Transducer separation from prop wash

TinBoats.net

Help Support TinBoats.net:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Thanks for the advice.

My boat's top speed is only about 22 or 23 mph; and I won't be using the SI at that speed. More like no-wake speeds, so I'll be good on that.

I took the old Lowrance that was transom-mounted in the pic and moved it up to the trolling motor. I'm finishing up that install now. Need to figure out how I'm going to get the transducer cable to play acceptably with the spot lock and inevitable twisting around the TM shaft.

You all know how it is; life seems to intervene when we want to get the boat out. Maybe next week.
does your terrova (I think you said) have the us2 transducer? It's been almost a decade since I had a terrova, but at the time you could plug in a humminbird or a lowrance 2d transducer cable into a wire on the head of the TM and use the built-in transducer, so you can spin around in circles until you fall over dizzy without having a cable issue. Otherwise, there are 2 solutions--there are a lot of videos on this as well.
1) The older (pre 2017 or so I think) terrovas had a groove in the shaft large enough that you could use silcone adhesive and glue the transducer cable into the groove and THROUGH the mount 9requires disassembly). I am told the newer terrovas have a shallower groove and this may no longer be possible.
2) simply do it like you would any TM, cable tie or tape the ducer cable along the shaft, leave enough slack for the head to spin 2-3x, and then back along the mount into wherever you route the cable to the sonar unit. Usually the spot lock wont spin multiple full revolutions, I have heard people say it happened but have had a spot lock MK motor of one flavor or another for 10 years now and have never personally seen it. If you are worried about this take an extra foot or two of slack beyond the above, coil it a few times and TAPE it along the mount--you can tape it to a permanent fixture along the mount if you want, but the idea is to use an attachment that will hold it in place only enough so if it actually pulls tight your tape will let go allowing the extra slack to prevent cutting the cable. I saw someone do this and they said no interference, etc, but personally have never seen the need. My ultrex is simply cable tied along the shaft, has a big loop of slack around the mount, then tied to the mount until it gets to the sonar unit. Photo is a little dark but you can see the transducer cable along shaft and slack...this is an ultrex, but same thing with spot lock and going around the mount:7124C1C6-CF0E-4860-BE52-D8F3D1066FD3.jpeg
 
does your terrova (I think you said) have the us2 transducer? It's been almost a decade since I had a terrova, but at the time you could plug in a humminbird or a lowrance 2d transducer cable into a wire on the head of the TM and use the built-in transducer, so you can spin around in circles until you fall over dizzy without having a cable issue. Otherwise, there are 2 solutions--there are a lot of videos on this as well.
1) The older (pre 2017 or so I think) terrovas had a groove in the shaft large enough that you could use silcone adhesive and glue the transducer cable into the groove and THROUGH the mount 9requires disassembly). I am told the newer terrovas have a shallower groove and this may no longer be possible.
2) simply do it like you would any TM, cable tie or tape the ducer cable along the shaft, leave enough slack for the head to spin 2-3x, and then back along the mount into wherever you route the cable to the sonar unit. Usually the spot lock wont spin multiple full revolutions, I have heard people say it happened but have had a spot lock MK motor of one flavor or another for 10 years now and have never personally seen it. If you are worried about this take an extra foot or two of slack beyond the above, coil it a few times and TAPE it along the mount--you can tape it to a permanent fixture along the mount if you want, but the idea is to use an attachment that will hold it in place only enough so if it actually pulls tight your tape will let go allowing the extra slack to prevent cutting the cable. I saw someone do this and they said no interference, etc, but personally have never seen the need. My ultrex is simply cable tied along the shaft, has a big loop of slack around the mount, then tied to the mount until it gets to the sonar unit. Photo is a little dark but you can see the transducer cable along shaft and slack...this is an ultrex, but same thing with spot lock and going around the mount:View attachment 113991
Thanks.

I have a PowerDrive and it does have the US2, but that US2 is not compatible with my Lowrance Elite 4 DSI. The US2 doesn't support down scan imaging like my Lowrance. The US2 works with the Elite 4, but not the Elite 4 DSI. I've already worked with Minn Kota to make sure I understand, and the bottom line is that it's no-go.

