British Royal Navy Yarmouth Castle class Combat Supply Ship:


In common with most major navies around the world, the Royal Navy converted all of their vessels from conventional fuels to fusion power during the second half of the Twenty-First Century. With fusion power finally practical, one could run ships at a fraction of the cost of what either conventional nuclear power or with fossil fuels.


Many navies did not maintain their fleets able to deploy around the world but the Royal Navy, like the United States maintained the ability to deploy forces practically anywhere. As such, while there was no longer a need for at sea replenishment of fuel, ships would still require resupply with regard to provisions and ammunition. As such, supply ships would still be required.


Looking at the cost of gutting older supply ships and rebuilding them would be close to the cost of building new supply ships. In addition, a new vessel would also have the advantage of a much longer operating life, especially using the new advanced composites and alloys. As a result, it was a relatively easy choice for the Royal Navy to develop a whole new class of supply vessel.


While the design of the Royal Navy supply vessel has many similarities to United States supply vessel designs, there are many important difference as well. Even during the development phase, an important consideration was that while the United States navy needed around twenty supply vessels, the Royal Navy was only looking at purchasing six. Basically, the idea was to be able to deploy one or two with each carrier group and have a couple to perform in other theaters.


Early during the development phase, there was some arguments about the possibility of simply adopting the United States Yosemite class design but the Royal Navy ultimately rejected it. At over fifty thousand tons fully loaded, the American design was considered a monster and the design that ultimately became the Yarmouth Castle class was quite a bit smaller.


H.M.S. Yarmouth Castle was laid down about three years after the U.S.S. Yosemite was commissioned and the British were able to make some observations of the American design before completing their design. Even though smaller, the British supply ship could still carry a respectable load of cargo and was better armed for self defense than the United States design. A major reason for this is that the Royal Navy supply ship made due with using a far less powerful propulsion plant. Still, the Yarmouth Castle class was able to do a respectable twenty-six26 knots on its two fusion reactors.


As the Yarmouth Castle class were newly constructed vessels, not conversions, they were constructed from the beginning out of the high strength composites and alloys that were far stronger than steel. Unlike many combat vessels, the Yarmouth Castle uses a conventional hull design as well as being built to civilian standards. Still, there was an effort made to reduce their vessel’s radar cross signature as much as possible. One issue is that it was almost impossible to reduce the radar cross signature of the cargo handing equipment by any significant margin and retractable equipment was considered too cumbersome.


For self defense, these ships were outfitted with a single tactical length Mk 41 vertical launch systems and four Mk 41 “Sea Sabre” point defense mounts combining a rail gun and short range missile launcher in one mount. Originally, SeaRAM launchers were planned but replaced by the “Sea Sabre” mounts during construction. These ships also carried four 30 mm auto cannon mounts but were rarely used due to having no advanced fire control. It was next to impossible to target any kind of fast moving targets.


As far as electronics, these ships had many systems in common with other vessels in the Royal Navy but were general less extensive due to the vessels not designed to truly go into harms way. With the S1650M rotating phase array, these vessels had reasonably decent air search capabilities. Chaff and decoy systems as well as a powerful electronics warfare suite were carried in order to give additional protection against missile threats. No sonar systems were fitted to the Yarmouth Castle but the supply ship did have towed decoys it could stream behind in order to give some measure of protection against torpedoes.


As designed, maximum cargo load was 6,000 tons of ammunition, 10,000 tons of dry stores, and 1,200 tons of refrigerated cargo. All cargo holds were environmentally controlled in order to extend the life of the cargo. Heat can do damage to ammunition as well as making it more likely for an ammunition fire to start. On either side of the vessel were four replenishment derricks along with the ship carrying a centrally mounted cargo crane.


In common with the United States Navy, British Navy discovered that it was too difficult to load vertical launch systems with any missile larger than a medium range missile while underway. However, the Yarmouth Castle was designed to be able to reload the missile launchers with larger missiles such as cruise and long range missiles when the two ships were tied together at a pier or at anchor in protected waters. All other replenishment including loading medium range missiles in the missile launchers could be done underway in up to moderate seas. Cargo transfer was done by helicopter in addition to using cargo derricks.


One of these vessels, H.M.S. Dartmouth Castle was part of the Ark Royal task force when the task force was attacked by Argentinian stealth bombers equipped with nuclear weapons. The Dartmouth Castle was believed to have been destroyed with the rest of the task force. The reality is that all of the nuclear weapons that would have hit the task force were destroyed although several nuclear warheads exploded prematurely. These activated the South American Triangle and moved the vessels far into the future to a time after the Great Cataclysm.


Author Note: With respect to time line, these designs may or may not reflect our modern time line. The time line of these writeups diverged from our time line starting around 1999. Consider the universe that these designs are created for to be an alternate universe not bound by ours.


Model Type: A-620 Yarmouth Castle Class Combat Supply Ship.

