Swarm Attack

We often talk about how effective various guns or missile systems will be against a swarm attack but we never look at a swarm attack from the attacker’s perspective in order to get a more realistic idea of what a swarm attack will be like.  If we had a better idea of the characteristics of the attack, we’d be better able to evaluate our defensive systems.  That said, let’s take a closer look at how a swarm attack will be conducted.

I have to preface this discussion with the disclaimer that I have no inside information about swarm attacks.  The ideas put forth here are strictly my own based on what I might do.  Iran practices swarm attacks, to some degree, but I’ve never seen an authoritative write up on the methodology.

The entire crux of the swarm problem is one of dwell time.  Dwell is the time that a weapon must remain focused on a single boat before it can move to the next target.  Until the target can be definitely observed to be killed, the weapon must continue firing.  Otherwise, the target continues to close.

The problem is that a kill may occur without being obvious.  Consider a boat coming straight at us.  Suppose the first shot (be it gun or missile) kills everyone on board, thus rendering the boat mission killed, but the boat continues on its course, at speed.  How will we know that the boat has been killed?  The answer is we won’t.  To all appearances, the boat is undamaged and continuing its attack.  Thus, we’ll have to fire a second shot.  And a third.  And so on, until it becomes obvious that the target is killed.

How do we know a target is killed?  When it’s dead in the water it can be assumed dead.  Ideally, this would occur catastrophically – the boat would blow up leaving just a partial hulk floating motionless on the water.  More likely, the boat will gradually slow down and eventually come to a stop due to accumulated hits and holes from shrapnel.  The problem is that this can take several minutes per target.  Meanwhile the remaining boats are approaching at high speed.   The math on this is grim.  Take a reasonable number of attacking boats, apply a reasonable dwell time of several minutes per boat, and do the math of approaching speeds versus dwell time and you’ll see the problem.  It doesn’t end well for us.

For those of you who doubt the concept of dwell and believe that one shot will equal one kill, please take a look at the videos that are available of gunnery target practice against small drone boats.  There are only a few videos available that I know of but they are consistent in showing the lack of effects from the gun rounds.  The typical drone boat motors back and forth in front of the guns (always at very close range and on calm seas) and over the course of several minutes eventually slows down and comes to a stop.  That’s dwell time.  Fragmentation munitions, which is what almost all the guns fire, just aren’t effective at instantaneously stopping a boat.  A multitude of small shrapnel holes just won’t sink a boat in a tactically useful time frame.

Similarly, the idea of a gun firing a contact explosive munition is unappealing and unlikely to succeed.  For starters, the odds of achieving a hit on a small, fast, bouncing target that is frequently obscured in waves from a bouncing, high speed, maneuvering firing platform is very low.  Recall the Vincennes incident in which many dozens of 5” rounds were fired at boats and no hits were achieved.  Let’s face it, hitting a small, fast, moving target from a another moving target is a very difficult thing to do.

So much for the problem.  Now, the enemy can figure this out, too, so what are they likely to do that would enhance their chance of success?  What can they do to increase the dwell time?

Armor.  The most obvious tactic would be to add some simple Kevlar type armor around the cockpit to help protect the crew and increase their survival time.  We’re not talking about battleship armor that can shrug off 5” shells but, rather, simple flak armor to lessen the effect of shrapnel.  Flak vests for the crew would be another obvious addition.  Depending on weight, some simple armor could be placed around the engine and throttle linkages to minimize shrapnel damage.  Remember, the goal is not to make an invulnerable boat but to increase the dwell time to the point where some boats are assured to reach firing range.

Decoy Boat.  A lead, unmanned, decoy boat is another obvious tactic.  A heavily armored, remote controlled boat or two placed in the front of an attack specifically to absorb incoming fire for several crucial minutes while the remaining boats are closing would be very effective.  We would have no way of knowing whether the boat is a decoy or not and would have to honor the threat by engaging it until it is dead.

Remote Control.  Along the lines of a decoy boat, an entire attack consisting of several unmanned, remote control boats equipped as “suicide” boats would be effective and expendable.  Shrapnel would have no effect on the crew since there wouldn’t be a crew and sinking a boat via tiny shrapnel holes is a very time consuming exercise.  Such high speed drone boats already exist for very little cost. 

Obscurants.  Infrared, visual, and radar obscurants exist which could be dispensed by launchers and provide protection against missiles, in particular.  This would be a cheap capability and one readily deployed from small boats.

Active Protection.  Active protection involves destroying incoming missiles by automatic, point defense systems.  The best known example of this on a small scale is the Israeli Trophy system that is mounted on their tanks.  A system small enough to be mounted on tanks can certainly be mounted on a small boat.  On the other hand, this is a more complex and costly option and is probably less likely.

Flares/Chaff.  They work for planes and there is no reason they couldn’t be mounted on small boats and be effective.

Multiple Angles.  Attacking from around the clock is still an effective tactic, especially against smaller ships that may only have one or two weapons and have blind spots masked by the ship’s superstructure.  This would be challenging to achieve against an alerted ship but would be effective.

These are just a handful of ideas off the top of my head that could enhance the effectiveness of a swarm attack.  I’m sure Iran can think of others.  The point is that with some idea of how a swarm attack might occur, we can begin to intelligently assess the effectiveness of our defensive systems.  Here are a couple of obvious conclusions.

Catastrophic kills are required to minimize dwell time.  This strongly suggests the need for missiles.  Guns, especially with fragmentation munitions, are ineffective in the swarm scenario.

Fire and forget missiles are needed to allow rapid, multiple engagements and avoid the one-at-a-time engagement scenario which leads to high dwell times.