# hummingbird 858c



## Juan More Fish (Apr 1, 2007)

Does anyone have a hummingbird where they can see fish , as they are going over the water at about 10 to 20 mph? i have this model 858c, any thing over 5 mph , and i cannot see fish? but when i slow down, you can see the fish marks. I have seen other peoples fish finders, seeing fish at 10 or higher. I might just have to make adjustments. But dont know how yet.


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## dwmikemx (Mar 22, 2008)

You should be able to see fish at 10-20mph. Are you able to get bottom readings at that speed??? Where and how do you have your transducer mounted on the boat??? Also, what kind of boat, alum or glass?

Need to know this info before I can make any suggestions..


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## Juan More Fish (Apr 1, 2007)

I have a alumnium boat. it 24 inches from the motor to my right.starboard side.off transom,Marks the bottom good,just not speed after 5 mph.


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## husky_jerk (Jun 6, 2011)

I have the same problem with my 898. Alum boat, mounted about 18-24 in to starboard of out drive. Not sure on exact measurement boat is still in water . All the features work when I am below 5 mph but any faster and everything goes blank even the depth reading.


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## Bad Bub (Jan 17, 2006)

I don't believe I've ever had a sonar read well at speed. I have a Lowrance on my Lowe 180w now, when I first mounted it, I mounted it low with the idea of reading depth while running. It never did and eventually was demolished by a piece of floating debris. The new transducer is mounted high enough that it is completely out of the water when on plane. Due to the way water flows across the hull at speed, it will create air bubbles, turbulence and cavitation around the transducer which creates the interference. Finding the perfect spot to mount the transducer (if there is a spot on that particular hull) is like finding a needle in a hay stack. With some boats, it works out first try. Others may never allow it.

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## dwmikemx (Mar 22, 2008)

Yeah what Bad Bub said. You need to find the sweet spot on your hull where the ducer will have a smooth water flow over it while on plane. Normally, that area will be closer to the center on the pad or flat area of the hull for an external mount. Also, it should be mounted 1/8 to 1/4 inch above the bottom edge. It takes some trial and error, but it can be done.

The surest way to get high speed readings is to have the ducer epoxied in the bilge for a shoot threw the hull application. I don't know if that would be an option for you on your particular boat?


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## MassillonBuckeye (May 3, 2010)

Theres definitely some art involved in transducer placement and I recommend a mounting board that allows you to experiment without drilling more holes in your transom. 










Also, the manufacturers don't recommend running the transducers out of the water as it may damage them. I never understood how, but thats what they say. When installed properly, most are designed to "kick out" when struck by something while underway and shouldn't be damaged.


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## Bad Bub (Jan 17, 2006)

MassillonBuckeye said:


> Theres definitely some art involved in transducer placement and I recommend a mounting board that allows you to experiment without drilling more holes in your transom.
> 
> 
> 
> ...


40 mph and a 2x4 will take care of one. Kick out bracket or not...

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## MassillonBuckeye (May 3, 2010)

Bad Bub said:


> 40 mph and a 2x4 will take care of one. Kick out bracket or not...
> 
> Sent from my DROID RAZR using Ohub Campfire mobile app


Some things you cannot avoid sure. All of your stars were aligned that day. All that water, all that displacement, that tiny splinter of wood for all intents and purposes, the small surface of the ducer... It seems like it was meant to be! lol


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## fiveeyes (Oct 16, 2013)

new guy here with my 2 cents..i have an 898,two years now,and can read sonar well to 38 mph, gps..gets a little blurry with more speed..IMO its all about transducer placement..took me a while to get it to where it is..YMMV 5


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## sady dog (Feb 10, 2008)

FURUNO...nuff said


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## Bad Bub (Jan 17, 2006)

MassillonBuckeye said:


> Some things you cannot avoid sure. All of your stars were aligned that day. All that water, all that displacement, that tiny splinter of wood for all intents and purposes, the small surface of the ducer... It seems like it was meant to be! lol


It's life on the Ohio river is all....

Sent from my DROID RAZR using Ohub Campfire mobile app


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## papaperch (Apr 12, 2004)

Bad Bub has it nailed. The transducer mounting plate installed on his boat permits trying several mountings without making your transom look like swiss cheese.

If you lose depth reading normally you have to lower your transducer or move it out of water flow pattern across your hull. Also try to insure you get level as possible. I have installed hundreds of these throughout the years for relatives and friends.


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