Hi Matt

Please advise if bottom composition is required to "add a depth highlight layer" to my fishfinder?

No - a "Depth Highlight" layer is just a set of depth isobaths in a single colour (default hot pink) that can be used to highlight a certain depth range (or ranges). To use a depth highlight layer, you need to generate in vector mode and then configure the visibility of the depth highlight layer on your unit. Each depth range will have its own chart category that can be toggled on or off.

Thanks Matt

Im sorted