Ask An Expert- Battleships

[DonBelt]

Looks like she is working on the SRBOC launchers.

[RustyBattleship]

Looks like she is working on the SRBOC launchers.

That is correct. Four SRBOC launcher sets (with 6 SRBOC bases on each set for 24 SRBOC's) were installed on each ship during modernization. The lockers for the launching tubes would be behind or by the right shoulder of the photographer.

Basically a Super Rapid Blooming Overside Chaff is just a 5-inch mortar shell. Its shape is more like the smaller Hedge Hog anti-submarine mortar/rocket. But rather than dropping the projectile into a tube like a mortar, it is already an "ALL UP" round in its launching tube that also serves as its stowage case inside the lockers. You just take the tubular cases out of the lockers and bolt them down to the foundations as shown in the photo. Then when necessary they are electrically fired and explode in the air to spread out chaff and "fireworks" to (hopefully) confuse an incoming missile.

[Burnet]

Question: were BB designed to fire their main guns along the centerline--over the deck--as well as broadside or were they always intended to be fired at an angle to the centerline?

[Gun Grape]

Question: were BB designed to fire their main guns along the centerline--over the deck--as well as broadside

Yes

[blidgepump]

Blown off the bow ....

Yes

GG,

Explain to me once again ( I have a short attention span ) how the 40mm gunners
kept from being blown off the bow with the 14 & 16 inch guns fired!

[RustyBattleship]

Yes

Yes, over-the-bow shots and over-the-stern shots were fired. But during modernization we found that the movie booth aft of Turret III on two of the Iowas had its whole port bulkhead caved in. On New Jersey, over-the-bow shots didn't do some of the mushroom vent covers much good either.

And to answer Bildgepump's question below, 16-inch shots required all decks up to 04 level to be cleared of all personnel. Exceptions were allowed during target practice when the big guns were fired at 90 or 180 degree azimuths. But even then no one was allowed aft of the after stack or forward of the bridge. Ummm, one more exception, if the guns are fired directly athwartships camera personnel (both uniform and non-uniform) were allowed up to the anchor hawse pipes.

Supposedly there were some cases in WW II where selected AA gunners were ordered to keep at GQ such as those in the 40mm stern gun tubs and the 20mm bow tubs. All other AA gunners amidships remained at GQ. As for those on top of Turrets II & III, I would recommend they head for the nearest coffee pot if I were the Captain or Gunnery Officer. Those turrets would be changing angles and elevations constantly while trying to take out their big targets and the AA crews would just be wasting ammo. Besides, there are no ammo passing scuttles on up the side of the turrets so what they had in their stowage racks behind the shields was all they got.

[Stitch]

You can fire along the centerline, but the problem is you bring fewer guns to bear when you do it that way, especially from the stern. With a broadside, you can bring all nine guns to bear (in the case of an Iowa), whereas along the centerline the most you would be able to bring to bear were six tubes. Naval engagements were usually fluid affairs, so the number of guns you could bring to bear would vary, depending on the bearing of the target(s); but with shore bombardment it was a fixed position, so a broadside makes the most sense.

[RustyBattleship]

You can fire along the centerline, but the problem is you bring fewer guns to bear when you do it that way, especially from the stern. With a broadside, you can bring all nine guns to bear (in the case of an Iowa), whereas along the centerline the most you would be able to bring to bear were six tubes. Naval engagements were usually fluid affairs, so the number of guns you could bring to bear would vary, depending on the bearing of the target(s); but with shore bombardment it was a fixed position, so a broadside makes the most sense.

True. Most Battleship uses were for shore bombardment though in the very few cases of BB against BB steering the ships parallel to each other allowed full broadsides. WW II had very few BB to BB engagements.

[Gun Grape]

GG,

Explain to me once again ( I have a short attention span ) how the 40mm gunners
kept from being blown off the bow with the 14 & 16 inch guns fired!

They were not manned when the big guns fired.

General Quarters is not a rigid "Everyone manning all guns" evolution.

