keels on kit are slightly too long- about 2mm at forward end and
about 4mm at after end. I admit that measuring the curving hull with a
steel rule is not too easy.
-Bow to forward end of armor belt is very close to correct.
- The Big Problem is the after end of the armor belt. The plan shows the
belt ending about 9 1/2 scale feet aft of the centerline of the wing
barbette. ON THE KIT the belt extends much further aft.

Measuring the plan from the stern at the waterline to the aft end of the
belt shows that the correct distance on the model should be 14.44 cm.
My actual measurement on the model is only 9.5 cm.

The model needs 4.94 cm. (1.9 in.) removed from the after end of the armor belt.
This is a big disappointment!

The question now becomes if the plan is correct or not. I have great
faith in Alan Raven, but I do not know the source of his information.

I began to look for photographic evidence. In the USS San Diego section of Navsource, the 29th photo, #0405332 shows the port quarter near the wing 5 in. mount. The armor belt doesn’t show because of the boot topping, but about 10 ft aft of the mount, water can be seen flowing from a discharge near the waterline. Since holes weren’t drilled thru armor for water discharges, I think this is proof that the belt does end where the plan shows it ending.

It looks like a lot of scraping is in store to correct this. The photos really show how smooth these hulls were. I’m going to sand almost everything off except the armor belt.

I tried to evaluate the “knuckle controversy” using the hull lines on the plan. They do not show it to be that prominent, and the best I could measure suggests it might be one mm too narrow on the kit, but no more than that. When I have finished sanding the hull, I will see what the rest of you think. I might lay a thin strip of styrene over it, but it doesn’t look that that much of an issue.

Thanks, John

Here are some images showing the extent of the armor belt. It only covered the machinery spaces, not even the magazine areas. The upper limit of the armor belt followed the sheer of the deck.






Here are images showing the knuckle, it should be quite noticeable. Also, this is a complex hull shape; it goes from a v-shape at the bow, works its way to a flat vertical sides for most of the machinery spaces, and becomes tumblehome towards the stern.

As Rick says, the armor belt follows the main deck, curving up at the fwd end The model is correct in this respect but the armor belt extends way too far aft.

On the underside of the Veryfire hull, I count 7 pair of round marks and 4 pair of oval marks. Does anyone have an idea of what openings were actually present? Do such openings correspond with USN DD design practices?
Thanks, John