Sunday, March 30, 2008

Set the Sea and Anchor Detail

Where we last left the USS Theoretical, the ship was auxiliary steaming alongside the pier. The ship is generating its own heat and power and is receiving potable water, telephone and sewer services from the pier.

Let’s get her underway.

Around the ship, the various electronics departments will check out their equipment. The Communications Division “come up on the broadcast,” receiving and sending its radioteletype messages, rather than use the services of the base communications station. The Assistant Navigator and the CIC Officer will hold their own pre-sail briefings with their teams to make sure everyone knows the visual and radar navigation features. If this is not the home port, the Captain, Navigator and the Sea Detail Conning Officer will have their own briefing. The Senior Watch Officer will run the officer’s watch bill by the XO and the Captain for approval. The Chief Bosun’s Mate will run the enlisted bridge watch bill by the First Lieutenant and the Weapons Officer for approval. Other divisions will set their own watch bills.

But enough about those guys, let’s concentrate on what is important: Engineering.

The ship will generally refuel the day before. Naval stations have fuel pipelines to the piers; the ship will top off the DFM and JP-5 tanks. Depending on the time the ship sails, for a single-screw ship, the other boiler will be lit off about four hours before sailing. If it is a twin-screw ship, the other plant will also be lit off. In either event, it is a fairly quick process, as the steam lines are already at operating pressure and temperature, so the boiler(s) being lit off only have to build to operating pressure. Once a boiler in the other plant is up to pressure, the interconnections between the two plants for condensate and steam are closed.

The electricians will call for a working party to help disconnect and drag the shore power cables up to their racks. Each one of the cables carries 3-phase, 440 volt, 400 amp power; they are very heavy. (The cables are left in place until before sailing in the event that an engineering casualty requires shifting back to shore power.) As close to sailing as possible, the boiler technicians will disconnect the fresh water supply lines. The hull technicians will disconnect the sewage line and route the ship’s waste lines to the Contaminated Holding Tank.

30 minutes before sailing, the Sea and Anchor Detail will be stationed. If the ship is going out for local operations, those in the detail will wear working uniforms; if going out for a deployment, they will wear the uniform of the day. Just before the brow/gangway is lifted off by a crane, the interior communications techs will disconnect the telephone lines.

In order to prevent someone from accidentally turning the throttle valves (which are themselves kept locked), a guarding valve keeps steam from going to the nozzle blocks which make up the steam throttle valves. The throttle valves are a series of poppets that lift off to admit more and more steam into the turbines. The bypasses around the guarding valves have been opened so there is 50psi of steam on the nozzle blocks to warm them up. The guarding valve is now opened.

Once the brow is lifted off, the Chief Engineer will request permission to test the rudder and to test the main engines with steam. In After Steering, where the rudder hydraulics are located (and which can function as a local helm station), A-Gang will start the pumps, warm up the fluids and then swing the rudder back and forth. The throttlemen will admit steam to the ahead and astern turbines to spin the screw(s) back and forth. The Chief Engineer will report “engines test sat, ready to answer all bells” to the Bridge. The Maneuvering Combination, “999" is rung up in the Engine Order Telegraph, which makes these commands available: Ahead: 1/3rds (5 Knots), 2/3rds (10 kts), Standard (15Kts), Full (20 Kts) and Flank (25kts). Astern bells are 1/3rds, 2/3rds, Full and Emergency (open `er wide). The throttlemen now will spin the engines ahead and astern to keep them warm, but they try not to generate enough thrust to move the ship.

By this point, one or two tugs will have arrived to help the ship move away from the pier, with a Harbor Pilot up on the Bridge to control the tugs. Destroyers and cruisers can get underway without tugs, but there is a risk of rubbing the sonar dome against the pier, so tugs are generally used. Once the tugs are made up, the command is given to “single up all lines.” Linehandlers on the pier will slip the doubled-up lines from the bollards on the pier and walk them down the pier to opposite the point of the ship where the lines go through the chocks before letting them go. A slovenly linehandler will just drop the lines in the water, while a good linehandler walks the lines over so they don’t go in the water and the uniforms of the linehandlers on the ship don’t get messed up.

When it is time to get underway: “Take in all lines.” When the last line is taken in, the Bosun Mate of the Watch keys the announcing system, blows a whistle, and passes the word: “Underway. Shift colors.” The jack at the bow and the ensign (nautical term for the national flag) at the stern are lowered; another ensign is hoisted to the top of the main mast. The tugs assist in pulling the ship away from the pier and turning it so it is “in the middle of the stream” (the center of the channel). The ship will now head out for sea at a speed commensurate with local practice. On a summer’s day, when a lot of small boats are in the river, ships will generally move slowly, unless there is an emergency or operational reason to move fast, as nobody wants to generate enough of a wake to swamp a rowboat with a bunch of kids in it.

Depending on the port, the Harbor Pilot will disembark with the tugs or will ride the ship out to near the last navigation buoy (the “Sea Boy”) and then climb down a Jacob’s Ladder into a pilot boat. After the Sea Buoy is cleared astern, the regular underway watch is set and the Sea and Anchor Detail is secured. In Engineering, the second boiler in each plant is wrapped up. Once the ship is far enough out to sea, the CHT lines are set to discharge overboard. As late as possible, to ensure that the sea water coming in is clean, at least one evaporator will be switched to distill to the potable water tanks.

The ship’s crew will settle into the underway routine.

2 comments:

Jimh. said...

What is a CHT line? I googled it and came up with little but reference to some sort of pump. Please explain.

The Earth Bound Misfit said...

"CHT" is the acronym for the onboard septic tank: "Contaiminated Holding and Treatment" (although no treatment was done). The CHT line was the sewage line to the pier.