[Pacfanweb]

Question: were BB designed to fire their main guns along the centerline--over the deck--as well as broadside or were they always intended to be fired at an angle to the centerline?

Yes. Here's the USS North Carolina on trials doing just that:

[Burnet]

Thank you gentlemen, for the informed replies. Next question: do the projectile and powder hoists rotate with the gun house or do they twist as the turret rotates?

[RustyBattleship]

Thank you gentlemen, for the informed replies. Next question: do the projectile and powder hoists rotate with the gun house or do they twist as the turret rotates?

Yes, of course they do (rotate with the structure). They are all part of the turret structure. It would take a bit too long to describe the loading procedures as the moving of the projectiles and the bags of propellant toward their hoists is a little different and takes a lot of manpower. But that saves one heck of a lot of time not having to traverse back to a battery position and it would be almost impossible to design a "twisting" projectile hoist to load a 6-foot tall, 2,700 lb Armor Piercing "bullet". Only the barrels have to be lowered to battery (which I think is only 3 degrees of elevation above level stowage position).

That's why each gun can get off a shot every 30 seconds because the next round is already at the top of the hoists ready for loading.

[JRT]

...until Zumwalt is "under way, making way" for the first time. I believe in my heart that variations of her all electric propulsion and electrical power distribution plant fed by some combination of LM2500, MT30 and/or diesel generation, driving either jet pumps a la the LCS or AZIPODs like HMS Queen Elizabeth is the wave of the future, but until I see "Agent Orange" on the move I'll withhold comment.

I will say this though; give me USS Gerald R. Ford's reactors, steam generators, SSTGs, and electrical distribution system, coupled with either LCS jet pumps or QE's, AZIPODs and you'll catch me with a raging engineering hard on! :)

I was very upset when GRF's designers didn't take that leap of faith and give her electric drive like QE. No balls, no blue chips. :(

Big electric AZIPODs with the Prairie cavitation quieting system would be very interesting. I would have liked to have seen that technology used on USS America (LHA-6) class. The later follow on builds, post LHA-7, will get well decks, and it would be especially interesting to see AZIPOD modular assemblies that are replaceable from the top within the well deck (without needing a dry dock, perhaps even something field replaceable might be possible).

Different from an AZIPOD, E-Boat has made some progress in developing a rim driven electric propulsor for use on higher speed ships. See the article quoted below (from ~10 years ago).

I suspect that adding Prairie to that rim driven propulsor would be problematic, a design problem in need of a creative solution, as it would require the pressurized air seal to operate at the much larger diameter of the rim instead of the small diameter of a shaft, so the seal would see much higher surface speeds, and drag, and wear.

Sea Jet's RIMJET, Advanced Electric Ship Demonstrator

The Sea Jet Advanced Electric Ship Demonstrator (AESD), funded by the Office of Naval Research (ONR), is a 133-foot vessel located at the Naval Surface Warfare Center Carderock Division, Acoustic Research Detachment in Bayview, Idaho. Sea Jet - built by Dakota Creek Industries in Anacortes, Wash. - operates on Lake Pend Oreille, where it is used for test and demonstration of various technologies. Among the first technologies tested was an underwater discharge waterjet from Rolls-Royce Naval Marine, Inc., called AWJ-21, a propulsion concept with the goals of providing increased propulsive effiency, reduced acoustic signature, and improved maneuverability over previous Destroyer Class combatants.

In a program of research and development which was years in the making, Office of Naval Research (ONR), Rolls Royce Naval Marine Inc. (RRNMI), and the Signatures Department (Code 70) prepared the demonstration of an advanced waterjet-based propulsion concept, named AWJ-21. RRNMI, Walpole, MA, has developed the AWJ-21 propulsor concept with the goals of providing increased propulsive efficiency, reduced acoustic signature, and improved maneuverability over DDG 51 Class combatants. For this demonstration, a 130-foot-long craft designated the Advanced Electric Ship Demonstrator (AESD) was built. The AESD is being funded by ONR to demonstrate advanced electric ship and propulsor technologies. The ground-breaking demonstration is sponsored by the Office of Naval Research. Additional benefits from the AWJ-21 technology are expected to provide more compact propulsion systems with reduced weight and volume.

