Keeping the blogosphere posted on the goings on of the world of submarines since late 2004... and mocking and belittling general foolishness wherever it may be found. Idaho's first and foremost submarine blog. (If you don't like something on this blog, please E-mail me; don't call me at home.)

Wednesday, January 10, 2007

USS Newport News Collision: The Ultimate Zoof ?

The Navy has apparently come up with an explanation for how the USS Newport News (SSN 750) hit the Japanese tanker M/V Mogamigawa that actually makes some sense and may spare the CO his career. From The Virginian Pilot:

The submarine Newport News was submerged and leaving the Persian Gulf when a mammoth Japanese oil tanker passed overhead at a high speed, creating a sucking effect that made the sub rise and hit the ship, the Navy said Tuesday.
That is the preliminary finding of Monday's collision between the Norfolk-based submarine and the Mogamigawa, a 1,100-foot-long merchant ship displacing 300,000 tons.
Both were southbound, crossing the busy and narrow Strait of Hormuz while heading into the Arabian Sea.
"As the ship passed over the sub, it ended up sucking the submarine into it," said Lt. Cmdr. Chris Loundermon, a spokesman for Submarine Force in Norfolk.
"It is a principle called the venturi effect," he said.
I'm sure they'll have to do some calculations to make sure this is plausible, but if the ship reported they weren't trying to come to PD, and assuming the ship control party didn't just randomly lose depth control at the worst possible time, this probably sounds as reasonable as anything else. There are lots of forces involved in operating a submerged submarine, and an upward force from the venturi effect is one submariners don't practice a lot in the dive trainer. (My old boat once popped to the surface because we hit a patch of colder water due to hitting the boundary where a river was discharging into open ocean, but that's another story...)

Assuming this explanation is true, the question now becomes: will the CO and crew be exonerated? The Sub Force has already shown that uncharted seamounts aren't a justification, and they do always warn you about the dangers of being "zoofed" -- submarine slang for having a surface ship pass directly over your position. The reason I always learned was that you didn't want to have someone above you in case you had to emergency blow, but it could be that there's a warning about the Venturi Effect buried in some tech manual. If there is, the CO is probably sunk. If this truly is a "first time we've thought of it" thing, though, the CO and crew might be fine -- unless, of course, all the "helpful" squadron, group, and force types who pour onboard a boat after an incident find anything that shows the Newport News wasn't operating completely in accordance with approved procedures...

In any event, the sub is apparently heading back to Bahrain for an inspection. If the boat really was sucked up into the tanker's stern, and if the tanker's propellers got ahold of the sonar sphere, we could see some interesting pictures.

Staying at PD...

Update 2014 10 January: Skimmer Dave over at The Galloping Beaver has a great explanation of the Venturi Effect near the bottom of this post. An excerpt:
I've handled a VLCC tanker. They leave a huge hole in the water, particularly when loaded to the marks and up to a typical service speed of 17 knots. That hole gets filled with water rushing into the cavity created at the stern of the ship. In simple terms the water filling the cavity rushes down from three sides and creates a force which moves in the same direction of the ship and operates like a swirling vortex, sucking everything from both sides of the ship down, once it reaches the stern and up and towards from the water column below. At the risk of over-simplifying a description, it's very much like effect of a vacuum cleaner nozzle.
A submarine too close to that vortex, with little warning, would be sucked into the filling cavity and propelled in the direction of the stern of the surface ship. The thing about it is, I've actually seen it happen...
You'll have to head over there yourself to read about what he saw.

Update 0903 15 Jan: Since Subsunk at Blackfive was kind enough to send readers here, I figure I should be helpful and direct them to my other posts on this topic as well -- here was my initial post on the collision, and here's my follow-up post to this one.


Blogger Harold said...

The submarine slang link in the post you linked to is down. :(

1/10/2007 12:18 PM

Blogger Dave said...

Many thanks for this! As a result of your comments and post I've seriously updated mine.

1/10/2007 12:32 PM

Anonymous Anonymous said...

