If you sail or cruise down the ICW, having a towing membership with Seatow or Towboat US is essential.
The ICW markers are poorly maintained, in some areas locals are putting out floating buoys to mark the real channel. In others, dredging has not been done in years and the channel at low tide is very narrow. Just about everywhere I've been, the markers are scattered around to the point of being near useless and the channel on the chart weaves around in unmarked turns and weaves.
In other words, you will run aground at some point if you are in the ditch for any period of time. Our last ungrounding would have cost $1100, but our $180 (?) in Towboat US subscription covered it. In that case, the money was the difference between sleeping in the marina and eating a nice breakfast and standing watch for 6 hours with the boat heeled over while we waited for the tide.
They are also invaluable sources of information when navigating tricky inlets. A 5 minute call gets you local knowledge and hazards. I've even had them offer to escort me through.