USN DE War Mobilization Prototypes.

[cowboy40]

As the USN started to square off with the Soviet Navy, in the 1950’s, one of the biggest problems it faced was the lack of a “modern” Ocean Escort (DE), and a reluctant Congress willing to spend the money to replace the war built ships with new construction. In response to this, the USN, took a look at her fleet and made some decisions on what to do. The General Board asked the BuShips to tender plans for consideration. What BuShips produced showed that the ships could be kept modern, but with the two months estimated time to convert them was almost unpractical for a “War Emergency Mobilization”.

These ships would be known as the SCB63A design, and three ships would be taken in hand for the conversion. The three selected SCS63A vessels would be:

DE-152 USS Peterson (FMR type geared diesels) of the Edsall class
DE-535 USS Lewis (WGT type steam geared turbines) of the John C. Butler class
DE-644 USS Vammen (TE type turboelectric drive using generators powered by diesels) of the Buckley class.

These three types were selected because they had the full designed horsepower of 12,000 shp that produced the planned speed of 23.5 knots, but could actually reach 24 to 25 knots in a full on run.

Like most mobilization ships, these vessels were austere, compared to fleet units, and meant to be optimized for the ASW role. To do this, engineering, electronic systems and weapons suites were modified.

The engineering changes were all done to the external components, by the fitting of newly designed props on both shafts, and new larger rudders designed to help the ship turn tighter.

The electronics suite was modified by the fitting of the newly developed SQS-4 scanning active/passive unit that had a detection range of four nautical miles. More modern ESM (ECM and ECCM) were fitted and a new SPS-10 surface search radar was fitted (This radar was chosen over the wartime fits, because it could pick up a periscope of snorkel from a fair distance).

The main visual change to the ships came in the redesign of the ships bridges. They were rearranged to place the CIC/underwater battery plot room, sonar control room, and the pilot house on the same level. This shows how important ship control is during ASW operations. Everyone in close to each other. This of course cuts down on time it took to plot and attack the target.

The SCB63A’s weapons suite was truly built for ASW and sacrificed most other areas of the battle environment. This can be seen in the elimination of the close in AA battery (the 20mm and 40mm AA guns), but they did retain their 3 inch or 5 inch guns. These changes were made to free up weight and magazine space for the ship’s new ASW suite that was built around depth charges, hedgehogs, and torpedoes. The hedgehog armament was built around the mounting of two Mk.15 trainable mounts placed at Gun No. 2 level, displacing one of the original 3in/50’s. (In the John C. Butler type, these were placed on No. 2 position that was created by rebuilding the bridge.). Next the ships carried one hell of a depth charge armament. They carried six double K-guns and a single K-gun on each side of the hull. The K-guns were designed to fire either the Mk.6 or Mk.9 fast sinking depth charges. Each gun was served by three ready use, plus one on mount, depth charges. The ships also carried two 12 charge racks on the stern, and these racks were served by six charge reload racks. This armament gave them the ability to produce about 19 patterns. The major change in weapons, over the WW2 vessels would have been in the ASW torpedo armament. This would have consisted of two tubes, one firing to each side arc that allowed the ships to fire the Mk.35 active/passive homing (spiral search) 21 inch torpedo, with six of these weapons being ready for use. The ships also had two Mk.2 release over-the-side racks for the 19 inch Mk.32 active homing torpedo used for point defense with four ready rounds.

I think what was produced would have been one hell of rework of an old hull for use against the subs of the era. Again the problem is the war would most likely be over before the War Emergency Mobilization ships would leave the yards.

[cowboy40]

DE-152 USS Peterson, the FMR type (Edsall class):


USS Peterson during World War II service....


USS Peterson after SCB63a conversion, note the heavy depth charge battery.


USS Peterson near the end of her active career, note the reduction in the depth charge battery that reduced as the weapon started to loose favor in the USN.

USS Peterson would be retired from duty in 1965. A tired but proud ship.

[cowboy40]

The reasoning of having two Mk.15 hedgehog mounts and the engineering modifications were made to allow the ship to make two forward thrown attacks using what was called a Gitmo turn, a tight turn being made at 20+ knots. This was done because of the reload time it took to arm the 24 spigots of the hedgehog.

