Equipment: M80 USV, Coda Octopus real time 3D imaging sonar
Purpose: To survey wind farm turbine pile foundations and check the scouring condition of the underwater cables.
1. 15Km 100KV main cable checking
2. 80Km 35KV loop cable checking
3. 38 units of turbine checking
4. Booster station area checking
The survey is conducted continuously day by day. The M80 USV surveys 20 km of cable and 20 turbine piles each day. By the real-time 3D imaging sonar data, surveyor is able to adjust the survey route of the USV and modify the scanning angle to extend the survey area when an abnormal scouring is found.
Pic.1 M80 USV transported on a mother vessel
M80 USV could sailing along the cable line and pile position with deviation of less than ±1 meter for precise survey, each survey mission can be saved and compared with historical data.
After few days’ inspection, scouring problems were found:
12 places of piles foundation have cable suspendedover 4m,
29 places of cable were scoured and exposed
4places 100KV cables were deviated from original coordinates over 5m
1 place cable were overbendingdue to external force
Pic 3. M80 USV in Survey
Pic 4. Pile foundation damaged, nearly 7m cable suspended
Pic 5. Booster station scoured area, 4m suspended and nearly 10m exposed
Pic 6. Pile foundation have 100m exposed cable
Pic 7. Overbending cable
With smaller and flexible survey platform, M80 USV is able to get close to turbine and provide more completed data coverage. The trimaran hull design brings more stabilities and quality data. Autonomous survey checking cable line save great time on filed. The launch and recovery of USV can be operated efficiently on mother vessel.
M80 USV work with mother vessel at offshore is great solution for hydrographic survey cost reduction, less operation labor force and much lower fuel consumption comparing with big survey ships.
Unmanned operation minimizes surveyors’ safety risk at sea operation, especially in restricted area like contaminated area, polluted or toxic water etc.