Underwater digital magnetic compass with trackback?

[marshallkarp]

I would like to set a waypoint at the entry point, then no matter where you are, you follow the arrow back to the entry point. GPS won't do this, but does anyone know if there is a digital magnetic compass with a trackback feature? Something like this:

Amazon.com : Bushnell GPS BackTrack Personal Locator (Gray/Orange) : Handheld Gps Units : Sports & Outdoors

But, it has to be magnetic, not gps based.

Thank you.

 

[stuartv]

If you set your compass to point at, say, the anchor on the bottom and then swim directly away going due North, your compass will still be pointing due South at the anchor. But, if a current pushed you 100 yards West, while you swam 100 yards North, how would a compass know that the anchor is now at a 45 degree angle SouthEast, instead of due South?

You would need GPS and for it to work underwater to achieve what you want. Or I am misunderstanding your question (at least equally likely).

 

[Chet_Chet]

If there is such a thing that work underwater, I want to hear about it too.
Anchor at "A", descend to 60fow for 50 minutes, return back to "A" with the help of such a device.

 

[stuartv]

Actually, there is a dive computer that does something like that. It has little transmitters that you have to affix to the items (e.g. anchor) that you want to track back to. I can't remember the name off the top of my head. I think the transmitters are ultrasonic. I think I've also read here that they are expensive and their reliability is not something you'd want to trust your life to.

---------- Post added August 18th, 2015 at 04:05 PM ----------

http://www.liquivision.com/en-us/products-repository/transmitters/l1-location-transmitter

 

[Chet_Chet]

Actually, there is a dive computer that does something like that. It has little transmitters that you have to affix to the items (e.g. anchor) that you want to track back to. I can't remember the name off the top of my head. I think the transmitters are ultrasonic. I think I've also read here that they are expensive and their reliability is not something you'd want to trust your life to.

---------- Post added August 18th, 2015 at 04:05 PM ----------

http://www.liquivision.com/en-us/products-repository/transmitters/l1-location-transmitter

OH MY...I'll stick to not going far from the anchor.

 

[marshallkarp]

If you set your compass to point at, say, the anchor on the bottom and then swim directly away going due North, your compass will still be pointing due South at the anchor. But, if a current pushed you 100 yards West, while you swam 100 yards North, how would a compass know that the anchor is now at a 45 degree angle SouthEast, instead of due South?

You would need GPS and for it to work underwater to achieve what you want. Or I am misunderstanding your question (at least equally likely).

Quite right, the analog compass or digital compass will take you back to a point where you miss the anchor. That is why I am looking for one with a trackback feature, where if you move, the digital needle will always point back to the anchor, or whatever. Probably no such thing for underwater gps, unless the military has one that the civilian world does not know about, but a magnetic digital compass should be able to do this. I hope.

By the way, it doesn't have to be scuba depth rated. Just set the entry point, put it in a clear pelican case, and take it with you.

 

[redlegs]

That would be a Lynx. They also have a boat kit that allows the diver with a Lynx to locate the boat (Omniscient Boat Kit).

 

[socaljohn]

I've often wished for an underwater INS buy the size of a gyro makes it not so portable

 

[JohnnyC]

Closest you're gonna get I think.

Never used one though.

[URL="http://desertstar.com/products/product-category/scuba-diving-system/]DiveTracker[/URL]

 

[abscuba]

Thats probably the closest you are going to get. The petrel 2 has a compass that a heading can be set on, however it won't compensate for drift or currents it just points to a set heading. An INS would be great but one with any kind of accuracy would be expensive.