Details on San Francisco Grounding Emerge
Robert Hamilton of The New London Day continues his series of articles revealing new light on the recent grounding of USS San Francisco (SSN-711). (Free registration required after one day.) An excerpt:
"In late morning, the ship was at periscope depth, checking to make sure it was on course. Everything checked out; the ship was just over 400 miles southeast of Guam, near the Caroline Islands ridge, but the charts showed that there was no water less than about 6,000 feet deep for at least seven miles around the boat, more than enough of a safety margin for submariners, who are known to be cautious.
"Some time about 11:30, after running through a safety checklist to make sure the boat was ready to submerge, the officer of the deck gave the order to dive. The San Francisco used the dive to pick up speed, and was soon running at flank speed, something in excess of 30 knots.
"Although its destination was to the southwest, it was headed in an easterly direction, probably because it had “cleared its baffles,” or changed direction to check to make sure there were no submarines trailing it in the spot directly behind the ship, where its normal sonar sensors cannot “hear.”
"At 11:42 a.m. Guam time, about four minutes after diving, the San Francisco crashed head-on into a nearly vertical wall of stone, a seamount that was not on the charts. In an instant, the submarine's speed dropped from almost 33 knots horizontal to 4 knots almost straight up as the bow whipped up and the ship tried to go over the obstacle — without success."
This article, while very informative, does have a few problems. Hamilton's use of the word "dive" in conjunction with the ship coming down from periscope depth (PD) is technically inaccurate; in submarine language, "dive" indicates a change in condition from surfaced operation to submerged operation, which is not what happened in this case -- the ship had been at a depth where it could stick its' antennae out of the water, and transitioned to a deeper depth. Also, his later discussion of "water space management" is inaccurate, but not enough to take away from the largely informative nature of the article. Read the whole thing...
Staying at PD...
posted by Bubblehead at 9:26 AM
6 Comments:
The word dive is also used to denote the condition of a submerged boat. "Dived" is an acceptable and "log-book correct" version of submerged, and the opposite of being surfaced, like a condemned man is hanged rather than hung. A ship's dive timeline occurs between sufaced conditions. As a boat proceeds into a dive, conditions of the ship are evaluated at various stages before proceeding to a deeper depth. Ordered depth changes are given to the helmsman as, "Make your depth 400ft." The helmsman responds with a "dive" or a "rise" to the ordered depth. From the standpoint of ship's control, a ship would dive from PD to a greater depth. This would be mirrored in observing a ship's movement. Hamilton is correct. I agree, read the whole article.
1/15/2005 4:59 PM
I agree that Hamilton wasn't trying to make it sound as if the boat went from a surfaced to submerged condition immediately prior to the accident, but rather that he used imprecise terminology. My actual point, which I didn't really express (I had to do some errands), was that it would have been unusual to have gone straight to a flank bell immediately after submerging (note the words in the 2nd paragraph I quoted: ..."after running through a safety checklist to make sure the boat was ready to submerge", which sounds a lot to me like a Rig for Dive checklist), without obtaining a good trim. Granted, the difference between "submerging" and "coming to a deeper depth" are a subtlety that only submariners (like you and I) would pick up on, but submariners are most of the (5 or 6) core readers of this blog.
1/15/2005 6:18 PM
I see what you're saying now, and I agree. I wonder if the author was merely condensing time. I guess that they could have also been doing angles to check stowage, or maneuvering and dive transients for training. One of the things that I loved about Pearl Harbor was the short maneuvering watches. 45 minutes tops. I've always taken for granted how fast depth fall out in the volcanic islands. If it were me, I probably would would have only made a brief check of depth and fix. What grabs me is the 25 year old chart. I'll bet every sub in the fleet uses it. Or did until last week. What happened is horrible, but I hope that the investigation is not just for punitive reasons. I'm also VERY pleased that those EB engineers work for us. I remember watching the Greenville returning to port after sinking the fishing ship, and feeling very safe. The top of the boat is designed to break through the ice, though, and after a deep flank collision with a mountain, I'm even more amazed. I wouldn't want to retest that.
1/15/2005 9:00 PM
The one thing that is still a mystery to me, is why the boat, going to Australia, was going flank to the east. The "clearing baffles" explanation does not make any sense.
Any ideas? A weird PMI plan perhaps?
1/16/2005 4:20 PM
That would be my guess. They were about to hit the Caroline Islands, so maybe their track took a jog over to the east to go through a deeper channel or something. Had they continued straight south, they would have hit New Guinea, so they had to go east at some point.
1/16/2005 5:59 PM
The age of the chart is not the issue. There are alot of older charts out there than the one this incident occured on. That is why the agency that produces such things sends out corrections. With the hundreds (if not thousands) of charts avaliable in the world, it would be almost impossible to issue a new edition to a chart for only one minor change.
Why a simple change was not issued is a problem.
My big question is why would any submariner go that speed within an island chain.
1/18/2005 2:23 PM
Post a Comment
<< Home