USSNewport News(SSN-750) departs Souda Bay harbor, Greece. Photo by Mr. Paul Farley.
Out of a total of 70 submarines in the Fleet today, about 46 are Los Angeles (SSN-688)-class submarines. The Los Angeles-class is reasonably maneuverable in the hands of an experienced shiphandler.
I have been a ship pilot in Pearl Harbor, Hawaii, for the past six years. Fifteen Los Angeles-class submarines are now homeported here, and all the rest of the Pacific Fleet submarines of the class have passed through at least once.
Twice a year, the Submarine Command Course is conducted at Pearl Harbor. The course includes submarine shiphandling classroom training and an unassisted landing and underway by each student. The conning officers on our Pearl Harbor homeported submarines are proficient at handling their ships, routinely making unassisted or minimally assisted moves to and from all our berths. This includes the winding channel to the weapons piers at West Loch, with a tight quarters 180 degree turn to the berth. Our submarine commanding officers have developed their shiphandling skills taking advantage of the unique characteristics of their vessel.
What is special about handling
the Los Angeles-class submarine?
Let’s review the basics of the vessel. While only 362 feet in length, the submarine displaces over 6,000 tons, a great deal of mass. The majority of this mass is underwater, and this mass tends to stay in motion. When in a turn, the submarine continues to turn long after the rudder is placed amidships or the Secondary Propulsion Motor (SPM) is stopped.
Since most of the surface area of the submarine is below the waterline, effects of current are strong, while effects of the wind are much less than on a surface ship. However, the submarine’s sail does act as a sail, and side winds will push the bow more than the stern at speeds through the water below about two knots.
Propulsion is via steam turbine.
The propeller turns clockwise with an ahead bell, counterclockwise with a backing bell. Since the propeller is at the extreme aft end of the submarine, aft of the rudder, the torque walk of the stern to port with a backing bell is reasonably pronounced. The torque walk is mitigated with certain types of propellers.
The rudder is large, extending above and below the propeller. As mentioned earlier, the rudder is placed forward of the propeller, so many normal rules of single screw shiphandling go out the window. With a little thought and practice, this rudder placement can be used to advantage in shiphandling.
Secondary Propulsion Motor (SPM)
The SPM, commonly called the “outboard,” is a retractable, azimuthing thruster located well aft and centerline on the Los Angeles-class submarine. The SPM can push in any direction, but can only turn about 200 degrees either side of dead ahead. So, to go from “port 160 degrees” to “starboard 90 degrees,” the SPM must be trained clockwise through dead ahead. This can create moments of great anxiety when the stern is quickly approaching the pier and the SPM must be trained to the other side to check the swing. The SPM can be trained while running, enabling fine control of the stern while making an approach or clearing a pier.
Another significant characteristic of the SPM is that it is either on or off; it has no throttle control, but is still very effective in maneuvering the 6,082 ton displacement submarine. This effectiveness is due to the SPM location well aft and deep in the water and the fact that the SPM propeller is in a nozzle designed to increase its pushing power by about 30 percent. Proven techniques for optimum use of the SPM are discussed throughout this article.
Sailors assigned to Los Angeles-class attack submarine
USSPhiladelphia(SSN-690) stand topside as the submarine gets underway. Photo by Petty Officer 3rd Class Octavio N. Ortiz
Where are the control planes?
On the earlier versions of the Los Angeles-class submarine, the forward dive control planes are located on the sail, in plain view. On the “improved” variant of the submarine, retractable forward control planes are located well forward and below the surfaced waterline. For all prudent shiphandlers, pilots, torpedo retrievers, water taxis, and tug operators: verify the bow planes are retracted before coming alongside.
There are occasions when the bow planes cannot be retracted—for example, due to hydraulic casualties. In this case, ensure any craft coming alongside are well aware of the exact location of the bow planes. Also, when coming alongside a pier with the bow planes extended, ensure the planes are clear of the forward fender before pushing in to the berth.
While we are on the subject of submarine control planes, it is worth a reminder that all classes of submarines have large horizontal stern planes extending well outside the width of the hull. The stern planes have proven capable of opening the bottom of a tug. Let’s talk a little more about stern planes, since they are always present but not visible.
First, any craft supporting a submarine and not familiar with submarines should be warned to stay well clear of the after area of the submarine. Second, make sure the stern planes will clear the fender, or camel, when landing or clearing a berth. Third, should a tug or vessel alongside drift aft due to loss of their propulsion or control, the immediate emergency procedure for the submarine is to back full to take the way off and have the screw wash push the craft away from the submarine’s stern.
While on the subject of stern planes, they are growing in length. The stern planes on the Los Angeles-class extend further past the hull than earlier classes of submarines. Some of the newer vessels of the class have sensors and configurations that extend the planes even further. With no changes in fenders or camels, the outside edge of the stern plane now rests only a couple of feet from the pier pilings. There is little room for error, and the prudent shiphandler must be constantly aware of how his actions affect the stern of the submarine with relation to the pier.
Making a landing
Half of a good landing is in setting up a good approach. Know the pier heading. Under most conditions, I recommend an approach angle of 15 to 25 degrees. For a starboard side to landing on a pier with an axis of 230 degrees true, a good approach would consist of steering straight for the forward fender on a heading of about 250 degrees true. At this angle, we reduce the risk of running the bow into the pier if we go forward of the bridge mark, and we have the stern far enough off the pier so that it can be maneuvered toward the pier to pivot the bow out, without running the risk of driving the stern planes into the pilings.
While coming alongside, I advise never having the stern closer to the pier than the bow, and to touch down on the forward fender with one to two degrees angle bow in. Once the bow is anchored against the fender with the bow line or with a tug pushing, bring the stern gently against the after fender with short runs of the SPM. Once alongside, with a maneuverable tug on the bow, we normally hold the submarine against the fenders by having the tug push just hard enough to hold the bow on the forward fender while continuously running the SPM on the beam toward the pier to keep the stern against the after fender. If the submarine creeps forward or aft, a small change in the angle of the SPM will check the motion.
Note: This only works well with a very maneuverable tug you regularly work with. In other situations, get the bow against the fender with line one tight, then bump the stern in with short runs of the SPM until the stern touches the aft fender and the slack is out of line four to hold it there. You can expect to constantly use short runs of the SPM at various angles to keep the submarine in place while getting the rest of the mooring lines over and doubled.
Get line one over early and take it to the capstan. Regular practice with the line throwing gun can speed the process immensely.
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