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Cleaning and Preventing Biofouling on Nortek ADCP Sensors (Signature 55, H-ADCP)

Safe external cleaning and biofouling control for Nortek ADCPs used in marine deployments.

Overview

Marine-deployed Acoustic Doppler Current Profilers (ADCPs) are exposed to biofouling from algae, barnacles, and other marine organisms. Over time, biofouling can reduce acoustic signal strength, shorten profiling range, increase power consumption, and degrade data quality.

This article provides generic, WISE Group–approved guidance for the safe external cleaning of Nortek ADCP sensors, including the Signature 55 and Nortek H-ADCP. It also outlines practical steps to reduce biofouling risk between deployments.

This article does not replace Nortek documentation. Manufacturer manuals and guidance remain the primary authority and should always be consulted for model-specific requirements.

Who this is for

  • Site personnel performing routine recovery and cleaning

  • Technicians supporting marine sensor deployments

  • Engineers responsible for maintenance planning and data quality

This article does not cover internal servicing, disassembly, or repair.

Prerequisites

  • Sensor(s) have been fully recovered from the ocean

  • All lifting and recovery operations are complete

  • Sensors or deployment cage are secured on deck or in a workshop cradle

  • Appropriate PPE for marine maintenance is available

Safety notes

Hazards: suspended loads, heavy equipment, marine contamination

  • Cleaning must only begin after sensors are fully out of the water and stable.

  • Do not work on sensors that are suspended from cranes, winches, or LARS systems.

  • ADCPs are heavy instruments; follow site-approved lifting and handling procedures.

  • Marine growth may contain sharp shells or biological contaminants.

Responsibility boundaries

  • This procedure is limited to external cleaning only.

  • Do not open housings, remove end caps, disturb seals, or access electronics.

  • Internal servicing is restricted to authorised Nortek service personnel only.

Step-by-step

1. Recover and secure the deployment

  1. Recover the deployment using the approved site method.

  2. Place the sensor or deployment cage on a stable, non-slip surface.

  3. Confirm the assembly cannot roll, rotate, or shift during cleaning.

2. Multi-sensor deployment cages

Some installations include multiple Nortek sensors in a single deployment cage, for example:

  • A Signature 55 ADCP

  • A Nortek H-ADCP

When cleaning multi-sensor assemblies:

  • Treat each sensor as an independent instrument.

  • Avoid contacting adjacent transducer faces with tools or debris.

  • Prevent fouling removed from one sensor from being dragged across another.

3. Initial fresh-water rinse

  1. Rinse all external surfaces with fresh water.

  2. Remove salt residue, loose debris, and soft biological growth.

  3. Use low to moderate water pressure only.

  4. Do not direct water jets at:

    • Acoustic transducer faces

    • Electrical connectors

    • Pressure ports or seals

4. Manual removal of biofouling

  1. Inspect transducer faces and surrounding housings.

  2. Gently remove growth using:

    • Soft plastic scrapers

    • Soft brushes or cloths

  3. Avoid:

    • Metal tools

    • Abrasive pads

    • Sharp implements

  4. Take particular care not to scratch or damage acoustic surfaces.

5. Cleaning agents (if required)

  1. If fresh water is insufficient, use mild detergent only.

  2. Do not use:

    • Solvents

    • Acids

    • Abrasive or aggressive cleaners

  3. Rinse thoroughly with fresh water after cleaning.

6. Final inspection and drying

  1. Inspect each sensor for:

    • Remaining fouling

    • Surface damage introduced during cleaning

  2. Check connectors and pressure ports are clean and unobstructed.

  3. Allow sensors to fully dry before storage or redeployment.

What you must not do

  • Do not open the instrument housing.

  • Do not lift or clamp sensors by the transducer head.

  • Do not apply coatings to connectors, pressure ports, anodes, or seals.

  • Do not assume a sensor is safe to handle based on visual cues alone.

Reducing biofouling risk

Biofouling cannot be eliminated, but it can be managed through planning and maintenance.

Common strategies include:

  • Selecting appropriate recovery and cleaning intervals

  • Considering site-specific conditions (temperature, nutrients, depth)

  • Using approved, thin anti-fouling measures where supported

  • Monitoring long-term changes in signal strength as an early indicator of fouling

Typical maintenance intervals for Nortek ADCPs are often 6–12 months, but this varies significantly by environment and deployment conditions.

Manufacturer guidance (recommended reading)

For authoritative, model-specific guidance, refer to Nortek resources:

Validation / What “good” looks like

  • Transducer faces are clean and unobstructed

  • No new scratches or coating damage present

  • No housings or seals disturbed

  • Sensors are dry and ready for storage or redeployment

Troubleshooting

Symptom: Reduced profiling range or signal quality
Possible cause: Progressive biofouling
Fix: Recover and clean sensor; review maintenance interval

Symptom: Visible surface damage after cleaning
Possible cause: Abrasive tools or methods
Fix: Stop work and escalate to WISE Group or Nortek support

FAQ

Does this guidance apply to both Signature ADCPs and H-ADCPs?
Yes. The external cleaning principles apply to both unless Nortek documentation states otherwise.

Can cleaning be performed while the sensor is still deployed?
No. Sensors must be fully recovered, secured, and stable before cleaning.