I've missed why you don't have one. We use the radar overlay almost as much at anchor as we do when we're moving.

Sitting at anchor and watching a rain squall approach is always an interesting informational experience. Looking at the image of a squall approaching in relationship to the landmass is mesmerizing.

We also use it at anchor a lot to see the relationship of our boat to others in the anchorage.. Boats drag, boats swing and the anchorage changes. When we arrive at a new anchorage there are many times when I'll turn the overlay on for a few minutes and put an 'X' on each boat near us. At 3:00 in the morning and we're in the middle of a squall or the wind pipes up to 30+ knots all we have to do is turn the radar on and we have a great picture of the landmass, our boats new position and where all the other boats have moved to. If you turn the radar off but leave the GPS on for an anchor watch, the track while at anchor gives you a great image of where you have moved to or where you are swinging. Again at 3 AM when the shit hits the fan you can turn on the radar and have an entire history of where you have been, where you are, where everyone else is. including the direction and speed a squall might be coming from. If you need to re-anchor it's also a lot easier to pick your way through boats and find a new place to drop the hook.

You get a lot of information from being able to use the overlay while at anchor.

Of course you still have the same information with just the radar but without the chart behind it there's a lot to interpret.