Stand Alone Defensive System

In previous posts we have used the phrase "Stand Alone Defensive System" (S.A.D.S.),here we will explain what such a thing is.

A Stand Alone Defensive System in not an existing weapon system,it is a concept for a future system.

It may be a missile system

It may be a gun system.

It may be a combination missile and gun system.

It may even be a directed energy weapon system.


Most elements of the system would be lower cost non-developmental items as there is a wide range of radars,guns,ammunition,Auxiliary Power Units (A.P.U.s) and other components available either "off the shelf" or made to order.

A Stand Alone Defensive System is a replacement for the many types of light cannon and Close In Weapons Systems in use today.

Many modern warships carry 4 short range guns,these may be replaced by just 2 well placed Stand Alone Defensive Systems reducing weight and manpower requirements.

A Stand Alone Defensive System serves the following primary purposes:

Short range defensive armament for warships in the event that their other weapons fail due to human error,technical problems or battle damage;

Short range defensive armament for civilian vessels,auxiliary naval vessels and other craft which would not otherwise be armed.

It may also perform the following secondary roles:

Engaging low value targets where more expensive weapons are not neccessary;

Firing warning shots.

There are three fundamental qualities which a Stand Alone Defensive System must posess:

It Stands Alone.

The system must be be a fully self contained unit,capable of fully independent operation,though it may also be able to operate with external control and power;

It is defensive.

It must be able to engage short range targets on land,on sea or in the air,even if the ship it is on has been hit and it's crew killed or wounded;

It is a system.

It must be a fully self contained unit including the weapon,ammunition,sensors,fire control system and power supply required for extended operation without external input.

These qualities require the following features:


It must not penetrate the deck on which it is mounted.

This allows it to be mounted above the bridge and helicopter hanger on warships.

This also allows it to be mounted on civilian or other vessels with only minor strengthening to the deck of the ship.

It must have it's own on board power supply.

This allows it to operate when external power is not available due to technical failure,human error or battle damage,though it may also be connected to an external power source when one is available.

It must have all of it's ammunition supply on the mount and ready to use.

This allows it to operate without the need for reloading by crew members who may have become casualties or be occupied with damage control duties.

This also allows it to be carried by a civilian or other vessel with no magazine space to store ammunition and no trained crew members to do the reloading.

It must be capable of operating for long periods with little or no maintenance.

This allows it to continue operating without needing maintenance to be done by crew members who may have become casualties or be occupied with damage control duties.

This also allows it to be carried by a civilian or other vessel with little or no support crew.

It must be protected against shock.

This allows it to continue operating after the ship which is carrying it has been hit by a missile or torpedo.

It must be protected against fragmentation.

This allows it to continue operating after the ship which is carrying it has been hit by a missile or torpedo.

It must be light enough to be mounted above the ship's superstructure.

This allows it to have wide firing arcs unobstructed by the ship's superstructure.

It must be able to engage targets on land,on sea or in the air.

This allows it to defend against the full range of above water threats.

It must have it's own on board sensors.

This allows it to detect,track and engage targets without the help of external sensors which may not be available due to technical failure,human error or battle damage.

This also allows it to detect,track and engage targets without the help of external sensors which may not be available if it is mounted on a civilian vessel which does not have such systems.

We are not aware of any current system which meets all of these requirements.

However,there are many existing systems which meet some but not all of these requirements.

The BAE Mark 38 Mod 2 25mm chain gun does not require any deck penetration.

Auxiliary Power Units are commonly found on military land systems such as the Gepard anti-aircraft vehicle.

Many systems carry large amounts of ammunition on the mount.

This Rolling Airframe Missile launcher appears to be mounted on shock absorbing wire rope mounts.

Protection against fragmentation was standard equipment on most anti-aircraft guns during the Second World War.

This Bofors 40mm Mark 4 is light enough to be mounted above the bridge or hangar on many large warships.

This Bofors 57mm Mark110 is capable of engaging the full range of air and surface targets.

This SeaRAM launcher has the full range of sensors required for autonomous detection and tracking of air and surface targets.


A Stand Alone Defensive System must combine all of these features.

The above illustration shows the firing arcs for 2 Stand Alone Defensive Systems (and a larger gun in "A position") mounted above the hangar and bridge on our Falklands class frigate template.

These 2 Stand Alone Defensive Systems provide better all round coverage and redundancy than the 4 side mounted light cannon carried by a Daring class destroyer,only 2 of which are capable of engaging missiles.


If a Phalanx anti-missile system fails on a Daring class destroyer it leaves a blind arc of about 180 degrees,requiring a turn of up to  90 degrees for the ship to bring the weapon on it's other beam to bear.


If a Stand Alone Defensive System fails on a Falklands class frigate it leaves a blind arc of only about 20 degrees,requiring a turn of around 10 degrees for the ship to bring it's remaining system to bear.



In total,the Stand Alone Defensive Systems on the Falklands class frigate provide about 680 degrees of coverage compared to about 360 degrees for the Phalanx systems on the Daring class destroyers.

The tumble home of the superstructure of the Falklands class,combined with the narrowness of the bridge and the pedestal atop the hangar,also allows excellent depression to engage targets very close to the ship.

The loss and damage of Her Majesty's Ships Sheffield, Coventry and Glasgow during the Falklands War of 1982,demonstrated the importance of a Stand Alone Defensive System on a modern warship.


In each of these cases the ships' main weapon systems failed to engage for various reasons but none of these vessels was equipped with an adequate back up short range air defence system.

The loss of the unarmed Atlantic Conveyor to an attack by an Exocet anti-shipping missile demonstrated the need for sea lift ships to carry an air defence system.

The bombing of M.V. British Wye by an Argentinian Hercules demonstrated the need for fleet replenishment vessels to carry an air defence system.

The loss and damage of the Royal Fleet Auxiliaries Sir Galahad and Sir Tristram demonstrated the need for amphibious landing ships to carry  an adequate air defence system.

During the same conflict the Argentinian corvette Guerrico demonstrated the importance of having a back up system which can engage land targets at short ranges when she suffered failures of her 20mm cannon,40mm cannon and 100mm gun while being fired upon by Royal Marines on South Georgia.

The attack on the United States Ship (U.S.S.) Cole in port in Yemen highlighted the need for a close range defensive system to engage small boats at close range.


On a Falklands class frigate there are 2 independent Stand Alone Defensive Systems covering most bearings,providing a high degree of redundancy in the event of a failure at a critical moment.






An aircraft carrier will require 4 Stand Alone Defensive Systems.


A surface combatant will require 2 Stand Alone Defensive Systems.



An amphibious dock ship will require 2 Stand Alone Defensive Systems.



A replenishment ship will require 2 Stand Alone Defensive Systems.



A sealift ship will require 2 Stand Alone Defensive Systems.



A minor warship intended for lower threat environments may need only 1 Stand Alone Defensive System.



A fleet such as the Royal Navy's may require a total of over 100 Stand Alone Defensive Systems.