Wormdrowner,
If you are just using it for contour lines and depth soundings, the level of detail between the Navionics Hot Maps Premium C6 chip and the Platinum C6 are equal. If your chartplotter supports the extra features such as 3D Views, Panoramic Lake Photo, Top-down Satellite Imagery, then the Platinum has these extra features.
Here is the Lake Listings for the Hot Maps Premium C6:
http://www.navionics.com/lakes/LakeList ... RegionID=5Here is the Lake Listings for the Hot Maps Platinum C6:
http://www.navionics.com/lakes/LakeList ... RegionID=5Start with this link and see which chips chartplotter supports first and then decide which features you are looking for.
http://store-mirror.navionics.com/no_nt ... otter_listFor most anglers here on the Bay of Quinte and the Eastern basin of Lake Ontario I recommend the Hot Maps Premium C6 unless your chartplotter supports the additional features and you are looking for these. However the level of detail in the actual chart itself is identical.
Hope this helps,
Jeff