Vesper Marine anchor watch, Merry Christmas!
The Vesper Marine WatchMate 850 Class B AIS transponder, which just received FCC approval this week, is already a very interesting product, as discussed here on Panbo in September. But an extra feature that hadn't been developed back then, and still isn't mentioned on the Vesper site, is the ability to use the unit as an anchor watch. And it can be an especially effective anchor watch thanks to the intrinsic nature of AIS and the WatchMate's particular characteristics...It's fairly obvious that an exceptionally low power display -- only 3 watts without putting it in silent mode -- with a built-in GPS and even an external high current alarm relay can serve as a conventional anchor watch. But the trouble with conventional anchor watches, as I learned from Panbo commenters a year ago, is that they think your anchor is where the GPS antenna was when you set the alarm, which is probably not at your bow. That's where two AIS transponder features come into play. One is that all transponders require the installer to specify where the GPS antenna is relative to the bow. The other is that most all Class B transponders can accept an optional heading input (which is valuable anyway, as then your boat target will point correctly even when you're stopped).
So with knowledge of your boat's GPS location and your heading, the WatchMate 850 can figure out exactly where your bow (and anchor) are when you set the anchor watch, plus keep your boat icon oriented correctly as the watch progresses (as seen in the image above from the manual, which unfortunately is not on the Vesper site). And the whole deal is a gift to folks who've already ordered the transponder. Plus the anchor watch feature will be available as a free software upgrade to all owners of Vesper's earlier display-only and display/receiver models -- though without the extra accuracy possible with a transponder. Which is all pretty neat, I think.