Marine growth (bio-fouling) is an important consideration for long-term mooring deployments. Over time, current profilers and other submerged instruments become coated with biological material, which can eventually block the transducers and reduce profiling range. To monitor fouling, track long-term trends in amplitude data. While short-term variations are influenced by factors like suspended sediments, zooplankton, and bubbles, biological growth—especially barnacles—introduces a slow downward trend. Profiling range gradually declines until signal strength becomes insufficient. With experience, you'll learn how long it takes before cleaning is necessary, allowing you to establish reliable maintenance intervals.
Initial Deployment vs. Post-Cleaning Factory-new instruments have smooth surfaces that resist fouling at first. After cleaning, rougher surfaces promote faster regrowth. Maintenance is typically required every 6–12 months, though this depends on factors such as:
- Water temperature and depth
- Geographic location
- Seasonal biological activity
- Growth is fastest in warm, shallow waters and slowest in cold, deep environments.
When calculating forces on the mooring line, include the effects of marine growth by increasing estimates for weight, diameter, and drag of all components.
To prevent bio-fouling from impacting your data collection, there are two main methods that can be chosen:
Anti-fouling paints
Can be used on transducers, but apply only a thin layer (~1 mm) to avoid impacting signal strength. Avoid chemically aggressive or particle-laden paints (e.g., containing metal flakes). Make sure that there are no air bubbles trapped between the paint and the face of the transducer.
Ideal for deployments over an extended period of time (> 1 year)
Do not paint anodes, grounding plates or pressure ports.
Users have reported positive results from using paint by Jotun (Primer + Paint e.g. SeaMate M or SeaQuantum)
If in doubt if the layer was too thick, perform a function test before deployment.
Anti-fouling adhesive patches
Supplied by Nortek. For further details, please contact your sales representative.
Made of silicone resin, polyester film and acrylic adhesive.
Durable and effective solution to double deployment time while reducing the environmental impact compared to paint.
Intended for shorter deployments of 3-6 months.
Ensure that no pressure/ temperature sensors are covered when applying!
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