Marine Robots

Buying advice

From consumer drone to survey vehicle

At our last update in October 2026, a buyer could spend as little as about $500 on the Chasing Dory or as much as about $50,000 on the VideoRay Scout, and all of them showed a price. Rather than comparing brochures, write down the single worst condition you expect to face, such as a tidal current along a fish farm or a silty harbour after rain, and ask each maker for unedited footage recorded in something similar. How a vehicle copes on its worst day tells you more than its best video. Ask also who was piloting in those clips, since an expert hand can make most vehicles look steady.

Hull footage that a class society accepts

If you want footage to count towards a ship's class survey, the vehicle is only half the question. Lloyd's Register told clients that firms carrying out close-up surveys with remote inspection techniques, ROVs included, need approval as service suppliers. That means the operator's procedures, training and records matter as much as the camera. Before buying for this work, ask the maker whether approved suppliers already use the vehicle, what video and position data it logs, and how files are timestamped. Owners filming their own hull for maintenance planning have more freedom, but should still keep routes and settings consistent so one dive compares fairly with the next.

Fish farm work starts with one job

Aquaculture sites ask a lot of a small vehicle, because nets move, currents shift and fouling builds between visits. SINTEF researchers studying an autonomous robot for fish farms split the task into environmental monitoring, net and fouling inspection, prevention of growth, and docking. Decide which of those jobs comes first, because it changes the vehicle you need. If net integrity is the priority, ask about station keeping beside a flexible surface and how the tether behaves around moorings and ropes. If fouling is the problem, ask whether cleaning tools can be fitted or whether you will still need a separate net-cleaning service alongside the drone.

What to look for

• Depth rating and tether length for the water you'll work in
• Camera, lighting and sonar options for low-visibility conditions
• Portability, launch method and battery swaps for long days on site

Common questions

What is an ROV?

A remotely operated vehicle is an underwater robot piloted from the surface, usually through a tether that carries live video and control signals. It lets you inspect and survey without putting a diver in the water.

Is an underwater drone hard to operate?

Consumer models are designed for straightforward use. Professional ROVs reward practice in piloting and tether management. Either way, check local rules for working on or near the water before you deploy.

Sources and further reading

• Class News 26/2018: service suppliers for close-up surveys using remote inspection techniques — Lloyd's Register.
  Notice that firms using ROVs, drones or crawlers for class close-up surveys need service supplier approval.
• Analysis of a novel autonomous underwater robot for biofouling prevention and inspection in fish farms — SINTEF (MED 2020 conference paper).
  Study of an untethered robot that would monitor fish farm nets, inspect fouling and groom nets to prevent growth.