This article is considered accurate for the current version (1.60) of Foxhole.
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The AC-b or “Trident”-class submersible brings much-needed versatility to the Republic Coastal Legion. Featuring a quick-loading ammo bay, the “Trident” is capable of quickly re-arming and returning to the hunt. Combat Magister Curia commissioned the skilled engineers out of Dimiourg to develop a submersible to help counter the rapidly progressing naval technology deployed by the Wardens and Nevish Alliance. Much of the senate criticised Curia for this decision, as they believe it more prudent to invest resources into airborne warfare innovations. After witnessing the return and redeployment of several successful trial AC-b operations, it wasn’t hard to convince the Senate.
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— In-game description
The AC-b “Trident” is a ColonialSubmarine. It is equipped with a sonar, two torpedo tubes, as well as a 120mm deck turret.
Controls the movement of the ship, and can see the remaining fuel in the tank (battery level when submerged), the speed in knots, and the azimuth of the ship in degrees.
Can see the distance and angle to the closest repair location (Dry Dock).
Diving Officer
Controls the Dive plane deflection angle of the submarine fins (between -45° and +45°) - Press W (dive) or S (rise)
Sees the Depth, Vertical Speed, Pitch angle, Dive plane deflection angle, and the battery charge.
Ballast Operator x3 (Main, Safety, Negative)
Controls the target flood level of the ballast - Press A and D
Sees current flood level of the ballast and the battery charge
Cannoneer x2 (Gunner)
Controls the movement, reload, and firing of the right or left Torpedo Tube.
Selects the range at which the torpedo will explode (between 30 and 150 meters ; torpedo also explodes on contact) - Press F.
Selects the depth of the target (between 0 and 50 meters) - Use Mouse Scroll Wheel
Can view 150m in every direction underwater with distance and azimuth displayed
Secondary Gunner
Controls the movement, reload, and firing of the 120mm deck turret
Switch the gun between indirect and direct fire mode with Shift + F
Seat accessed from the ammo room
Periscope Operator
Can view 230m in every direction with distance and azimuth displayed, but cannot detect ships on the surface if the submarine's depth is below 10 meters.
Can act as the ship commander to direct the other crew members.
Sensor Operator
Operates the ship's sonar.
Switch between Long range directional and Short range omnidirectional modes - Press F
Engineer
Not an actual seat
Switches each of the two ship engines below deck between "Forward" and "Reverse" mode using a Wrench while crouching
Torpedo Operator
Not an actual seat
Transfer a Torpedo into the dedicated slot of the Torpedo tubes by using a Wrench while crouching on the torpedo stockpiles
Additional soldiers can be on the ship's decks for various purposes (transport, helping load guns, bail water in bottom deck, fix leaks, etc...). The ship can have a total of 30 players onboard, any more and it cannot cross region borders.
Crewmembers inside the submarine are immune to Gas Grenade clouds.
Armament
120mm Cannon
Mounted on a turret on the ship deck (20 degree firing arc), turns 15° per second)
For the torpedo gunners to be able to reload, a torpedo from the corresponding torpedo stockpile at the front needs to be manually loaded into the dedicated ammo slot by using a Wrench on it.
The Trident's Torpedo stockpiles can be refilled at a Dry Dock by depositing a Material Pallet or Small Flatbed Car loaded with Torpedoes on the dock's loading area with a crane. The operation can also be done anywhere by opening the submarine's cargo hold and depositing the pallet or small flatbed car directly inside with a crane.
Sonar
The sonar system helps detect other ships and can be used while surfaced or submerged. The operator aims in a direction with RMB and "fires" the sonar with LMB. It has two modes that can be switched with F:
Long range directional (500m): Detects vessels within 500m and in a 20° cone
Short range omnidirectional (50m): Detects vessels within 50m in every direction
For every detected vessel, the operator receives a ping which is represented by a white line aiming towards the target with the azimuth displayed.
If the vessel is far (Long range mode only), the sonar ping will show "Distant contact signature" and display the Strength of the ping (value between 0 and 100, the higher the strength the closer the contact), but won't show the target's Depth.
If the vessel is close, the sonar ping will show "Close contact signature" and display the Depth of the target. The exact distance is not displayed but the white line will stop right under the vessel and become vertical.
Every sonar use consumes about 0.67% battery. The sonar can be fired once every second.
Inventory
It has 15 inventory slots in the control room. There are two dedicated Torpedo slots (1 max) and two stockpiles that can each hold 3 torpedoes in the torpedo room. It can carry a total of 8 Torpedoes. It also has a third stockpile that can hold 300 120mm shells.
