Earlier in the summer I bought the Garmin Topo Alaska Enhanced map card ($100) from Accupoint in Anchorage and plugged it into my Garmin Oregon 450 (thanks Ken!). A few weeks ago, while on Denali's Whale Tail, I had a chance to test it out.
I have a love/hate relationship with GPS units. I think they detract from geophysical mountain skills of map, altimeter and compass. On the other hand I need every advantage when guiding. Also, it's nice to make progress in a whiteout. After purchasing Alaska Enhanced my question became: could the GPS map take the place of a 1:63,360-scale map printed by the USGS? (Alaska's most detailed maps are 1:63,360.)
I imagined using Alaska Enhanced for tour planning, while in the tent in the backcountry, by creating waypoints on the GPS before heading out into low visibility. The problem was I had too much good weather in Alaska this summer. I did find a whiteout on Mount Logan, but that's in Canada. There I followed waypoints that I entered while on the trail during the ascent.
Then a couple weeks ago we woke to fog soaking our camp on the Whale's Tail. In Alaska. Yes! Sometimes I am so stoked for whiteouts.
During our foggy day on the Whale's Tail we followed a ridgeline for 10 miles with 5,000 feet of ascent. Ridgelines in zero viz are not straightforward. They split, they broaden and become indistinct. All day I kept the GPS hanging around my neck, referring to it constantly to keep us on the ridge. Alaska Enhanced made the day almost a no-brainer and kept our group on the move.
During the day I did go back to my paper map. Part of the ridge was too craggy for hiking and we traversed steep tundra slopes along the side. A cliff appeared in the fog and I consulted the GPS map at right - no cliff. The cliff did show up on the 1:63,360 USGS map with 100 foot contours (left).
When micro-route finding, those minute map details make a huge difference. While Alaska Enhanced is worth every cent, I found it doesn't take the place of the USGS-printed map for complex terrain.