Back in the late 70's while on patrol we had a large merchant go over us and her bow wave pushed us down about 60 feet. The dive ordered the COW to pump DCTs, the OOD countermanned the order and told the dive to flood DCTs, which he did, we went down a further 100 feet. Good thing we did because the when his stern went over us we were sucked up about 50 feet.

1/10/2007 1:16 PM

Anonymous Anonymous said...

A continuing pattern of U.S. submarine collisions tends to implicate command training deficiencies as much as the COs of the subs involved. The "zoof" (passing tanker suction theory) explanation would support the training deficiencies theory.

If we can save the careers of good submariners, I am in favor.
Assuming sonar was manned (pretty safe assumption) during submerged transit, certain equipment would have indicated sudden changes in ambient pressure, and data would have been routinely recorded, potentially absolving a crew.

That leaves two major problems, however. Near a known, crowded bottleneck such as the strait, why would extra caution not have been exercised prior to approach?

Next, the size of a tanker necessary to create the alleged suction effect would have been known long ago from studies performed at such places as the Charles Stark Draper Laboratory and disseminated during routine submariner training classes. (According to Daniel Boone sailor's anecdote above, that is probable).

Problem is, this was no boomber and the ship size of the tanker was so large it is presumed no submarine crew should be unaware of its presence. Perhaps too many of the crew are asleep these days! -Mad Dog

1/10/2007 1:54 PM

Anonymous Anonymous said...

if the sub commander is "experienced" then he is well aware of the "zoof" phenomena

so, what is the excuse for not (and i mean NOT) leaving a big cushion between your sub and a VLCC passing overhead ???

~ theDdoubleSstandard

1/10/2007 2:33 PM

Anonymous Anonymous said...

"so, what is the excuse for not (and I mean NOT) leaving a big cushion between your sub and a VLCC passing overhead ???"

How about "because you're already hugging the bottom and there was no place to go"

I don't know enough about this incident to judge anyone one way or the other. But keep in mind the following...

The strait of Hormuz is relatively shallow - less than 200ft, and is somewhat confining - less than 20mi wide at places. Couple this with the relative speeds of the two vessels and the "hull masking and baffle effect" of a very large tanker approaching from the stern noted earlier, and it might be that the NN couldn't have avoided what happened because of their submerged condition, the lack of maneuvering room in the strait, and the lack of timely warning about what was about to happen.

It may be that I am completely wrong and the crew of the NN screwed up royally. Be that as it may, I am willing to give them the benefit of the doubt and cut them a large amount of slack until all the facts are in.

1/10/2007 2:56 PM

Anonymous Anonymous said...

dear Roy Greenwell:

thanks for the insight and possible explaination

but your response raises a more disturbing issue

your post correctly implies that this was very foreseable accident

so, this make the situation worse 'cause if this realistic problem was forseable then it was also preventable !!!

side note - kinda like this Iraq fubar

~ theDDoubleSstandard

1/10/2007 3:12 PM

Anonymous Anonymous said...

I've read of the same venturi effect taking place on surface ships doing unrep. And "Hiya", Harold :)

1/10/2007 5:56 PM

Anonymous Anonymous said...

I would love to give the crew of the NN the benefit of the doubt on this one.
Unfortunately, having seen firsthand how mishap investigation boards are conducted with the submarine force, I am not so optimistic about the outcome for this sub's skipper.
Undoubtedly as was earlier implied, the squadron "helpers" will identify some mundane detail (WQC-2/RACS wasn't sufficiently monitored and could have prevented said zoof...) that was overlooked and leverage that to crucify the skipper.
I wish I could be more optimistic, but ultimately the submarine force is hell bent on self-inflicted misery. Why do you think we average nearly two collisions/groundings a year despite all the training/requirements/assessments forced upon us?
Did anyone else note that this occurred on the second anniversary of the USS San Francisco grounding? Spooky...

1/10/2007 5:59 PM

Anonymous Anonymous said...

