Deployment Notes: West Palm Beach/Singer Island, October 2023
We hit the water at 05:30, fighting a stiff northeasterly breeze that was already whipping the surface into a choppy, grey mess. The air felt heavy, typical for a Florida October, and the smell of salt and decaying seagrass was thick near the lagoon edges. As we maneuvered the skiff toward our target coordinates near the shelf edge of Singer Island, the current was already pushing us hard toward the mainland. This isn't your typical open-ocean drift; it's a violent, localized tug-of-war between the Florida Current and the restrictive geometry of the barrier islands.
The water state was volatile. We saw surface ripples shifting rapidly, a clear sign of the vertical shear that defines this region. To the east, the Atlantic drops off into the deep, but right here, the bathymetry is a chaotic mess of shifting sandy shoals and sudden troughs. It's a hydrodynamic bottleneck. The volume of water forced through the narrow gaps between the mainland and the islands creates velocity spikes that make standard regional models look like guesses. If you aren't accounting for the semi-diurnal tidal regime—two highs and two lows that pump water through these channels like a piston—you're missing the real story.
What We Found
The data hit us with a shock: the velocity gradient was far more aggressive than our pre-deployment simulations predicted. We recorded surface currents screaming northward, while just a few meters down, the water was practically stagnant or even reversing direction. This kind of shear is a nightmare for calculating total discharge. Honestly, it's a classic scenario where surface-only measurements lie to you. We found localized velocity spikes that peaked during the ebb tide, coinciding with wind-driven surges that pushed the water column into a state of total instability.
The most frustrating part was the signal attenuation. During a brief storm surge event mid-deployment, the bottom basically liquefied. The resulting turbidity created a wall of acoustic noise. We lost the first three bins entirely—pure bin contamination. The suspended sediment load was so high that the acoustic pulses simply couldn't penetrate the lower water column. It reminded me of a 2021 run where we saw similar signal loss; when the Florida coast gets stirred up, the water becomes an opaque soup for sonar. We had to perform a sanity check against our shore-based gauges to ensure the ADCP hadn't simply shifted on its mount.
Equipment Performance
I stuck with the 600kHz ADCP for this run, and it was the right call. In these shallow, high-energy zones, you need the spatial resolution to catch the shear layers before they blur together. However, the mounting was a gamble. We used heavy-duty spiked mounts because I've seen instruments tilt 15 degrees in a single week in this area due to sand migration. Even then, the shift was palpable. The unit held, but the noise floor rose significantly during the peak tidal flows. We got a clean signal during the slack tides, but once the Florida Current started interacting with the island's shelf, the data got messy. It wasn't a failure, but it proves that in West Palm Beach, the environment always wins the first round.
Recommendations for Future Deployments
If you're heading back to Singer Island or the surrounding inlets, don't trust the sandy bottom. It's a conveyor belt of sediment that will move your gear if you let it.
- Use 600kHz units exclusively to maintain bin resolution in the shallow shear layer.
- Avoid standard tripod mounts; use weighted, spiked anchors to prevent tilt-induced vector errors.
- Set a higher ping rate during known storm windows to better characterize the onset of turbidity.
- Increase the blanking distance slightly to avoid surface noise from wind-driven chop (especially during NE wind events).
- Perform ground-truthing with handheld current meters at multiple depths to validate the ADCP's vertical profile.
Field report by Elena Rodriguez. Elena is a specialist in underwater acoustics and oceanographic instrumentation with two decades of experience mapping coastal sediment transport in high-energy environments.
Field Deployment Report: Velocity Profiling and Sediment Flux at Singer Island, West Palm Beach