LCB Architecture

Locked Architecture

• Reference LCB footprint: 60 ft long x 25 ft wide.
• Longitudinal orientation places the 60-ft axis fore-to-aft; crosswise orientation rotates the same bay 90 degrees so the 60-ft axis runs port-to-starboard.
• Standard flush module height: 15 ft unless a certified deep-penetrating weapon envelope is assigned at build.
• Locked APM exception: the 60 ft x 25 ft IWM rises 25 ft above the weapon deck and extends 15-20 ft below it, reserving 40-45 ft total depth.
• Locked position counts: FFG 3, DDG 5, CAG 8.
• Shared services: structure, securing, power, cooling, data, exhaust where required, drainage, firefighting, shock protection, access, and safety interlocks.
• Single-LCB packages are the normal heavy-system envelope; approved double-LCB packages support oversized future systems where the host class permits them.
• LCB position, framing, and count never change after construction. An installed IWM or IMM may change only after authorization through a certified major refit.

Permanent LCB Placement Maps

These maps show the locked structural zones carried into detail design. FFG deck bays remain longitudinal. DDG and CAG designated deck bays rotate crosswise. Every stern slide-in LCB remains longitudinal: 60 ft runs fore-to-aft, 25 ft runs port-to-starboard, and 15 ft runs vertically, with an aft-facing opening at the waterline.

FFG-64: three longitudinal centerline LCBs: 1 forecastle, 1 midships, and 1 stern slide-in bay.

DDG-152: five permanent LCBs: 1 longitudinal forecastle bay, 2 crosswise midships bays arranged fore and aft, and 2 longitudinal stern slide-ins arranged port and starboard.

CAG-3: eight permanent LCBs: 2 crosswise forecastle, 1 crosswise midships, 2 crosswise aft-gun-deck, and 3 longitudinal stern slide-ins.

Stern LCB Fit Within Each Class Beam

The stern installations use the same 25 ft bay width and 60 ft fore-aft depth without consuming the full hull beam. The FFG centers one bay, the DDG carries two side-by-side bays, and the CAG carries three side-by-side bays, all at the same waterline elevation.

Gross beam allocation: the FFG retains 41 ft total outside its single bay, the DDG retains 38 ft total outside its two bays, and the CAG retains 33 ft total outside its three bays. Final clearances are reduced by hull curvature, framing, fire boundaries, access trunks, and structural separation.

Stern Integration by Class

These aft-quarter studies distinguish three separate structures: the enclosed aviation hangars, the raised 01-level flight deck, and the longitudinal stern LCB openings at the waterline. The DDG and CAG aft guns remain on their lower 00-level gun decks forward of the stern openings; no Trinion installation occupies a stern slide-in LCB.

FFG-64: 66-ft beam, 2 enclosed MH-60 hangars, and 1 centered stern LCB. UAV maintenance and mission preparation use shared aviation-support spaces rather than a third full hangar.

DDG-152: 88-ft beam, 3 enclosed hangars, and 2 side-by-side stern LCBs. The centerline aft gun remains on the separate 00-level gun deck forward of the stern openings.

CAG-3: 108-ft beam, 5 enclosed hangars, and 3 side-by-side stern LCBs. Shared Viper and Venom bays plus 3 individual MH-60 bays store all 7 baseline manned helicopters.

Placement Lock by Class

Configuration control: the location count is fixed. Choosing Trinion, Mk 45 Mod 4, VLS, APM, railgun, mission infrastructure, or another certified IWM/IMM does not create a new bay or move an existing one.

Empty LCB at Construction

An empty standard LCB is 60 ft x 25 ft x 15 ft. Longitudinal positions extend 60 ft fore-to-aft; designated crosswise deck positions rotate the same structural envelope 90 degrees. Its welded framing, shock-rated foundations, fire boundaries, and capped common services are installed during construction; it is not a removable container or port-swappable module.

• Permanent: bulkheads, girders, deck beams, foundations, access routes, fire boundaries, drainage, and service trunks.
• Build selected: the IWM or IMM payload, its internal machinery, local controls, magazines, handling equipment, and mission-specific connections.
• Not interchangeable in port: changing a deeply integrated payload requires a certified major refit, not a pier-side module swap.
• Separate ISO doctrine: rapid port-change missions remain the function of dedicated ISO positions, not LCBs.

Integrated Weapon Modules (IWM)

IWMs are deeply integrated combat-power installations selected for permanent LCB positions at build. A later IWM replacement is an authorized drydock major-overhaul/refit alteration, not a routine module swap. The permanent bay, foundations, access, and common structural, power, cooling, data, exhaust, fire-protection, handling, and software interfaces allow a future weapon to be designed against a controlled fleet standard. That pathway does not guarantee fit: every new or replacement IWM still requires ship-specific engineering and recertification.

