I think the transducer is passive, and I think mine wasn't "completely dead" either, it just was less sensitive and sometimesin the end it worked sporadically near the dock in shallow water. I didn't replace the electronics. Just bought another totally differenttransducer and wired it in. Apparently 200khz is kind of a standard although there are some others. One thing to think about. At 200khz, the wavelength (which of course depends on the speed of sound through the materials)in water thats going to be something like say 1/5". (pretty small) If different paths were 1/10" different then they would cancel out. Another funny thing. I might be imagining it, but I had a lot of trouble with my depth finder.....as I was passing the submarine base at Indian Island :-) kind of funny... #175 Sonic Weapon Follow Up!! | | | | | | | | | | | #175 Sonic Weapon Follow Up!! This is the follow up to our last episode #174 A SONIC WEAPON ??? It's Driving Us MAD!!! https://youtu.be/bCp3Ln... | | | On Friday, June 19, 2020, 4:23:20 PM PDT, Keith R. Martin <keith.richard.martin@gmail.com> wrote: Another Electrical Engineer here.... My M17 is 1982 (one of the first of the v2 M17), I also have the Hawkeye, depth sounder, which I rely on pretty heavily up here in the Pacific Northwest.. The Hawkeye transducer in my M17 is mounted dead center on the V hull in front of the keel where the hull thickness fairs out flat to its thinnest point before shaping into the re-enforced ridge of the keel which is much thicker and narrower. The two challenges of getting good performance with a thru hull include positioning it at a "clear spot on the hull" & making sure a solid acoustic connection is maintained over time. Once epoxied in place, over the years if the hull is repeatedly bounced in the water (rip tides, standing waves etc ) the transducer with its smooth surfaces can become very slightly dislodged which can cause the sensor to quit working. To address these issues I found the following worked well; 1. Selected the most reliable spot by temporarily mounting it with a vaseline layer on the bottom of the transducer to provide a consistent acoustic medium and a little duck tape over top to hold it in place, and sailing about in a variety of depths and adjusting the position for best results. (did this for a few trips ) 2. Once the best position is found, a permanent mount was constructed using slow cure 2 part epoxy with enough epoxy to get a well defined "mounting shoe" created when the excess epoxy formed around the outside of the transducer. 3. Carefully dislodge the transducer from epoxy mount by gently tapping it out horizontally per the instructions in the Hawkeye documentation.. 4. Fill the formed epoxy shoe with a thin layer of vaseline and refit the transducer into the shoe. The surface tension of the vaseline holds the transducer in place and presents a good acoustic medium. 5. Every year I just pop the transducer out of the epoxy mounting shoe and reapply vaseline at the start of the season. I have found the performance to be very reliable with this setup. Cheers, Keith *Keith R. Martin P.Eng.* *Vancouver/Burnaby B.C.* *Serenity M17, #353* *http://www.msogphotosite.com/Scripts/Boats/boatsdetail.php?id=105 <http://www.msogphotosite.com/Scripts/Boats/boatsdetail.php?id=105>* On Fri, 19 Jun 2020 at 14:38, Rob Bultman <rob.bultman@gmail.com> wrote:
Thanks, Lawrence, for the input. That is so weird regarding "blowing out" periodically. It seems like a fault of the system design (I'm an EE by training and an embedded firmware developer by vocation). I wonder if it could be an energy coupling problem where the system design assumes a certain amount of absorption via the hull/water interface. If the absorption is not there, energy is absorbed by the electronics in the transducer, thereby causing failure.
My transducer appeared to be held in place with a big RTV blob, and was popped out of the blob when I looked under the v-berth. The installation video says to only use slow-cure 2-part epoxy.
Regards, Rob
On Fri, Jun 19, 2020 at 5:06 PM Lawrence Winiarski via montgomery_boats < montgomery_boats@mailman.xmission.com> wrote:
I bought one of those depth finders and tried a lot of different mounts. It "kinda" worked at first and then Itried various ways to put it in (silly putty,wax,and eventually epoxy) it worked most of the time then1/2 the time then pretty much not at all over 3 years.
I was determined to figure it out and brought out an oscilloscope and researched these things. Kind of interestingactually. the "transducer" is an oscillator that has a natural period of oscillation at 200khz and the devicesends it a signal that is about 150 volts peak/peak for about 100 oscillations and then uses the same wires tolook for an echo that is just a few millvolts but at roughly the same freq. ( That actually makes it challenging froma probe problem to look at the same signal with 4-5 orders of magnitude of variation)
What happens (or I should say happened to me) is that the transducer basically blew it self out and couldn't receive the sensitiveecho. So I would NOT recommend gluing the thing in.
I found a bunch on ebay for $10 and took a risk buying them. They worked fine and I put in an RCA jack so that I could easily replace them. It seems to work pretty good just in a pool of water (held down with a spring) on the hull. Works pretty good now on the first replacement. My advice...Do NOT glue them in. They seem to have a limited life and you will probably need to replace them.
On Friday, June 19, 2020, 1:47:50 PM PDT, Rob Bultman < rob.bultman@gmail.com> wrote:
My 1977 M17 has a HawkEye depth finder installed by a previous owner. I'm not sure what exact model is installed, but it appears to be similar to the DepthTrax 2B currently shown on their website (
https://hawkeyeelectronics.com/collections/sailing/products/depthtrax-2b-boa...
). The transducer is "glued" to the hull in the v-berth area. I finally got the boat out this weekend for my initial shake-down sail but the depth finder just showed 0 depth. The previous owner did not mention any issues with it.
The info on that page states: Glue-In Installation is for NON-CORED hulls or aluminum hulls thinner than 1/8” ONLY. Glue-in mounting of the transducer is NOT suitable for all vessels.
Does the M17 have a cored hull or should this finder just work?
Thanks, Rob