Topic: XHS 9 HDSI 180 Transducer Bracket Play

[muskyhunter]

Just a question about this transducer mount and the bracket. 

The large top pin that goes through the bracket is joined to a allen bolt, a washer, and a nylon bushing.  When this is snug, the locator assembly has movement in two directions.  The inner part on the top has some left and right play where it seems there should be a thin washer in-between.  The long bolt comes through the other side and even with the nylon bushing, there is a bit of the bolt end sticking out.  The washer that goes against the bushing has a smaller hole diameter so that it can not allow the longer bolt to pass through.  When tapping the transducer when mounted has a noticeable rattle and movement.  Is this normal? 

I also noticed that when assembled that the transducer does have some tilt play.  The two inner ribs of the bracket that provide a barrier for the inner nylon block allow the transducer to tilt upward and downward a bit.  Is this by design to allow the transducer to tilt when not on plane to maintain a flat position? 

I have added a washer to the outer side of the bracket to move the longer bolt outward so that this can be snugged up a bit more which solves the play and tilt, but I am wondering if it is detrimental to do so?

[Jolly Roger]

Musky,

the "play" of the transducer inside the bracket is normal and necessary to allow the transducer to kick up if it hits an obstacle in the water. The line up of the parts like your drawing shows is correct.

Regards / Harry

[Moose1am]

Back in 1986 I bought and installed a Humminbird LCR 8000 Unit.  The transducer bracket on that unit is the very same one used on the new Humminbird 898c SI unit that I recently bought.

My metal bracket was already attached to my aluminum bass boat and all I had to do was take the old 2D transducer off the metal bracket on my boat and install the new Humminbird 898c SI transducer onto the same metal bracket. 

This saved me a lot of installation time and trouble.  I was very surprised but pleased with this situation.   

The transducer bracket is designed to allow the transducer to kick up and out of the metal bracket's lower hold if you hit something with the transducer.  That's why it's got that much play in it. 

Just a question about this transducer mount and the bracket. 

The large top pin that goes through the bracket is joined to a allen bolt, a washer, and a nylon bushing.  When this is snug, the locator assembly has movement in two directions.  The inner part on the top has some left and right play where it seems there should be a thin washer in-between.  The long bolt comes through the other side and even with the nylon bushing, there is a bit of the bolt end sticking out.  The washer that goes against the bushing has a smaller hole diameter so that it can not allow the longer bolt to pass through.  When tapping the transducer when mounted has a noticeable rattle and movement.  Is this normal? 

I also noticed that when assembled that the transducer does have some tilt play.  The two inner ribs of the bracket that provide a barrier for the inner nylon block allow the transducer to tilt upward and downward a bit.  Is this by design to allow the transducer to tilt when not on plane to maintain a flat position? 

I have added a washer to the outer side of the bracket to move the longer bolt outward so that this can be snugged up a bit more which solves the play and tilt, but I am wondering if it is detrimental to do so?

[muskyhunter]

Okay, I understand the need to save the transducer and have it kick up when an object is hit.  Attached is a photo with the transducer kicked up.  You can see that the side plates need to flex out in order for the transducer mount body to clear the side ribs of the transducer bracket.  Notice the amount of side flex where it almost would touch the allen screw head.  On top of the bracket notice the thickness of the nylon bushing.  If I mount this with the nylon bushing, unless the bushing fragments, there is not enough side play with the bushing where the transducer would kick up.  I have tried to simulate an impact and can not get the transducer to kick up when the nylon bushing is installed.  If I install the transducer without the bushing, I can see how the transducer would kick up.

If the transducer won't kick up with the bushing, the rattle and movement of the transducer (even with the bushing) serves no purpose.  I have a rubber washer that I can put between the nylon bushing and the steel washer to firm up the mount.  Also, with the side to side motion as well as the up/down motion of the tranducer, is this beneficial in helping keep the transducer more stable as it is slightly decoupled from the movement of the boat, or is a firm mount a better performer?

[Humminbird_Greg]

I guess that I am not following you here muskyhunter.  The nylon washer fits on the outside of the metal bracket, over the headed pin and between the metal bracket and allen head screw.

Someone on this or another forum posted that they got clearer images when they installed a piece of foam between the plastic pivot arm and the metal bracket.  This did not allow the transducer to wiggle as it gently pushed it outwards to the indents on the side plates of the metal bracket.  It also did not interfere with the kick-up action of the transducer.

[muskyhunter]

Greg.  I think I confused folks with the nylon bushing sitting on top and not attaching the allen screw.  It was hard to capture a photo of what I was trying to say.  Looking at the attached photo above, look at the side of the bracket and the distance it needs to flex to allow the transducer to kick up.  In other words, the side plate needs to flex outward about 1/4".  Lets say the nylon bushing is 1/4".  If the bushing is in place, the bracket can not flex outward.  If the bushing is removed, the bracket will flex outward up to the end of the bolt shown.  Does that make sense?

