A Navy sub got pulled into the bottom of a speeding oil tanker in the Straight of Hormuz:

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'll bet the sub skipper's got a lot of 'splaining to do.

"Japanese oil tanker passed overhead at a high speed..."

A 300,000 tanker doesn't travel at "high speed." My guess is that it was probably going no more than 12 knots (a Los Angeles class submarine can reportedly do over 31 knots). I think that there are also speed restrictions for large vessels through the Strait.

A check of the tanker owner's website does not indicate the vessel's maximum speed, but does provide a damage report on the tanker:

http://www.kline.co.jp/news/2007/070110_e.htm

"VLCC "Mogamigawa" arrived at Khor Fakkan, United Arab Emirates at 13:10 of Jan. 9 local time (18:10 of Jan. 9 Japan standard time). Inspection by diver commenced around 15:00. At this moment following damages have been found on bottom of ballast tank No.5 which locates about 70 meters ahead of stern on the left:
- approximately 1 m x 5 m of dent, maximum 40 cm in depth
- approximately 10 cm x 35 cm of hole
- approximately 10 cm x 35 cm of hole
- some scratches
Temporary repair was made to stop sea water inflow into ballast tank."

She was a double-hulled tanker. Virtually all new tankers now are double-hulled as a result of the Exxon Valdez accident.

Here's a skipper with a finished career. Go into the scullery, get a fork and stick the C.O. with it, cause he's done.

The Captain is always responsible, but who had the watch? How the hell is it that you allow a ship that big to get over top of you, in a sea lane, with limited room for maneuvering? More than one head should roll on this.

A 300,000 tanker doesn't travel at "high speed." My guess is that it was probably going no more than 12 knots (a Los Angeles class submarine can reportedly do over 31 knots). I think that there are also speed restrictions for large vessels through the Strait.

According to a former submariner friend of mine, while LA class subs can hit high speeds, they rarely travel at those speeds due to noise and the difficulty of SONAR work. The high speeds are primarily used for sprints while the subs real work is slower and more stealthy.

The captain's done for, but it's not entirely his fault even if he will shoulder all the responsibility. The issue isn't just the captain's ability to avoid the tanker, but the fact that the Navy has consistently stuck with large, expensive nuclear boats as exclusive policy. If we had brown-water boats (diesel-electrics or AIPs) in addition to the much larger nuclear boats, operations in conditions such as those in the Gulf would be dramatically easier, safer and more effective.

But that's not as sexy as large, expensive nuclear submarines.

> the fact that the Navy has consistently stuck with large, expensive nuclear boats
> as exclusive policy. If we had brown-water boats (diesel-electrics or AIPs)
> in addition to the much larger nuclear boats

The new Virginia-class and UUV are specifically designed for littoral warfare.

"If we had brown-water boats (diesel-electrics or AIPs) in addition to the much larger nuclear boats..."

Electric is not very flexible in warm climates. The batteries put out less power when the water is warm. The Gulf would be a poor place for a diesel-electric or anything relying on batteries.

Sure, but AIP boats do just fine there. The Virginias are beautiful, but still too large. The UUVs, on the other hand, have great potential in littoral operations.

The new Virginia-class and UUV are specifically designed for littoral warfare.

Just not against a Collins class. ;)

And if the Australians are after you and you're in a Los Angeles class sub or aircraft carrier, your best bet is to surface, ditch, and start waving a white flag.

Electric is not very flexible in warm climates. The batteries put out less power when the water is warm. The Gulf would be a poor place for a diesel-electric or anything relying on batteries.

That's strange. Every battery that I'm aware of puts out less power when cold, not when hot. That's why car batteries are rated by "cold cranking amps" - winter is hard on batteries and cold engines are harder to start.

"That's strange. Every battery that I'm aware of puts out less power when cold, not when hot."

Batteries suck - they're very sensitive to environmental conditions. Power output can be reduced by operating too hot or too cold. There's also a difference between a car battery that's required to produce power for the relatively short period required to crank your car and a battery that has to produce power for an extended period. Cooling starts to become a problem during extended operation. Finally, durability for batteries can be severly compromised by operating at high temperatures. I've heard figures from the telecom industry that lifetime decreases by 50% for every 10°C above room temperature.

> And if the Australians are after you and you're in a Los Angeles class sub
> or aircraft carrier, your best bet is to surface, ditch, and start
> waving a white flag.

No, you just launch your airstrikes from further offshore. There's no reason for a carrier to enter littoral waters.

Assuming the US goes to war with Australia, which is pretty unlikely.

The Australian Navy is mostly a coastal defense force. The US Navy has a broader range of missions. It also has fewer ships than it did in the past. That means each ship must perform more missions, and a ship remains in service for decades so it must be designed for more than just the current threat.

There are lots of specialized ships the Navy would like to have in an ideal world, but in the real world, its budget is very constrained. No matter what you hear on tv, the defense budget is very tight right now. Anything that isn't directly supporting combat operations in Iraq and Afghanistan is getting squeezed hard. Liberals and "compassionate conservatives" would rather spend money on domestic programs like prescription drug coverage and Apollo II than increasing (or even maintaining) the size of the Navy.

"Liberals and "compassionate conservatives" would rather spend money on domestic programs like prescription drug coverage and Apollo II than increasing (or even maintaining) the size of the Navy."

Which is good. I won't cry if the Navy is finding itself a bit squeezed in the financial department.

OK, here's some data from someone who has actually worked in submarines.

I've checked, and it has been declassified that 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.

Now some other facts/opinions: The RAN is not a "coastal defence force". Its mission is to protect the EEZ, also esc orting merchant ships and intervention forces in blue-water conditions, and engage in co-ordinated stand-off attacks vs invaders. Aircraft are Australia's main coastal defence assets, and all our combat aircraft are capable of launching guided weapons outside SAM range. Doctrine is similar to the old Soviet style, but instead of Backfires firing AS-6, think F-111s with AGM-84. Instead of Su-24 with various guided weapons, just lots of F/A-18s also with AGM-84. Plus whatever UGM-84s we could donate from subs etc. All coming in at once, because unlike the Soviets, we had the good computers and links to co-ordinate properly. And in littoral waters, some torpedo attacks at the same time, just to make life interesting.

Even in a Collins (as upgraded) I would not like to take on even an old Flight I Los Angeles sub in littoral waters (assuming the USN still has some flight I's left). Too much of a crap shoot. USN submariners are very, very good. The quality of the boat is only half of it.

Which is good. I won't cry if the Navy is finding itself a bit squeezed in the financial department

That is a short-sighted opinion. It's a watery world and the Navy is uniquely able to project power to where it's needed most, on short notice. This is more than waging war but more about the value of the dollar abroad and having a prosperous economy.

And to .. if you have a large standing Navy then you don't need a large standing Army. Republics with a large Army don't stay republics very long.