GPS for Scuba

Beatlejuice · Aug 28, 2008

Am I the only one who thinks a GPS designed for Scuba is a good idea? I realize the satellite signals won't penetrate the water, but it seems to me that a waterproof unit could come in real handy for tracking where you entered the water on the beach, where you ascend after kicking out, and where you surfaced. I could be a tool, along with your compass bearings, to help you (or help a friend) find that reef or other landmark that you came across a few months or years ago. It wouldn't have to function under water, but it would have to be waterproof to depth so you can keep it with you. It also wouldn't have to have an integrated map, but I suppose it could. Maybe it would be integrated with your computer. Coordinate information would then be uploaded to your dive log along with everything else.

I'm just thinking out loud. (Sometimes that gets me in trouble!) Anyone have any thoughts? Maybe the manufacturers are listening!

D_B · Aug 28, 2008

Here is a working solution ...

kayakdiver:
I'm the above-mentioned person using Magellan GPS underwater. (You may have seen my
recent article in Underwater Magazine). A free eBook is available at:
http://groups.msn.com/divergps *(a non-commericial site...nothing for sale).
I use one of 3 possible deploment methods, depending on depth and conditions. Lately, I've been "towing" a clear housing (Otterbox 9000) on the surface...the housing is only pulled below briefly to "mark" a point, or to gain awareness of the boat's position.
Here's the set up... The housing floats on the surface with an attached nose cone (to reduce drag)...this is followed (on the surface)--by about 25 ft. of bouyant poly-line....which is attached to a unique "no drag" dive flag. I simply tug lightly (to get the housing to move forward to the desired position)--then, pull down in a hand-over-hand position...gain data...drop the housing (which returns to the surface).
I've been using different variations of this method for about 6 years with good results.
As stated...the above-mentioned web site will provide further details, and further methods of deployment. *Be sure to see the photo section. **To answer a frequently asked question: It's often asked if this method allows the housing to drift to a distant point (rendering a mark innacurate)...not a problem, in this applicaton...it's where the housing is pulled below (losing signal) that matters. This is easily controlled by the diver. Most divers are not in the water enough to bother, but researchers and the most avid divers can have plenty of fun with this! You can test the basic theory on land: Take a Magellan gps and set up a land simulation. You simply cover the antenna with alluminum foil (to simulate periods of signal loss underwater). In real world applications (after significant periods of signal loss)...it takes about 60 seconds to get a fresh signal. However, in the above described surface-tow method, the wait is avoided, and data is available in mere seconds. Constant signal?---towed antenna??...that's fine if you want to go to the trouble, but I'm trying to use the most basic method possible.

There is more info in the link provided above and here is one pic from that link
http://groups.msn.com/_Secure/0RQCc...aXGKDxadw/gps2 003.jpg?dc=4675571654915005996

danclem · Aug 28, 2008

We have toyed with a surface unit and a couple of different ways of sending wirelessly to a display under water. So far limited success. I think the wired option above is the only reliable method so far.

Dan

Ken abucs · Aug 28, 2008

A local diver uses a GPS in a plastic waterproof case. When he reaches a landmark, he send it up on a line, leaves it on the surface for a minute to get a waypoint, then reels it back down.

D_B · Aug 28, 2008

In the link that I posted, the advantage is that it's in signal contact all the time, you have a running trail back to your starting point if you want , and can mark a current position fix without waiting, and your displaying the required in some places dive float

Arizona · Aug 28, 2008

What about a beacon from the boat to a receiver carried by the diver or dive leader underwater?

John512 · Aug 28, 2008

I have heard rumors of the navy having a unit with a long disposable antenna, when they want to know where they are they deploy the antenna to the surface. No idea if it really exists but it sounds plausible enough, a camera type case that allows you to push the gps buttons and instead of a flash assembly have an antenna that goes to the surface.

Realistically the best bet would probably be what others have mentioned, placing a regular unit in a waterproof box. I like the idea of towing it or deploying it to the surface to get a bearing, especially if it is just barely buoyant enough so it goes up fast enough and comes down easy.

Nemrod · Aug 28, 2008

The technology exist now for inertial guidance. Not a GPS but instead inertial guidance. The initial fix would be sourced via GPS or manual imput from some known position, once initialized an inertial guidance system needs no external imput. This is how submarines navigate silently, spacehips reached the moon and outer planets with inertial guidance. It used to require gyros and all sorts of expenisve electronics but has now been integrated into chip size units. It requires no antenna or anything. A three axis electronic gyro chip with acceleration sensors should suffice. I think it would be possible. It would use magnetic sensors to assist and whenever a GPS signal was present it would update and reinitialize and correct deviations.

You know of course, a simple compass can do wonders if you have a basemap but for the most part divers have no basemap.

Inertial navigation system - Wikipedia, the free encyclopedia

http://www.memsense.com/?gclid=COq1n4SJspUCFQUQswod-DogRQ

N

Thalassamania · Aug 28, 2008

Or ultra-short acoustic baseline like we use with the subs.

GPS for Scuba

Please register or login

Beatlejuice

Contributor

D_B

Kimber/TekDiveGirl storyteller and memory keeper

danclem

Contributor

Ken abucs

Contributor

D_B

Kimber/TekDiveGirl storyteller and memory keeper

Arizona

Contributor

John512

Registered

Nemrod

ScubaBoard Sponsor

Thalassamania

Diving Polymath

Similar threads