[Humminbird_Greg]

That makes sense muskyhunter but the design needs the nylon washer in place to have the right amount of friction for the kick-up feature.

[reddog]

The top bolt goes thru the mounting bracket.

The  bottom transducer bolt goes inside the mounting bracket.

The mounting bracket will "flex" enough  at the bottom to allow the transducer to kick up far enough to clear the  object when struck.  It doesnt have to have clearance at the top, just the bottom.   You may not be able to replicate a strike in the shop, because its going to be considerably harder than you would allow yourself to strike a perfectly good transducer.

[Humminbird_Greg]

Good points there Reddog.  It is the bottom of the bracket that needs to flex when it kicks up and unless you are a deranged (former) Quality Tech I doubt that you would want to hit that transducer hard enough to kick it up.

[muskyhunter]

I found a solution to deal with the up and down movement of the transducer without effecting the kick up function.  On the back side of the plastic block where the top through bolt passes through, there is a post that is hollow.  I inserted a screw so that the block can not tilt towards the boat and keeps the block pushed out a bit against the side ribs of the metal spring bracket.  Hard to explain without actual pictures but if you have the bracket in hand, it all makes sense.

[Humminbird_Greg]

Genius!
You know I have never found out why that boss was put there.  I showed this to one of the Manufacturing Mechanical Engineers and he said it was almost like we knew we were going to have to use it for this years ago when it was designed.  You definitely get the Two-Thumbs Up award for this muskyhunter!

[muskyhunter]

Thanks Greg.  I was fearing that some folks thought I was a bit wacked (they may anyway).  On the back side of that plastic block there is a tab towards the bottom which rests against the back of the metal spring bracket.  It is not long enough to keep the plastic block tighter against the spring bracket ribs.  A better solution would be a slip on cap that is like a c-channel cap that slips over to give that tab a bit more length.  I couldn't find anything around the garage that would have worked. 

The problem I had with that up/down play is the change in angle is significant.  If I tilt the transducer mount so that it is tight up to the spring clamp ribs, then moving it forward changed the transducer angle quite a bit.  What I do to set up the transducer is take a straight edge to the transducer bottom and run it underneath the boat, then measure the distance from the straight edge to the boat; close to and far away from the transducer.  Right now it is set to 20mm parallel using the set screw as shown above, limiting the rocking action to 1mm.  Without some kind of way to limit that up/down rocking, the change in angle over a 1 foot straight edge was about 9-10mm.  (sorry for the metric dimensions, I couldn't find my other tape measure.)  Without trig, I would guess that to be about 2 degrees of play.

It just seems a bit sloppy.  I would like to see the through hole of the spring bracket drilled back towards the spring clamp ribs.  Without measuring I would guess moving the center point 3/32" inch towards the ribs so that the block fits snugly against those ribs.  Some of that block movement is also due to play in the block hole and through bolt. 

[Humminbird_Greg]

muskyhunter,
Most who modify the bracket add some foam, rubber or some other substance with a little ‘give’ to it on that tab you referred to.  You have been the first to make use of the boss.

I have only seen one documented event that showed that the movement of the bracket caused any problem at all.  Usually the forwards movement of the boat will pin the transducer backwards in the bracket and there is no movement once underway. 

Setting the transducer so that it is parallel with the bottom of your boat’s hull may be best for measuring the amount of play in the transducer bracket but not for setting it for using it.  The best way to do this is to set it according to the angle of your boat while underway at the same speed you will be using your Si sonar.  Now this is usually something we can’t do so it is far easier to just image a vertical object (pole, bridge piling) and see if it gets displayed straight outwards from the centerline.  If it slants up towards the top or bottom of the display than it needs to be adjusted.

I don’t know if we could move the holes n the bracket and get consistent results.  These are press formed parts and its harder to get tight tolerances from parts like this.  We could but that would run the cost of these up which is something no one here wants to do (add to the cost of building the product) unless absolutely necessary.

[nmanley]

Thanks Greg.  I was fearing that some folks thought I was a bit wacked (they may anyway).

Got that right!!!     All us Titan owners are WACKED! 

[muskyhunter]

Greg, here is a question for you.  In your last reply you stated "The best way to do this is to set it according to the angle of your boat while underway at the same speed you will be using your Si sonar."  With the motor obstructing the transducer, it will need to be trimmed up and bringing the bow up as well.  Optimizing the transducer pitch for this condition makes sense, but would that also not cause a condition for turbulence at speed since the leading edge of the transducer will be deeper in the water than the trailing edge?  What is the best setting to optimize the transducer for both sidescan and on plane?

[Humminbird_Greg]

Yes it will muskyhunter.  I don’t know what to optimize the transducer if you have to do this than.  I guess the answer would be you would set it to whichever angle gave you the best reading for the sonar type you want: Si or high-speed readings.  You could also look at installing a second inside-the-hull transducer for high-speed depth readings or possibly a second Si transducer on the other side of the motor so you won’t have to trim it up.