Hmmm... I'm not even sure I've ever seen a watch that charts tides, although I'm sure one does exist!
Beyond that, I'm not sure a watch alone will prevent your friend from getting lost. A map and/or GPS would certainly help. But a good watch can be a very handy navigational aid. I'd suggest one that has both compass and altimeter features, as with direction and elevation, which should help you sort out location pretty easily.
But which one? Lot of good choices. My own watch is a St. Moritz VS-1 ($235). I like it for its varied range of features, excellent altimeter accuracy, and reasonably easy-to-use interface. Plus it's petty rugged, with a stainless steel case, and water-resistance to 165 feet. I've taken it up Mount Rainier, down into the Grand Canyon, on long bike tours, more.
Suunto makes a whole range of good altimeter/compass watches. One example is the Suunto Core Extreme ($329). It includes compass/altimeter/barometer, with elevation displayed to 29,500 feet (as if!), and records of elevation gain/loss. It even reads depth down to 30 feet. Plus its very snappy-looking—all black, with a bright red ring around the watch face (or, you can get a less aggro-looking silver-trimmed watch).
Garmin's Forerunner 210 GPS ($300), meanwhile, incorporates a GPS tracking unit for really good directional and way-back accuracy. It's also heavy on heart rate-monitor features, if that's important to your friend. One drawback is that it's battery-intensive; the rechargeable battery has about eight hours of life under heavy use, three weeks on standby. That makes it best for day use, rather than multi-day trips. Everything has a tradeoff!
Hope that helps!
P.S. Of COURSE there is a tide-tracking watch! Many, in fact. One is Rip Curl's A1001-WH1 ($380). It has tide charts for 200 locations world-wide, so you're never at risk of losing your crab pots, as I once did when I dropped them into too-deep water at a very high tide. Down went the buoy, under the waves, never to be seen again.