Overview

In cold water environments, ScanFish units can experience intermittent or progressive depth/pressure sensor misreading due to connector seal degradation. This article explains the root cause, how to recognice it, and the steps to resolve it.

Root Cause

Cold water can cause the synthetic rubber in SubConn connectors to stiffen, reducing its natural elasticity and its ability to maintain a tight seal. This can allow electrical current to leak into the surrounding water from the 2-pin main power on the controller, which in some cases has caused interference on the 4-pin pressure sensor millivoltage signal.

Symptoms

  • Sudden changes in ScanFish depth readings, typically jumping to 0 m
  • As a result, sudden jumps in the Calculated Seabed value (altimeter + depth input)
  • If Set Min Altimeter Depth is configured to >0, this could easily be mistaken for an altimeter failure, as the altimeter would appear not to be functioning
  • In Fixed Depth or Parking mode, this can lead to sudden unintended dives

Fix - Connector Sealing Procedure

  1. Disconnect the pressure sensor and pow-com (2-pin) connectors from the controller.
  2. Slide heat shrink tubing — preferably adhesive-lined — onto the pigtail, long enough to cover both bulkhead connectors and approximately 3 cm of the pigtail.
  3. Apply a layer of MOLYKOTE® 44 Medium grease to the female connectors, corresponding to a minimum of 1/10 of the socket depth.
  4. Fully mate the male and female connectors to ensure optimal distribution of grease on all contacts and in the sockets.
  5. Slide the heat shrink over the bulkhead connectors and use a heat gun to shrink the tubing in place.
  6. Run a pre-flight check and confirm the depth sensor is reading correctly before redeployment.

If Sealing Does Not Resolve the Issue

  • Inspect the sensor membrane for physical damage or sediment build-up
  • Replace the depth sensor and repeat the steps in the Fix section above
  • Contact EIVA support