Underwater Surveying and Inspection ROVs

The vehicles

• Deep Trekker inspection-class ROVs. The main platform: rugged, quick to deploy from a boat or a quay by a two-person team, with the thrust to hold station in a tidal flow and the depth rating for UK ports, rivers and reservoirs.
• Blue Robotics modular ROVs. For confined and shallow water: culverts, intake screens, outfalls, harbour walls and fish-farm infrastructure, where a small, configurable vehicle gets in and a larger one does not.
• Payloads. 4K video and lights for condition, Voyis imaging where clear stills matter, Teledyne imaging sonar for the parts that turbid water hides, and ultrasonic thickness probes where a project needs steel readings below the tidal zone.
• Beyond our fleet. Work-class vehicles for deep offshore structures, and diver intervention, are arranged with partner operators and coordinated by NDTScan, not claimed as our own.

What the ROV is used for

• Piles, dolphins and jetty steelwork: coating breakdown, pitting, holing, missing anodes, marine growth and damage, pile by pile.
• Quay walls, sea walls and bridge piers: face condition, voids and undermining, and scour at the toe recorded by sonar.
• Culverts, outfalls and intakes: lining condition, blockage, joint displacement and scour where entry is impossible or unsafe.
• Reservoirs, tanks, lock gates and screens: inspected in service, with the structure left full.
• Hulls, pontoons and moorings: condition below the waterline and the state of chains, shackles and anchors.

Video or sonar

Video is the record the engineer wants to see, and in most UK water it is useful within a metre or two of the structure once the lights are on it. Beyond that, and in silt-laden rivers and estuaries, it shows nothing. Imaging sonar does not care about visibility: it returns the shape of a wall, a pile group, a scour hole or a debris field as an acoustic image. The survey plan says which parts of the structure get which, and most structures get both.

What the engineer receives

• The structure on a plan with every element numbered, and findings against each one.
• Stills and clips for every defect, referenced to the element and the depth, and sonar images where used.
• Thickness readings where taken, tabulated per element and level, for the corrosion assessment.
• The vehicle, payloads, state of tide and visibility for each pass, and what could not be resolved.
• A repeatable route and grid, so the next survey measures change.

The interpreted report follows within an agreed number of working days. The vehicle is one method within an underwater survey; the same visit usually covers the soffit, deck and steel above the waterline from the boat, and the whole scope is described under marine surveys and ROV inspection services.

What an ROV cannot do

It cannot measure a crack width, take a sample, clean a patch for a gauge reading, or make a repair. It cannot see through silt, and it cannot hold station in a current beyond its thrust. Each of those limits is stated in the report where it applied, and where a hand on the structure is needed, that is arranged through diving partners rather than worked around.