Ask An Expert- Naval Forces

[Gun Boat]

A question I hope the resident retired US Navy ranking officer and warship engineering guru will be able to answer.

There is speculation that the explosions that occurred on the Yamatos were caused by some boilers going up. What kind of explosive force is contained within a pressurized naval boiler? My googling has given me this base for TNT:

"The explosive yield of TNT is considered the standard measure for strength of bombs and other explosives with 1 ton of TNT equaling 4.184 gigajoules. So 1 kg of TNT then equals 4.6 megajoules, thus a single gram of TNT is equivalent in energy to one Calorie."

Can the energy stored in a boiler be quantified in a Joules?

I found this article relating to the Japanese 'Kampon' boiler but it's written in some strange code only the warped minds of engineers can read (I'm assuming):

http://www.fischer-tropsch.org/prima...%20S-01-12.pdf

I've seen the world war 2 footage of the US airforce strafing german trains and the resulting boiler explosions and the bang is big but not 'tear apart a battleship big'. I think a steam train's boiler is rated around the 1500hp output where as a Kampon is around the 12500hp but even imagining a 6 x by magnification of the steam train bang I still don't see it being 'tear apart a battleship big' . I'm also not sure whether the concussive force of a boiler explosion would set off cordite etc.

Thanks in advance for any info.

[desertswo]

A question I hope the resident retired US Navy ranking officer and warship engineering guru will be able to answer.

There is speculation that the explosions that occurred on the Yamatos were caused by some boilers going up. What kind of explosive force is contained within a pressurized naval boiler? My googling has given me this base for TNT:

"The explosive yield of TNT is considered the standard measure for strength of bombs and other explosives with 1 ton of TNT equaling 4.184 gigajoules. So 1 kg of TNT then equals 4.6 megajoules, thus a single gram of TNT is equivalent in energy to one Calorie."

Can the energy stored in a boiler be quantified in a Joules?

I found this article relating to the Japanese 'Kampon' boiler but it's written in some strange code only the warped minds of engineers can read (I'm assuming):

http://www.fischer-tropsch.org/prima...%20S-01-12.pdf

I've seen the world war 2 footage of the US airforce strafing german trains and the resulting boiler explosions and the bang is big but not 'tear apart a battleship big'. I think a steam train's boiler is rated around the 1500hp output where as a Kampon is around the 12500hp but even imagining a 6 x by magnification of the steam train bang I still don't see it being 'tear apart a battleship big' . I'm also not sure whether the concussive force of a boiler explosion would set off cordite etc.

Thanks in advance for any info.

I'd have to find a good Moliere Diagram to determine the the Btus/Calories for 600 PSI superheated steam to give you a really good answer, but your instinct is correct; tearing a ship apart with a boiler explosion is a tall order.

[gunnut]

I've got a question regarding amphibious ships.

Looking at the America class, the Wasps and Tarawas, they all appear to have the same function.

Their hull classification symbols are, respectively are

LHA(R)
LHD
LHA

What is the difference between these designations? I'm not sure what makes one different from another.

Ed

The closest I can find is that LHA may or may not have a well deck. LHD definitely has a well deck.

Landing Helicopter Assault - Wikipedia, the free encyclopedia

And "dock" sounds less offensive than "assault."

[85 gt kid]

This is from wiki the most trusted source ever :whome:

"The ship's [America] design is based on*USS*Makin Island*(LHD-8), but to allow more room for aviation facilities she does not have a*well deck, and has smaller medical spaces.*"

[Gun Boat]

I'd have to find a good Moliere Diagram to determine the the Btus/Calories for 600 PSI superheated steam to give you a really good answer, but your instinct is correct; tearing a ship apart with a boiler explosion is a tall order.

Thank you sir.

That's good enough for me. Would I be right in assuming the boilers on one of your ships such as the Constellation have a lot more energy storage potential than a WW2 era Japanese Kampon unit?

[Squirrel]

The new LHA's (save for the first two) are supposed to have welldecks. The AMERICA doesn't have a well deck, but a bigger hangar bay. And ya know... they got some pretty sweet new racks in the berthings.

[desertswo]

Thank you sir.

That's good enough for me. Would I be right in assuming the boilers on one of your ships such as the Constellation have a lot more energy storage potential than a WW2 era Japanese Kampon unit?

OK, got my hands on the aforementioned Moliere Diagram and I may have to reassess my previous opinion. Converting metric to English units slows me down a bit but anyway, there are 253 Calories per BTU, and 400 Btu per one PSI of steam at the boiler's operating pressure. The Kampons operated at 427 PSI: so 400 X 427 = 170,400 Btu X 253 Calories = 43,111,200 Calories. According to your Wikipedia information, if one Calorie = one gram of TNT, then 43,111,200 divided by 1000 = 43,111 Kg = 43 tons of TNT, right? You can figure out the Joules; I'm done. LOL!!

Anyway, the main propulsion boilers in every ship in which served had 1200PSI boilers operating at 976 degrees superheat. So yeah, there was a lot more energy stored in those boilers, than those Kampon boilers. With that sort of pressure and the degree of superheat, I was ever so glad we had steam drum safety valves, because whether such an explosion would tear a ship apart or not, an explosion would be catastrophic just the same.

[DonBelt]

Get rid of the LHA designation, use only LHD for the vessels that have a well deck and bring back the LPH designation for the America and Tripoli. Then it'll be less confusing.