The AESD is an approximate quarter-scale destroyer class combatant with a length of more than 133 feet and a full load displacement of 120 tons [239,000 pounds]. The AESD hull form is based on the 5565 tumble-home hull tested early in the DD(X) program. As a result of availability of the AESD demonstrator craft, planning is underway to conduct other technology demonstrations. One such effort is the design of a low signature deckhouse for the model.

On 30 November 2005 the Advanced Electric Ship Demonstrator (AESD), Sea Jet, tied-up to the pier after completing its first day of sea trials on Lake Pend Oreille at the Naval Surface Warfare Center Carderock Division, Acoustic Research Detachment in Bayview, Idaho. The ship would test Rolls-Royce patented AWJ-21™ waterjet technology over the following six months on Lake Pend Oreille at the Navy’s Acoustic Research Department in Bayview, Idaho. The AWJ-21 is designed to increase ship speed, making hulls sleeker by working without rudders, shafts and propeller struts. Unlike conventional waterjets, the system works completely underwater, reducing noise and surface wake and improving stealth. The lightweight and compact AWJ-21 allows ships to operate in shallow waters. Its integrated steering and reversing system improves maneuvrability at low speeds.

Carderock Division’s Acoustic Research Detachment in Bayview, ID, is where most of the testing commenced in FY 05. Members of Philadelphia’s Code 90 supported machinery and electric drive quieting for the AESD. General Dynamics Electric Boat division similarly applied its expertise to the electric drive propulsion system. ARL at Penn State provided test support for the early waterjet development, and MIT assisted with the waterjet pump design. Computer Sciences Corporation (CSC) is responsible for the overall AESD boat design.

The RIMJET is a novel type of podded propulsion system that relies on a permanent magnet motor to drive the propeller, making it similar to the systems featured in this issue of Solutions (p32). In the RIMJET propulsor the motor is mounted not in the hub but in the rim, which GD Electric Boat believes provides a number of advantages. One of these is that because the RIMJET makes use of the same hydrodynamic principles as a waterjet, its applicability to high-speed vessels is much greater than conventional propulsors. Advantages over waterjets include high rotor torque capacity, rim attachment of rotor blades, minimal hull contour impact and azimuthing capability. The RIMJET’s high efficiency derives from its use of a phenomenon known as swirl recovery. Moreover, because it operates at a relatively low rpm, blade area is reduced, there is minimal duct and strut surface area, and the propulsor has low duct and strut velocities compared to hub-driven propulsors. The RIMJET has excellent cavitation performance because it operates at low rpm, it has very uniform inflow to the rotor, and the rim prevents the formation of tip vortexes. General Dynamics believes the RIMJET will also have better ‘off-design’ performance characteristics because the duct provides uniform mass-flow at off-design conditions.

It also promises to be much more reliable and maintainable than hub-driven pods. GD Electric Boat says the ‘canned’ permanent magnet motor at the heart of the RDP and stator are both sea-water cooled, eliminating the need for a cooling system and anti-condensation heating system. Having a seawater-lubricated journal and thrust bearings removes the need for a bearing lubrication system and seals, and having the strut outside the propeller wake reduces cavitation erosion. The duct also shrouds the ship’s hull from blade-induced pressure fluctuations.

[Sanjac]

In this picture from the Wikipedia, it looks like the battleship USS Iowa has skidded about half the width of her beam while firing a broadside. Is that really what's going on?

[Battleship IOWA]

In this picture from the Wikipedia, it looks like the battleship USS Iowa has skidded about half the width of her beam while firing a broadside. Is that really what's going on?

It's a common myth that a big gun ship like the Iowa actually recoils from a board sides and slides sideways. What you are seeing in the photo is the water being pulled away from the ship from the force of the blast wave. The weight of the shells being fired would have to outweigh the ship itself for it to slide sideways.