Some information is beginning to leak out of the investigation into the collision between the submarine USS Philadelphia and the M/V Yaso Aysen, a Turkish merchant ship. Beyond the fact of damage to both ships and the relief of the Philadelphia's Commanding Officer, little concrete information is available. Some inferences can be drawn from news articles such as Robert Hamilton's recent New London Day article, "Sub Collision Hinges on Right-of-Way" (28 Sep 05).

It is now clear that the Yaso Aysen approached the Philadelphia somewhat abaft the starboard beam. Speculation turns on whether this was a crossing situation or overtaking situation under the rules of the road. These International Rules of the Road govern how ships in sight of each other maneuver to avoid collision. They apply in most situations where ships find themselves outside of US territorial waters.

The specific issue that current speculation turns on is whether the Philadelphia was crossing in front of the Yaso Aysen or Philadelphia was being overtaken by the Yaso Aysen.  The dividing line is two points abaft the beam. To a seaman a Point is 11.25 degrees (there are 32 "Points" to the compass). If the Yaso Aysen was approaching the Philadelphia from more that 22.5 degrees behind Philadelphia's beam she was overtaking and the Rules of the Road enjoin her to remain clear of the Philadelphia.

In contrast, if the Yaso Aysen was forward of this angle on the Philadelphia's beam, the Yaso Aysen was enjoined to remain on course and speed. Philadelphia would then have to remain clear. The "Sidelights" are arranged to enable those controlling ships to easily recognize the developing situation. However, actually seeing these lights can be tricky at sea. While it seems simple and clear, to a seaman it is well known that many things can cause misreading of lights.

In the case of submarines, the configuration of lights does not always precisely conform to the Rules of the Road. There is provision for that. The Secretary of the Navy files a letter with the International Maritime Organization stating that submarine lights may not precisely conform and outlining the deviation. This is allowed so that unique structure and design of various ships and submarines may be accommodated. For example, the submarine's stern light is mounted on the rudder. Since the entire rudder moves, the arc of the stern light moves and thus can be confusing when a submarine is moving its rudder.

An issue of the final maneuvers of the Philadelphia (L., USN Photo)just prior to the collision has been raised as confusing the matter of liability. Under the Rules of the Road, such confusion should not exist. The governing point is that the Yaso Aysen and Philadelphia approached each other, each steering certain courses. The geometry of the situation will govern and subsequent maneuvers to avoid collision do not change the initial situation from crossing to overtaking or vice versa.

As I see it, the maneuvers mentioned in news articles describe actions taken "in extremis." Under the Rules of the Road this is that point in the developing collision when action must be taken by both ships to avoid collision. Notably, until this point the Rules of the Road impose on the vessel known as a "Stand on Vessel" a constraint to maintain course and speed so that the other vessel can knowledgably and safely maneuver to stay clear.

From the news descriptions, the crux of the issue will be which ship was required to remain on course and speed. Thus far, it has been presumed that the Philadelphia was being overtaken, and thus responsibility for remaining clear belonged to the Yaso Aysen. However, if this was truly a crossing situation then Philadelphia was to remain clear. 

This should be apparent from required logs on the Philadelphia. Surely the story told by these logs had something to do with the evolving investigation and the decision to relieve Cdr Steven Oxholm, the Philadelphia's CO.

There is potential for the Navy's relief of Cdr Oxholm to prejudice the Navy's case at Admiralty Court. This will be a minor issue overall. 

There are two significant issues of Philadelphia's required display of running lights. First the "movable stern light", and second the possibility that the Submarine Identification Beacon was not shown (though it is commonly shown) had potential to confuse those on the Yaso Aysen's bridge. These may work against the Navy.

I believe that the propensity of large merchant ships to steam through and ignore small boats, expecting them to get out of the way, had something to do with this collision. My sense is that Yaso Aysen interpreted the Philadelphia's lights as those of a small boat and ignored the rest of the developing picture. 

Cdr Oxholm and his Officer of the Deck were obligated by the Submarine Force Ethos to turn away 10,000 yards earlier, regardless of the Rules of the Road. He did not and has paid the price.

Commanding Officers have a document called Standing Orders that interpret law and regulation and give personal direction to Officer's of the Deck. It is surprising how few COs will say simple and direct things like "Don't have a collision" in Standing Orders. In my observation, the best COs always had simple things up front in their orders, like: "what ever else you are doing don't have a collision." 

Officers of the Deck solve many problems and cope with many things during their watch. Sometimes they may allow the wrong thing to be at the top of their "to do list." Such direct and simple guidance by their CO goes a long way to make sure the priorities of the Officer of the Deck are kept right.

Will this case go into Admiralty Court? Not necessarily. Depending on the desire of the United States to seek a claim against the owners of Yaso Aysen or the size of a claim submitted by those owners against the Navy this may not be worth taking to court. 

If the Navy were to concede liability, the Secretary of the Navy is authorized to pay "small" claims directly and without seeking Congressional approval. This direct authorization once was for claims of less than $1 Million dollars.

The Navy's investigation will have to meet certain requirements. It is done in contemplation of litigation and will determine the path the Navy takes with regard to admiralty proceedings.

So, in the end, it probably will not go to court unless the Navy is confident of prevailing or the owners of the Yaso Aysen are greedy.

Lt. Raymond Perry...