NTNU Trondheim · Autonomous submersible

It planes on the surface.
Then it goes under.

Mobula is a student-built autonomous submarine, designed and engineered at NTNU in Trondheim for the 2027 season. It runs fast and flat like a surface boat, then dives, and its own drone lifts out of the hull to stay with it. A custom 532 nm optical link carries data from the submarine up through the water to the drone, where radio simply cannot go.

Explore the vessel See the optical link

Render of Mobula on the surface with its amidships bay hatch raised and its quadcopter airborne just off the deck — Hatch up, aircraft away: the drone bay sits amidships, on the vessel's centreline.

About the project

An engineering project out of NTNU Trondheim.

Mobula is designed, built and tested by students at NTNU in Trondheim. It is the third machine in a line that runs through Ligmax, the roll- and pitch-stabilised autonomous trimaran that competed in 2026, and it is a deliberate change of category rather than another surface boat.

Ligmax proved the team could take a vessel from bare hull to autonomous operation. Mobula asks the harder question: what happens when the vessel leaves the surface entirely? Diving solves for stealth and sea state, but it costs you your radio link and your view of the world. Mobula's answer is a drone in the hull and a beam of green light through the water.

A project of Dialga, the student engineering organisation behind it.

2027: Target season
532 nm: Optical uplink wavelength
5–10 MHz: Link modulation rate
1: Drone carried in the hull

The vessel

One hull, two ways to move.

Most vessels pick a side: fast and flat on top of the water, or slow and quiet beneath it. Mobula is being built to do both with the same welded hull: planing across the surface when speed matters, then trimming down and swimming when it doesn't.

The hull in profile. Every facet is a plate; every edge between them is a weld.

Construction · 2027

Welded aluminium plate

Mobula's hull is cut from aluminium plate and welded up. That is the change the renders give away: a hull built from flat plate is a hull made of facets. The angular, low-poly look is not styling. It is what you get when every panel is a sheet of metal and every edge between them is a weld.

Ligmax, last year's trimaran, was 3D-printed in sections and hand-laminated in carbon fibre: light, and quick to redraw and reprint when the geometry changed. A submarine asks a different question. Every seam now has to stay watertight with pressure on the outside of it, and that is the part a printed and laminated hull was never going to do.

Side render of Mobula with the drone bay hatch standing open above the deck, one lidar dome at the tip of the bow and a second on the aft rim of the bay both picked out in blue, and the quadcopter airborne off the stern — Surface configuration: bay hatch open, drone away. The two lidars, one at the tip of the bow and one on the aft rim of the bay, are picked out in blue.

Mode 01

Surfaced / planing

The hull is chined and faceted to lift and plane, driven by twin propellers on a stern strut. On the surface Mobula behaves like a fast autonomous boat: it covers distance, it carries its drone, and it has a radio link and a horizon to look at.

The tall panel standing up amidships in the render is the drone bay hatch, hinged at its forward edge and open because the aircraft has just left; it closes flush with the deck before the vessel dives. The two lidars are the parts picked out in blue: one in a fairing at the very tip of the bow, the other on the aft rim of the bay, where the hatch covers it once it is shut. Both do the surface navigation, which is work that only exists while the vessel is up here.

Three-quarter render of Mobula from astern showing horizontal and vertical control surfaces at the tail — The stern control surfaces: horizontal planes for depth, vertical fins for heading.

Mode 02

Submerged / swimming

Control surfaces at the tail take over once the vessel is under: horizontal planes for depth and pitch, vertical fins for heading. They are what makes depth something the vessel can hold rather than something that happens to it.

Sea state stops mattering the moment the hull is below it, and so does anything on the surface looking for it. What it gives up is the radio link, which is the problem the optical uplink exists to solve.

Head-on render of Mobula's bow showing the forward sensor dome and a blue camera aperture either side of it — Head-on: the forward dome with a camera aperture either side of it.

Sensing

What it sees with

A pair of cameras sits either side of the forward dome, low and close to the waterline where the vessel needs to see obstacles first. They are the vessel's own eyes, as opposed to the drone's.

Below the surface they and the lidars are equally blind, and the drone overhead becomes the only thing with a view, which is why it is part of the vessel rather than an accessory to it.

The optical uplink

Radio stops at the surface. Green light doesn't.

This is the problem that defines the whole project. Put an antenna underwater and it goes deaf: seawater absorbs radio almost immediately, which is why a submarine normally has to come up to say anything at all. Light is the exception, and not all of it: the water column is clearest in the blue-green, right around 532 nm. So that is the wavelength Mobula transmits on.

Mobula running just below a dark water surface, four green 532 nm emitters blooming through the water, with its drone holding station directly above the hull — The link running: hull shallow, emitters lit, drone holding station overhead. The fiducial marker on the bay floor is just visible through the water.

Close-up render of a recessed LED module on Mobula's hull: three green emitters on a green board, throwing a cone of light across the faceted plating — One of the recessed 532 nm emitter modules, set into the hull plating.

