As important as keeping the ship afloat is, the purpose of a warship is not to float. It is intended to fight, and there are many ways a ship could be knocked out of a fight without succumbing to flooding or fire. Even though the crew would vastly prefer a mission kill over an actual kill, it's nearly as good from the enemy's perspective. In addition to their attention to the aforementioned threats, designers and operators thus have to figure out how to keep fighting despite damage.

A turbogenerator in engine room 2 of Iowa¹

The most likely source of a mission kill is loss of power. If the steam stops, the ship is a sitting duck,² while loss of electrical power renders the ship unable to fight effectively. The main defense is redundancy. The boilers, which provide steam to both the engines and the generators, were usually split into two or more separate systems in separate spaces. This required careful design, and some early systems were reportedly compromised by common lubrication oil lines. Cross-connections allowed the crew to route around damage, so that a ship which lost, say, boiler 3 and engine 2 could use boiler 2 to power engine 3. Primary electrical power was from steam-driven turbogenerators, and these were dispersed throughout the engineering spaces. Diesel generators were fitted to provide reduced power if steam was lost, and widely separated from the turbogenerators and each other. Read more...

Improvements in underwater protection after World War I posed a problem for torpedo designers. Torpedo defense systems had reached a point where they could keep a ship operational after at least one and probably several hits. One option would be to increase the amount of explosive in the warhead, but this would take space away from the propulsion system, making the torpedo slower and less effective.³ The alternative was to find some way to bypass the TDS, and designers in all of the major powers quickly realized that a magnetic pistol could set off the torpedo underneath the target ship. These did not always live up to their designer's expectations, with the American version proving particularly notorious, but when they worked, they made the torpedo much more effective.

A destroyer sinking after being torpedoed

The biggest factor was the simple impossibility of protecting the bottom of the ship. While a TDS might be able to provide 10-20' for the explosion to expend its energy before reaching the ship's vitals, providing similar standoff for underbottom explosions would dramatically reduce the volume available for said vitals.⁴ Instead, a double or triple bottom of 6-8' was standard, intended to protect the ship from grounding, provide extra liquid storage, and give at least a little resistance to attack from below. Read more...

While the only thing that could actually sink a ship was flooding, fire could leave it a gutted, useless hulk, or reach something explosive, which could let water in. This flammability may seem counterintuitive, as the main ingredient in a warship is steel, but many things inside the ship need to be made of flammable substances to allow the ship to function. As a result, designers have always gone to great lengths to reduce the risk of fire, and to give the crew the tools required to fight those that broke out, whether from enemy action or accident.

Iowa's crew fights the fire after the explosion in Turret II

The first step in this process was to reduce as far as possible the amount of combustible material onboard. During WWII, it was found that many fittings installed in peacetime to make life more comfortable were dangerous in action. Cork insulation, upholstered furniture, linoleum, and clothing not stored in metal lockers all fed fires that ultimately led to loss of life and ships, most notably in the battles off Guadalcanal. These were all ruthlessly stripped from ships, and those flammables that could not be removed were either limited or packaged in such a way as to reduce the risk.⁵ Read more...

In early April, 1982, Argentina invaded the Falkland Islands, a few desolate rocks in the South Atlantic. The British mobilized their fleet, sending it south by way of Ascension Island. On the 25th, a force retook South Georgia, a even smaller and more desolate island that Argentina had also captured, while the main task force closed in on the Falklands.⁶

Even as the echoes of the Black Buck Raid were fading, the carriers were preparing to go into action with a coordinated raid on Port Stanley and Goose Green, a secondary Argentine base. First over the target were a pair of Sea Harriers from Invincible flying CAP.⁷ They had the secondary responsibility of getting photos of the damage to the runway before withdrawing to patrol altitude.⁸

Sea Harriers operating from Invincible

A few minutes later, the first Sea Harriers took off from Hermes. Nine aircraft were aimed at Stanley, while the other three were to attack the Pucaras at Goose Green. The Stanley aircraft had been airborne only ten minutes when the first formation launched their bombs, four of them tossing a salvo of airbursting 1000-pounders onto the known defensive positions. With the defenders' heads hopefully kept down, the other five roared over the airfield at 200' or less, sewing a mix of cluster and retarded bombs. Aircraft and buildings suffered damage, but the retarded bombs failed to penetrate the runway. The defenders greeted them with missiles and gunfire, but only scored a single hit, with a 20mm round punching a hole in the vertical stabilizer of the last Harrier in the formation. All of them were recovered safely, and even the damaged aircraft was operational again by the end of the day. Read more...

I've decided to cover the former cruise liner Queen Mary, the WWII-era cargo ship Lane Victory and the Los Angeles Maritime Museum in one post. I certainly didn't visit them all in one day, but there wasn't enough material to sustain a full post for each.

