Building an underwater ROV for a student project: parts list

A tethered ROV with six thrusters, a camera behind a dome, two lights and depth hold, built from parts rated for the water rather than waterproofed by hand. It suits a final-year project, a club vehicle, or a first step towards the MATE competition.

What the vehicle is

• A frame you cut yourselves from HDPE sheet. HDPE is easy to machine, doesn't corrode, and at about 0.95 g/cm³ floats very slightly, so the frame adds almost nothing to the ballast sums.
• Six thrusters in the vectored layout: four horizontal at 45° for forward, sideways and turning, and two vertical for depth. ArduSub has this layout built in.
• One pressure housing holding the controller, the camera behind a dome, and the battery.
• A tether to the surface that carries Ethernet: live video down, commands up.
• Lights, a depth sensor for depth hold, and a leak sensor, because every housing leaks eventually.

Voltage and thrusters

Build it on a 6S battery (22.2 V nominal). Blu-Sub's thrusters, lights and power switching all run in that range, and a higher voltage means less current for the same power.

The list uses the [Blu-Thrust Z60E](/products/blu-thrust-z60e-500). Blu-Sub rates it at 4 kgf forward and 3.7 kgf in reverse at 24 V, 290 W at most, 300 m, and 245 g. It has its speed controller built in, so it wires straight to power and a signal line and the housing holds no ESC boards. Order three clockwise and three counter-clockwise so the torques cancel.

Two alternatives:

• The [Z80E-170](/products/blu-thrust-z80e-170), also built for 24 V, gives 5.3 kgf forward at 270 W on a larger propeller. It costs more and weighs twice as much, but a more efficient thruster means a longer dive.
• Blue Robotics' [T200](/products/t200-thruster) with a [Basic ESC](/products/basic-esc) is the thruster Blue Robotics describes as the usual choice for MATE and RoboSub teams, and it has the most documentation and forum help behind it. Blue Robotics rates the Basic ESC at 30 A on 7 to 26 V. With the separate ESC it costs roughly twice as much per thruster. Our thruster selection guide compares them in more depth.

The current budget

Six Z60Es at full power draw about 1,740 W, which is almost 80 A from a 6S pack. The battery, the switch and the wiring would all have to be sized for that, and a student ROV in a pool never needs it.

What saves you is how propellers behave. Thrust rises roughly with the square of propeller speed and power with its cube. Limit the thrusters to 70% of full speed and each one draws about 0.7³ = 34% of its full power, while still giving about half its full thrust, around 2 kgf forward. Six at that limit draw 6 × 290 × 0.34 = 590 W, or about 27 A. Set the limit in ArduSub by narrowing the thruster outputs' range. The pilot gain alone isn't enough, because depth hold can still ask the vertical thrusters for full power. It keeps the whole vehicle under the 30 A power switch in the list below. These are approximations, so measure the real current on the bench with the thrusters in a water tank before the first dive.

Dive time. A 6S Li-ion pack of 21700 cells at 4,500 mAh holds 97 Wh. Use 80% of it: 78 Wh. Gentle piloting might average 100 W on the thrusters, the electronics take about 10 W and two lights at full brightness 34 W, which adds up to 144 W. That gives 78 ÷ 144 × 60 = about 30 minutes. Log the real current on your first dives and correct the figure.

The pressure housing

• Tube. A Blu-Sub [cast acrylic tube](/products/subsea-enclosure-acrylic-pv), 115 mm outside diameter and 400 mm long, with 102 mm inside for the tray, the electronics and the battery. Blu-Sub rates its acrylic tubes from 20 m to 250 m depending on diameter and length. Ask for this size's rating with your quote. Either end of that range is plenty for a pool or a lake.
• Flanges. An aluminium [flange](/products/subsea-aluminum-flange) at each end, sealing to the tube with a double O-ring.
• Front. A polycarbonate [dome](/products/subsea-optical-dome-end-cap) for the camera. A dome distorts the view less than a flat cap under water.
• Rear. An aluminium [end cap](/products/subsea-aluminum-end-cap) with 14 M10 holes for everything that passes through.
• Inside. A [tray](/products/electronic-tray-set-for-enclosure-pv) for the electronics, with the battery strapped underneath.
• Leak test. A [vent and vacuum plug](/products/subsea-m10-self-sealing-vent-vacuum-plug), so you can pull a partial vacuum with a hand pump and watch the gauge before every dive. If the vacuum holds for fifteen minutes, the seals will hold. Our guide to acrylic and aluminium housings explains the trade-offs of each material.

