Topic: Left Side SI image problem

[Jay415]

Well I've been using my 998C Si unit in fresh water with no problems. I recently bought a second transducer for my saltwater boat. I haven't been able to get good images on the left side. I could only assume that the transducer is not level from port to starboard, but how do I know? It looks level when on the trailer. Is there a way to tell by looking at the recordings, like when it's not level bow to stern? I tested it in a canal with bulkhead on both sides and I get a clear image on the right, showing each individual piling and everything. But on the left not so good. It's installed on the starboard side, so I though maybe the motor was blocking it, but no change trimming the motor up. Here's a sample image and the Google earth image of the same area.

FYI: I have the unit set for Salt (shallow) water type





Here's a Humviewer image of the same area.

[newkid4si]

If your boat is trailerable, loosen the three screws that attach the mounting bracket
and lower the left side of the transducer some to see if the image improves.
Use caution when "tripping" the transducer so you can get to the screws.
If lowering it doesn't improve the image, you likely have other problems.

          Mike

[Jay415]

You think the left side is shooting to high? I was kindof thinking the opposite, that it was shooting too low.

[Humminbird_Greg]

I agree Jay, if the left side was too high, the right side would be too low and would not give good Si sonar detail for those things that are up near the water’s surface.

I would take the transducer off the mount and install it temporarily on a pole so that I could hold it over in the water (boat does not have to be moving for this) and rotate it around and compare the left and right Si beam readings when they point at the same objects.

[Jay415]

I actually just got off the phone with Humminbird tech support and they didn't have any options for me yet except that something is blocking the SI path. But I am going to email them the photos above along with photos of the install before I make any changes. I'll post the install pics when I take them and keep you informed.

I just realized I posted this in the wrong section, It's was meant for the 998c forum

[Jay415]

Thanks for moving this to the right section Greg!

I'm leaning towards a bad transducer. I went to pull the boat out of the water today and scanned the same canal the other direction. To my amazement left and right side were working perfect!! Then suddenly it stopped. I didn't change a thing. I don't get it.

Here is the same section of the canal as above both sides scanned well. (Just scanned in the opposite direction.)



Then suddenly the left side went out.


 
Here's a video of the scan, you can see how the left side stops working.

Side Imaging Problem - Left side not working

[Jay415]

Here's pictures of my install

[newkid4si]

Jay415
   After you and Greg pointed out the obvious error that I made, I agree with both of you.
   I was so focused on getting the screws loose that I rotated the transducer the wrong way.
   Sorry.

         Mike

[Jay415]

After watching my latest recording in Humviewer, I'm wondering if it is just interferencing as speed increases. In the video I posted, when my speed was in the low to mid 3mph range the images were clear. I just noticed it's when my speed increased above 4mph the left side went out. Gonna have to test that out. Not sure if it was just coincidence. Any ideas what could cause that?

I know the interference band in the video at 34 seconds is when I was trimming the motor, but other than that I didn't touch the trim on the motor.

Here's the video again

Side Imaging Problem - Left side not working

Greg The 200 works good not much interference at all.Its the 83 that's giving me problems.The side image blacks out on the left side when i go any slower than 6mph.Last trip out i took some snap shots for you guys to look at.First is split screen 83-200 you can clearly see the interference on the 83 side the 200 is fine.If i slow down to an idle the interference will go away.Second is a full screen 83 once again the interference is outta control.Third and fourth is the SI on the 3rd you can see I'm going 3.5 mph and look at the left side image half of it is blacked out.Now on number 4 you can see I'm going 6.4 mph and the black has gone away i did nothing different but go faster.I will try to lower the angle of the xducer for the next trip and see if there is any change.What do you think of the snap shots?....Thanks Jim

I also noticed I am having the opposite problem Double Digit was...I wonder if the fix is similar? Although he never updated the thread.

[Humminbird_Greg]

Jay,
Looking at the install pictures you posted; the only thing that could be blocking any sonar would be you boat motor and then only if you trimmed it down too far.  You would be able to see this with the boat stationary.

The boat speed could be the reason for this.  The turbulence water coming off the outside of the hull could be blocking some of the Si sonar near the surface.  Because the transducer is offset to the right side of the hull, its Si beam may actually be shooting under this turbulent water on the right side of the boat.  Best way to check to see if this is happening is to get back out on the water and try driving at different speeds to see if it is speed related or not.  If you look at the video again you will see that you get more and more horizontal lines on both side of the Si sonar as the boat speed increases.

[Jay415]

Thanks! I confirmed yesterday it's definitely related to speed, motor doesn't block the signal at slow speeds or stationary. I am going to try readjusting transducer. I just don't know if I should go up, down, tilt etc. I read that if you tail down a little it'll help shed bubbles.

[Humminbird_Greg]

I guess it really depends on if the turbulent water is being generated at the transducer or (my guess) off the sides of the hull.  Lowering the back end of the transducer may help if it is at the transducer (as would lowering the transducer) but if at the hull than lowering is your best option.  Lowering the transducer would be your best all-around bet here Jay.  To lower may also mean that you have to move it more towards the center on the hull...

[Jay415]

So what your saying is possibly lowering it so its closer to the motor? I was just going to lower the bracket to allow it to hand lower in the same spot. I thought the suggestion is to be as far away from the motor as possible.

FYI I have a Y cable for my through hull transducer so I'm not looking to get anything from the SI transducer but SI and DI at low speeds.

[Humminbird_Greg]

I was meaning both Jay.  I would start with trying it lower where the transducer is now.  If that does not help enough, you should move it closer to the motor which will allow it to be lower in the water.

