Humminbird Matrix 17 questions.....

[Steveatpa]

Hello,

I've been trying to delve into the understanding of how my depth/fish finder works.....and I think I've come to the conclusion that there's so much to know that community colleges should offer 101 classes just on this subject.

I've been trying to figure how most of what my HB Matrix 17 can do and how to do it, but sadly the manual is terribly vague and trying to contact Humminbird directly failed to provide me anything. I was actually surprised about that too since most companies are happy to help with their products. But what I got instead was someone quick to tell me that my "outdated" unit was not serviceable and wasnt supported anymore. That was all before they even heard what I was calling about.....

So since I got nowhere with HB, can I ask here and see if anyone can help?

My simply (I thought) questions are:
1) Whats the difference between 200Hz and 85Hz and is it something which I can use, or is it too complicated for anyone but the ultra serious fisherman?
2) Sitting on the trailer the depth recognized is 9ft but the transponder is only 2ft off the ground. Yes the transponder is not broke, clean, and facing downward. So that said, I found a shallow depth offset on the unit whereby I entered a -7ft and it now says 2ft.....but is this the wrong way? Will it now read inaccurate or accurate in the water? Is there a difference if its in the water??? Again, I'm not sure what all these settings are so maybe this is not what the depth offset is for.
3) I have more questions about sensitivity and water clarity settings, but I'll let those go for the moment as I'm more concerned with it at least telling me how shallow the water is. I care more about the potential damage from shallow objects/ground rather than how many fish are down there.

Thank you.

 

[dingbat]

1. The longer wave length of 85 kHz allows it to penetrate deeper into the water column but restricts the size of the object it can detect. The lower frequency also has a wider detection range.

2. Sonar is a based on the time it takes from the signal leaving the transducer, hits the bottom and returns to the transducer.
Since sound travels further and faster in water, it's effectively out of calibration if used in air.

3. Never heard of a water clarity setting. Some units have fresh and saltwater settings but that's more of a gimmick than anything. The difference in the speed sound travels in the two elements is minuscule.

Sensitity is in effect a gain setting.
Too much and your screen is full of "noise" aka clutter. Too little and you miss details that otherwise might show up on the screen.

 

[Steveatpa]

Thanks dingbat. What about the depth offset? I tried to research what its for and what I came up with was kinda (I thought) odd. Seemingly its to adjust for depth changes in water levels, which I think is weird because if its capable of knowing the depth then why would I have to adjust any depth for it depending on water levels changing over time. Thats one I cant wrap my mind around.....

 

[GA_Boater]

Depth offset is used to set the distance from where the transducer is mounted to the lowest underwater part of the hull.

For example, if you have a fixed keel sailboat with the bottom of the keel 6 feet below the waterline, the offset is set to 6 feet. With a typical I/O or outboard, the lower unit is the lowest part of the boat, so you could measure from the transducer to the bottom of the LU. With an inboard the rudder is the lowest point to measure.

The offset then is used for shallow water warning so you don't run aground because water depth is measured from the transducer to the sea or lake bottom. The offset from the surface triggers the alarm so you can safely, within reason, motor through shallower water.

Hope this helps some.

 

[ajgraz]

I have the Matrix 20 on my old trihull, maybe I can help...

First off, sounds like you were trying to get a depth reading with the boat sitting on the trailer out of the water? Transducers can't read accurately through air. So you set the offset based on that reading, right? The offset is intended to compensate for some wierd circumstance where your transducer is mounted like 3' under the surface. Unless that fits you, set it back to zero.

As for all those water clarity settings, I find them gimmicks only...but then 75% of my fishing is in saltwater in thick, thick kelp, and no sonar is going to "declutter" that. The other 25% is drifting in saltwater looking for transitions between hard bottom, soft bottom, and weeds, and I find the unit excellent for that.

 

[Steveatpa]

Perfect answers guys..... THANK YOU.