Custom emitters, custom driver

Mobula carries its own 532 nm LED arrays, recessed into the hull facets in clusters so the beam pattern covers the water above the vessel rather than a single narrow spot. Behind them sits a purpose-built driver circuit that switches the emitters between 5 and 10 MHz.

That switching speed is the entire point. An LED you can only blink slowly is a signal lamp; an LED you can modulate in the megahertz is a data link. The circuit is being designed and built in-house alongside the vessel, because nothing off the shelf does this at the wavelength and rate the mission needs.

The drone closes the loop

The submarine runs shallow and points its emitters up. The drone holds station overhead, watching the water for the signal and carrying it onward to the shore station. Mobula stays under; its link stays open. Neither half works alone, and that is why the aircraft is built into the hull rather than bolted on.

532 nm: Emission wavelengthGreen: the window water lets through.
5–10 MHz: Modulation rateDriven by a custom circuit built for the vessel.
Sub → drone: Link directionUp through the surface, to the aircraft holding station.

The drone

Built into the boat, not carried by it.

A submarine that cannot talk and cannot see above the waterline is a submarine with a problem. Mobula's answer flies. The aircraft launches off the deck, holds station over the vessel, and comes back to a marked pad inside the hull.

Render of Mobula on the surface with the bay hatch raised and the quadcopter airborne just off the deck — Hatch up, aircraft away. The bay sits amidships, on the vessel's centreline.

Launch

The hatch is part of the hull

A hinged hatch amidships opens onto a bay sized around the aircraft. Closed, it is part of the hull line and the vessel can dive with it. Open, it is a launch and recovery deck.

That is the constraint the whole bay is designed against: it has to be a flush, sealed section of a diving hull most of the time, and an airfield the rest of it.

Top-down render looking into Mobula's open drone bay, with a fiducial marker on the bay floor and the quadcopter descending onto it — The fiducial marker on the bay floor is the drone's landing target.

Recovery

It lands on a marker, not a guess

The bay floor carries a fiducial marker. The drone's downward camera picks it out and uses it to work out its own position and angle relative to the deck, precise enough to put itself back into a bay only slightly larger than it is.

Landing on a small deck that is itself moving is the hard half of the problem. A marker turns it from a guess into a measurement.

It is the vessel's antenna
Above the water the drone has the view and the radio path the submarine gave up. It receives the 532 nm signal from below and relays it onward, which makes it part of the vessel's communications, not an accessory to them.
It is the vessel's eyes
Submerged, Mobula's own cameras and lidars see very little and its bay hatch is shut. The aircraft holding station overhead is the only thing left with a view of the surface and of what is on it.
Neither half works alone
A drone with no boat has minutes of endurance; a submarine with no drone has no link and no horizon. Building the aircraft into the hull rather than bolting it on is what makes the pair a single vehicle.

In three dimensions

The whole assembly, turn it yourself.

This is the CAD model the vessel is being built from: hull, drone bay, emitter modules, propulsion and the aircraft, as one assembly. Drag to orbit, scroll to zoom.

Drag to orbit · scroll to zoom

Drone bay, lid and landing pad
532 nm emitter modules, fore and aft
Lidar and sensor shelf
Twin motors, mounts and propellers
The drone itself, down to the airframe hardware

Roadmap

The road to the 2027 season.

Three things have to work independently before any of it works together: the hull has to dive and come back, the drone has to launch and land on a moving deck, and the light has to carry data through water. The plan is built around proving them in that order.

2026
Design
Hull and dive-plane geometry locked, drone bay packaged around the aircraft, and the 532 nm emitter and driver design settled on the bench.
2026
Build
Hull fabrication, propulsion and control-surface install, first power-on of the electronics and the optical driver.
2027
Test
Surface running first, then dive trials, then the link: emitters in the water, drone overhead, measuring what actually gets through.
2027
Compete
Mobula goes into its first competition season as a complete vessel: submerged, autonomous and connected.

Leadership

Meet the team leaders

Mobula is led by NTNU students who are highly capable across both software and hardware, and who stay hands-on with every subsystem, from the hull and the optical driver circuit through to the autonomy stack.

Team leaders listed in alphabetical order.

Andreas Lindeman
Co-team lead
NTNU student working across the full breadth of the project, from hull fabrication and power electronics to perception and autonomy software.
andreaslindeman.com
Jacob Hansson
Co-team lead
NTNU student equally at home in hardware and software, building everything from the drivetrain and battery systems to the control stack.
jacobhansson.no

The work behind them

Naval architecture
Electrical & power systems
Optical communications
Autonomy & controls
Drone systems
Software & ground station

Partner with us

Help put Mobula in the water in 2027.

Mobula is student-run and student-funded, out of NTNU in Trondheim. Partners get a real stake in an unusual build: a diving vessel, a drone in its hull, and an optical link none of it works without. Tiers start at 10 000 NOK, and in-kind support counts the same.

Brand visibility

Your logo on the hull, on the drone, and everywhere the vessel is shown and run.

Access to the build

Workshop visits, demos and a direct line to the students designing the vessel and its optical link.

Early talent

Direct access to NTNU engineering students working hands-on with subsea autonomy, drones and optical communications.

It planes on the surface.Then it goes under.