[85 gt kid]

Speaking of steam propulsion Captain were there many major incidents with steam plants involving injuries/death? Only one I can think of was a Tarawa class maybe in the early 90s that was bad. Seems like we had a good safety record with them for the most part kind of like our old gun turrets as far as I know there were just 3 incidents that were bad which in 50-60 years is manageable.

[desertswo]

Speaking of steam propulsion Captain were there many major incidents with steam plants involving injuries/death? Only one I can think of was a Tarawa class maybe in the early 90s that was bad. Seems like we had a good safety record with them for the most part kind of like our old gun turrets as far as I know there were just 3 incidents that were bad which in 50-60 years is manageable.

Not Tarawa class but the LPH USS Iwo Jima. I did the Artlcle 32 investigation that informed the Board of Inquiry stood up in the aftermath. It happened during Desert Shield in Manama, Bahrain. 11 killed, 10 instantly, and one lingering until late in the evening, screaming in agony. The cause was a valve bonnet in a 600PSI main steam line was improperly repaired using black oxide coated brass fittings instead of the Level One carbon steal required. The brass got soft when brought to temperature and carried away, filling the entire space with superheated steam, thus par boiling the watch standers.

There are few accidents of that sort because good operators follow the rules and stay on top of things.

[85 gt kid]

That's the one and I think I remember you posting about this (might be why I know this). A little unrelated but my "aunts" step dad was career Navy and unfortunately I don't know allot that he did but he was in engineering on a nuclear surface ship at one point and I remember him saying how safe the Navy reactors are compared to land based units. I also remember him saying about using a broom handle to check for leaks so you don't lose any digits! Haven't seen him in 10 years now I'll have to see how he's doing.

[Gun Grape]

I've got a question regarding amphibious ships.

Looking at the America class, the Wasps and Tarawas, they all appear to have the same function.

Their hull classification symbols are, respectively are

LHA(R)
LHD
LHA

What is the difference between these designations? I'm not sure what makes one different from another.

Ed

Going from memory

LHA (Tarawa Class) front 2/3s of the well deck was split. You could park a LCM on each side but not a LCAC. They were limited to the back 1/3 of the well deck. P-Ways and ladderwells were smaller and more angled. LHAs were also shorter (by 10 feet) than a LHD. Well deck could hold either 4 LCUs or 2 LCUs and 1 LCAC. On the east coast LHAs never carried a LCAC.

The LFOC/SAIC was smaller and pretty bare bones.

Flight deck is smaller at the bow. Use to have a gun turret mounted both port and starboard.

LHD (Wasp) Well Deck not split. Could carry 3 LCACs. Wasp Class also have a monorail system in the upper V/well deck area to shift cargo. First amphib designed with the Marine Corps involved. P-ways are wider and ladderwells are not as steep. Easier access from troop berthing spaces to embark stations. LFOC/SAIC set up like a CIC. Flight deck full size at bow. Better troop berthing, better 1st Class Mess and Goat Locker

LHA (R) ??? Never been on one

[Gun Boat]

OK, got my hands on the aforementioned Moliere Diagram and I may have to reassess my previous opinion. Converting metric to English units slows me down a bit but anyway, there are 253 Calories per BTU, and 400 Btu per one PSI of steam at the boiler's operating pressure. The Kampons operated at 427 PSI: so 400 X 427 = 170,400 Btu X 253 Calories = 43,111,200 Calories. According to your Wikipedia information, if one Calorie = one gram of TNT, then 43,111,200 divided by 1000 = 43,111 Kg = 43 tons of TNT, right? You can figure out the Joules; I'm done. LOL!!

Anyway, the main propulsion boilers in every ship in which served had 1200PSI boilers operating at 976 degrees superheat. So yeah, there was a lot more energy stored in those boilers, than those Kampon boilers. With that sort of pressure and the degree of superheat, I was ever so glad we had steam drum safety valves, because whether such an explosion would tear a ship apart or not, an explosion would be catastrophic just the same.

Holy moly. That would mean that there is probably more 'kaboom' potential in the BB engine rooms than in the magazines. The Iowas had 60000 more horse power than the Yamatos - they must have had the explosive potential of a small nuclear bomb down in engineering.

Mind Blown.

Sir, after retrieving your figures what's your opinion on the Barham capsizing and explosion? I'm getting the 'Boilers did it' T shirt that's for sure.

[SharkPilot]

Holy moly. That would mean that there is probably more 'kaboom' potential in the BB engine rooms than in the magazines. The Iowas had 60000 more horse power than the Yamatos - they must have had the explosive potential of a small nuclear bomb down in engineering.

Mind Blown.

Sir, after retrieving your figures what's your opinion on the Barham capsizing and explosion? I'm getting the 'Boilers did it' T shirt that's for sure.

Strictly an amateur's opinion, but what about the boiler explosion aboard the old Norway? Okay, it was just one boiler that burst, but it was a large boiler. She was a powerful steam ship in her early days. The explosion of course killed everyone in the fire room and also burst some non-structural bulkheads a few decks up into crew quarters areas. There were casualties there too. But the ship was by no means "torn apart". I'm sure her machinery spaces were a mess but she survived well enough to be towed first to Germany then on to Alang for scrapping.

[Albany Rifles]

Just a quick thought/question....

One of the more famous videos from World War 2 is of the HMS Barham exploding while rolling over after a torpedo hit.

Question...was that the boilers letting go or would that have been her magazines?