I have the bottom of my 25 Mk1 down to bare gelcoat. I figured now is a good
time to replace all the thru hulls including the old knotmeter and depth
transducer. These have not been functional since I've owned the boat. I've
gotten by with an old hand-held Garmin GPSmap 76. To be honest, I'm mainly
just looking to plug the holes in the bottom. I managed to replace the old
analog knotmeter with a combination of new and rebuilt parts. I'm now looking
to replace the transducer. At some point the prior owner had a GPS or
fishfinder mounted in the companionway because the bracket is still there. I'm
looking to do something similar. I want a mounted GPS, and I want to be able
to plug in the transducer for an actual depth measurement (rather than an
approximate measurement from the electronic chart). And I'd like to do this
for less than $500. I'm not looking to find shipwrecks or the last fish in the
ocean, and I don't care about water temperature or what is 1000 feet below me.
I just want to be able to anchor, avoid running aground, etc. At this point I
think what I want is an obsolete Garmin GPSmap or Echomap 500 series, with an
Airmar transducer. There's not much info online that's geared towards day
sailors. Any advice or recommendations?
Most thru-hull transducers seem to be 2.125 inches in diameter. The one I
removed is 2.0. It's difficult to open up a 2.0 hole to 2.125 with a hole saw.
Would you recommend grinding the hole larger with a Dremel?
The transducer I removed was mounted in a wood fairing block. The deadrise
angle seems to be about 10 degrees. I see that some of these transducers are
internally gimbled up to 20 degrees. Is that the preferred approach for a
sailboat considering the heeling angle on opposite tacks, etc.? Or should I
just make another wood fairing block?
Mark
C&C 25
Dartmouth, MA
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