[Jay415]

I am going to try the tail down first. I thought it was recommended to keep the transducer at least 15" away from the motor. Isn't there a lot of turbulence closer to the motor?

[Moose1am]

Speed does indeed influence the image. Try to stay less than 4 mph and adjust the chart speed to match the speed of the boat.  To stretch images out turn up the chart speed.  To make them smaller slow down the chart speed.

I too have problems with the left side of the image.   I could be the way the water flows under my boat.  I have a flat bottomed john boat with ribs and rivets which can cause turbulence with the water that's in contact with the bottom of my boat.  I also added about 75 lbs of lead pellets to the left side of my boat to help level the boat when I'm by myself and sitting on the Right Side of the boat. 

Check the scum line on the back of the boat and see how your boat sits in the water.  My boat lists to starboard most of the time. I line my transducer up to be level with the scum line which is equal to the water's surface while I'm in the boat.  I've tilted my 35HP motor up to make sure that it was not blocking my left side transducer signal and I still don't get as clear an image on the left side. I also have a very bright thin line just to the left of the middle of the screen.  Something is reflecting sound waves back to the transducer.  Perhaps it bubbles coming under the boat on the left side?   Remember that the propeller turns either clock wise or counter clock wise and you should installed your transducer on the proper side of the boat according to which way the propeller turns.  And make sure that the transducer is at least about 18" from the prop.  Maybe it's 12" away.  Look that up in the manual to see for sure the proper distance.  I know I read that in the manual under the installation  section.

After watching my latest recording in Humviewer, I'm wondering if it is just interferencing as speed increases. In the video I posted, when my speed was in the low to mid 3mph range the images were clear. I just noticed it's when my speed increased above 4mph the left side went out. Gonna have to test that out. Not sure if it was just coincidence. Any ideas what could cause that?

I know the interference band in the video at 34 seconds is when I was trimming the motor, but other than that I didn't touch the trim on the motor.



Here's the video again
Side Imaging Problem - Left side not working

I also noticed I am having the opposite problem Double Digit was...I wonder if the fix is similar? Although he never updated the thread.

[Jay415]

Greg I have a side note question for you. I also had problems getting high speed depth so as per customer service rep and reading online, I bought a Y cable and shoot thru hull transducer. I've been testing different spots and I'm having difficulty finding a good location that reads well. Are there any other transducers I can use with the Y cable for high speed depth? The skimmer type worked fine with my old FF. Can I use that kind? If so what part number, so I can buy one? Thanks

As for the left side imaging problem. Tail down had little to no improvement. And I don't have the time to keep taking the boat out of the water to adjust the transducer. I also don't want to drill more holes in my hull just to "test" to see if it works. I was thinking when I get a chance I will pull the boat out and install a starboard mounting plate. That way I can keep moving the transducer to test without making more and more holes in the hull. 

[Humminbird_Greg]

I believe that the install manual states 15 inches Moose1am but that really does not apply to an outboard motor as all of the turbulent water from the prop is behind the transducer (unless you are backtrolling).  I would guess that your problem is turbulent water flowing off of the hull.  Easy way to tell is to see if it goes away when the boat is drifting.  If the lines go away you can keep trying to locate the transducer where you won’t get these on either side or install a second Si transducer (and AS0Si-LR-Y cable) as some have had to do to get rid of those lines and get better Si readings to the left side.

This may be Jay’s problem as well.

Jay, an inside-the-hull transducer is the best option for high-speed water depth readings on fiberglass hulled boats.  I would keep at it as the results are worth the effort.  Make sure that you have a solid fiberglass hulled boat – no cored hulls or wood stringers or supports in the way.

You could use an externally mounted 2D transducer but then it would be in the way of either the left or right Si sonar beam and block a portion of it.

Definitely install a transducer mounting plate to keep the hole count down.

[Jay415]

I believe that the install manual states 15 inches Moose1am but that really does not apply to an outboard motor as all of the turbulent water from the prop is behind the transducer (unless you are backtrolling).  I would guess that your problem is turbulent water flowing off of the hull.  Easy way to tell is to see if it goes away when the boat is drifting.  If the lines go away you can keep trying to locate the transducer where you won’t get these on either side or install a second Si transducer (and AS0Si-LR-Y cable) as some have had to do to get rid of those lines and get better Si readings to the left side.

This may be Jay’s problem as well.

Jay, an inside-the-hull transducer is the best option for high-speed water depth readings on fiberglass hulled boats.  I would keep at it as the results are worth the effort.  Make sure that you have a solid fiberglass hulled boat – no cored hulls or wood stringers or supports in the way.

You could use an externally mounted 2D transducer but then it would be in the way of either the left or right Si sonar beam and block a portion of it.

Definitely install a transducer mounting plate to keep the hole count down.

I think I found a spot with the inside the hull 2d transducer. I get good reading over 8', from 0-8' it's so so. I think I could live with that.

As for my SI, I made another tilt adjustment while it was in the water. I tried putting it back the way it was (parallel to the hull bottom) but looking through the water who's knows how well I did. It seems to be slightly better. and amazingly I got a decent SI reading at 27mph!!! I wasn't expecting that!! I was just playing around and noticed the SI screen didn't go black how it normally does when I go fast. So I went over an area of a known wreck. Of course it's very compressed, but the cool part is I can see it passing it at 27mph! Now I have to just get rid of the spray that is soaking my motor.


Here's me passing under a bridge the same day. I can live with this adjustment, I just have to play with the speed to get a good picture.