The Panama Canal is 49 miles long, including the entrance and exit channels.
It took 34 years to build, from 1880 and being completed in 1914. Originally started by Ferdinand de Lessops, who built the Suez Canal, it was completed by the Americans. De Lessops went bust, and ruined his health in trying. Over 20,000 people died in the attempts, mainly from maleria, yellow fever, and of course accidents.
The maximum size of vessels the Canal can handle at present is around 100,000 tons. However the Canal Company (wholly owned by the Panamanian Govt.) is building two new super locks, one at each end, to handle the largest boats imagined. Each of these new locks will lift a vessel the full 84 feet in one go.
When entering a lock, a ship is moved forward by its own power. It is held in the center by 'mules'. These are electrically powered locomotives, each weighing 50 tons. These move in time with the ship, under the command of the Canal Pilot on the bridge of the transittee. This transit is the only time that a ship's master hands control of his ship to an outside body. Everywhere else in the world, the master is in charge, taking advice from the pilot.
Approaching from the Pacific side, the first locks are the Miraflores. Two locks, which each raise a ship 28 feet. Next is the Miraflores lake, 1.2 miles long, and then the Pedro Miguel lock, which takes ships up another 28 feet. This is the highest water level, and the ships move through the 8 mile long Gaillard Cut into the Gatun lake. Like the Miraflores lake, this is man-made.
having crossed the lake, the Gatun locks take ships back to sea-level in a flight of three successive locks. The last section of the canal is the channel taking the ship into the Caribbean, passing the port of Colon.
We made a fast transit, entering at about 7.15, and exiting at just after 2pm. The normal time is 8 to 12 hours. The best parts are the locking up and down, particularly the down if one is following another vessel. On this occasion, we were at the head of the west bound convoy, so had the locks to ourselves.
Having left the Canal, Black Watch turned north, destination Puerto Limon in Costa Rica.