[cowboy40]

DE-644 USS Vammen of the TE type: Buckley class


USS Vammen during World War II


Vammen in 1957, notice the heavy depth charge battery


Vammen at the end of her career in 1968. She would be the only scb63a to be in service in the late 60's. Again note the reduction in depth charges, but by this time she was also armed with 21 inch Mk.37 Mod 3 active/passive homing torpedoes (These replaced the old Mk35 torpedoes in teh mid 60's). The 19 inch Mk.32 torpedoes and the Mk.2 drop racks were replaced with two 12.75 inch Mk.32 twin TT and six Mk44 or Mk46 LWT.

She proved that the War built DE's could still be viable as late as 1970. USS Vammen would be the last of the three SCB63A vessels in active service, being passed to the reserve fleet in 1969. She would linger there as pier side NRF training ship until she was destroyed as a target in 1974.

[cowboy40]

DE-535 USS Lewis of the WGT type: John C. Butler class


USS Lewis during World War II....


USS Lewis at the end of her career. Again with a reduction in depth charges, but look at her rebuilt bridge compared to World War II appearance.

USS Lewis would decommission in 1960, and be sunk as a target in 1966. Her engines and hull were just worn out....

[cowboy40]

The Navy did have a SCB-63A plan for the TEV Rudderow class ships, even though none were converted, because the engineering POC was proven on USS Vannem (TE) of the Buckley class and the ASW suite was being evaluated on the USS Lewis (WGT) of the John c. Butler class. It would have been spending valuable R&D and upkeep money on a redundant project.

[cowboy40]

When forced the USN proved it could make do with what it has...in this project!!!!

[cowboy40]

Another part of the DE mobilization program was the more heavily modified SCB-63 program. This would be a more thorough program to update the war built destroyer escorts.

As part of the program a WGT vessel, the USS Tweedy (DE-532) was selected for conversion. The plan called for improving habitability, weapons, sensors and external engineering components.

The same engineering modifications were made to the Tweedy. The improved props and the larger rudders. The sensor suite was pretty much the same, with the fitting of the SQS-4 sonar and the fitting of the SPS-10B radar. Like the 63A’s she retained her World War II air search radars, but she was fitted out to be reequipped with SPS-6C air search radar when and if founds became available.

The improvements in habitability included better living areas, a larger superstructure, and better a rearrangements of the galley. This installed the rearrangement and redesign of some the below decks compartments. Though the most visible difference was in the size of the superstructure and the redesigned bridge. This new structure contained a larger more capable CIC/underwater fire direction center with more semi-autonomous processing systems, then what could be put on a 63A. This cut down on the work load of both CIC staff and Sonar room staff, with even bigger boost in the time it took to plot, classify, and prosecute the attack. Like on the 63A the bridge, plot room, and sonar room were on the same deck level. The larger superstructure also made the habitability improvements possible.

Even though both the Tweedy and her 63A half-sisters all used the Mk.105 FCS/underwater battery fire direction system, the Tweedy used automated systems to cut down plotting and engagement time, much of this still had to be done by hand on the ships like Vannem.

This rebuild also allowed for a heavy ASW suite to be carried. On top of the new bridge structure she carried four Mk.11 hedgehogs. This allowed her to make two quick attacks firing 48 mortar rounds at the target in a single attack. This was double the firepower being delivered. Her depth charge armament was on par with the 63A ships, but she carried a heavier torpedo armament. She carried a total of four tubes that fired 21 inch Mk.35 active/passive homing torpedo, with 10 ready rounds. She also carried the Mk.2 racks with four 19 inch Mk.32 active homing torpedoes for point defense.

The yardwork for this design in wartime was an estimated 9 months, this was about half the time of new construction, but in no way could it be considered an “emergency mobilization” prototype, but the USN justified the design as being proof of concept for features planned for a future class of ocean escort. Many of her features would later be found on both the Dealey and Claude Jones classes.

The irony here is that USS Tweedy would probe to be a better ship then the Claude Jones and her sisters. The Claude Jones was abject failure as an escort vessel.

[cowboy40]

USS Tweedy DE-532 of the WGT type John C. Butler class


Tweedy after conversion. Note her her larger superstructure with the four Mk. 11 hedgehogs above her bridge, and her impressive depth battery.


