SIGHTINGS chartbooks — cont’d
detail for safety. Steve Martin once observed, “Comedy That puts the burden on guidebook authors like us and Point is not pretty.” But when you’re 1,000 miles Loma Publishing to try to fill the voids. Mexico Boating Guide (2nd from land, trapped in pitch darkness in a edition) is a huge improvement, but voids remain, to be sure. tiny locker with only a screwdriver while For example, the first time we charted Isla Isabela in the Sea of the boat rolls on under autopilot. . . well, Cortez, we circled the island and sounded the bottom from sea level it may not be pretty, but it’s pretty dang using the boat’s own depth sounder, accounting for the tide and funny. correcting to MLW. The unwitting comedian in this case We anchored in two spots, South Cove, then Las Monas. (Like was Bill Merrick, who at the time was racat Isabela, we have visited chartable spots many times in different ing last month’s Singlehanded TransPac boats and different weather conditions.) We took photos of the rarace. He’d been having SSB transmission dar screen showing the general layout of each anchorage, along with the boat’s GPS position at anchor. Then, by dinghy, we sounded the anchorages and shorelines using a handheld depth sounder and a lead line. Using a handheld GPS, we recorded triangulations (GPS positions in at least three prominent locations, which form a triangle), along with compass bearings to prominent land features from each GPS position. We snorkel the anchorages to check out the bottoms and note any underwater dangers. Going ashore to pace off distances is important, too, because we compare distances derived from hand-bearings to those recorded via the ‘shoe leather’ method. Meanwhile, we’re clicking photos like mad. For example, during just one 90-day research voyage around the Sea of Cortez, we shot more than 1,500 Fugichrome slides. Now that we’re fully digitalized, we shoot way more. Our portable hard drives and IPOD hold almost 10,000 high-res photos and GPS positions. Back in our San Diego office, we create the charts digitally. We purchase and download satellite images from LandSat 7, which are geocoded and high resolution — but not free like the Google stuff. We scan the newest charts, topo maps and our radar-screen images. All these become oversized background layers that we align and then flip back and forth (the same method astronomers use for locating new comets) to find any shoreline discrepancies — deferring to the satellite images as most accurate — and checking the shoreline features against our onsite GPS positions and cross bearings. Finally, we digitally trace the land outlines, place our master GPS approach waypoint and scale, insert soundings and hazards in reference to the known shore positions, and add the secondary shore stuff like topos, roads, villages, etc. In the second edition of Mexico Boating Guide (and upcoming 6th edition of Cruising Ports) we used hi-res satellite imagery not only to make Work is nearly complete on the new Angelo’s restaurant on Angel Island. It really gives the new charts, but to correct the shorelines of cove a Mediterranean look, don’t you think? our previous charts wherever we found errors. Changing all our charts into four-color (what most of you would term “full color”) was expensive, but it makes them much more readable. We do the best job we can on our charts, but continued on outside column of next sightings page
Page 112 •
• August, 2006
The August 2006 issue of the West's premier sailing and marine magazine.