Underwater GPS (sorta)

Since water blocks the radio frequency used for GPS triangulation, GPS is considered pretty useless for SCUBA divers. Apparenlty some of them are finding it useful to waterproof off the shelf units for tracking the beginning and end of dives. (Dives in open water often involve currents that can really move you along.) To avoid any wiring, a floating case is used. When the diver wants to grab a waypoint, he/she lets the gps surface for a short while to acquire a fix. Then the diver can pull it back down and mark the waypoint or record the coordinates.

25 thoughts on “Underwater GPS (sorta)

  1. As a scuba diver myself, i think that this is an excellent idea… a way to know where you are in relation to your surroundings (although you really should know already, but nobody is perfect).

  2. many gps units can accept an external antenna…how useful/difficult would it be to have a buoy and tether with gps antenna up top for continuous tracking? possible tangle hazard? what about measuring the water pressure and inserting a negative altitude value in the NMEA stream, hooking into a waterproof camera, now you can track the whole dive and place photos on the path.

  3. @macegr
    The problem with a tether and buoy system is if any slack is in the tether then the buoy can drift away on a surface current most likely in a direction other than your own. Loose tether = random buoy movement.

  4. As a diver and a geek (lvl 70 Pally)I have to say WTF.
    I have done dives in oil (tanker hulls) and I had a pretty good idea of where I was. Off hand I can’t think of an application for this other than ” we do what we must because we can”. I would rather see a portable waterproof sonar device for tracking big beasties. Charcharodons for example.

  5. @ackphlat

    First, I am not a diver, but…

    I don’t think the idea is for something like a ship dive. In the description he brings up open water dives with current involved. In those instances, I can see it being useful. Also say you come across a point of interest. Wouldn’t it be more convenient to be able to send up the GPS and take a point, so next time you can easily start there?

  6. I, too, am a diver and I agree with @ackphlat and others – being able to mark a point of interest on a long dive is an excellent idea.(rebreathers are good for up to 10 hours)The problem with floating antennas is described above and whoever can up with the simple solution of temporarily floating the GPS to the surface was brilliant! One has to wonder what you do with the 100′ of line after you retrieve the GPS unit, though. Do they make corrosion-resistant fishing reels?

  7. i havnt read the link yet, but I would guess that a good use for it would be mapping and locating “items of interest” on the seafloor, etc. I cant imagine that dive maps are %100 accurate nore all inclusive. GPS would be of deffinate use to sport divers who dive the same areas often.

    Also, very usefull for marking accurately the placement of experiments.

    anyway, I would think that, as mentioned, 100 feet of bouy line would be a pain in the ass for a diver to manage. How about a corrosive resistant compact electric powered fast winch to pull this thing back down to the diver again?

  8. LOL, now underwear GPS is something I can see many uses for! For a shallow dive I suppose it would prevent going to the surface to mark a waypoint but no way will it work on a deeper dive in a stiff current for several reasons. One, the current will pull the device off the mark so if you are at 80′ the device may surface 60′ upstream of your location. If you tried you could not make it surface directly overhead. Two, no way am I dealing with 200′ of line at 100′ with a current. The 15′ on my Mares is enough to deal with. Three, God invented compasses for open water dives. For points of interest, I do know where I am without a GPS. Now start working on the underwater sonar and the underwear GPS!

  9. I have used this for years as a diver. I am working on getting the antenna and a calculation for the error on the floating antenna based on the diver depth. I’ll let you know once I have it figured out.

    Happy diving…

  10. As you can see someone is already making an underwater gps. The main reason I know of using this is for underwater surveying.

    The comment about the accuracy of gps’s is wrong. I average 10ft (3 meters) when in waas mode. This varies on coverage too. This is with a garmin fortrex 101.

  11. Why not use three or more buoys randomly placed on the surface, each with their own GPS and a transponder to do “LPS” based on the buoy positions. Think of the buoys as being local GPS satellites themselves, on different frequency that will penetrate hundreds of feet of water easily. They could then report back to the main buoy node connected to the dive boat which would report the location information as calculated by all the differential signal timing information – exactly like GPS does it globally – and offset the known GPS surface points by the relative distances from each buoy location.

    Eventually dive clubs could install semipermanent buoys in popular areas for public use. Call it “DPS” (dive positioning…)

  12. All great ideas, this last one is excellent but to much stuff to do and not immediately available, like going to the store and buying a GPS.

    How about this, similar to last idea.

    If up put a mark at the starting point (a transmitter) and rig the GPS show this point as a marker on the GPS,.

    So you start your dive with a top side riding of you area , activate the transmitter on the Boat, beach etc.

    It should track you position with relation to the transmitter. Yes? Maybe? I don’t know. Just and idea.

  13. I never tried gps underwater but if the signal makes it underwater to xx depth it probably makes it deeper. just get more battery power and a stronger antenna on the gps unit. Or just hack into the satellite downlink and boost the power to microwave strength and you can reach 100 foot, but dont get the boat in the way of the signal as it will melt. :-)

  14. …lot’s of speculation about the topic. I’m the author and have been using this and similar methods for about 10 years at moderate depths. It is often assumed that the housing drifts a great distance from the diver, rendering the “mark” useless…not so. The diver controls the line deployment…even in current, hasn’t been much of an issue. Recently I’ve been towing a dive flag that has the ability to deploy and recover the gps unit…it’s just like pulling a flag…no more complex. One advantage of the methods I use is that the diver works with a small diameter line, not a data cable / floating antenna. My goal is to keep the equipment from dominating the dive. Also…many divers will not “get” the need for gps because they do not dive frequently enough to make it worthwhile. This is intended for researchers, public safety divers, law enforcement teams, and the more avid divers that live near frequently visited sites. Aside from marking points, a constant awareness of the anchor position is maintained.

  15. You have to open your mind, you take a GMRS/GPS two way radio make an enclosure and put one on the boat. You take a reading before you get in the water from your anchored boat. Or if you are just a diver you take your boat reading for interesting stuff to revisit or emergencies. So you have a problem you are in a forgein country and like it has happened so times the don’t do an accurate dive count and you and your buddy surface, no boat. Well rescue is going to monitor all radio channels and go to the last place the boat was. So know you can send out emergency radio calls stay in the area the boat was and comminucate with rescue boats and aircraft. The radio options allow you to communicate and track others also presetup, that helps solve some of the issues of missing divers if they have made it to the surface or close to the surface. I would imagine soon they would put in a ping, user activated to help again rescue find you. Yeah bad idea, but I will spend 1,000.00 on something to save my life.

  16. Sound Ocean Systems, Inc in Redmond, WA has a handheld diver GPS unit. Originally developed for covert military diving, it has been successfully applied to commercial and recreational diving. Check out the Sound Ocean Systems website when you get an opportunity.

  17. The photo on this topic is one that I took a few years back when describing my original deploy and recover method. I’ve been using a new adaptation of the method…can be seen on Youtube by searching, “underwater gps”. *This method is designed to be very low cost and to eliminate the need to tow cumbersome equipment.

  18. So was Phil Coke. Also, less experiment in terms of converting a reliever as experiment in terms of using a subpar MLE as a starter. (Come on, you don’t really expect that strikeout rate to translate, do you?)

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