Can ram and instantly destroy ice on frozen bodies of water during Snow Storms
Cannot move while anchored.
It can pass under a closed drawbridge, even when surfaced. It can also pass under destroyed bridges while submerged.
Top speed is reduced to 7.8 knots when submerged, heavily reliant on pitch and ballast settings of the submarine.
Diving Mechanic
The submarine can dive to avoid detection.
Buoyancy:
By default the Main and Negative Ballast start empty and the Safety Ballast starts fully flooded (0/0/100). Changing the flood level of the ballasts affects the overall buoyancy of the submarine. If positive the submarine slowly goes to the surface, if negative the submarine slowly sinks. A 99/0/100 setting (Main Ballast at 99%) makes the buyoancy very slightly negative while 98/0/100 makes it slightly positive. Water inside the submarine from leaks also affects the buoyancy.
Plane Deflection Angle:
On top of its buoyancy, the ship's depth is also affected by the plane deflection angle of its fins, controlled by the Diving Officer, but only when the ship is in movement. At the default 0°, moving forward gives the ship a very slight downward effect. When moving forward, a negative angle gives a downward effect and a positive angle gives an upward effect.
Important Depths:
The periscope can no longer sees surface vessels if below 10 meters.
The submarine is not detected by Map Intelligence and is silent and invisible to surface observers if below 6.75 meters.
If the ship goes below the Crush Depth (20 meters), it will start getting leaks and will sink if the crew doesn't react quickly.
Sea Mines can only be deployed between 15 and 30 meters.
Submarines automatically surface if there is no crew on-board (occurs after a slight delay).
When submerged, the Trident's top speed is 7.8 knots.
Battery
When submerged, the submarine operates on a limited battery power. Driving the sub and using ballasts or sonar consumes battery charge. Being submerged consumes 0.1% of the battery charge per second (6% per minute). The battery automatically recharges when the submarine is surfaced and immobile, at a rate of 1% per 3.6 seconds by consuming 1L of Heavy Oil. A fully depleted battery (0%) takes 6 minutes to recharge fully (100%).
When the battery is depleted (0%) the following actions are possible with these effects:
Driving at 1/5th the normal speed.
Ballast function at a reduced rate.
Torpedoes are functional.
Sonar is disabled.
Health & Armor
The AC-b “Trident” has 28500 HP. It has "Large Ship" armor resistance: it can soak small arms fire, shrapnel, 12.7mm machine guns, 20mm anti-tank bullets, and it is immune to Flamethrowers. It's also fairly resistant to Anti-Tank Explosive and Armour Piercing damage. High explosive shells are very effective against it. It has subsystems that have a chance to be disabled by heavy explosives and anti-tank weaponry if hit specifically: Turret/Cannon: 5%. It has Tank Armor. With it, in best case scenario, penetrating projectiles only have a 10% chance of penetrating and doing damage. That chance goes up quickly if the armor is worn or if it is shot from up closeor with ammo that has penetration bonuses. As a Large Ship, its health, Tank Armor, and subsystems can only be repaired at a Dry Dock, costs 10 Naval Shell Plating, and takes some time.
Sinking Mechanic:
With their massive health, large ships are hard to kill the normal way, but they can also be sunk.
Interactions
Friendly soldiers in the water can instantly climb aboard the ship with E while next to it.
You can drop items on the ship decks.
The ship has 4 Gangway ramps that can be toggled with E. The anchor must be lowered and there must be solid flat ground for the gangway to deploy (Shipyard, Beach, docks, Dry Dock, Navy Pier, etc...).
The ship's bottom deck contains 4 rooms separated by bulkhead doors which can be toggled with E. Closing a room's bulkheads prevent water from leaks from spreading to the adjacent rooms.
Water in the ship rooms can be bailed using a Water Bucket (reloading) and thrown overboard.
Open/Close the cargo hold with the lever in the cargo room (ship must be anchored)
Shippable must be loaded/offloaded with a Crane - the player must have access to the ship.
Shippable needs to be removed from the cargo hold for the submarine to be unanchored.
Squad Reservation
The ship can be reserved for a Squad (via a button in the menu) to prevent any non members from toggling the ship's anchor or changing the engine settings and to allow members to eject any player from the driver seat with the "Eject Driver" button in the menu . The reservation doesn't prevent other friendly players from using the ship's seats or accessing the ship's inventory however.
