USS Cole bombing - regarding the bomb itself

I assume that any bomb, even a large one, that can blow a hole through the hull of a destroyer must employ a shaped charge. My understanding of these things is quite limited and I may well be wrong about this, but is it not the case that for a shaped charge to “work”, i.e. to penetrate an armored or reinforced target, it must be either abutting, or very close to, the target surface?

My question, then, is: just how close was the terrorists’ boat to the Cole when the bomb detonated? Was it actually touching the Cole (or within a foot or so)? If not, then how could the shaped charge be effective? And, if it was actually touching the Cole (or within a foot or so from it), then why was the terrorists’ boat allowed to get that close, notwithstanding the ostensible rules of engagement?

Thanks!

I have not read details on the Cole bombing, but I believe the damage was caused by a large bomb but not a shaped charge. It was a large hole, not characteristic of a shaped charge. And if I remember correctly the first time they tried to bomb a ship, the small boat they used sank at the dock. The Cole was the unlucky target of a second attempt. As for the tactics, they simply motored up to the side of the Cole. At the time, the Navy was not willing to shoot or intercept anyone just for getting too close. They were warned away, but obviously didn’t pay attention.

That seems to be the signature of all successful terrorist attacks-find a weak point and be successful once.

Obviously the Navy now has strong rules against allowing any vessels approach a Naval vessel. Small boats are deployed and if necessary guns.

“According to former CIA intelligence officer, Robert Finke, the blast appeared to be caused by explosives molded into a shaped charge against the hull of the boat. Around 400 to 700 pounds of explosive were used.”

http://en.wikipedia.org/wiki/USS_Cole_bombing

Following that link from Wikipedia you get the actual comment:

*ROBERT FINKE, FMR. INTELLIGENCE OFFICER, CIA: Well, Roger, based on what I’ve seen, I have some difficulty. I think it’s a very complex situation here. Number one, I have not heard conclusively was the boat fiberglass or was it a Zodiac type. If it were, say, the fiberglass type, they could have had explosives, either very high like Symtex or some other type of explosive, molded to form a shape charge.

Now, based on the hole in the side of the ship, I have a strong feeling that some of those explosives were carried below the water line on that boat that went up to help moor it.

Now, as for an imprint, once the immediate search team gets in there – well, they’re already in there now, they’re going to start in the blast area and work outwardly. And they are going to be able to make determinations from some of the residue just from field testing there – there’s several field tests they can do – of possibly what type of explosive it was.

Again, I feel like, just watching all the coverage on it, that it was some type of shape charge. I don’t think that boat could have held thousands of pounds of explosives.*

I would have guessed with rbroome that it was not. Traditionally I think of shape charges making (relatively) small but deep cuts/slices into thick armor. The pictures of the USS Cole show quite a large hole that doesn’t look “pierced.”

But who are we to say, I would probably take Mr. Finke’s word over mine.

I question the assumptions of the OP. First off, are ship hulls armored nowadays? When I was in Newport (as the token Army guy) ships seemed to be eggshells armed with hammers. Major ships were armored, but I am not aware that smaller ones are.

I am willing to be corrected.

Next please remember that for best effect a shaped charge has to be the correct distance from the target for the jet to form. Too close is just as bad as too far. (Of course the blast alone will still take the starch right out of your shorts.)

In my own professional opinion, the large hole made by the blast indicates it was not a shaped charge.

No, not the way we think they are. The last of the “armored” ships were the old school destroyers but they cost way too much in fuel costs to run. They are designed to be sailed in almost all environmental conditions, save from breaking ice that is. The USS Cole is a guided-missile destroyer so its fairly “light”.

The old-school ships like the USS Wisconsin, on display at the Nautilus in Norfolk, with its 16" thick hull was probably the last of a generation of armored ships. But, in all reality, it is much more effective to use guided missiles or air-to-surface to attack another ship.

Also, as the US military is so conscious of public opinion that at that time they did not really prevent small craft from getting too close. Now a days, they will have people on watch with 50 cal’s, surface rovers with M16s and other small arms, plus a patrol boat with a 50 cal on it. Even then, the chance of a speeding boat being intercepted is still slight as it’ll be moving too fast for anyone to make a decision in time to open fire.

They may have tried forming it into that shape, but from a manual I’ve seen there’s an upper bound to a shaped charge diameter effectiveness of around 6 inches. The damage is just from the 400-700 lbs of explosives detonated next to the hull.

Reading Mr. Finke’s comments above, you can see he’s speculating before the investigation even began. In other words, he’s a news media “instant expert” giving an interview, not part of the investigating team.

So I’d discount his comments about 50-75%. Reading the actual Cole incident report would be one of the few reliable info sources.

Thanks everyone. I hadn’t realized that the hulls were relatively thin. That could certainly explain why a non-focused blast could tear right through it.

