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Discussion Starter · #22 ·
You should be able to keep sonar running at top speed on a 185. As long as it's behind a smooth run of hull it should work up to about 60-70 mph on any model boat for that matter. Some bass boats have wings and other designs that limit sonar to 20 mph. The limitations are whether the transducer can remain fully submerged on plane, and whether the hull has a design that allows production of excess air bubbles on plane. I have a PT175 Tracker with 50 hp and usually keep good sonar going up to 35 mph. It won't go faster so I don't know what the upper limit is.

On plane set the ping rate to 100% to get a maximum nuimber of pulses returning to the transducer. Sound is so fast in water, roughly 4900 ft per second, that in inland lakes at 70 mph most outgoing sound pulses will have plenty of time to bounce back to the transducer at 100% ping rate. The issue is whether the pulses are directed at an angle allowing reflection to the boat, or are they glanced off bottom. That's why the transducer needs to be close to parallel to bottom.

Jim
 

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Discussion Starter · #24 ·
You might post a photo of your transducer so we can evaluate it. It needs to be at one outside corner of the transom as far from the outboard as possible. There ought to be a flat run of hull leading forward, for minimum bubble production. If it is mounted too high maybe it isn't in the water at those speeds. Some boats are practically entirely out of the water on plane.

Jim
 

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oldschool said:
As long as the transducer is pointed at the ground, it will acquire the a reading. The reading in the air to ground is about 4X off due to the difference from air and water density. I have done this several times to check out my electronics.
Tom
FYI, When I got home I fired up the electronics to check to see if would hold depth in the air without blinking and the 19c blinks and repeats the same depth, so that must be normal with the digital units.
Tom
 

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Discussion Starter · #26 ·
Most modern sonars blink whenever the trolling motor is pulled up with the sonar going.

Water is roughly 800 times more dense than air, and sound travels about 4 times faster in water. In order for sonar to work in air it would take maybe a million watts to travel to a target 50' away and have enough power left to return to the transmitter. It COULD work in air, the same thing a bat uses to locate prey in mid air. Just wild guessing to get a million watts, multiplying 800 times about 1000 watts for 50' water. My sonar operates up to 2400 watts for 900 feet of depth, or something like that.

Jim
 

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It's been my experience that 1 1/2 to 3 feet was no problem getting a decent signal to adjust the zero on the paper graph with 1500 watts. The digital signal processor is faster and acquires the initial signal return OK, just drops it and starts to blink and repeat the initial reading. Might be something in the chip program, however the returned signal does indicate to me that everything is working.
Tom
 

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Thank you Jim and Tom for all the time you spend taking care of us Bassholes. I don't have a boat but really appreciate you guys and what you do for us!
 

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Discussion Starter · #29 ·
Thanks, Mary. Tom & I have been a tag team for sometime before Tom came helping us out. Between us we could flesh out lots of things like this. We grew up about the same time doing much the same things fishing-wise, so our backgrounds keep us thinking a lot alike.

I went out there and looked at readings off concrete, both from the transom and bow. All I could get was mostly red, expecting (hard surface) yellow. All sorts of ice cicles in several layers. Cool abstract art. :thumbup01: Anyway, neither unit popped up a message saying no transducer was detected, so they are still working. :dance01: Depth showed 30 feet on one, 58 on the other.

Jim
 

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Discussion Starter · #31 ·
For long trailering trips I pack it all away. One stop for fuel could see them removed over a 10 second spree while you are paying for a soda. If non-stop and local I leave mine on unless using a gravel county road. I wouldn't want a stray rock blasting one of those $550 head units. They are made to withstand a tough ride on the water, extreme vibration, and some ride through rain. Some are not "waterproof". Even those claiming that distinction can get vapor condensed inside the outer glass screen plate. That requires removal to a very warm dry place. If trailering with the units mounted be sure not to leave the face cover on. I see lost covers on both sides of the highway around the lake. They are best used to store the unit to protect the screen.

Jim
 

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I have always taken off my sonar units when traveling and is one more reason to use a RAM mount.
I also store the units in the locked boat compartment, padded with towels and spare jacket etc, when traveling. If you have a boat cover, do not travel with the cover on, as it generates heat under it and the cover may damage the gelcoat. Put the cover on for overnight stops if necessary. Don't store you sonar units in the boat if you keep it outside and covered, because of the heat issues. The units are solid state today and the circuit boards are tough, but subjected to temperatures that exceed 140 degrees, like under your covered boat, can damage them.
This is the main reason that I don't like built in sonar units.
Tom
 

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I have a LMS-525c DF fishfinder by Lowrance, that comes with a very large skimmer transducer. I own a 12'-6" sea eagle pontoon boat. My problem is the width of the transom is too narrow to attach the skimmer correctly. The water turbulence from my 9.9 outboard will cause the unit to operate poorly. So I was thinking of attaching the skimmer to the trolling motor. My question is will I loose any of the high quality features that this unit boasts, by attaching the skimmer to the trolling motor? I do realize that I must use two sources of power for trolling motor and Lowrance unit. Please help, I'm tired of spending 8hrs. on the water and fishing more than half my time in water that doesn't even hold fish.
 

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If you mount your TD on the TM you will be unable to utilize the depth finder at cruise speeds. Most pontoon manufacturers these days attach a TD bracket to the rear of one pontoon. If your boat does not have this bracket contact your dealer to see if they can aftermarket one for you. By doing so you will be able to utilize the depth finder while you cruise your lake looking for fish holding structure.
 

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Discussion Starter · #37 ·
Not at all. But maybe we need to start a section for Humminbird so other brand users won't have to wade through it all? If you think that will help I'll start it.

Jim
 

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lowrance LMS 525C-DF

Hello Buddy,
I have a lowrance with GPS & fishfinder and trollling motor on my boat. Will the trolling motor cause interference with the fishfinder if it's connected to the same battery? Will I require two batteries on the boat?
 

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Discussion Starter · #40 ·
Wow, I'm seeing this half a year later! Sorry for not picking it up... :wack:

It's always best to run electronics separately from a trolling motor battery. Besides the electrical noise possibilities, the voltage on the trolling motor battery will drop too much while trolling, asnother source of performance-robbing on your sonar equipment.

I've used a 12 volt garden tractor battery quite successfully, running electronics. The drawback on those is they conk out in the second year. If you have a StaynCharge ALLCHARGE unit installed it will recharge the battery each time you crank up. You are ahead of the game with an extra deep cycle battery and wiring run to the electronics.

Jim
 
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