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mobile sonar unit

Thread Status: Hello , There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.
Alun,

Is your sounder working acuratly enought to verify the depth of the bottom plate?

I once read a post by Eric F. about a guy who was doing constant no fins to 50m but the bottom plate was still around 65m or something like that, of course a nasty bo was the result.
 
i've only used it properly that one time, but yes i think it recorded the depth fairly accurately - certainly within 3m. but we would never set the bottom plate according to the sonar - only by the markings on the rope.
 
Alun,

Here's my version of it: I got a Humminbird 343c (http://humminbird.com/products.asp?ID=567) and put it on an old Pelican 1450 case (Thank you Ebay!). The unit attaches via velcro on the base and strapped on tight. The transducer hangs underneath (not shown). The power cable runs to the 12V sealed gel battery inside the case through the case's vent hole, which is potted with silicone to seal it during usage.

Second picture shows the case open with everything disassembled and stored for transportation. When deployed the battery (center of gravity) is moved to the center so it's balanced.

I sealed all the extra electrical contacts so everything is waterproof except the power interface to the 343c unit topside, which I haven't found a good method yet. So it can take a few splashes but no dunking.

Haven't had a chance to test it for real yet, but will let you know how it goes.

Peter S.
 

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I read this entire post and am still not sure of the purpose of these units
as it relates to freediving, beside the fact that it looks like fun to design the stuff. Will someone please enlighten me.
 
Ramstam,

These sonar units may become useful in depth competitions where the surface crew can track the diver in real time and activate the counter balance (or other safety measures) when the diver stops for whatever reason - caught lanyard, blackout, etc - longer than an allotted period. This will cut out the time delay and the crew can act right away instead of wasting precious seconds waiting for the diver to reach an expected location (bottom plate, 20m safety diver, etc).

In my case, I have a real need to know where the bottom is. The water level of the lake/reservoir where I train can vary by 10m easily during the year and I have to paddle far to find depth. Even with my GPS with contour map it's still hard to know where it is to a high degree of certainty because there are underwater structures like trees and houses that can be 5-8m tall. Believe me you don't want to run into those in pitch black water.

I'd rather save the money and spend it on something more fun myself, but I'd like to get out of the water in one piece first!

Peter S.
 
Here is my unit on a friend's(Ant Williams) rig which has 100m of line on it. I'd be interested to hear what settings people are using to track divers as there are lots of setting adjustments on this Navman console?
 
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