RAM B 107 Fishfinder Mount

[dgax65]

James
They have those watertight cable outlets and cable clams at Whitworth's.

Watertight Cable Outlet These are used to pass un-terminated cables and cables with small connectors.

Cable Clam These are used for cables with larger connectors.

You might try using Selly's All-Clear to fill the gaps between the cable and the grommet. It doesn't look pretty, but it does the job.