In terms of the size of the ‘hole’ itself, teach me: are you saying that anything other than a well circumscribed, “small” hole suggests that a shaped charge was not used?

A large nasty gash is an indication an explosive charge was used. Looking at the edges can give a clue if they were high- or low-explosives.

A small hole can be made by a projectile (or an explosively-formed projectile) or by a shaped charge. You would have to look at the after-armor effects to tell the difference.

A HESH (high explosive squash head) would, I suppose make something in-between, a large but well formed hole.

Yes. A shaped charge produces a neat hole which almost looks like it was made with a drill or a punch. The ones from RPGs are an inch or so in diameter, and the biggest I’ve ever heard of make holes ~6 inches across*.

A hole 10 feet across couldn’t possibly be directly caused by a shaped charge. Now if a shaped charge penetrated a compartment and whatever was in that compartment exploded, e.g. ammo, then you could certainly get a big ragged hole. But the edges would be bent outwards, not inwards as they were in the picture I’ve seen of the Cole.

  • I did see an experimental door opener which was a collection of many small shaped charges attached to a flat frame shaped like a ship’s hatch. You tack this thing to the outside of a substantial steel door & set it off & it’ll cut a neat hatch-shaped hole in the door so your troops can charge in. So you got a neat hole about 3’ x 5’ but the actula blast damage was a long narrow strip 1/2" wide shich cut out the 3’ x 5’ panel.

“Light”?

The ship weighs almost nine thousand tons. That’s almost about as big as a WW2 Heavy Cruiser (Northampton class).

Heh.

The hull is not armored in the Arleigh-Burke. Globalsecurity.org says that the “topside” areas are armored but gives no details. I assume that the modern warship is built with missile attacks in mind. Below the waterline, and it’s subdivision that ensures ship survivability. I can’t find out how thick the hull (construction) is.

I was surprised that the Cole had to be “lifted” back to the states for repair. A large ship, a small (looking) hole. I guess they were afraid of rough seas making the damage worse.

Shaped charges can project a plasma “beam” with pretty good range. As much as a hundred yards, possibly more.

Video of a shaped charge killing a tank at longish range:

http://www.youtube.com/watch?v=4YscTXC1AmM

I’m told that the SEC in this case is about the size and shape of a snare drum.

Is it possible for the hole made by a shaped charge (or, what’s more likely, the forces that made the hole) to compromise the remaining target surface to such an extent that its structural integrity and strength are severely compromised? And, in turn, would that make it possible for the “residual” explosion of the bomb/warhead (i.e. that not yet detonated by the time the shaped charge forms and blows) to blow apart the rest of the surface?

In other words, is it ever the case that the warhead is designed such that the shaped charge is “trailed” by more explosive, with the former breaching the target surface thereby allowing the latter to finish it off? If so, I suppose that could explain the damage seen in the Cole bombing photos.

Yes (and no). Lots of HEAT rounds (shaped charges) come in tandem configurations. This is to defeat spaced armor. The first, tiny warhead goes off to blast away the tin plating on the real armored surface. The main warhead then takes on the target.

Do not underestimate the after-armor effects of the plasma stream entering the target. All the bad things it did to the armor, it will try to do to everyone and everything inside. It is messy.

30+ years of explosives experience doing testing/demolition/damage assesment. Not a shaped charge. You’d get a small hole with very limited effects to surrounding metal/surface. The Cole was floated back due to substantial damage to the overall structure. A sea journey, if all the controls could have been restored, would have sunk the ship in any substantial sea state.

Not a traditional HEAT style shaped charge, rather it’s an Explosively Formed Penetrator. Which I guess is just another type of shaped charge, now that I think about it.

Per the cite, the explosive molds a metal dish-shaped cap into a metal projectile, which can then travel a considerable distance—150 m or so, per the SADARM wiki—at its ballpark Mach 5 velocity. A HEAT plasma jet moves much faster—IIRC, around 15,000 feet per second—but must be much closer to the target. Contacting it is ideal. I had thought that self-forging projectiles were difficult to build and design, but the cite indicates that they’re popular IEDs in SouthWest Asia. Who knew? I’d have thought you needed a great deal of uniformity in casting the explosive, if you wanted a decent projectile. And maybe you do if you want it to penetrate a MBT at 150m.

For the OP, global security mentions the DDG-51’s all steel hull construction, but unsurprisingly doesn’t list hull thickness. It does mention that “Extensive topside armor is placed around vital combat systems and machinery spaces”, but doesn’t specify the amount, composition, or thickness. FWIW,this article from The Guardian claims that C-4 explosive was used; the wiki claims between 400 and 700 pounds. (Surprised it wasn’t Semtex or ordinary TNT, assuming the Guardian didn’t just use “C-4” as a generic term for high explosive) Even with no hardened casing, and limited tamping, that quantity of explosive in contact with the hull is going to be bad news for any modern surface combatant, and it was. Thankfully, the U.S. Navy trains very hard at damage control.