Vehicle Type: Ocean, Auxiliary (Stores / Ammunition Vessel.)

Crew: 218 (16 officers, 16 chief petty officers, 186 enlisted [Has a high degree of automation.])

Troops: 8 Merlin crew members, 8 power armor pilots (Gypsy Moth power armors), and up to 20 troops for protection of special cargo.


Robots, Power Armors, and Vehicles:

Power Armor Compliment:

 

8

BA-V FPA-05D Gypsy Moth Power Armor (with Flight Packs.)

Aircraft Compliment:

 

2

Westland Merlin HM 1 helicopters (Transport Versions.)


M.D.C. by Location:

 

Hanger (aft):

500.

 

[1] Rear Flight Deck

500.

 

[2] Main Bridge / Superstructure:

800.

 

[3] Marconi/Signaal S1855M Air/Surf. Search Radar (superstructure):

160.

 

Cargo / Ammo Gantries (8, 4 on each side):

120 each.

 

Cargo / Missile Crane (1, center)L

400.

 

Mk 44 “Sea Sabre” Combination Anti-Missile Defense System (4, sides):

200 each.

 

30mm Mark 44 Bushmaster II Auto Cannon Mounts (4, sides):

50 each.

 

Mk 41 Tactical Length 16 cell Vertical Launchers (2, bow):

160 each.

 

[4] Sea Gnat Chaff / Decoy Launchers (4, superstructure):

10 each.

 

Outer Hull (per 40 foot / 12.2 meter area):

85.

 

[5] Main Body:

5,000.


Notes:

[1] If the flight deck is destroyed, no aircraft can be launched or land.

[2] If bridge / superstructure is destroyed, the ship can still be piloted from engineering but with a -15% to piloting rolls. Communication and sensor equipment are not concentrated on the bridge to reduce the effectiveness of bridge hits.

[3] Destroying the S1855M Air/Surface Search Radar will destroy the ship’s main fire control systems but the vessel has backup systems with a shorter range (Equal to robot vehicle sensors)

[4] These are small and difficult targets to strike, requiring the attacker to make a “called shot,” but even then the attacker is -4 to strike.

[5] Destroying the main body causes the ship to lose structural integrity, causing the ship to sink. There are enough life preservers and inflatable life boats to accommodate everyone on the ship.


Speed:

Surface: 29.9 mph (26 knots/ 48.1 kph).

Range: Unlimited due to fusion engines (needs to refuel every 20 years and requires maintenance as well). Ship normally carries several years of supplies on board (Most goes to other vessels it is resupplying.)


Statistical Data:

Draft:    33.5 feet (10.2 meters) fully loaded.

Length:  658.8 feet (200.8 meters) waterline and 682.4 feet (208.5 meters) overall.

Width:   93.5 feet (28.5 meters).

Displacement: 15,800 tons empty and 34,600 tons fully loaded.

Cargo: 6,000 tons (5,443 metric tons) of ammunition, 10,000 tons (9,072 metric tons) of non refrigerated dry stores, and 1,200 tons (1,089 metric tons) of refrigerated dry stores.

In addition, each enlisted crew member has a small locker for personal items and uniforms. Ship’s officers have more space for personal items.

Power System: Two nuclear fusion reactors, average life span is 20 years. Usually only goes 10 years between refueling.

Black Market Cost: Not for sale but costs around 300 million credits to construct. If found and sold on the black market would probably cost one to two billion credits. Cost does not include embarked craft and power armors.


WEAPON SYSTEMS:

  1. Four (4) 30mm Mk 44 Bushmaster II Auto Cannon Mounts: Four 30 mm cannons were mounted on the main deck, two on each side. These weapons had a good range and rate of fire, but lacked the punch to do damage to large targets. Since they were manually aimed, they were little good against missiles, and the crew often joked that they were only good for “Shooting life boats and survivors in the water.” Primarily however, they are for defense against small boats and similar threats. Each gun can rotate 270 degrees and has a 90 degree arc of fire.

    Maximum Effective Range: 10,000 feet (3,048 meters).

    Mega-Damage: 2D6 per round, and 1D6x10 for a burst of 30 rounds.

    Rate of Fire: Equal to the combined hand to hand attacks of the gunner (usually 4 or 5).

    Payload: 600 rounds (20 bursts) each. Ship carries an additional 12,000 rounds of ammunition in magazines. Auto cannons requires 3 minutes (12 melees) to reload by properly trained personnel (Double for untrained crews.)