Tweedy at the end of her career around 1969. Notice the lack of depth charges and what replaced them. Here you can see her new Mk.32 tubes for 12.75 inch torpedoes (Mk44 or Mk46) and the VDS (Variable Depth Sonar) gear of the SQS-10 type replacing the stern racks. Not seen is the fact that the old Mk.35 torpedoes were also replaced by Mk 37 mod 0 or mod 3 21 inch homing torpedoes fired from her fixed tubes.

As i said before it is to some irony that the war built ships of the SCB-63 and SCB-63A were actually better ships then the approved "war emergancy mobilization" production type of the Claude Jones class!!!
She was still capable up to the end.

[starcruiser]

Necessity is the mother of invention...

This is part of the reason using an existing hull for the FFG(X) makes more sense than creating a completely new design. I believe that competition is still not quite over and we still have about 3-4 designs that could end up being built but...nearly $1B each?!?

FFG(X) Program

My personal preference would be:

Alvaro de Bazan

It's not just a good looking ship - it's big enough to last a good while. It's got room for future improvements and it's already mostly using US gear (ECM/ECCM, Guns, Missiles, Engines...). It's around 6500 tons so, not exactly a small "Frigate" in the old Ocean Escort style.

The truth is, in a modern naval war, the old escorts probably wouldn't last long. They wouldn't survive a single Exocet hit (~1000 tons - at least they were mostly steel). The OHP class did survive ASM hits, on a couple of occasions and they were partly aluminum.

[cowboy40]

i look at these ships and i wonder what it would have been like being aboard a Whisky or Zulu class submarine being worked by these things. Those escorts were redesigned to use the attributes of a XXI hull against itself. The average speed of a type XXi hulled boat was around 22 knots. Those escorts could maintain 24 knots in the attack.

The Tape XXi could only maintain those high speeds in a straight run. This hull form has a nasty habit to want to heal over in a high speed turn about 11 knots. There are stories of some of the GUPPY and Tang type US boats of almost rolling over in a turn. Those damn escorts were designed to make a very tight turn at 20 knots. (A piece of irony is that the purpose built DEs of the late 50's and 60's couldn't make this Gitmo Turn).

to make matters worse when running at a good speed, your hull becomes noisy and those American ships had one of the best scanning passive mode sonars of the 50's and early 60's, and it was good enough to track you out to 4nm.

All that above is going to have to force you deep and slow, but here that sonar comes into real good use. It can go active and ping you.

Now to make matters worse that skipper has a choice for his attack. He can make a Hedgehog/depth charge attack, and harass you for quite awhile by dropping 19 patterns on you, because most likely the charges won't sink you, but the sure terror of having them rain down on you. I have talked to WW2 submariners and they have told me, the charges really get to you, By the time they are done you want to surface and surrender just to get your nerves back. Hedgehog may look crude as an ASW weapon, but it was effective. One US DE during Second World War ran up a Japanese picket line sinking six boats in 24 hours. The England proved the weapon works.

Or if he doesn't want to play with you he can just drop a Mk. 35 ASW torpedo on top of you. This damn thong goes active and will give chase to you once it hits the water. Your decoys will probably ward it off, but given its spiral search pattern it will most likely reacquire and chase your ass away, forcing you to make so much noise that the escort will get you on sonar again.

Now if you get close enough to make your counter-attack he has those last ditch defense Mk.32 ASW torpedoes. You might get him, but those torpedoes are likely to get you too.

Who says the submarine has its own way?

And even in the 60's the engagement would probably play out the same way, but with better torpedoes being dropped on you.....I don't think Tango, Romeo and Foxtrot could evade these ships. November with her speed could, and that is what made them obsolete; the Soviet's finally building enough nuclear boats, but even in 1970, there weren't that many of them to go around.

The SCB-63 types would still have a place in the fleet..if they were needed!

[starcruiser]

The Hedgehog was deadly, when used right. All it took was one solid hit poking a hole in your boat and down you go (or up, to surrender).

The only real issues with Hedgehogs and Depth Charges is the need to be right on top of a sub. Modern subs are MUCH more dangerous than the old WW2 era boats - quieter, faster and better equipped. They can dive deeper and take more punishment (depending on boat and depth).

