Does anyone have any experience or opinion on a transom mounted transducer? Both Garmin and Raymarine are on sale at West Marine giving a free real bison or tru vision transducer in addition to sale price, but they are transom mounted. I was told these transom mounted are not the recommended for sailboats but wondering where the znonsuch has a wider transom than most sailboats and hell’s much less (I am told and will find out soon). It might work. Would be grateful for any input. Thank you
I have heard that the transom mounted transducers can be installed inside and shoot thru the hull. Articles have said that they can be mounted in a water filled container glued to the hull, others say they used epoxy or caulking to bond the transducer to the hull.
Has anyone here tried that? My new Garmin came with a transom mounted transducer, but I have not been able to work on the boat yet this Spring. I hope those stories are true because an in the hull transducer would cost as much as the Garmin costs. I could replace the existing through hull transducer that no longer works, but I am not sure that a new one would fit the existing though hull fitting. I don’t know if the existing transducer is the type that can be removed while in the water, I would hate to find out that it is not and have to quickly plug that opening.
Will be really interested to hear more on this. West Marine has big sale on Garmin that ends today with units that include a g51 transducer. I am looking at the Echomap plus 93 SV $699
My DataMarine DS, of uncertain vintage but likely of an earlier generation of electronics, works fine shooting thru the hull. It is installed just forward of the engine in a poly pipe cemented to the hull and filled with antifreeze.
Bob D,
Nonsuch 30C #170
No experience yet but will have this summer. There is a slight chance the depth only function will work when mounted on the transom underwater as far away from the rudder as possible. But that will look ugly, may catch lines and other stuff too easily and the prop wash and rudder may prevent it working reliably anyway.
PlanA is to mount the GT52HW-TM outside through the existing through hull. I made a prototype mount that I will fit next time I go to the boat.
I may not do this because there is a chance that a rope or anchor line might catch on the transducer and rip it off. Very small chance but if i don’t feel good about it I won’t do it.
PlanB I don’t think this transducer will work through the hull from inside, however it is powerful and worth a try. Nothing to loose. It might work at a reduced range in depth only mode if at all.
PlanC get a compatible basic depth sounder for the existing 2 inch through hull.
GPS Central has a good deal on now with last years model Garmin 75cv at $530 CAD, you may still be able to find one in the US.
https://www.gpscentral.ca/products/garmin/echoMAP-Plus-72cv-73cv-74cv-75cv-g3.html
This seems like a good deal to me because my map upgrade on my old Garmin would have been $149 and and the new unit has latest NAVIONICS map with sonar data.
It comes with a transom mount transponder which for this price you could just throw away and buy a proper one. The documentation is poor. It is supposed to have a forward looking function but it may not. It is really meant for fish finding.
After doing some research I found the Garmin manual is almost useless as it covers many models of Chart plotter and includes settings for all transducers. You have to be careful to filter and understand only the parts that apply to the hardware you have.
This GT52 transom mount fish finder transducer in “Traditional” depth mode has two settings; 24 degree beam(conical) at 150khz or 16 degree beam at 240khz. Both can go up to 800feet and are 250w power.
There is no forward looking function. You can buy a more expensive PanOptix transducer if you want this feature.
I’m also disappointed with Garmin. I wrongly assumed that a newer 75 unit (9 years newer with 5 years newer firmware) will have improved the poor software that was in the old 421 unit. The User Interface is really confusing and I’d give it a 2 out of 10 just like the old one. After you get it all setup it will be OK if you don’t need to change settings. The manual doesn’t help much because it lists functions for all Chartplotter models and screen shots showing menus that are not available. I upgraded the firmware from 9.2 that it came with to the newest 11.2, made no difference in the interface. It will be fine as a basic chartplotter.
I have used transducers mounted inside the hull with epoxy for the last fifteen years and have been very happy with the performance. Only problem I had was the epoxy came loose from the hull on a previous boat which caused very spotty readings. Once the problem was found and repaired the device went back to working fine.
Tim,
It's not too complicated. The inside of the hull needs to be cleaned and ground down to remove the painted surface so you've got good fiberglass to grip onto. Build a little dam with wood or plastic or anything that's available. Glue that down to the hull downhill of where you want the transducer located. This position, of course needs to be in front of the keel and in a spot that is always under water. Any air between the transducer and the hull or between the hull and the water will prevent a good reading. Pour a puddle of epoxy "upriver" of the dam and settle the transducer into the epoxy being sure there are no bubbles between transducer and epoxy. Use something to secure the unit in place until cure. Connect to depth sounder.
I'm sure that the transducer needs to be one that is recommended for this type of installation. Check with the manufacturer if the manual doesn't suggest it. Mine has worked flawlessly since installation six years ago.
As I remember the manufacturer suggested a trial using water to determine your hull's suitability to transfer signal, but not as a permanent solution.
