Monday, June 29, 2015

New Toy

Recently when anchored in a familiar bay, we saw a boat anchored in a location that was filled with submerged pilings. Or at least in the past it was... Years before, we had actually surveyed this part of the bay by dinghy at low tide and marked the locations of the pilings we could see using a hand-held GPS.  Did he know something we didn't?  Or was he blithely happy in his ignorance (and lucky)?

I'm sure a similar situation has happened to you - you might be interested in taking the boat between those two small islands as a short cut, but the chart detail in the passage was totally inadequate to take the risk.  Those of you with $15,000 RIBs as tenders probably already have a depth sounder installed and can then use the dinghy to do a quick bathymetry survey.

But we don't have that kind of dinghy.  So what to do?  Not wanting to do a permanent installation on our dinghy, I considered hand-held depth sounders.

There is one that is shaped like a flashlight - to use it, you dip the big end in the water and press the button for a reading.  Great for spot soundings, but awkward for taking more or less continuous readings.

And then there are the ones that have a hand-held read-out, connected to the transducer by a cable.  This is better, since the read-out is in your hand, right side up and easily read on a continuous basis.  But there's that cable.

And then I found the answer:  A wireless depth sounder.  There are several varieties - being a cheap frugal mariner, I bought one direct from China instead of one sold by a name-brand manufacturer (also made in China).

It's a cute little hand-held unit - not waterproof, so don't drop it in the drink.  It communicates with the completely separate transducer via radio.  And the transducer is a tiny little thing:

A friend suggested that it should have been molded with a duck's head on the post
The transducer is powered with a single CR2032 coin battery and there is no on/off switch.  Instead, there are two exposed metal contacts on the underside - when it is placed in water, it turns on.  There are a couple of holes molded into a fin on the bottom (you can just see one at the tip of my finger) that you can use to attach a towing line.  Or a fishing line!  Yes, it is small and light enough that (should you be a fisherman) you could cast it over to that deep hole where the lunkers might be hiding.

I am very much looking forward to using it to survey our favorite anchorages to maybe expand the territory available to us!


SV Pelagia said...

If you need to attach a line to it (obviously), how is that different from a cabled portable sounder?

Check its calibration... we've had one for many years but rarely use it due to battery and reliability issues.

Robert Salnick said...

Pelagia -
The line attached can be short and tie to the dinghy. That is substantially different than having 12-20 feet of cable in the dinghy with you to manage.

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