Destroyers - Fletcher Class

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"Back to the tour... but first some food"

A ships crew sails on the food served.

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Thanksgiving Holiday observance

A ships crew sails on the food served.

We will pause the thread for observance of the traditional holiday weekend.
Happy Thanksgiving to all!
All hands report to the Officer's Mess.

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Chippers & Scrapers fore & aft.....

The tour of U.S.S. Kidd resumes as we gather starboard amidships to inspect a device with sole purpose to deter submarines from operating in the vicinity.

[Ken_NJ]

I did not do a search since I would rather see it discussed here. I was expecting the depth charges to be larger, more like the size of a 55 gallon drum, unless this is a more modern version. The depth charge in the launcher looks to be different than the rack. Are these deployed differently, or, what is the difference between the two?

[kato]

The one in the launcher looks like a Mark 6, the ones in the rack are Mark 9 (the final model used during WW2).

The Mark 6 had a 300 lb charge, and could only sink at 8 feet per second. The Mark 9 had a 200 lb charge, and could sink at 14.5 feet per second. The Mark 9 also had a more stable underwater trajectory, and in later versions could be set to up to 1000 ft depth (Mark 6: 300 ft).

There was only one larger depth charge in WW2, the Mark 7 with a 600 lb charge. Same length as the Mark 6 in the picture (ie. 70cm), but with a 63cm diameter instead of 45cm. Essentially: Mark 6 - 30 gallon drum, Mark 7 - 55 gallon drum. The Mark 7 couldn't be fired from projectors, only dropped from launch rails.

[Ken_NJ]

With the Mark 9 being lighter I guess it's the aerodynamics that let it it sink faster? Could any WWII submarine's approach 1000 feet? The I-400 could get to 330 ft and I-200 360 ft according to Wikipedia.

Then it was the classic Mark 7 that could be seen rolling off the stern racks in the movies.

[kato]

German subs could do below 500 feet (Type VII: 750 ft; Type XXI: 720 ft; Type XXIII: 600 ft), hence why the Mark 8 and Mark 9 were seen as needed, and why the Mark 6 and Mark 7 were modified with deeper settings and a faster sink rate - by replacing part of the charge with ballast - from about 1942/43 on.

[Ken_NJ]

Last questions. I take it the both the Mark 6 and Mark 9 were both fired from this station? And when they were fired, was it compressed air or a charge of some sort that propeled the DC away from the ship? The holder (for lack of a better term) beneath the DC was also fired and lost along with th DC? I recall seeing sub hunt video's and you would see the DC and the 'holder' flying away from the ship. If that's the case then they needed a supply of these to reload for the next shot?

[kato]

Last questions. I take it the both the Mark 6 and Mark 9 were both fired from this station?

Yes. The Mark 9 was also specifically built to fit the system previously used for the Mark 6, hence the guide rail rings on those Mark 9 in the rack. The K-Gun (shown in the pic) replaced the earlier Y-Gun and became the standard system in 1942; the Y-Gun had two "barrels", had to be centered over the keel of the ship (used since 1917), and had a shorter range.

And when they were fired, was it compressed air or a charge of some sort that propeled the DC away from the ship?

The K-Gun used explosive charges to fire, effectively it was a mortar. The short stump to the side was used to load the charges. There were three different standard charges resulting (for Mark 6 / Mark 9) in 50/60 yards, 75/90 yards and 120/150 yards range.

The holder (for lack of a better term) beneath the DC was also fired and lost along with th DC?

Yes. Correct term was "arbor". Additional arbors were usually stored below the DC rack, and are missing in that pic.

[Ytlas]

For fun. My Dad standing on the fantail of the USS Orleck DD 886 with the rack full of Mark 9's.

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How to Depth Charge a submarine

Interesting discussion about the crush depth of various submarines.

How deep in the water can a submarine continue to operate before the vessel fails?

The tour guide for a Gato Class sub recited that a "top secret of WWII" was how deep a submarine of this class could continue to operate. The number given was 750-ft


Thus an enemy's depth charges were to explode above a Gato, due to this critical point of information about the maximum diving depth lscking from the enemy knowing how to set the charges.

If there are any submariners lurking on the board, it would be interesting to hear their accounts.

Salty, attached is the view of the stern rack on the USS Kidd illustrated in living color. Thank you for sharing the black & White photo of you Dad. Note the difference in the structure of the two racks, a steel rod used to hold the vertical c-channels vs. shaped steel in your photo.

If the object is to have a depth charge make a large pocket of gas underneath the hull of a vessel thereby using the force of mother nature to have an equal reaction by slaming several million pounds on pressure on both sides of a cylinder in a matter of microseconds
then marksmanship is a key objective ;)

[Albany Rifles]

For fun. My Dad standing on the fantail of the USS Orleck DD 886 with the rack full of Mark 9's.

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Great pic!

Question: What is that on his left breast pocket...a MAA badge?

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Another view on the Port side ....

There were a lot of depth charge dispensers on a Fletcher Class DD

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Great pic!

Question: What is that on his left breast pocket...a MAA badge?

Quite a few hash marks on your Dad's left sleeve, too!

[kato]

Those numbers i gave for the three German sub classes wasn't the crush depth, but actually the operationally tested maximum depth for combat operations. Crush depth for German subs of the era was calculated at around 900 feet back then.

Side note: Does the USN still simulate depth charges by throwing (blast) hand grenades into the water? I remember a submariner telling me how they did that to his sub during an attack run on a CVN - six destroyers and frigates running a nice little spread pattern above and dropping a couple dozen grenades into the water. That was in... 1980 or 1981 if i remember right.