Raymarine Depth Data Lost — Transducer Connection Fix

What it means

Raymarine 'Depth Data Lost' (the depth number greys out, shows dashes, or the plotter alarms) means it's no longer hearing from the depth transducer or the instrument that feeds depth onto the network.
This matters — you're navigating without a sounder.
The cause is almost always a connection: the transducer cable at the plotter, an iTC-5 converter, or a SeaTalkng instrument that's gone offline.

Affected Models

Raymarine Axiom / Axiom Pro with RV / CPT / DownVision transducers
Raymarine Axiom 2 Pro RVX
Raymarine eS / gS Series fed depth via SeaTalkng
Systems using an iTC-5 or i70 instrument as the depth source

Common Causes

Transducer cable unplugged or loose at the back of the plotter
iTC-5 transducer converter lost power or dropped off the SeaTalkng backbone
Depth source instrument (i70, ST70) switched off or failed
Transducer face fouled with weed, barnacles, or a thick coat of antifoul
Air bubbles under the transducer at speed (planing boats) — intermittent loss only when moving fast
Failed transducer (water ingress into the element)

How to Fix It

Check what feeds depth.

Go to the data source settings and look at where depth comes from.
If it's a transducer plugged straight into the Axiom, the issue is that cable.
If it's another instrument on the network (an i70, an iTC-5), that device is the thing to check first.
Reseat the transducer cable.

At the back of the plotter (or at the iTC-5 / instrument), unplug and firmly reconnect the transducer cable.
Check the locking collar is fully turned.
Look for corrosion or green crust on the pins — a clean with contact cleaner often brings depth straight back.
Check the depth instrument is alive.

If depth comes via an i70 or similar, make sure that instrument is powered and showing data.
A blank or frozen instrument display means it has dropped off the SeaTalkng backbone — check its spur connector and the backbone power.
Inspect the transducer (when hauled).

Next time the boat's out of the water, look at the transducer face.
Weed, barnacles, or a heavy antifoul coat over the element kills the return signal.
Clean it back to bare face — don't paint the active element.

Frequently Asked Questions

Depth only drops out when I'm on the plane — why?

At speed, water flowing past a hull-mounted transducer can carry air bubbles across the face, and the sounder loses its bottom return.
If depth is rock-solid at displacement speed and only dashes out above planing speed, the transducer is in a turbulent spot on the hull — it may need relocating to clean water, or fitting a fairing block to smooth the flow.