Re: [caborico] New depth transducer? .

[Mickey Panayiotakis]

Mine had the big bronze from Ray. Diameter roughly an inch. Needed a fairing block.

Cheers
Y

On May 2, 2013 8:50 PM, "Donna" <dma...@bellsouth.net> wrote:

Hi Everyone-

Any suggestions for replacing the old depth transducer?  I'm looking at the Airmar Smart Triducer DST800.  Not sure the diameter of the old '85 thru-hull until the boat is pulled out in two weeks.  Any thoughts would be helpful.  Thanks

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[Tom]

Funny you should ask as I've been researching exactly this over the last week or so.  If it's an '85, your boat may be the same or similar to ours (an '87).  The depth transducer  (ducer from here on) on Eclipse is in the stem on the forward edge of the the keel. It's in its own little cutout int the stem that puts the ducer on the center-line and also permits the ducer to be vertical without the need of fairing blocks.  The stem is probably the thickest part of the hull.   Our instruments are the original's from Data Marine and the ducer is a long skinny stem type.  The stem is about 0.8 inches in diameter.  These ducers are still available from DMI.  Here is a picture: DMI Ducer .  (DMI is basically a very small (one guy I think) company that services older Data Marine instruments and he also sells some newer stuff)  I have it on reasonably good authority that the Data Marine ducer was / is manufactured by RadarSonics and is this Transducer  which is available here Gemeco.   DMI (the guy) said it's a custom ducer that you have to buy his ducer or it won't work.   If you buy the ducer from DMI it's $195.  I've seen the RadarSonics ducer for about $93.  Do your own math.  Here is my plan:  I'm going to replace my existing ducer with the RadarSonics model.  This allows me to continue to use my old Data Marine instruments for a while.  I plan to upgrade all electronics in a couple of years and when I do, there aren't any modern integrated systems that will take an old analog depth ducer.  Everything will be NEMA of one flavor or another.  So, a company called Actisense makes this box which will take your existing analog depth ducer, old pulsed speed ducer, and water temperature and convert them to NEMA 0183.  I like this solution as the Actisense box uses very little power.  The Airmar smart sensors seem a bit power greedy at least according to the published specifications.  I plan to use an Airmar analog ST800 for speed and temp.  

Another option is to use the Airmar B122.  This will require enlarging the hole in the stem to 2 inches.  The B122 is a smart sensor with depth and temp.  Available in either NEMA 0183 or NEMA 2000.  Match with with a Smart sensor version of the ST800.

A third option is the DST800 you mentioned.  This would not work in the stem because I think the speed sensor paddle wheel would be adversely affected by the flow in the cutout.  It *could* be mounted in the location where the existing speed sensor is located.  The only problem is the minimum deadrise on the hull is about 21 degrees.  This is right at the max recommended by Airmar.  What this means is that the ducer would likely not read bottom when on one tack if heeled very much.  The DST800 is really not long enough to permit a fairing block.

Airmar told me in an email they have a new version of the DST800, The DST800L has a long stem that I suppose could be used with a fairing block.  

And finally, you could install an Airmar DT800 with a 20 degree tilt.  These have the internal depth ducer element tilted in the housing at 0, 12, or 20 degrees. Smart sensor.   This would require a new hole.  I hate drilling more holes in my boat.

My decision for going the route I'm planning is as follows:

1. I like keeping the depth ducer on the center line and normal to the sea-floor.  This give you the best chance of triggering on low depth when heeled on the one side.
2. I like that I can keep my old Data Marine stuff for a couple of years till I'm ready to re-instrument everything.  I don't need new everything right now as we're just bay sailing.  By the time we're ready to do the kind of sailing needing more advanced instrumentation (Chartplotter / radar / autopilot etc) more advanced gear and choices will be available. 
3. The actisense box converting speed, depth, and temp to NEMA 0183 consumes well under 1 watt.  The NEMA 2000 smart sensors consume about 2.4 watts.  I'm all about consuming less power.  
   
4. I can turn on just the depth instrument and its associated sensor (the Actisense box) and have depth information.  I can leave the rest of the system off if I wish. If using NEMA 2000 sensors, the entire bus is active and everything on it.  This could be a lot of power.  I'm also suspicious of bus systems where one failed component brings everything else down with it.  However, there are *LOTS* of new installs using all NEMA 2000 and seem to be working just fine.  Make your own call here.

Hope this helped and didn't just confuse things more.  Probably more detail than you wanted.  I design low power instrumentation systems (not for boats) so I tend to climb through this stuff with a bit more zeal than most. 

  -Tom

S/V Eclipse

CR38 # 115

Rock Hall MD.