Carry the weight.
Uncrewed underwater vessels designed to carry real tonnage. The HD-18 is designed to carry 42.63 m³ and 17.0 tonnes in an 18-metre hull — and to be configured around whatever you need to move.
The idea
Most uncrewed submersibles are built around a sensor. This one is built around a hold.
A torpedo-form vehicle is shaped by its diameter. Everything inside has to fit a tube, every payload becomes a custom cylinder, and the useful volume left over is measured in hundreds of litres.
The HD-18 starts from the opposite end. Three rectangular compartments, together 42.63 m³ and 17.0 t, sized so that ordinary containerised kit fits without being redesigned. The hull is then wrapped around that volume rather than the volume being squeezed into a hull.
That single decision drives the whole boat: the flat deck, the hinged hatch pairs, the parallel middle body, the ballast solution and the two-leg range profile all follow from wanting the cargo to come first.
Three sealed compartments
14.21 m³ each at 3.50 × 2.80 × 1.45 m, pressure-balanced and dry at one atmosphere, on four-point flange mounts with the connector penetrations already in the boundary.
Two legs of endurance
4,528 km of diesel transit at 6 kn on the generator to reach the area, then 486 km submerged at 4 kn on a 750 kWh battery once there.
Loads like a ship, not a torpedo
Six upward-hinging hatches give a 1.15 × 2.50 m clear opening onto a 3.40 m flat deck. A quayside crane and a pallet are the whole handling concept.
General arrangement
The shape follows the cargo, not the other way round.
A 10-metre parallel middle body carries the payload where the hull is fullest. A small radius at the deck corner and a large one at the bilge give a flat deck 3.40 m wide, so a 2.50 m hatch lands on flat plate with margin instead of overhanging the shell. Three-metre entrance, five-metre run.
Loading
A crane, a pallet and twenty minutes.
Each hatch pair opens onto a scissor lift that lowers the module into the compartment and locks it onto its flange mounts. The lift is 3,071 kg including the module tare — inside the reach of the mobile crane already standing on most working quays.
There is no special handling frame, no dry dock, no shore facility to build. If you can load a shipping pallet onto a workboat, you can load the HD-18.
Inside
Everything forward is cargo. Everything aft is what moves it.
Three compartments occupy stations 2.70 to 13.50 m. Aft of them sit the generator, the compensated fuel, the reduction gears and the twin shafts. The battery runs beneath the payload deck, low, where it doubles as ballast.
Endurance
Range is a profile, not a number.
The HD-18 does not pretend to run 5,000 km underwater. It runs a 4,528 km transit at 6 kn on the generator with the mast up, which is how it reaches an operating area three days away, and then a 486 km submerged leg at 4 kn on the battery, which is how it does the part that matters.
Sprint is 12 kn for 79 km when a window has to be met. Hotel load is 2 kW passive and 8 kW with a payload drawing power, so a sensor fit costs endurance in a way you can calculate rather than guess.
Configured to the mission
One platform. Built around your payload.
The hull, structure and energy system are common to every HD-18. What changes is what you put in it — payload fit, sensor suite, endurance profile, handling arrangement and the interface to your own systems.
Because the platform is defined by a single engineering model, a configuration is a specification exercise rather than a redesign. Length, payload volume, endurance and sensor fit are parameters, and the structural and stability consequences of changing one are solved rather than estimated.
Mission profiles
Four jobs the architecture was chosen for.
Naval logistics and resupply
Volume and deadweight between two points, without a crew or a manned hull at risk.
02Coast guard and port security
Hosted sensing on a 486 km submerged leg, with the range to reach the area and return.
03Payload host for primes and integrators
Three dry one-atmosphere compartments on flange mounts, with the penetrations already in the boundary.
04Commercial subsea support
Dry transport of tooling and consumables — the payload arrives as it was loaded.
One architecture, six to twelve bays
The hull stretches. Nothing else has to change.
The compartments, their trunks, their hatches and their lifts are identical units on a 3.60 m pitch. Adding a bay pair adds hull, one compartment, two modules, two hatches and two lifts — and nothing else moves. The bow group, the energy group, the mast, the stern gear and the control planes are the same parts in the same relative positions.
| Variant | Length overall | Payload | Payload volume | Displacement | Declared range | BG |
|---|---|---|---|---|---|---|
| 6 bays | 18.00 m | 3 compartments | 42.63 m³ | 82.9 t | 5,014 km | 0.609 m |
| 8 bays | 21.60 m | 4 compartments | 56.84 m³ | 103.9 t | 4,477 km | 0.778 m |
| 10 bays | 25.20 m | 5 compartments | 71.05 m³ | 124.9 t | 4,030 km | 0.887 m |
| 12 bays | 28.80 m | 6 compartments | 85.26 m³ | 145.9 t | 3,660 km | 0.964 m |
Every row is a solve
Each variant was run through the same solver with no adjustment beyond the length. Every one closes on trim, passes all 15 design assertions and all 38 containment checks, and clears the clash check. Twelve bays is 2.00× the payload volume of six.
And what it costs
Two things move against the stretch, and both are stated rather than buried. Declared range falls, because a longer hull carries more wetted surface on the same installed energy. And fixed ballast grows steeply, because deadweight is currently pinned at 17.0 t by the compensating tank capacity while the sealed volume keeps growing. Scaling that capacity with the bay count would convert most of the iron into payload — a decision the platform has not yet been asked to make.
Structure
Designed for the fault, not the fair day.
The compartments are pressure-balanced: charged with air that tracks sea pressure as the vessel goes down, so the boundary sees a 1.00 bar design differential instead of the 2.011 bar head outside it. That is a choice of architecture, and it is what makes a rectangular hold at depth affordable to build.
The case that decides the closures is the one that should never happen: total loss of pressurisation at operating depth. Sea pressure then drives each cover onto its seat at 66.6 t — in the direction the hatch is strongest, and unloading the dogs entirely. A cover that opened outward would have exactly the opposite property.
Every compartment is still hydrostatically proof-tested to 3.017 bar, the full unbalanced head with half again on top, before it is installed.
Handling
Nobody gets into the boat.
The compartment floor sits 1.42 m above the baseline and the hatch seat 3.34 m, so a module has 1,670 mm to climb before it is clear of the coaming. Doing that on a crane hook alone means somebody rigging it from inside the compartment. Doing it on a lift under the module means the crane only ever picks up something already standing proud of the deck.
Six lifts, one per module
Scissor tables, 250 mm collapsed, 1,670 mm of stroke, rated at 3,071 kg — the module tare plus its share of cargo at a 1.3 marine dynamic factor.
Electromechanical, not hydraulic
Stainless ball screws on pressure-tolerant motors. A hydraulic leak inside a sealed compartment contaminates all six modules at once and cannot be cleaned at sea.
Interlocked
Absolute position feedback on every node, overload and slack-line detection, a hatch-open interlock, a surfaced-only interlock and a mechanical pawl.
Programme
Entering construction.
The design is frozen at V10. Structure, arrangement, closure design, energy system and payload interface are all released, with a full CAD set and a costed bill of materials behind them.
Build slots in the first series are open now. Configuration is agreed per customer, and delivery position is allocated in order of commitment.
Tell us what you need to move.
Payload, mission, endurance and delivery position. We will come back with a configuration and the technical pack under NDA.