Correct angle of SI Transducer

[Jeffry Skidmore]

Should the butt of the transducer be kicked up a little when fine tuning the installation. I'm somewhat OCD about detail, comes from my career. My thinking is that, with two bodies, gas and gear in the boat idling along scanning, the back of the boat is angled down. If the 'ducer is mounted square, then the beam is not shooting "parallel" to the bottom. Is this a reasonable theory, and if so, will the performance of the transducer be affected?

Thanks!

 

[Humminbird Greg]

Very reasonable.
Most planning type boat hulls run ‘nose-up’ at slower than planning speeds. These slower speeds are when you use your Si sonar so your Si transducer should be a little kicked up in the back so that it will be parallel to the surface of the water. I’ve seen where some have used levels and such to try and fine tune the angle but I prefer to idle by a vertical pole and see whether the shadow it makes sticks out 90 degrees from the bottom (meaning the transducer is parallel to the surface of the water) or whether it is angled up or down to far.

 

[Jeffry Skidmore]

Thanks Greg, for the positive reinforcement and tip!

 

[THOMMO59]

I'm with Greg ther, that's how it was pointed out to me that my transducer needed adjusting. Now that your OCD has kicked in, how about side to side level with only 1 person in the boat?

 

[Jeffry Skidmore]

I'm with Greg ther, that's how it was pointed out to me that my transducer needed adjusting. Now that your OCD has kicked in, how about side to side level with only 1 person in the boat?

Sit in the middle?

 

[THOMMO59]

Funny as it may seem, in very shallow water, your SI will give a darker reading on one ide if it's not level side to side, in deeper water or when your moving it doesn't seem to matter. What I have found from trial and error is if you have the ducer a touch high at the back, it will lose readings at a lower speed as bubbles pass under it.

 

[Jeffry Skidmore]

Funny as it may seem, in very shallow water, your SI will give a darker reading on one ide if it's not level side to side, in deeper water or when your moving it doesn't seem to matter. What I have found from trial and error is if you have the ducer a touch high at the back, it will lose readings at a lower speed as bubbles pass under it.

When you say "very shallow", how shallow do you mean? Usually, I/we are reading the TM mounted 998 in water less than 4-5 ft. Also, when "scouting", typically I'm/we're moving at idle. Btw, at times I/we fish in water that is 1ft under the TM. My biggest bass have been caught in those depths at winter pool.

 

[Wayne P.]

When you say "very shallow", how shallow do you mean? Usually, I/we are reading the TM mounted 998 in water less than 4-5 ft. Also, when "scouting", typically I'm/we're moving at idle. Btw, at times I/we fish in water that is 1ft under the TM. My biggest bass have been caught in those depths at winter pool.

Humminbird Side Imaging will "see" the whole distance of the SI range as long as the transducer is not buried in the lake bottom and the bottom is flat enough.
SI "sees" from the water's surface to past vertical under the transducer on both sides.

This image shows where I was following a creek channel after a summer rain storm to see if any fish had moved to the cooler run-off water. The creek channel is on the right side and I had 100' of bottom coverage, note the depth--




This image shows checking along a spawning flat next to a dollar pad field that the pads had not grown yet, just the stems were present and not visible due to muddy water. The pad stems are on the left side and I had 80' of bottom coverage this time. Note the depth--- The marks on the top right are outboard skeg/prop tracks done by someone not knowing the depth.

 

[Jeffry Skidmore]

Humminbird Side Imaging will "see" the whole distance of the SI range as long as the transducer is not buried in the lake bottom and the bottom is flat enough.
SI "sees" from the water's surface to past vertical under the transducer on both sides.

This image shows where I was following a creek channel after a summer rain storm to see if any fish had moved to the cooler run-off water. The creek channel is on the right side and I had 100' of bottom coverage, note the depth--




This image shows checking along a spawning flat next to a dollar pad field that the pads had not grown yet, just the stems were present and not visible due to muddy water. The pad stems are on the left side and I had 80' of bottom coverage this time. Note the depth--- The marks on the top right are outboard skeg/prop tracks done by someone not knowing the depth.

My point was that in shallow water (depth range you are showing) I am on platform and reading from the unit on the TM, not the unit mounted at the helm. At that depth the big motor is usually trimmed high, unless I am using it as a Power Pole. :>) So in that scenario, I wouldn't typically be "off center". My OCD has limits, so when scouting by myself I have to chew my nails and live with dark spots. :>)

 

[Wayne P.]

My point was that in shallow water (depth range you are showing) I am on platform and reading from the unit on the TM, not the unit mounted at the helm. At that depth the big motor is usually trimmed high, unless I am using it as a Power Pole. :>) So in that scenario, I wouldn't typically be "off center". My OCD has limits, so when scouting by myself I have to chew my nails and live with dark spots. :>)

Those images are with my bow unit and trolling motor mounted SI transducer. There are no "dark spots" unless you have Lowrance with Structure Scan which does not have the horizontal coverage like Side Imaging does.

 

[Jeffry Skidmore]

Those images are with my bow unit and trolling motor mounted SI transducer. There are no "dark spots" unless you have Lowrance with Structure Scan which does not have the horizontal coverage like Side Imaging does.

Wayne, I understood Thommo59 to post that if the transducer for the unit at the console wasn't "tuned" sideways also, at shallow depths the images on the console unit would have dark areas because when alone, sitting at the helm, the boat would be skewed to the left causing the transducer to be skewed and not parallel to the bottom. I do not "scout" with the console unit in depths less than 5 ft. At those depths I am typically on the platform fishing, so it wouldn't matter to me what the console unit was showing, because I wouldn't be looking at it. The TM unit pretty much stays on split screen map/sonar or map/SI. Btw, I'm running HB1198 @ console/helm and HB998 on TM.

 

[Wayne P.]

A hint to set the imaging transducer parallel to the water's surface.
When passing by docks with posts or standing timber, you want the shadows of them horizontal on the display.
If the shadow is tilted towards the top of the screen, the temp sensor end is too low
If the shadow is tilted towards the bottom of the screen, the temp sensor end is too high.

IF you use the imaging transducer of on-plane depth readings, you can't set it for the best idle speed images.

Wayne, I understood Thommo59 to post that if the transducer for the unit at the console wasn't "tuned" sideways also, at shallow depths the images on the console unit would have dark areas because when alone, sitting at the helm, the boat would be skewed to the left causing the transducer to be skewed and not parallel to the bottom. I do not "scout" with the console unit in depths less than 5 ft. At those depths I am typically on the platform fishing, so it wouldn't matter to me what the console unit was showing, because I wouldn't be looking at it. The TM unit pretty much stays on split screen map/sonar or map/SI. Btw, I'm running HB1198 @ console/helm and HB998 on TM.

Yes the SI transducer when tilted to one side will show one side darker than the other if the bottom is flat. If tlted to starboard, the whole left side will be darker than the whole right side since the left side will not be getting the more direct sonar returns like the right side.
The same will happen if the transducer is not tilted to one side and the bottom is sloping perpendicular to the transducer, the deeper side will be darker.