Anchor
The anchor interaction area is marked by an arrow at the front of the ship on the Port side (left).
Respawn
The Trident does not act as a "Forward" Spawn Point and players can't deploy onto it from the Home Region.
Region Borders
The ship can cross a region border with up to 30 players on board, provided the destination would not exceed its population capacity; otherwise the ship must wait in queue. While preparing to cross the border, the ship must be idle for 60 seconds. Moving or firing any ship weapons resets this timer.
Must be fully researched in the Vehicle Tech Tree in order to be produced.
Storage & Transport
The AC-b “Trident” cannot be stored in a Storage Depot, Seaport or Storage Ship. It can be anchored anywhere. It cannot be packaged or transported by another vehicle. As such, it must be driven to its destination, regardless of where it is.
Tactics
While stationary with the Safety Ballast set to 100%, setting the Main Ballast to 99% will cause the submarine to slowly sink into the abyss and 98% will cause the submarine to slowly rise to the surface. It may be necessary to periodically switch between 98% and 99% Main Ballast to maintain depth while stopped in open water.
Moving forward with the Main Ballast set to 98%, Safety Ballast set to 100%, and Negative Ballast set to 0% will cause the submarine to slowly descend and eventually stabilize around 13.5m at max speed, rising again as the speed is reduced. This is useful for solo travel when covertness/battery use is desired or when crew count is inadequate to fill all roles.
If surfaced, the submarine's deck is low enough that enemy soldiers on other vessels can board it (also worth mentioning you can't close the hatches when above water, that plus no respawn room for the crew makes them incredibly vulnerable to being decrewed by boarding parties while surfaced).
The AC-b "Trident" has a hefty deck gun, the ability to resupply without a drydock, and the crew and storage space for better survivability than its Warden counterpart, but it also has very poor acceleration, presents a large target to enemies, and is extremely vulnerable to boarders.
There are three hatches that lead to the upper deck. This means there are more damage control options- a sealed compartment can be bailed out without having to drydock the ship- but it also means there are three ways for boarding parties to attack. These hatches should be guarded if the submarine is traveling alone or in enemy territory.
The deck gun on the trident is quite good at being the final blow to crippled threats, once all torpedos are fired it's highly likely that most if not all crew on the enemy ship is on damage control, this gives the trident the option to engage on the surface with minimal retaliation from the enemy (however outside factors such as gunboat escort, enamy subs in area, ect, are still something to think about, surfacing makes you incredibly vulnerable to those threats so this strategy is not advised when you know those are present)
The deck gun and command deck can both be run while bulkheads to ladder rooms are sealed so it is advisable to seal the command room when surfacing to fire the deck gun for any reason, if the torpedo crew or engineer is killed and the ship is boarded the sub can still operate through it's entire fire mission then submerge until it can get marines to reboard and clear out any threats, however in this case the dive officer will have to be comfortable working with only main ballast
The cargo hatch allows the AC-b "Trident" to load more torpedoes without having to return to a drydock. Just reloading from a coastline will work, but this also means that it can resupply at sea from a deployed BMS - Bluefin.
The 120mm deck gun has a limited arc of fire, reducing its potential use as a defensive weapon against gunboats. Despite this, it can still be useful against larger and more distant targets that the crew judges to be not worth using (or impossible to use) a torpedo to destroy.
All of these aspects combined mean that, unlike the Nakki, the AC-b "Trident" might be at its best as part of a fleet than as an independent raider.
Trivia
The Colonial submarine draws inspiration from a variety of warships, but its unique mechanics have caused it to go its own way in some respects. There are strong similarities to the British M-Class submarines specifically and to interwar cruiser submarines in general, but the hull shape and massive cargo hatch- useful gameplay and design language features but impractical on real submarines- appear to be Foxhole originals.
Due to a surface ship-like hull shape and extra length added by the cargo bay, the AC-b "Trident" is not only significantly larger than the Nakki-class submarine, but is also slightly longer than the Conquerer-class destroyer.
As of Update 1.56, The AC-b "Trident" is the only faction-specific Large Ship that can accept pallets of cargo directly as well as through the Drydock.
Gallery
The top deck of an AC-b “Trident”
The bottom deck of an AC-b “Trident”
Render Models of the AC-b “Trident” submarine from a top down view, above and below deck.
Showcase of the AC-b “Trident”'s cargo bay to resupply its Moray Torpedo stockpiles.
The Trident-Class Submarine introduced in the Update 1.56 Dev Stream
