Over the years, naval architects have come up with a variety of unusual hull types for specialized roles, and it's worth taking a look at some of them. There are benefits and drawbacks to any departure from the conventional monohull, and while for most roles, the tradeoffs aren't worth it, a few have seen reasonably wide use. We'll start with the oldest of these by far, the multihull. Typically, these can be divided into catamarans, with two fairly similar hulls and trimarans, with a single big hull in the middle and two smaller hulls out on the sides.

A replica Polynesian catamaran

The basic idea of making a ship with more than one fairly conventional hull dates back to the outrigger boats used by the Austronesians in their expansion across the Pacific. At first, these were simply two dugout canoes with a platform between them, a design probably adopted in search of the great advantage of the multihull, excellent stability. The reason for this is extremely straightforward. Stability is the resistance of a ship to rolling over, and it comes from hull on the downward side being pushed deeper and displacing more water while the hull on the upward side displaces less. On a catamaran, with the hulls split apart, this effect is significantly stronger, a useful feature if you are planning to carry a large sail on a small boat. But any case where there are two or more separate points of contact with the water can produce the same effect, and the Austronesian catamaran eventually evolved into the more typical outrigger designs used in the astonishing expansion across the Pacific Ocean.¹ Read more...

On May 17th, 1987, USS Stark was on patrol in the Arabian Gulf. Iraq and Iran had been at war for most of a decade, and things had escalated from a simple battle for territory into both sides trying to interdict the oil that was funding the other's war machine. Iran was faced with a trickier situation. They had cut off direct Iraqi access to the Arabian Gulf early in the war, so Iraqi oil was transshipped via neutral powers, such as Kuwait and Saudi Arabia, and those same powers were funding Iraq's war effort. Kuwait had finally become concerned enough to request American involvement in protecting its tankers, and while the actual program had yet to begin, the USN was increasingly active in the region. Iraq had the easier job of things, as Iran's main oil facilities were quite close to its territory and the tankers that moved its oil out of the gulf were relatively easy to attack with French-made Exocet missiles. In the previous 10 months, they had flown 340 sorties and launched 90 Exocets, which had reportedly damaged about 40 tankers. And while this was annoying to the insurance companies (because the Exocet was too small to be a serious threat to a tanker) bystanders were generally safe.

Stark earlier in her career

On this specific day, Iraq was deploying a new plane. The Dassault Mirage F1 had been the backbone of Iraq's naval strike force for several years, but its range was pretty limited, so the Iraqis had requested that Dassault modify a Falcon 50 business jet into a "trainer". A Mirage F1 cockpit was installed on the right side, and an Exocet hardpoint was fitted under each wing. As the plane, codenamed Suzanna,² headed out over the Gulf, it was picked up by a USAF E-3 Sentry operating out of Saudi Arabia, which thought it was a Mirage F1, and classified it as a friendly fighter on the Link 11 network operating in the Gulf. Read more...

This is the second half of John Schilling's two-part effortpost on SCUBA diving, originally written for Data Secrets Lox. The first part covered basic recreational diving, while this one looks at more advanced topics.

This time we’ll be focusing on technical and professional diving. Note that these aren’t strictly the same thing. “Technical diving” refers to anything beyond the limits of no-decompression open-cycle scuba diving. And there are amateurs who learn those skills for recreational purposes, e.g. visiting interesting or historically significant shipwrecks at 40-80 meters. There are also professionals who can do their jobs using nothing but recreational-grade scuba gear and techniques. But for our purposes, I’m just going to fold them both together into the broad category of stuff beyond ordinary recreational diving.

Most of this is going to be stuff that’s more difficult, more expensive, and more dangerous than ordinary recreational diving, but also more rewarding. Let’s start with the risks. I already listed all the things that could kill you in the course of a brief recreational dive to no more than forty meters, if you aren’t careful. Here’s a few more to worry about if you’re going really deep. Read more...

This is the first half of a two-part effortpost on SCUBA³ diving originally posted at Data Secrets Lox by John Schilling. This part is devoted to the basic principles of scuba diving and the hobby of recreational diving, while the second half will cover more advanced technical diving, and professional or military diving activities.

Diving is not actually all that difficult, at the most basic recreational level. You’re not going to suffocate or run out of air – there’s plenty of that no more than twenty meters (65’) away, and you’re buoyant enough that if you drop your weight belt you’ll float to the surface in seconds. You shouldn’t be diving deep enough or long enough that even an emergency ascent will give you “the bends”. And the sharks aren’t going to eat you.

But it absolutely does require training, about two full weekends’ worth, because there are some ways to kill yourself very quickly if you do something stupid and the not-stupid things, while easy to describe, are neither obvious nor instinctual. Your first few dives need to be with an expert watching closely to make sure you don’t do anything stupid. At that point you scan safely spend an hour or so looking at already-known Neat Stuff down to about twenty meters, in calm open water in daylight. Highly recommended if you live or vacation anywhere with good diving, because there’s a lot of neat stuff to see. There are several agencies that certify recreational divers; PADI (Professional Association of Diving Instructors) is probably the largest, but the others have their fans (and occasional holy wars). Without a certification card from one of them, nobody will rent you dive gear, nobody will fill your air tanks, and nobody will let you on board their dive boats. Read more...

