Transom Mount Transucer Issues

[Scott W.]

I have a Garmin 120 Fish Finder on my boat and it has been on there for about the last 7 years or so. It is one of their less expensive models but has worked great for me as I really only use if for the depth and temp. Year before last I started to get some rather erratic depth readings from time to time, but not that often. This past season it got really bad I was getting really erratic readings on the depth all the time. The transucer is set at the 1/8 to 1/4 inch below the bottom of the boat as suggested by Garmin and is in a postion such that it should be about level when the boat is up on plane. When sitting still I will get a good reading then as the boat comes up on plane I will get really erratic readings like 128 feet in 6 feet of water. If I make a really hard turn to the starboard (the transducer is to the right side of the prop on the right side of the boat) and really put the right side of the boat down in the water, I will generally get a good reading. As I come out of the turn back up on level the reading is generlly lost again to some wild number. As I slow the boat down to a near stop I will once again get a good reading. The unit has been fine for many years so I do not know what could cause turbulance for the transducer all of the sudden over the last two seasons. Is there some way to test these things out of the water. I cannot drop it in test it then take it back out as the marina will charge me for each trip. I have thought of replacing the entire thing this year, but do not know if it is necessary or not. Can anyone offer any information on testing the tranducers or what they might try. I did try cleaing the transucer before I put it in the water last season, not sure it that helped or not really. Thanks for any info.

Scott W.

 

[nickysc]

I have a Lowrance 522c. It does the exact same thing. I bought a seperate unite to run the transducer on, thinking that would solve the problem. still does same thing. Hopefully someone on here has the solution.:grin:

 

[tdappleman]

I have a Humminbird cheapo model as I don't really use it for fishing. It was giving weird readings and losing bottom in real shallow water where it used to be fine. Mine has indents in the mounting and I adjusted it one setting so it was more level and it's worked fine. Maybe as simple as just being out of alignment a bit.

 

[Scott W.]

I am going to try to adjust it once again I think and see what happens. I was down looking at it today and there is nothing in front of it that would cause any turbulance, so I will give it one more try at a little different angle. I would replace it but if it is reading when I am going slow it must be working, something is just screwing it up when I am up on plane. They say it should be level when you are on plane, but that is kind of hard to judge. Perhaps my estimate of level on plane is off. I do have trouble hanging a picture straight according to my wife, so perhaps this is the same type of thing.

Scott W.

 

[Lazy Daze]

I don't know of any way to test them out of the water. If there's nothing on the hull (or growth) causing the turbulence, then the ideas above about being level are about the only other thing it could be. Based on what you are saying, I don't think there is any issue with the transducer being bad.

 

[nickysc]

I will try changing the pitch as well. Makes sense.

 

[Scott W.]

Just not sure how to change it to get it right. First time I did it, I gave it very little thought and it seemed to work fine for years. I have it at what I think should be about level when the boat is on plane, but it must be a little off as it is not working properly all the time. I will give it another shot when I get to put the boat back in the water.

 

[Lazy Daze]

Scott - start with the transducer parallel to the boat bottom. Use a straight edge to verify. See how that works when you get around to putting the boat back in the water.

 

[Scott W.]

Thanks Dennis I will give that a try.

Scott

 

[Plane 2 Sea]

I've installed marine electronics for 20 + yrs. Make sure the front edge of the Xducer is slightly above the bottom edge of the transom. ( 1/8 " or so) than level with the bottom of the hull, and level horizontally. Should work fine slow or fast..