Inside the historic Liberty ship SS Jeremiah O’Brien

Ahoy to the SS Jeremiah O'Brien, one of the last remaining Liberty ships, and a participant in Operation Neptune, aka the D-Day invasion of Normandy. 

For more about this ship and this tour, check out Legendary Liberty: Inside the only remaining Liberty ship from D-Day.

Liberty ships were designed to be cheap and fast to build and reliable to run.

The O'Brien was built in Portland, Maine, and made multiple trips in the Atlantic, and later the Pacific and Indian oceans. 

She's 441.5 feet long (134.5 meters) and 57 feet (17 m) wide.

Most Liberty ships had either four, or like the O'Brien, five cargo holds.

Liberty ships typically had between 59 and 102 men, depending on the voyage and overall mission.

They could transport around 10,000 tons of cargo.

With no guarantee they'd be operating in a traditional port, they had extensive equipment to aid in loading and unloading their cargo.

Liberty ships had minimal defensive weaponry. On the stern the O'Brien had this 5-inch/.38-caliber gun.

The O'Brien is docked at Fisherman's Wharf in San Francisco, right behind the USS Pampanito, which we also recently toured.

The officers' mess.

The chief steward's compartment. He would oversee the meals, cooks, cleaning duties and so on.

The upper portions of two of the O'Brien's holds are partially open, containing a museum within a museum.

None of the lower holds are entirely open, but there are viewing areas like this one, allowing you to see down into them. Pretty sure that guy is going to get in trouble for relaxing on the job.

There's also an extensive area dedicated to the D-Day landings. Several years ago we checked out the Normandy Beaches for the 70th Anniversary. 

In addition to the landings themselves, the O'Brien completed 11 journeys between the UK and France between June and September 1944.

The Liberty ships carried food, ammo, jeeps and whatever was needed by the troops. In the lower holds they could carry water, grain and more.

Youth groups can sign up for an overnight stay.   

After the war, the O'Brien was mothballed near San Francisco for 33 years. 

It's a bit of a hazy day, but you can make out the Golden Gate bridge to the left and Alcatraz to the right.

The petty officers' mess.

The oven was, and still is, heated by coal.

Compared to warships, the crew accommodations on Liberty ships are quite lavish. This isn't the captain's cabin, or even the first mate. It's for the second assistant engineer.

Even more expansive, this is the cabin for the third mate.

The first mate's cabin has a bit more of an office feel to it, fitting for his role on the ship.

Since the O'Brien isn't just a museum but a seaworthy vessel, these have been restored to Coast Guard-approved levels.

One of two locations where the ship is piloted. We'll visit the flying bridge a little later.

If you stand in front of the porthole, this is the view. From the wheel, not so much. Generally speaking, though, the person manning the wheel didn't need to see out, just follow orders from the officers who could.

Adjacent to the wheelhouse is the chart room. 

Not really that much bigger or nicer than most of the other cabins. 

The chief radio operator's cabin with some period radio gear.

The main radio room with gear that still works and still has a licence to broadcast.

The O'Brien had eight 20mm anti-aircraft guns.

The two oil-fired boilers exhaust through here. We'll head down to the engine room shortly.

The view forward from the flying bridge.

The O'Brien typically had a complement of 41 merchant marines and 18 Navy gunners.      

Watch your fingers, toes and noggins as you head into the (working!) engine room.

Steam generated by the boilers gets fed into this triple-expansion steam engine. 

This was already decades-old technology when the O'Brien was new, but it was rugged and inexpensive.  

Speed was not a priority. Liberty ships cruised at around 13 mph (21 km/h).

Conveniently, there were two engineers on duty during my visit.

The only way to keep a 70-plus-year-old engine running is with continual maintenance. 

The boilers are lit several times a year for cruises around San Francisco Bay.

The boilers can produce 24,000 pounds (10,886 kg) of steam per hour each.

The switchboard still works.

The three generators can create 20 kilowatts each. Only two were originally used to create power for the ship. The third was used power a coil that circled the entire ship and created a magnetic field in a technique called degaussing. This helped the ship avoid magnetic mines.

Small, medium, large and extra-large. Also note the sea level line in the upper right.

The "triple expansion" describes how the steam is used three times, across three increasingly larger cylinders.

The O'Brien's engine room doubled for the Titanic's in James Cameron's 1999 classic film.

The boilers generate heat by burning fuel oil. The steam lets the engine generate around 2,500 horsepower. 

Via the National Archives, this is an unidentified Liberty ship being loaded in Boston Harbor in 1943. The O'Brien likely loaded up at a similar dock the same year before its first trans-Atlantic crossing.

This picture, also via the National Archives, shows another unidentified Liberty ship loading cargo from a different part of Boston Harbor circa 1944. 

With a foggy Golden Gate bridge behind, the SS Jeremiah O'Brien sits ready for visitors or a tour around the calm waters of the San Francisco Bay. 

For more about this historic ship, check out Legendary Liberty: Inside the only remaining Liberty ship from D-Day.