These submarines are not built to play it safe...there is risk in what they do to protect the interests of tax payers........the biggest problem for the crew right now is that this incident is in the press.

In the big scheme of things, this is nothing but a sideshow.

Anybody who has served knows there are plenty of incidents unreported in the press where the C.O survives...commended privately in fact.

If anything it's a P.R. mess that will be fixed with a relief or two.

1/10/2007 6:09 PM

Anonymous Anonymous said...

Even if you get that "perfect" moment to start moving out into the straits (as I have learned when I went thru the Straits of Gibraltar), there are so many variables that, as in a chess game, though foreseeable, are not always avoidable. And then things that you couldn't possibly have foreseen pop up out of nowhere, leaving you with little or no time to react. Your only choice is to but ride it out until it passes, and assess the situation afterwards.

I am not familiar with the Straits of Hormuz, but based on the conditions stated by Mr. Greenwell, there may well be mitigating circumstances for this incident. I certainly hope so, the Sub Force could use a lucky break for once. It's heartbreaking to see good submarine sailors, some of them friends, careers end from things like this.

As it just so happens, I may have an inside source on this particular incident. If I am able to get any first hand information, I will post it on in my blog - observing the all important security caveat, of course.

1/10/2007 6:30 PM

Blogger lazlong said...

As far as the "zoof" theory, I have heard about it (I was a Nuke), so I don't think that training was an issue. If it was, then the CPOs would be most to blame, because it is little nuggets of wisdom from their experience that teaches the crew about this effect, and I highly doubt that every CPO control watchstander would forget something like this, in shallow water, where there is no room for error. Not to mention the experienced OODs, CO and XO who would, by their time in the Navy, would have known about it and explained it to the other OODs, the DOOW and COW, sonar, etc. Oh, and don't forget their squadron who must have trained the control watchstanders during inport periods (while the nukes were busy fixing stuff on 18 hour days to get to the striaghts!)...suffice it to say that training wouldn't have been a factor, and only time will tell what exactly happened.

As for this happening on the 2 year date of the SFO grounding.....I discussed it with some of my shipmates from there, and yes, it is kinda freaky that it happened on that date (allthough it is merely a coincidence).

1/10/2007 10:22 PM

Anonymous Anonymous said...

Not to beat a dead horse too much, but until the facts are in, I'll give the NN crew a break.
Being a Nuke on a couple of 688's and part of the tracking/PCO training party during the 80's & 90's, we were well trained on zoofs. I left active duty in the mid-90's because the PACFLT mentality wasn't "doing it right" as I was/had taught, but "looking good" when reviewed. I had the privilege to train some of our current Flag Officers when they were PCO's.
I think the current batch of CPO's and CO's need to reevaluate how they've trained. After visiting my old boat prior to their last deployment, I was shocked to find out I knew more about the "old" & reliable equipment in the control room than the FTLPO. He knew the buttons to push, not the knobs to turn. Everyone's post points to one fact, now they are relying too much on technology when the hard data right in front of them.
I think some of those senior people forgot what reality looks like. The US Silent Service has been a little too noisy. 12 lost (publicly) in 6 years is a little too much for me.
I just want to hear about the new boats, "toys", liberty ports and more ways for the Nukes to visit them more often. Sorry for the rambling folks!

1/11/2007 1:41 AM

Anonymous Anonymous said...

It's obvious the AN/UYK-43 4 STOPPED. Now if they had the Q-70 install, they would have been able to detect the ambient pressure changes discussed by the 'tard before

1/11/2007 10:23 AM

Anonymous Anonymous said...

why don't you geeks quit trying to solve some "Gov'ment Conspiriacy" and get back to your worthless job at the comic book store selling Magic cards to other geeks!!!!

1/11/2007 10:31 AM

Anonymous Anonymous said...

Back in the day when i was "lucky" enough to go though the straits we had all the sonarmen up on almost battlestations. There where so many contacts that it was very hard to keep them all organized. It was very shallow 200 feet and sound was bouncing all over. We ended up saying if its on the right moving right and on the left moving left leave it alone. The CO was even driving the boat on the way in and way out.