Mk 45 Mod 4 IWM Study

The IWM includes the gun and its supporting magazine, handling, protection, access, and ship-service interfaces; it is not merely a deck-mount adapter.

Mk 75 76 mm Gun IWM Study

The optional Mk 75 package integrates the compact gun with its magazine, ammunition handling, local controls, cooling, fire protection, and fleet-standard LCB connections.

Mk 41 VLS Compatibility IWM Study

The compatibility IWM is an engineered launcher installation inside the permanent LCB, not loose cells placed into a generic bay.

• Trinion 10-inch IWM: heavy naval-fire family with shared ammunition and magazine interfaces.
• Mk 45 Mod 4 IWM: mature baseline gun package.
• Mk 75 76 mm Gun IWM: optional rapid-fire package with an integrated IWM magazine, ammunition handling, local controls, cooling, fire protection, and combat-system interfaces. It may be selected for FFG, DDG, or CAG when the mission requires another medium-caliber gun, subject to class-specific structure, stability, firing-arc, magazine-safety, and Navy certification.
• Mk 51 AGS IWM: conditional reuse or competitive replacement path for the 155 mm Advanced Gun System. Selection requires a government technical-data-rights audit, an affordable competitively sourced ammunition family, and proof that the gun, magazine, recoil, loading, and handling installation fits one deep LCB or an authorized double-LCB package.
• Mk 41 VLS Compatibility IWM: legacy missile-launch fallback.
• Mk 57 PVLS IWM: primary distributed missile-launch architecture.
• APM Large-Payload IWM: locked four-tube, 12-round CPS pathway in a raised/deep-well 60 ft x 25 ft module with a 600-short-ton loaded-weight reservation. Open the APM engineering baseline.
• Railgun IWM: developmental RFP pathway covering the mount, pulsed power, energy storage, cooling, barrel life, projectile family, loading, fire control, electromagnetic compatibility, and maintenance. It enters the fleet only after land and at-sea qualification and may use a double-LCB envelope if one bay is insufficient.
• Advanced DEW/Counter-Air IWM: future high-power defensive-fire pathway.
• Close-In Defense IWM: optional high-density terminal-defense package that trades primary weapon volume for added protection.
• Double-LCB Future Weapon IWM: reserved envelope for systems too large for one LCB.

SLCM-N Reserved Launcher Paths

Every TriSeadon class preserves three potential launcher paths for a future Navy-certified SLCM-N: Mk 41 VLS Compatibility IWM, Mk 57 PVLS IWM, or a dedicated adapter/canister in the APM Large-Payload IWM. These are reserved integration paths, not current certifications. Final selection must wait for the Navy's SLCM-N missile, launcher, and canister interfaces, followed by ship-specific safety, launch-control, nuclear-surety, handling, security, and operational certification. Open the complete SLCM-N integration boundary.

Integrated Mission Modules (IMM)

IMMs are deeply integrated mission-infrastructure installations selected for permanent LCB positions at build. A later IMM replacement is an authorized major-refit alteration, not a routine module swap.

• ASW/UxV Operations IMM: UUV, USV, UAV, sonobuoy, handling, maintenance, and control support.
• Mine Operations IMM: mine-laying and counter-mine handling infrastructure.
• RHIB/SOF IMM: craft, armory, maintenance, and maritime-interdiction support.
• Amphibious/SOF Lift IMM: embarked-force vehicle, insertion, and recovery support.
• Drug Interdiction/LEDET IMM: boarding craft, evidence, detainee, K9, and communications support.
• Anti-Piracy/VBSS IMM: boats, teams, armory, medical, and sustained vessel-search capacity.
• VDS/Towed Array IMM: variable-depth sonar and towed-array machinery and handling.
• Extended Fuel/Logistics IMM: endurance and afloat-logistics support.
• Medical/Command IMM: casualty-response and mission-command augmentation.
• Directed-Energy/Counter-Air IMM: additional power, cooling, and control infrastructure.
• VLS Reload/Magazine IMM: protected missile staging and transfer support.
• Gun Reload/Magazine IMM: ammunition handling, protected storage, and transfer support.
• UxV Attack IMM: armed unmanned-system support infrastructure.
• Expeditionary Repair/Workshop IMM: deployed fabrication and repair capacity.

Separation from ISO

LCB-installed IWMs and IMMs are deeply integrated, semi-permanent systems. ISO Mission Modules are separate rapid-change packages for temporary mission needs and use dedicated ISO deck positions.