I strapped the Lowrance Transducer to my PowerDrive like you have in your picture. However, I don't have the "scissor style" mount like your picture. It has a mounting base like shown in this picture:

Screen Shot 2023-03-22 at 12.12.06 PM.png

The cable cannot be tied to the shaft between the motor and the base. Taking the transducer cable from the motor up above the mounting base would result in a high risk of cable damage as the spot lock feature (from the ProNav) will often send the motor around in the same direction 360 degrees often, sometimes past 720 degrees. This is a common happening with ProNav; I've seen reports of the same from the OEM spot lock capabilities.

I haven't quite figured out what I'm going to do. I have an idea, and I'm likely to just try it and see what happens. I can do beta testing and then refine it. I'll post a pic when I do it.
 
Oh, that's right, I am sorry--it HAS been a while! I forgot about the mount...One of the reasons I went with an ultrex instead of a terrova on my bigger boat...apparently I am having a senior moment a little early! Yeah, that's why I ran the cable inside the groove on my terrova, so it would slide inside the mount when stowing TM. If yours has this groove this is absolutely the way to do it. This details how I did mine:

If that isnt possible any longer (I am told it's not possible on the lift-assist models?) then it looks like folks are using something around the cable to protect it and add some coiling effect--either spiraled around the shaft like this:
Or in a separate coil away from shaft like this: 2018 Terrova transducer install

Regarding pronav versus spotlock, cant speak to that, just that my oem spotlock hasnt ever done more than 1 revolution, so a wrap or two worth of slack has been plenty.
 
Last edited:
I’d like to be able to read the side view at higher than 15mph if possible.
Sorry to say but that isn't going to happen. SOund NAvigation and Ranging works by sending out sound waves of a certain frequency and looking for the reflections. By the time the reflections from a fish (relatively small) get back you are way past it. It works the same whether looking downward or to the side. Down sonar your going to get a reflection from the bottom which will be strong enough to get a reading but you won't get an accurate "picture" at higher speeds.
To demonstrate this, find a spot that has a submerged structure (tree stump, reef or whatever) and go over it at high speed and then go over it real slow (1-3 knots). You'll see much more detail.If you are looking for fish you have to go slow.
 
Thanks for the advice.

My boat's top speed is only about 22 or 23 mph; and I won't be using the SI at that speed. More like no-wake speeds, so I'll be good on that.

I took the old Lowrance that was transom-mounted in the pic and moved it up to the trolling motor. I'm finishing up that install now. Need to figure out how I'm going to get the transducer cable to play acceptably with the spot lock and inevitable twisting around the TM shaft.

You all know how it is; life seems to intervene when we want to get the boat out. Maybe next week.
The SI/DI chart cannot really write accurately at speeds above 5mph..... you want your chart speed about 1-2mph faster than your actual speed.
in other words, if you are doing 3mph...set your SI chart speed to 4-5. The slower the speed the more detailed your output will be.
DI/SI are both designed to have the boat moving....if you are sitting...use your 2D switchfire sonar instead. Mega 360 is more designed to be sitting in one place. .....
When you are up on plane, don't even bother having SI/DI screens going.....2D will work better, but not very accurately.
 
I've now been using the Helix 7 since April. When all was said and done, I ended up mounting the H7's transducer on the already installed mounting plate that is shown in the picture early on in this thread. I had to give up on meeting H'bird's recommended spacing as that's just not possible on my 14' tinnie. I don't have issues with interference from the motor's lower unit; side imaging works just fine.

Also as stated earlier, I only look at SI at slow speed when scouting an area. Once I start fishing a spot, I usually depend on the 2D sonar.

My preferred display is the split screen with 2D on one side and SI on the other.

Regarding the old Lowrance Elite 4 DI: I took it off the boat completely. There was enough benefit from having it up front to make it worth dealing with the hassle of the cabling as the transducer was mounted to the bottom of the trolling motor. I ended up reconfiguring the old Lowrance into a portable fish finder with transom mount bracket; I took that setup with me to Canada a couple of weeks ago and used it on the lodge's boats for walleye fishing.
 

Latest posts

Top