Navigation device recommendation please.

[Landau]

Upgrade your dive buddy to a better navigator

Or upgrade your buddy’s buddy

 

[Rred]

You can dive the tropics, with 100 meter visibility. Or dive on wrecks, where you've got a downline that you can tie into, and plain common sense to go back and forth from it on the wreck. Or you can dive on beaches and jetties, where the slope of the bottom and other physical factors let you navigate pretty well. Or perhaps "piloting" is the better word since you are relying on visual marks.

If your certification did not spend much time on "navigation", that is also usually available as advanced training.

I have at times used a long line tied onto the anchor line, because visibility was so poor. And a short line, tethered to my buddy, because literally if we were five meters apart we'd never see each other.

Electronics underwater are best left in submarines.

 

[Pertti Arvonen]

This is the solution for you:
www.uwis.fi

and video

 

[Kharon]

I emphasize. My dive plan is usually to wander and browse and be amazed (not jaded after about 300 dives). I will leave either a semi-inflated SMB or (on night dives) a flashing light at a specific depth at a point where I go directly to shore. I make sure to take a bearing 90° from shore so I can head directly back from my marker.

 

[Pertti Arvonen]

Basically, as GPS signal cannot go deeper than a few centimeters underwater, so GPS cannot be used. Underwater Navigation Systems use two types of technologies :
1) Inertial navigation
2) Acoustic signals
For 1) the system tracks accelerations and magnetic headings to define the current position referenced to the starting position.
For 2) the system tracks the direction from where the acoustic signal comes, so as you can navigate to the source of the signal.
The system 1) has only one device carried by the diver. It basically will have a screen where you can see your course and you can reach the starting point marked in the initial point of the course.
The system 2) needs to install a transmitter in the starting point (for example the dive boat), so as you are guided back to it.
Systems like 1 are still under development, are expensive, big and heavy.
Systems like 2 are available but you need to install the transmitter in the starting point and no one should touch it.

Please check out UWIS Systen in www.uwis.fi. Ready and really works