Build a more modern ASW ship and give it the Mk.48 ADCAP torpedo, instead of the little 12.75" airdrop toys the helos use. And then maybe, just maybe, create a PROPER ASW missile system instead of the old ASROC/VL-ASROC systems still being used.

[cowboy40]

Comparatively given the time frame of the SCB-63 builds, and what they were facing in the late 50's and 60's, I don't think they come off badly. It was until the very late 60's that the Soviets finally got the Victor I to sea.

The suite that these ships were rebuilt around was very adequate in dealing with the majority of Soviet boats in that era. That suite was built around a heavy torpedo, the MK.35 (and later the Mk.37 Mod 0 and Mod 3) that was heavy enough to deal a killing blow to the Soviet subs. Also the proven method of Hedgehog and depth charges in what would be more of a physiological attack on the Soviet ships. All that said, yes by the time the Vammen (a 63A) and Tweedy (the 63) were withdrawn, the Soviets were finally getting the Victor II in service, and their weapons suites would be useless against them, but honestly most of NATO's ASW weapons had to be rethought in the 70's. What worked in the 60's just didn't cut it in the late 70's.

I do think the SCB-63 took the wartime DE types to the ultimate of what could be done with the hulls. In no way were these ships a failure after conversion. I think it was a shame that only four vessels were brought to this standard.

Also when you look at ships like the 60's generation of escorts like the Bronstein, Garcia/Glover/Brookes, and Knox class vessels, you realize these ships even had trouble dealing with Soviet subs in the late 70's and 80's. It is true that the nuclear sub using the teardrop hull form was a game changer that made the ASW game that much harder....but not impossible.

Now back to the 63s, given what they were designed to fight...they did a good job...and they proved the 50's proof of concepts in the rebuilds.

[cowboy40]

Modern hedgehog!!!!

[cowboy40]

One of the biggest agreements, I have seen out there, is over what was a better weapon; Squid or Hedgehog.

Both were effective weapons when they were introduced to service during World War II.

They were both introduced by the British, but Hedgehog was put to good use by the USN, while Squid was preferred by the Royal Navy.

In most cases the depth charge produced around a 7% chance of obtaining a kill on a submarine, while the hedgehog in USN service gained around a 25% kill chance. Hedgehog also made it possible for the DE to maintain sonar contract with the submarine, that is until it continued its run to drop charges. Hedgehog killed the sub by hitting the boat directly.

Squid also probed to be an improvement over the depth charge. Squid actually takes up more weight then Hedgehog and requires a precise reading on depth to make its three heavy depth charges useful. These three charges formed a triangle pattern around the target sub and destroyed it with the over pressure that the charges caused when they exploded. Again something like a 25% kill rate was achieved.

both weapons were ahead thrown.

The real promise in ASW was being shown by the USN in a new ASW killer the homing torpedo. One of the USN weapons to be deployed was the Mk.27 passive homer. 106 were fired 33 acquired targets and achieved 28 kills. Not bad for a defensive weapon fired by submarines. This was a 19 inch diameter weapon that was actually swam out of the tubes, not fired by compressed air. Mk.37 of later 50's used this same method out of US submarines.

The MK.32 was also developed in World War II. Not to effective but was placed in production because it was an active homing torpedo, but due to its limitations was used for point defense only. but it was a good first step to the other defensive torpedoes such as the 12.75 inch MK.43

The real star of the new torpedoes was the Mk.24 passive ASW torpedo. These ships killed 68 submarines, but being passive this came at a cost of over 360 releases, but it did show the promise of the idea. The Mk.27 was a development of the Mk.24. Should be pointed out that the weapon was retained in service for years after the war.

So you can see the ground work was laid for the "modern" ASW trade.

[starcruiser]

Hedgehog would be excellent in Littoral waters. That's what the SAAB system is for and it looks like a proper update to the old system.

You need reach for deep water operations. The old ASROC system's short rang1e is it's big disadvantage and hasn't been dealt with. The last idea the US had was "Sealance". That was cancelled in 1990. The VLASROC has a range of about 24km - while that sounds good - most modern subs can attack with an ASM from much further away than that.

