The latest version of Garmin Mapsource v5.0 has an incompatibility with
Bluecharts v5.0 (and possibly others). Here is the problem:

Use the "Find Nearest" feature in Mapsource. If you select Marine, with the
subcategory of All, you get mostly spot soundings in the "found" list. This
is of no use to mariners, for nobody cares how close a spot sounding is.
Spot soundings are not considered precise locations to which a fix can be
referenced. Spot soundings are useful as a way to crossreference ones
current position with ones depth, and vice versa. But they are not accurate
enough to be fix points. Furthermore, they are completely nondescript in
their naming. What I mean is that seeing a whole list of 7, 9, 25, 25, 25,
37, 42, 44, 44, 44, 44, 42, 44, 25, 26.... etc., does me no good.

The latest Mapsource should either completely ignore spot soundings, and
perhaps even cartographic markings when searching, or should allow for
"multiple selection" of search criteria, rather than the drop-down menu that
only gives the option of all or one.

--
DJO