  2. Four (4) Mk 44 “Sea Sabre” Combination Anti-Missile Defense Systems: One is mounted on the front of the superstructure, a second is mounted on the rear of the superstructure, and there are two mounted to either side of the superstructure. Bought from the United States as a replacement for aging defense system. Mounted on the sides of the superstructure. This anti-missile defense system combines both a rapid fire rail gun and a short range missile launcher. While mounted in one system, both defense systems have separate tracking and fire control systems. The short range missile launchers can target up four targets and can fire a volley up to twice per melee. Quite powerful, the rail gun is capable of destroying any missile or inflicting serious damage on aircraft. The rail gun can fire on automatic at up to six targets per melee (Has +3 to strike missiles and +2 to strike aircraft). In its design, the rail gun is very similar to those carried on the Sea King cruiser and it is likely that the Sea King’s rail guns came from a prototype of this system. The system also can be used against other ships and ground targets. The system has a 360 degree rotation and can elevate up to 90 degrees to fire at targets directly overhead.

    Maximum Effective Range: Rail Guns: 11,000 feet (2 miles / 3.2 km). Short Range Missiles: As per short range missile type (See revised bomb and missile tables for details.)

    Mega-Damage: Rail Guns: 3D4x10 M.D. per burst of 40 rounds (Can only fire bursts). Short Range Missiles: As per short range missile type (See revised bomb and missile tables for details.)

    Rate of Fire: Rail Guns: Six (6) attacks per melee round. Short Range Missiles: Two (2) attacks per melee round, can fire short range missiles one at a time or in volleys of two (2) or four (4) short range missiles.

    Payload: Rail Guns: 8,000 rounds (200 burst) each. Short Range Missiles: Sixteen (16) short range missiles each.

  3. One (1) Mk 41 Tactical Length 16 Cell Vertical Launch System: Mounted in the front of the vessel. An American design which was much more flexible than the French Sylver A-50 launcher, the slightly larger cells allowed for two long range missiles or four medium range missiles to be loaded into one cell. It also provided a better rate of fire. The tactical length version could not carry cruise missiles and used almost exclusively to house surface to air missiles. From the beginning, the launchers have been found to be very flexible and adaptable and the launcher can carry two long range missiles or four medium range missiles per cell. Anti-Submarine rocket launched torpedoes also can be fired from the launcher (See revised Rifts torpedoes for details) although never carried in service.

    Maximum Effective Range: As per long or medium range missile type (See revised bomb and missile tables for details.)

    Mega-Damage: As per long or medium range missile type (See revised bomb and missile tables for details.)

    Rate of Fire: Can fire missiles one at a time or in volley of two (2), four (4), or eight (8) missiles for launcher per melee round and can be fired at multiple targets at the same time.

    Payload: Sixteen (16) missiles cells in VLS launcher (possible total of 32 long range missiles.) Two (2) long range missiles or four (4) medium range missiles may be carried per missile cell. Usual complement was eight (8) long range missiles and forty-eight (48) medium range missiles.

  4. Four (4) Sea Gnat Chaff / Decoy Launcher: Located on the superstructure of the ship, they are designed to confuse incoming missiles. All four launchers must be operated or effects will be reduced. Rifts Earth decoys systems are assumed to not be effective against Phase World / Three Galaxies missiles due to technological difference. Reduce effects by 20% against smart missiles (Add +20% to rolls for smart missiles) and reduce effects of launchers by 10% per launcher not used (Add +10% to rolls per launcher not used.) Only useful against missiles, not useful against torpedoes underwater.

    Range: Around Ship.

    Mega Damage: None.

    Effects:

    01-35

    Enemy missile or missile volley detonates in chaff cloud - Missiles are all destroyed.

     

    36-60

    Enemy missile or missile volley loses track of real target and veers away in wrong direction (May lock onto another target.)

     

    61-00

    No effect, enemy missile or missile volley is still on target.

    Payload: Six (6) each for a total of twenty-four (24) canisters. One-Hundred and Forty-Four (144) reload canisters are carried, reloading takes two melee rounds.

  5. Four (4) SLQ-25F Nixie Towed Decoys: A special decoy which is towed behind the ship. The Coalition has not seen a need for this system so has not equipped their ships with it. It generates a sound like the ships propellers in order to confuse incoming torpedoes. Only effective at speeds 28.8 mph (25 knots / 46.3 kph) and below. Otherwise, the noise of the ship’s systems and propellers is too powerful to mask. Rifts Earth decoys systems are assumed to not be effective against Phase World / Three Galaxies guidance and targeting systems due to technological differences.

    M.D.C.: 5 each.

    Range: Not Applicable although decoy is deployed approximately 1,000 feet (304.8 meters) from the vessel.

    Effects: The decoy has a 65% chance of fooling ordinary non military sonars and non smart guided torpedoes, the decoy has a 35% chance of fooling military level sonars (like those of the Coalition) and non “smart” torpedoes, and the decoy has a 10% chance of fooling advanced military sonars (Like those of the New Navy and Triax) and “smart” torpedoes.

    Payload: One ready to use, with three more ready to deploy. It takes approximately three minutes (twelve melee rounds) to reel out another decoy.

Special Systems:

The ship has all systems standard on a robot vehicle plus the following special features:



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Writeup by Kitsune (E-Mail Kitsune).


Copyright © 2002 & 2018, Kitsune. All rights reserved.



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