Anyway - more hulls are needed - and better weapons and sensors are needed to equip those hulls so that they can be effective.

It's always going to be a trade-off since the hulls cost money to build, man and maintain - and the bigger and more complex they are, the higher those costs are going to be. Smaller hulls can be useful to a point but, can't support as much equipment and aren't as durable; whether they see action or not.

I personally think we need to look at proper torpedo systems on ASW surface ships, to supplement missile/rocket based ASW weapons. I would probably keep the 12.75" torps but, try to turn them into interceptors against torpedo attack. Let the little torps take out a wake homing torp or the like...

[cowboy40]

I don't disagree with you. Modern ASW has become to reliant on aviation assets. We do need the hulls again. The US really has no low cost ASW hulls left with the Knox and Perry classes gone.

OUr present destroyers spend their time playing with the carriers.

To answer you about using Mk.48 ADCAP from a surface...it won't work...a surface has to react to fast to handle wire guided torpedoes. That is one of the reasons there was the free firing Mk.37 Mod 0/3 systems. The same torpedo was wire guided from submarines in the Mk.37 Mod 1/2. Mk.48 also may be to big on a modern surface escort.

We do need a good new generation of weapons.

As for Sealance. it was decided to develop it as a submarine launched weapon with a range of 35nm. It was to carry a MK.50 LWT. It was going to replace SUBOC. It would have been a nice weapon and it was actually ready for production and then it was cut because of priority changes following the Cold War.

[cowboy40]

I have been using the SCB-63 and 63A hulls in games using both the table top Harpoon rules and Command on the computer. I now am willing to say these "mobilization" ships were will worth the design factor and money spent...more hulls should have been converted...

[starcruiser]

Up to a point, they should be useful.

The problem - in real life - is manning, training, maintenance etc... When you also realize that these old DE's were relatively slow, you add the issue of needing a lot of them in one area to box in a threat.

The more you need, the worse the operating costs get. A faster and more modern design should (assuming it's properly designed, and that's definitely a problem these days) be more efficient but, would also be larger and able to support more modern weapons and support systems.

Still, those ol' tin cans did a fantastic job WW2 and for some years after that.

[Deleted]

Just an aside...

My great Grandfather build D.E.'s during and after WWII.

USS Rich (DE-695) (22 June 1943)
USS George (DE-697) (20 November 1943)
USS Jobb (DE-707) (4 July 1944)
USS Cronin (DE/DEC-704) (5 May 1944)
USS Holt (DE-706) (15 February 1944)
USS Kleinsmith (DE-718), (12 June 1945)
USS Courtney (DE-1021) (2 November 1955)
USS Lester (DE-1022) (5 January 1956)

DeFoe shipyard built the hulls upside-down (it was faster), flipped them over to add superstructure, slid them into the Bay City river, and cruised them (unfinished) through the great lakes, through Chicago, and on to New Orleans. My great grandfather was part of the crew that completed the build en route (he got the electrical systems finsished). Once they delivers the ship, the crew took a train back to Michigan, and started the process over again.

[cowboy40]

Mar 13, 2020 21:00:04 GMT -7 starcruiser said:

Up to a point, they should be useful.

The problem - in real life - is manning, training, maintenance etc... When you also realize that these old DE's were relatively slow, you add the issue of needing a lot of them in one area to box in a threat.

The more you need, the worse the operating costs get. A faster and more modern design should (assuming it's properly designed, and that's definitely a problem these days) be more efficient but, would also be larger and able to support more modern weapons and support systems.

Still, those ol' tin cans did a fantastic job WW2 and for some years after that.

Again you have to look at the era the conversion was designed in. They were actually very good conversions for the late 1950's and 1960's work against the Soviet Type XXI hulled boats of the Whiskey, Romeo, and Foxtrot boats. The engineering improvements increased speed and made them more agile. Electronics were updated to a good SPS-10 radar that could pick up snorkel and periscope masts at a good distance. They had a state of the art sonar for that time period. the redesign of the superstructures allowed for better response, classification, tracking and attack. They had one hell of an ASW battery.

The boats they were meant to fight were fast only in a straight line. Type XXI hulls had some nasty things about them. These conversions were designed to use that against them.