Queen Mary

Website

Queen Mary from outside¹⁰

Queen Mary is a major attraction in the Long Beach area, with a hotel, restaurants, and the like. I'm ignoring all of that, and treating this just as a museum ship. Read more...

When I discussed underwater protection, I focused only on the systems designed to keep water out of the ship. But naval architects had long been concerned about flooding, and included a second line of defense to deal with water that got inside the ship. This could be from a torpedo, a mine, a shell hit near the waterline, being rammed by another ship, or even running into rocks. In any case, the basic principles were the same, as were the problems they faced.

Patching a hole in a partially-flooded compartment

The first and most important line of defense was compartmentalization. Ships sink when the inside fills with water, and dividing the interior of the ship up into watertight compartments means that, in theory at least, the ship will only sink if enough of those compartments are damaged and opened to the sea. The downside to this arrangement is that watertight bulkheads get in the way of actually using the space. Machinery, for instance, requires large spaces below the waterline, and living spaces are more difficult to use if access routes have to go through a limited number of doors. The resulting inefficiencies drive up cost and ship size. As a result, standards have been developed specifying that all large ships, military and civilian, must be able to remain afloat and stable with a certain number of compartments flooded. The general measure of resistance to sinking is known as "reserve buoyancy", and is calculated as the volume of the hull between the waterline and the height at which water will begin to enter the ship if the ship sinks that far.¹¹ Read more...

It's time once again for our regular Open Thread.

I've taken to highlighting a link in these posts, and for today, I'm going to call out the blog WWII after WWII. It's an investigation of the postwar careers of various pieces of equipment, ranging from guns to ships. Particularly good posts are on the experimental destroyer Timmerman, the mothballing of the fleet, and catapult aviation.

Also, anyone who can't see the captcha should try going to navalgazing.net. I'm migrating to my own domain, and it seems that a few things aren't working at the previous one.

When World War I ended, the world looked poised on the verge of another naval arms race. The United States, which had aimed at parity with Britain under the 1916 Naval Program, was talking about an even larger fleet program, to firmly surpass the Royal Navy. In the Pacific, Japan was building the so-called 8-8 fleet, aiming to have 8 new battleships and 8 new battlecruisers. This would pose a major threat to British and American holdings in the Far East. Britain would traditionally have simply outbuilt these threats as they had with Germany a decade earlier, but the war had left them nearly bankrupt. So when American Secretary of State Charles Evans Hughes called a conference on naval armaments in November 1921, all three countries showed up, as did France and Italy.¹²

Hughes opened the conference with a dramatic series of proposals, calling for the immediate suspension of all capital ships currently under construction, no new construction for the next 10 years and rules on when older ships could be replaced. Older ships would be scrapped to bring capital ship tonnages in Britain, the US and Japan to 600,000, 500,000 and 300,000 respectively.¹³ All other categories of ship would be limited on similar lines. Read more...

My first visit back to Iowa after my move to the Midwest was great. I got to see the ship again, meet readers, hang out with my friends on the crew and take a look at what they've been up to in the past year.

First, there's the Full Steam Ahead tour, which was about to start when I left. All five people who showed up to the meetup did the FSA in the morning, and said that they enjoyed it. I shadowed part of the tour, as I wanted to get to the boiler room and plotting rooms. Read more...

While the heavy AA guns and their dual-purpose successors could be potent weapons against aircraft in the right situation, there were also cases where their limits were sharply revealed. Even the fastest-firing of them was limited to no more than one round every three seconds or so, and when the target was a strafing fighter or a torpedo bomber closing in for the drop, they simply could not respond fast enough. Smaller weapons, of limited range but capable of filling the air with steel, were needed.

Octuple Pom-Pom on HMS Rodney

Initially, these were simply versions of the standard machine guns used ashore, fitted with ring sights and bolted to a convenient railing. These were adequate in World War I, but shortly after the end of the war, the British saw the need for something better. They had also made use of the 2-pdr Pom-Pom,¹⁴ a 40mm autocannon, for AA firepower and decided to base their future light AA weapon on it. Development began in 1920, but lack of funding slowed development, and the famous octuple 2-pdr Pom-Pom didn't enter service for another decade.¹⁵ It was a revolutionary weapon, introducing director control¹⁶ and power operation to automatic AA weapons. The 2-pound shell was powerful enough for aircraft of the era, with a 0.16 lb bursting charge. On the downside, rate of fire was only 90 rds/min/gun, and the choice to use existing ammunition limited muzzle velocity to only 1,900 ft/sec. By the late 30s, this was clearly insufficient, and an improved version capable of about 2,300 ft/sec was designed. It was not capable of firing the old ammo, and for some bizarre reason, both low and high-velocity weapons were kept in production throughout the war. Read more...