1/11/2007 2:26 PM

Anonymous Anonymous said...

hey guys ive spent plenty of time in the SOH. It is a difficult place to operate, with deep draft merchants, high speeds, narrow angles on the bow, and shallow water. Give the guys a break. Submarining is a tough buisiness,shit happens, and its a wonder that we only have the few accidents that we do.

While every news show is trying to get our soldiers and marines back from Iraq, our submariners will continue deploying in harms way.

1/11/2007 2:59 PM

Anonymous Anonymous said...

What a bunch of scat comments. How many have stood DOOW more than a couple of watches here?
How 'bout some get a clue on shallow water ops and what happens-and how much time you have to react to it?
This is a very plausible event. My jack @ss has never been trained for being zoof'd in shallow water by a high speed 300,000 ton, 1100 foot tanker at speed. I've got 16 yrs of standing dive.
Joel? Is this an actual training topic? I doubt it.
Take a look up on water physics for near bottom and near surface hydrodynamics. Mebbe some of you guys will learn something.

1/12/2007 2:47 AM

Anonymous Anonymous said...

As a former sonarman, I will first admit that I've never operated in the Strait of Hormuz. After first hearing about the collision, I went and did some reading about the bathymetry in the SoH and noted a few interesting things.

First, it's shallow, as has been mentioned. High contact-density in a shallow area is already no fun to begin with.

More interestingly, though, is the mixture of salty Persian Gulf water beneath a layer of fresher Indian Ocean surface water. Even with an otherwise predictable temperature curve, these vertical variations in salinity could really adversely affect sonar performance and buoyancy. When I was in, we were never terribly concerned with vertical variations in salinity except in certain areas near ice and river mouths. With a few exceptions, it was generally accepted that salinity was relatively uniform in a given water mass.

Now, no one knows PRECISELY where the collision happened, so I could be rambling for nothing here.

1/12/2007 4:55 AM

Blogger Alan said...

I don't know much about hydraulics, but the zoof explanation seems plausible. What it is not, however, is the venturi effect.

The venturi effect requires a constricted space, like a funnel. The liquid or air moving through a smaller space will speed up.

It might be the coanda effect.

1/12/2007 8:25 AM

Anonymous Anonymous said...

rebootinit said:

This is a very plausible event. My jack @ss has never been trained for being zoof'd in shallow water by a high speed 300,000 ton, 1100 foot tanker at speed. I've got 16 yrs of standing dive.
Joel? Is this an actual training topic?

I have transited submerged in the Strait of Juan de Fuca on a SSBN and this happened to my ship (minus the suction and subsequent collision, boomers are bigger!). It was spooky - the whole ship started shaking. A really big trace appeared on the AVSDU and we figured out what happened. In Bangor (late 90's) there were discussions ("training"??) and lessons learned about not traveling right in the middle of the traffic lane and also to frequently check your six to make sure you weren't getting run over. I never deployed to the Gulf but I gather there are Lessons Learned published somewhere about this topic. Maybe not though.

And Maybe NN was checking their six and being very careful and avoiding the commonly used traffic lanes but this still happened. The degree to which NN "planned" their submerged tranist of SOH and employed ORM will determine the fate of the key players. So we wait for the investigation results and trust in the system.

Yes, I know, been there. Let's hope everyone keeps their integrity on this one...

1/12/2007 7:07 PM

Blogger Zoe Brain said...

To simplify (for non-submariners):

The huge machinery of a tanker is well shielded by the 300,000 tons of the ship and the oil in it, when "viewed" by a sonar directly from the front.

The straits are a place with lots of reverberation : a tanker side-on and 5 miles away may be 100 times as loud as the one coming towards you at 0.5 miles, and the sound bounces off the bottom, seeming to be omnidirectional. The background noise is huge, like trying to sort out what someone behind you is saying during a noisy party.

Directly behind a ship (or sub) are the "baffles" - that is, the place where the ship's sonar is deafened by its own propeller noise.

