Using waterwayguid.com, I can search for marina or anchorage in an area of the map. On Navionics I can search for marinas, fuel,...etc but not anchorage. I remember I could do that previously on Navionics but I don't see that option now.
I think it is still there. Hit search and put in "anchorage". Problem is that a lot of "anchorage restaurants" and things like that pop up, but also anchorages that have been listed by different users.