The rear cap's 14 holes, counted:

Each gland penetrator must match its cable. The Z60E has a 3-core 20 AWG cable and the lights a 3-core 16 AWG one, and Blu-Sub makes a gland variant for each. The low-depth glands are rated to 100 m. Our penetrator guide covers when a connector is worth its extra cost.

Buoyancy. The tube alone displaces a little over 4 litres, so it can hold up about 4 kg in fresh water before its own weight and contents are counted. Weigh the finished vehicle in air, then trim it in water with foam and lead until it floats very slightly and sits level. Our buoyancy calculation guide walks through the sums.

Control, tether and power

Controller. Blue Robotics' [Navigator](/products/navigator-flight-controller) sits on a Raspberry Pi 4 and runs ArduSub under BlueOS. It carries its own IMU, compass and barometer, 16 PWM outputs and inputs for two leak probes. The six thrusters go on outputs 1 to 6 and the lights on a spare output, which dims them.

Sensors. Blu-Sub's [M10 depth sensor](/products/subsea-m10-depth-sensor-0-30bar) uses the MS5837-30BA chip, rated for 300 m, on I2C at address 0x76, the chip and address ArduSub reads for depth hold. It ends in a DF13 plug, so a JST-GH to DF13 adapter connects it to the Navigator. The [SOS leak sensor](/products/sos-leak-sensor) puts probes at the low points of the housing.

Tether. A pair of [Fathom-X boards](/products/fathom-x-tether-interface-board-pair) carries Ethernet over a single twisted pair. Blue Robotics measured about 80 Mbps and rates it for tethers of 300 m and more. One board goes in the vehicle and one at the surface, with an Ethernet cable to the laptop. The surface board needs its own small power supply. If you'd rather not build that, buy Blue Robotics' FXTI, a ready-made surface box, with a single Fathom-X board for the vehicle instead of the pair. Choose a neutrally buoyant tether, so it doesn't pull the vehicle up or down.

Power switching. A switch that opens the housing to turn the vehicle on defeats the leak test. The Blu-Sub [M10 rotary switch](/products/subsea-m10-rotary-onoff-switch) sits in the rear cap and drives a [MOS low-side switch board](/products/mos-low-side-switch-board) inside. The rotary switch is rated for only 0.5 A, but it doesn't need more: it drives the board's input, and the board carries the vehicle's current. The 30 A board works on 13 to 28 V, which covers a 6S pack from full to empty. Put a fuse in the battery lead as well.

Camera and lights. Blue Robotics' [Low-Light HD USB Camera](/products/low-light-hd-usb-camera) sits behind the dome and plugs into the Pi. Two Blu-Sub [dimmable LED lights](/products/subsea-dimmable-led-light-1500-lumens-6000k), 1,500 lumens each at 17 W and PWM-dimmable on 10 to 28 V, go on the frame to either side of the camera, well off its axis, so the particles they light up stay out of the picture. Our lighting guide explains the geometry.

Building for MATE

MATE classes power the vehicle from a surface supply defined in each year's competition manual, with a fuse the vehicle must stay under. If you are building for MATE, design the power system to that manual instead of an onboard battery, and do the current budget against its fuse. The rest of this list still applies. For an untethered vehicle, see our competition AUV guide.

Sources.

• Thrust, power, voltage, depth rating, mass and cable of the Blu-Thrust Z60E and Z80E-170, and the specifications of the Blu-Sub housing parts, penetrators, depth sensor, rotary switch, switch board and lights, from Blu-Sub's published specifications.
• Navigator features from Blue Robotics' Navigator page (accessed 2026-09-23)
• Basic ESC rating from Blue Robotics' Basic ESC page (accessed 2026-09-23)
• Fathom-X bandwidth and tether length from Blue Robotics' Fathom-X page (accessed 2026-09-23)
• Thrust and power against propeller speed from the propeller affinity laws. Treat the figures here as estimates, and measure your own.

Published 23 September 2026. Last revised 25 September 2026. Corrections to sales@vebixautomation.com.

Building for a team or a lab?

Send us the depth, the dive time you need and whether it is for MATE, a project or research. We will check the thruster, housing and penetrator choices against each other and send a quotation your institution can raise a purchase order against. Ask for a quote.