It's time once again for the regular Open Thread. Talk about whatever you want, so long as it isn't Culture War.

Overhauls are my review of Batfish, the list of US museum ships, Italian Battleships in WWII, NWAS Light Attack Part 1, NWAS Cruise Missiles Part 1, Zumwalt Part 2, my review of Hornet, Military Spaceflight Part 2, and for 2024, Military Spaceflight Parts nine and ten, Air Attack on Ships Part 6 and Southern Commerce Raiding Part 9.

I'm going to designate tomorrow (8/2) at 1 PM Central Time (GMT-6) as the Schelling Point for anyone who wants to hang out in voice chat on the Discord. I will probably be there, but might have other things going on.

As a companion to my series on US military aircraft, I'm going to take a similar look at the military aircraft of our allies, and then of the rest of the world. Note that this is less comprehensive than the US version, as there are a lot of countries operating a lot of planes, and I am not going to tear my hair out trying to find all of them. But I will mention the major players, along with a few interesting oddities.

Fighters

Fighters worldwide play much the same role they do for the US, although it is worth noting that nobody outside the US, Russia and China operates bombers, so for all of our allies, fighters also handle the high-end ground attack work. Adoption of US fighters has been reasonably widespread, but major countries often build their own as a matter of national sovereignty and to support their aerospace industries. Read more...

The utility of space-based imagery was obvious almost from the moment that people thought of putting cameras in space, but for the first decade or so of spaceflight, the ability to launch things was limited to only the USSR and the US, and they used this capability primarily for military purposes, with limited exceptions for communications and meteorology.

Dick Gordon sets up a Hasselblad camera in the Apollo 12 simulator

Because of the cloak of secrecy that shrouded both side's reconnaissance satellite programs, the first good look anyone in the wider world got at the Earth from space was through cameras carried aboard manned spacecraft. At least on the US side, these were Hasselblad handheld cameras, and produced stunning photos that had nowhere near the resolution of something like Corona. But they were still of great interest to researchers in fields like agriculture, forestry, hydrology and geology, who had a new window onto the planet that they studied. Pressure began to build for a dedicated platform to produce low-resolution imagery for Earth scientists, finally culminating with the flight of Earth Resources Technology Satellite-1, later known as Landsat-1, in 1972. Read more...

One of the major issues that I didn't discuss in my early coverage of military spaceflight was operations by nations outside of the United States, most notably the Soviet Union. The Soviets were somewhat slower to adopt satellite reconnaissance than the United States, as they were able to take advantage of the openness of American society to gather information on their enemy. Instead, they spent the late 50s protesting the "illegal" American satellites, although development began on recon satellites shortly after Sputnik went up.

A Zenit capsule

The Soviets faced several challenges. They were shorter on technical skills than the Americans, limiting the number of programs they could run at one time, and because, unlike the US, they had not spent the last decade and more building up their strategic reconnaissance capabilities, they were also short on the sophisticated cameras that would be needed by a reconnaissance satellite. Fortunately, they could kill two birds with one stone, by using the same Vostok capsule that carried Yuri Gagarin into orbit, but with a bunch of cameras instead of an astronaut. This was very useful, as it meant the cameras and film were kept in a pressurized environment, and the cameras could be reused, although it required a significantly larger booster than the American system.⁴ This program, codenamed Zenit, lasted until 1994, although with significant evolution over its lifespan. The early versions had no ability to alter their orbits, and relied on batteries, limiting them to only a few days in orbit, while later versions could stay up for two weeks thanks to solar panels and could remain over a specific area for most of their operational life. Read more...

After the attempt to visit Hornet fell through, we took a look around for other museums to go to. There was discussion of trying to hit Jeremiah O'Brien, but timing ruled that out, and eventually we decided to stay in the area and go to the Oakland Aviation Museum, which we had found out about because we noticed a sign to it on the way up from San Jose. And I was pleasantly surprised by what I found.

Website

The museum is small and kind of out of the way, on the outskirts of Oakland airport. But the collection was better than I would have expected for a museum that is pretty clearly taking whatever planes it can get. Inside, there's a replica of the Vin Fiz Flier, the first airplane to fly coast-to-coast (not nonstop, and definitely not without crashing), a MiG-15, a couple of light planes and a few helicopters. There was also a room of Navy artifacts and models, which allowed me to recycle a lot of the material I had prepared for Hornet, and another room dedicated to Jimmy Doolittle, which was mostly notable for having a Norden Bombsight on display in a replica bombardier's position, as well as discussing events that I think are overdone. Read more...

It is time once again for our regular Open Thread. Talk about whatever you want, so long as it isn't Culture War.

Cassander, long-time commenter here, is looking for a managerial data science/product management role, preferably in aerospace. Email tint.michael@gmail if you have suggestions or leads.

Overhauls are Falklands Part 3, Coastal Defenses Part 3, Coastal Defenses Part 8, On the Border of Land and Sea, and for 2024, Distributed Maritime Operations, Military Spaceflight Parts seven and eight and Air Attack on Ships Part 5.