Underwater GPS for recreational divers would have been the most exciting product at the 2009 DEMA SHOW, if it were real! Here is what the the press release said and notice the present tense – “Navimate™ is the first product to provide divers with the full functionality, convenience and safety of GPS navigation and positioning while underwater. This affordable wrist-mounted product displays the diver’s exact latitude and longitude, as well as his or her position on a high resolution map of the underwater terrain.” Everything in the press release and the slick color flyer gave us the impression that it was both amazing and available now (see http://www.shbinstruments.com/Navimate.htm). Then we got to the booth and things got a little more clear.
What we saw was a big poster and a plastic mock-up of a wrist banded platform with some fake buttons and a paper map. The booth guys admitted it was a prototype, but it would be out next year, they claimed. Here is the back peddle message from the team leader, Dr. Barry Megdal. He writes, “We never intended anyone to think that the units we showed at DEMA were production units, or were waterproof …We have been developing algorithms and hardware with prototype units which have given excellent results, but are not “pretty” enough for a show.”
Since GPS signals will not travel through water, the idea behind Navimate is to have a floating buoy or transponder hung from a boat ($300 msrp) that picks up the signal. The wrist units ($700msrp) are suppose to use multi beam rf to determine range and bearing from the buoy and accurately show the position of each wrist unit. Soon after the initial release of Navimate, Shb (the Navimate company) says
they will be offering a “no display” unit at reduced price (not yet set), which are supposed attached to the tanks of students or on divers being led by a divemaster. The instructor or divemaster will be able to keep track of the location of the other divers in his or her group, but those divers will not have the distraction (or the cost) of a wrist-mounted unit. They also plan to offer free buoy units with the purchase of multiple wrist units.
We interviewed other experts in the field including a DARPA researcher who works with underwater communications and a GPS engineer/entrepreneur that sold his GPS company for millions. We asked them what they thought about this product. Both independently disagreed with Megdal’s approach. They said that if Navimate makes it to market, it would not be reliable or accurate. They pointed to the most obvious and significant challenges of communicating with the wrist units through various water environments and at angles relative to the buoy and the problems with triangulating from a such a small platform (the buoy). Also there are currently not many accurate and/or detailed maps for most dive sites. They both believed that when a practical working underwater GPS is developed it will like be based on inertial sensing and not this model. With that type of unit, you would lock in a GPS location before the dive and the unit would use sensors to track your progress during the dive. You would only need the wrist unit and not the buoy. Much of the inertial sensing hardware and software needed is currently available.
The discussion on the web certain indicates that divers are hungry for a practical and affordable underwater GPS. We can only hope our gut and experts are wrong and wish Navimate success. We will keep the rating stars in the star pouch until we see one in the silicone.