This article, Silence in the deep: Inside the HMS Ocelot stealth submarine, originally appeared on CNET.com.
For 29 years, Her Majesty's Submarine Ocelot quietly patrolled the Atlantic. Many of her missions are still classified to this day, nearly 30 years removed from her decommission in 1991. For months at a time, her crew of 69 men would stealthily listen and track enemy subs and ships using advanced sonar arrays.
She covered over 90,000 miles in her years of service and her duties, at least the declassified ones we know about, ranged from routine patrols, advanced equipment testing and even a rescue operation. She was the last boat built for the Royal Navy at Chatham Dockyard, where she now sits.
As a museum ship, she is in fantastic condition and easily accessible, sitting high in a former drydock. A rarity for a sub, you can actually walk under her hull, and get up close and even touch the 1,600 tons of metal and plastics. Here's how she looks, inside and out.
Here's a look at Her Majesty's Submarine Ocelot, which was launched in 1962 and served for 29 years.
You can read more about this tour in Silence in the deep: A look inside the HMS Ocelot.
Like all diesel-electric subs, in addition to periscopes, there are air intake and exhaust snorkels for the engines, when running.
The propeller is gone, but in its day the sub had a top speed of 20mph/31kph when submerged, and 14mph/22kph on the surface.
The bulbous bow houses sonar equipment.
Up front were 6 torpedo tubes. Initially, there were two more in the back, but these were later removed.
The Ocelot helped contribute to the testing and development of the Royal Navy's Mk 24 Tigerfish torpedo.
In case of emergency, this compartment would be used as a staging area for escape, through this small hatch. In the dark. Wearing bulky survival gear.
Said survival gear, along with the respirator that would be plugged into emergency air tubes that ran along the ceiling.
To give the men a burst of energy while waiting potentially hours for their turn to escape, inside these cabinets were rations of barley sugar candy. Apparently they tasted terrible, perhaps as a preventative measure to ward off snacking sailors.
The Ocelot could carry up to 24 torpedoes, most of which would be stored in here. You enter through the torpedo loading hatch.
Eventually every sailor would get their own bunk, but that isn't always the case in older subs.
If you weren't on shift, you were probably in your bunk or in one of these areas. The Ocelot had 7 officers, who had their own areas, and 62 enlisted men, who had bunks all over the ship.
I've toured a lot of subs, and for one of this era, the Ocelot/Oberon-class had a relatively large amount of space dedicated for the crew.
Apparently the dress uniforms were strictly for formal events. Once a sailor was on board, it'd go under his bunk to stay "pressed." He would default to shorts and a t-shirt.
As with all navy vessels, the officer's accommodations are a little nicer.
Silence is the key
The Ocelot, named after the cat of the same name, is the 8th ship in the Oberon-class, and the oldest remaining. Designed in the '50s to replace the post-war Porpoise-class, they were an improvement in a number of ways, not least stealth. Anything that could make noise was isolated from the hull. She was one of the quietest ships of her day, and was tasked with a number of Cold War missions that we'll probably learn about eventually. But maybe not. The steel used for the hull was also an upgrade, allowing the sub to dive even deeper into the abyss.
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The bulbous nose held an advanced sonar array, the ears, and technically "eyes" of the sub. Initially, she had six forward torpedo tubes, and two aft. As you'll see in the photo tour, the rear two were removed as the Ocelot's mission evolved.
While the Ocelot's sister ship, the Onyx, fought in the Falklands War, the Ocelot never saw open conflict. In addition to patrol and training missions, she also helped test a new torpedo for the Royal Navy. She was decommissioned in 1991. The BBC interviewed some of the crew about what life was like on board.
Far side of the world
While the Oberon-class was built for the Royal Navy, several were sold to allies and nations of the Commonwealth. The Ocelot is the only one left in Britain, but others are available to tour around the world.
The most remote is the HMAS Ovens, in Freemantle, just south of Perth on the west coast of Australia. I toured the Ovens in 2015, which you can read about in Hot sub time machine: A photo tour of the HMAS Ovens submarine and see in the gallery below.
The HMAS Ovens, a museum ship dry-docked in Fremantle, Western Australia, served in the Royal Australian Navy for 26 years.
The diesel-powered ship was not named after a gas range. Rather, it honors Irishman and Australian explorer John Ovens (1788-1825).
For the full story behind the tour, check out "Hot sub time machine: A photo tour of the HMAS Ovens submarine."
Before you head out to the ship, in the museum itself is one of the 448 battery cells. Each is 2 volts, run in series in two batteries, for a total of 440 volts.
As you walk out to the ship, on display is a nose cone from an Oberon-class boat. The torpedo with the orange stripes is a WWII-era diesel-powered torpedo.
Quite a tight fit, though I guess that makes sense. Up top, sonar array.
On the walk to the sub is a hydrophone, the "ears" of the sub. Never knew what these looked like before.
Three torpedo tubes on each side. Originally there were two more in the stern, but as you'll see, they're gone.
No fancy pump jets for this sub, just two old-fashioned screws, driven by electric motors (and electricity from two V16 diesel generators).
Originally the Ovens was just equipped with torpedoes, but eventually it was able to fire Harpoon missiles, horizontally, from the torpedo tubes. They'd head to the surface, light their booster rockets and scream through the air toward their target.
You enter the Ovens by going up a few flights of stairs, and climbing down through the torpedo loading tube. This is surprisingly common, since the original way of entering the sub involved enlistment (kidding; a ladder).
Silence IS golden. Note the Jolly Roger.
The railing is for the safety of sailors so they wouldn't slip off into the sea (from which there's no easy way back up again).
Down you go! This is the view back up the entrance. It's a fairly tight fit.
Here you can see all six torpedo tubes. The orange suit is used in an emergency evacuation. The silver tube at the top of the picture (with the two lines of red tape) is the escape trunk.
The next room down is the main crew bunks. Each main crew member gets his own bunk. This is also where the crew ate their meals.
The main entrance. Rather nondescript, isn't it?
Guns and ships and so the balance shifts
The Ocelot is located at the Chatham Historical Dockyard, about an hour east of London. It's worth taking a bus to the docks from the train station, if you're going on foot. The walk is longer than it looks on Google, as the pedestrian entrance is on the far side of the facility, not where Google Maps says it is. There are two other ships and more to see, and we'll be covering them in a few weeks.
Guided tours of the Ocelot are available throughout the day, and after you buy your ticket for the Dockyard, you can pick a time that's convenient for you. Tickets are £24 (approx. $32USD/$43AUD), and are a bit cheaper if you buy them online. The Docks are open mid-February to early December, 10am to between 4 and 6 depending on the season.
In the meantime, check out the gallery above for a look inside this classic diesel-electric submarine.
In his alternate life as a travel writer, Geoff does tours of cool museums and locations around the world including nuclear submarines, medieval castles, iconic music studios and more.
You can follow his exploits on Twitter, Instagram and on his travel blog BaldNomad. He also wrote a bestselling sci-fi novel.