Locating a sunken boat in a high-altitude lake with a drone echo sounder

The challenge

Laguna San Pablo is one of the largest and deepest lakes in Ecuador. After the boat sank, the local search and rescue team could not find the wreck, so the divers asked ADS for help.

A boat or ROV with a multibeam echo sounder or side-scan sonar would normally be the first choice for this kind of search. But getting a multibeam system meant more time and coordination with national emergency services, and the wait was too long. A drone with a single-beam echo sounder (SBES) was available straight away. The team also faced:

• a remote upland site, far from cities, where moving heavy search equipment is hard and expensive;
• a search area 450 m from the shore;
• an altitude of 2,650 m, where thin air reduces lift while the drone carries the echo sounder;
• the narrow coverage of a single beam, which called for a much denser survey grid.

The solution

ADS flew a DJI M350 RTK carrying SkyHub, a radar altimeter, an obstacle avoidance sensor and an ECT D052S echo sounder. The mission was planned with the Area Scan function in UgCS and flown from the shore.

• The lake had no vegetation or obstacles and the water was calm, so the echo sounder was towed at up to 0.7 m/s along west–east lines.
• Line spacing came from the estimated depth and the 7° beam width. The beam footprint on the bottom worked out at 4.28 m, so lines were set 5 m apart for about 90% coverage and a near-zero chance of missing the target.
• A check line was added to the mission.

The result

Watching the live echo sounder data, ADS saw a rise of about two metres on the south-eastern side of the search area, matching the boat's size. The rescue team confirmed the boat was there. The data was later processed in Hydromagic, which showed the anomaly and a 3D model of the object.

SPH Engineering stresses that the team's skill in reading and using the data was key, and that a single-beam system can do this job in the right hands despite its limits.

Where this applies in India

Drone echo sounders can support underwater searches and inspections where boats or divers are slow to deploy. Realistic uses include:

• supporting disaster response and search teams on lakes, reservoirs and rivers;
• locating submerged objects or obstructions near dams, intakes and bridges;
• surveys of remote or high-altitude lakes where heavy equipment is hard to bring in;
• rapid depth checks before divers go in.

SPH Engineering's bathymetry training is also available through HobiTech.

The equipment, available from HobiTech

Drone	DJI Matrice 350 RTK
Echo sounder	EchoLogger ECT D052S
Onboard computer	SkyHub by SPH Engineering with the SkyHub echo sounder software
Altimeter	Radar altimeter for True Terrain Following
Flight planning	UgCS - Drone Flight Planning Software
Processing	Hydromagic (used in the project)

Case study by SPH Engineering, published August 2024. This page summarises it in our own words; the search was carried out by Aerial Development Services, not by HobiTech. Read the original case study on SPH Engineering ↗