GPS Underwater

[GMDGeek]

Out of curiosity and sense I am not finding any information and I am still looking I thought I would call once again upon the wisdom of my more experienced and knowledgeable divers of this forum.

Are there any Underwater GPS Devices out there that work? Weather it be real time 40' under or a device I can plot my findings with as I am exploring the underwater realms?

Gerry

[GMDGeek]

Scary when you do a Google search on the past year and this post I made literally 5 minutes ago is 2nd on the list...

[inventor]

There aren't any underwater GPS devices you or I can get. One of the technologies coming out in the next two years is relevant location devices. It stems from the crappy G-Analyst motion sensing technology. For example, your dive computer will sense GPS where you enter the water, by sampling the signal. My guess would be by a wire wound about the computer's hose, and once water turns on the computer, it would pick up the signal that way.

Anyway... Your dive computer would pick up the GPS, and then all of your motion and depth would be recorded. When you surfaced, the dive computer would again pick up the GPS, and coordinate the info so that you would have a 3-D representation of your dive.

[CompuDude]

There is no underwater GPS. I'm surprised you couldn't find a post on this in a search, because the topic comes up pretty regularly.

The satellite signals can only penetrate a couple of feet into the water, at best, IIRC. Even 30' is completely unrealistic. This is the case with almost all higher frequency signals... even military subs have to ascend to a depth where they can extend an antenna line to the surface to broadcast.

Some people track dive progress by towing a float with a a GPS on it, but that's not going to help you figure out which way to go at depth.

The day someone figures out how to have 100% working GPS at depths is the day that person can start their plans to buy an island and retire.

[navyhmc]

The only radio signals that penetrate water to any usable degree are ELF signals-Extremely Low Frequency. And at that your band width is so narrow, it takes literally 2 minutes to send a 10 character message. GPS is a very complex signal. I am not a research physicist, but I would imagine that a gps signal given it's current strength will penetrate less than 1' in the water and at that 1', the signal is degraded to the point of unusable.

Even Subs don't use GPS underwater, rather a very, very, very sensitive inertial navigation system that is updated w/gps on those few occasions when they surface. I'd imagine a diver's swimming pattern and erratic motion (at least that's how a INS would read us swimming) would make a Scuba INS untennable too.

[GMDGeek]

I did do a "GPS" search and it came up with several threads not relevant or current, but I do apologize for the questions ... and I have found a couple good threads after digging.

I did find 1 GPS device but consider it to be rather inconvenient as it relies on a cable line run to the surface that you attach to a float.

Several Google searches after my post and a few emails to Garmin and Magellan I was able to find out they are working on some devices like mentioned about that will take your last GPS reading then use an internal compass and set of calculations/algorithms to do live positioning underwater, then complete and cross check upon reaching the surface. Garmin is hooping to release something end of next year, Magellan couldn't tell me an estimated date... We shall see.

Again I really appreciate everyone's patience with me as I get a feeling for the Scuba world and community.

[navyhmc]

Originally Posted by GMDGeek

I did do a "GPS" search and it came up with several threads not relevant or current, but I do apologize for the questions ... and I have found a couple good threads after digging.

I did find 1 GPS device but consider it to be rather inconvenient as it relies on a cable line run to the surface that you attach to a float.

Several Google searches after my post and a few emails to Garmin and Magellan I was able to find out they are working on some devices like mentioned about that will take your last GPS reading then use an internal compass and set of calculations/algorithms to do live positioning underwater, then complete and cross check upon reaching the surface. Garmin is hooping to release something end of next year, Magellan couldn't tell me an estimated date... We shall see.

Again I really appreciate everyone's patience with me as I get a feeling for the Scuba world and community.

I'm going to guess: $$$$$$$!!! $$$$$$$$$$$!!!!

[CompuDude]

Originally Posted by GMDGeek

I did do a "GPS" search and it came up with several threads not relevant or current, but I do apologize for the questions ... and I have found a couple good threads after digging.

I did find 1 GPS device but consider it to be rather inconvenient as it relies on a cable line run to the surface that you attach to a float.

Several Google searches after my post and a few emails to Garmin and Magellan I was able to find out they are working on some devices like mentioned about that will take your last GPS reading then use an internal compass and set of calculations/algorithms to do live positioning underwater, then complete and cross check upon reaching the surface. Garmin is hooping to release something end of next year, Magellan couldn't tell me an estimated date... We shall see.

Again I really appreciate everyone's patience with me as I get a feeling for the Scuba world and community.

No worries, keep asking. And you get credit, in my book, for at least having tried to search, even though you didn't find what you were looking for. Sometimes it can be tricky hitting the right search terms to find the threads.

[db83]

Originally Posted by navyhmc

I'm going to guess: $$$$$$$!!! $$$$$$$$$$$!!!!

I'm curious as to how much something like that would cost.

[GMDGeek]

Most likely my first born and my right n*t...