Any experience trying this with a Raytheon transom-mount transducer, by any chance?
Also, since we must have pretty near identical 26’s, I’m guessing you glued the transducer to the hull in the forward bilge section underneath the table between the two settees. (That’s where the manual suggests putting depth and speed thru-hulls.) Is that right?
I don't know anything about the Raytheon unit. Check with the manufacturer. You could also do a test as mentioned in an earlier post using a dam and water.
Last year I purchased a 9” CHIRP type plotter/ fishfinder. I found that for the most part the plotter function is the same in all of those price range units whether it be a GPS Map or a Chirp. Because WM started matching prices and Jamestown had great sail on the Chirp units, I chose one without any regrets. It’s a great unit but the transducer was useless as I felt there were a number of stern area limitations such as the coring and turbulence. However while doing some steering maintenance I could see where the coring appeared to stop near the center of the boat.. I Built a little wooden pool, double back taped the pool to this narrow un-cored? area and filled it with water. Stuck the transducer in it and It worked. Thought about this over the Winter and decided that was not a good location for a number of reasons. During the last few days I recalled that I had a similar concern with a depth finder on my Coronado 25 30 years ago. Back then and just for hee haws I bought a tube of silicon gel and squeezed on the transducer and pushed it into the hull (inside of course} and it worked till the day I sold the boat. So, today I looked forward on the boat near the mast and sure enough there is the same type area I found near the engine that looked un-cored. Went to hardware store, bought a tube of silicon sealant ($8), smeared the gel onto the bottom of the transducer, laid it against the hull with little pressure and connected it to my plotter and by golly it works. I’m not really smart when it comes to electronics, so please have mercy on me for any technical faults that you recognize in my experiment. I like the idea that it is safely stored on my boat, having some use rather than in a box of stuff in my garage that I will never use. The location I found is the area just before the mast. In my classic model there is a plywood board (on an angle ) that lifts up. In fact my other transduce can be found in the same area. The cable which is more than long enough can be run down the bilge pathway to the engine room. Have to figure out how to get the cable up through the pedestal yet.
We are not allowed to use our boats so my tests were done sitting at slip.
Note that the blue material on top of some pictures was my pedestal cover to quit sun blinding me and the plotter to get pics. Also, I need to learn how to use the sonar now that it appears to work. I hope this writing is of benefit to some. Assuming it is a viable approach possibly the engineering type could make it even better.
LOL. Great question Mark. Had me wondering for a moment or two. On that day along with a couple days before we had some horrific winds that sucked the water out of the Chesapeake Bay creating an extreme low tide. As well, I have not taken the time to figure out how low my transducer placement is.
Normally Whiskers II sits at the 7.5' level with about a foot and half of variation between high and low tide. Have not touched bottom yet.
The picture you were looking at was at the low of the day.
Cheers,
Butch
Butch Garren
Nonsuch 30, #196
Whiskers II,
Solomons, MD
Follow up on the transom mount transducer installed in the hull.
Last winter I purchased a Garmin 721SV chartplotter with a GT52 transom mount transducer that Garmin was selling off.
The head unit was installed on the arch just above the compass. It affects the compass but I don’t use the compass as it is rare to be out of sight of land. I replaced the bracket that came with it with a couple 3D printed “wings” that fit over the arch these can be easily removed by lifting up and also can be turned around so I can see the display from the cabin while on anchor watch.
The GT52 was installed in the old KnotLog hole. The Datamarine knotlog stopped working years ago but now I just use the speed from the GPS. I had to 3D print a shoe for the transducer because for the side view sonar to work properly it has to be mounted level. By luck the cable is just the right length to reach from in front of the keel, under the floor, up the arch to the head unit on a 26C. I did not have to cut the cable.
The sonar works really well. Both the traditional depth and the sideview chirp. Much better than watching the numbers on the old sonar because you can open a window and see the history or the trend even while you are distracted doing other things.
The chirp sideview function is more of a curiosity, It shows you interesting features on the bottom like logs and rocks and wrecks and can produce really nice images in parts of Georgian bay that have rocky bottom. It does work for finding a good anchorage because you can tell the difference between sand/mud and rocks/boulders. The traditional sonar window shows the bottom and weeds or no weeds clearly. You can easily see the chart, traditional sonar and side view at the same time on the 7 inch display.
The old Datamarine sonar is still there and working and the two usually report the same depth. The old Datamarine is confused by weeds however and often reports depths shallower than my keel in my marina late in the season.
Unfortunately this information starts under the hull so only tells you information about where you’ve been, not where you will be. As far a fish finding, I have no idea. There are some massive targets and what look like some large schools occasionally but I don’t know if these are a glitch or are real. On the whole it works well and searching for wrecks is fun so I no regrets I went to the trouble of mounting the transom transducer under the hull.