Given these circumstances, a sub near the bottom may not have had any chance of detecting and tracking the VLCC behind it until it was too late to avoid. It was probably detected, but range unable to be determined.

So it got "Zoofed", run over by a tanker going 17 knots, when it was going maybe 5. And sucked up into the VLCC's stern, as there wasn't enough clearance to the bottom to avoid this.

Have I got it right?

1/13/2007 2:03 AM

Anonymous Anonymous said...

The strait is ONLY 20 miles wide ,traffic separation schemes are in force, transit dates times for large draft ships are available on web, really high speed 300000 ton tanker at 15-17 Knots !!!?
why dont they just admit that they were trying to sneak out of gulf using tanker as cover, ( happens often as know of instances in my 20Yrs + experience in Merchant marine ) and somebody fucked up.

1/13/2007 2:12 AM

Blogger Bubblehead said...

As always, Zoe, you're spot on.

1/13/2007 7:29 AM

Blogger gary84 said...

I've heard stories about large, heavy, bolted-on panels on hulls of ships & subs getting torn away by venturi forces at high speed, despite all the calculations and modeling predictions of the smartest nav-archs, despite the bolts, it still happens sometimes. Venturi effects, small and large, are not news.

1/13/2007 10:01 AM

Anonymous Anonymous said...

As the Mother of one of the sailors on the NN, I appreciate the concern that some of you have shown for those involved in this collision. I have spoken to my son and of course, the conversation has been rather disjointed for obvious reasons, but I have learned some interesting facts on this site and for that I am grateful. Hopefully this will be resolved shortly and the NN can return to the job that they set out to accomplish for US! Thanks you guys! A "bubblehead" Mom

1/17/2007 12:59 PM

Blogger beenthere,donethat said...

This comment has been removed by the author.

2/26/2007 10:10 PM

Blogger beenthere,donethat said...

Let's get things straight - it is the venturi effect, it is in the manuals, and they should have had precautions in place to prevent just such an incident. If there were no way to safely conduct the transit then they shouldn't be doing it! Risk vs. gain. It's how subs (in particular) are supposed to do business. Therefore, either they screwed up, or the SOH isn't safe to be transited. I strongly suspect the former.

Let's see, since 2001 there have been a couple of groundings, at least four collisions and a several other incidents (including four guys washed overboard) that have resulted in many millions of dollars of damage and twelve dead.

Some people just shouldn't be driving subs. Sad, but true. There's a good reason that when WWII started quite a few of the current COs washed out for lack of skill. There is clearly not enough emphasis on knowing how to drive a sub and how to keep it safe. I treated every SSM just like an RPM. How many others did that? Too few, I suspect. It's nice if you've been an Admiral's aide, but how's that going to help in the big bad sea when things get rough?

Getting sucked up is a boot mistake, or should be. Hopefully the powers that be (who, unfortunately, put all these guys there in the first place) figure this out and fix it.

2/26/2007 10:13 PM

Anonymous Anonymous said...

"why dont they just admit that they were trying to sneak out of gulf using tanker as cover."

Ok, whoever put that is not a smart guy. Anyway, I was there. We did everything we could, but due to not being able to maneuver the way we would've liked aided in allowing the venturi effect to happen. Its like that one scene from the movies when someone is walking down the middle of a busy road. He could see traffic infront of him and could only hear it comming from behind him. He could clearly see ahead and could estimate range. With just a sound comming up from behind, it is difficult to estimate range without turning your head and looking.

And Beenthere, donethat...Get a life man. Venturi isn't covered in any SSM or even in the Oceanography manuals onboard.

4/23/2007 5:43 PM

Anonymous Anonymous said...

The Newport News was warned about this exact thing by the previous deployer. The ship won the battle E and blew off the lessons learned message. The root cause was compliancy and arrogance.

12/15/2007 3:18 PM

Anonymous Paulina said...

So, I don't really believe it may have success.

9/08/2012 11:24 AM


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