For its age it was actually a good redesign. so much to the point, it was actually better then the approved emergency war production class of the Claude Jones type of DE

[cowboy40]

Some thoughts on the weapons these ships carried. First look at the gun armament. These ships kept most of the heavy guns aboard, if you can call them heavy. They carried either two 3in/50 or two 5in/38 guns. Both of these weapons were very proven ordinance. Both were excellent against a surfaced submarine or small raiding vessel. they had a fairly good AA capability against aircraft, but as jets became faster and faster this kind of went to the side.

So they had good guns!!! They could fight off a surface attack and give some worry to slower aircraft...

[cowboy40]

World War II ASW hold over weapons. These are pretty much the same weapons you would have found on the ships before conversion. Just better directed. Lets first look at the Depth Charges carried by these ships and other vessels in the USN. The primary depth charges were the Mk. 6, Mk. 7, Mk. 9, and the Mk 14. These weapons were designed to be dropped from stern racks or fired from K-guns.

The Projector Mk. 6 (K-gun) could fire a Mk 6, Mk. 9, or Mk. 14 to a range of around 60-150 yards with a flight time of between appointment 3 to 5 seconds. Most of the DE type ships that weren't converted were equipped with eight of these 310lb weapons. The conversions carried up to 14 of these projectors.

The stern racks developed during WW2 were designed to drop the Mk.6, Mk.7 or Mk.9 charges and could carry from 9 to 12 charges depending on the type. Each ship carried two of these racks.

The Mk.6 depth charge had a total weight of around 420 lbs with a 300 pound charge of Torpex explosive. With lead weights these charges had a sinking rate of 12feet/second and a depth of 600ft. it had a hydro-static pistol for its detonator.

The Mk.7 depth charge was dropped only from stern racks. It had a total weight of 768lbs with a Torpex charge of 600lbs. Weighted this weapon had a sinking rate of 13f/s with a depth of 600ft.

Both the Mk. 6 and Mk. 7 were of the ashcan variety.

The Mk.9 was a teardrop shaped depth charge that weighted around 340lbs with a charge of 200lbs of Torpex. It had a sinking rate of 14.5 f/s, but when weighted this increased to 22f/s and it also used a hydro-static pistol that could reach a depth of 1,000 ft.

The Mk. 14 is a weapon similar to the Mk. 9, but instead it is detonated by an acoustic Doppler pistol, developed by RCA, with a sinking rate of 23f/s to a depth of 1000ft.

these weapons were withdrawn from the USN in the early 1960's but remained with allied navies until the mid 1970's

[cowboy40]

The other hold over from World War II were the Mk. 11 Hedgehog. The Hedgehog allowed the DE to through weapons ahead of the ship while she still had contact with the target. It was a system developed by the British, but perfected by the USN. The RN units were designed to fire 24 spigot mortar rounds with a circular pattern of 140 feet at 200 yard range with a flight time of 16 seconds. the British used DC over hedgehog if the enemy boat was below 400 feet. The British didn't have very good luck with the weapon. Sink rate for the British rounds was around 22f/s.

With the Mk. 11, the USN, developed the system to be able to achieve a range of 230 to 270 yards with an circular pattern of 139 feet. But the mortar rounds were designed to have only a 10 second flight time. The sink rate was around 26f/s..The stronger propelling charge allowed the faster sink rate. The Mk. 10 Spigot mortar fired the same rounds but in an elliptical pastern that could be adjusted to 168 feet to 196 feet. The USN had much better success with the weapon then the Royal Navy. With the faster sink rate and quicker flight time...the weapon could be used against boats at a deeper depth then 400 feet. USN doctrine called for a combined Hedgehog and DC attack no mater where the enemy boat was at.

In US Service, and RN, the projectile weighed 65 pounds with a charge of 35 lbs of Torpex. the weapon had a diameter of 7 inches.

The post-war Mk. 15 projector was a development of the Mk. 11 projector, but it was on a fully trainable mount that allowed for elevation and traverse. The mount was designed to be linked to the Mk. 105 FCS system that allowed it to be trained automatically. The typical pattern for the Mk. 15 was 250 ft circle and took 18 seconds to sink to 200 feet range was between 200 yards to about 300 yards. flight time was around 10 seconds depending on range...