Two depthfinders on one boat?

[sutor623]

The best thing that I have noticed about SideImaging, being a live bait fisherman, is that it makes catching schools of bait, even in the winter, way easier. THe only complaint that I have is that the transducer is on the transom, so I have to really backtrack to net the bait once I find it.

I have an 898 on the console. I'd like to be able to read and cater to my graph while Im on the casting deck. I have 2 options to make my life easier.

Option #1. Get a swivel mount so that I can turn the unit to face up front, and also get a second transducer for the trolling motor with a transducer switch. Id also have to get a swivel mount.This way I can see whats going on up front, and have my SI working from the front when bait hunting, instead of way out of reach in the rear of the boat. Can be had for about $280. Upside is larger screen, SI up front, and no more battery draw. Down side is the sides would be backwards, and it is a bit pricey.

Option #2. Get a humminbird 345 DI and mount in on the bow, with the transducer on the trolling motor. Can be had for $217.00 Upside is dedicated unit, and who wouldnt want a second unit? Down side is DI but no SI up front, smaller screen, more main battery draw (for very little time), and chance for sonar interference. Id like to be able to network two units, but I don't want to drop the $700 for the network capable 788 DI.


What do you guys think? Seems like Im leaning toward option #2. My main concern is the interference between units. Is there an easy way around this?

 

[fishrdan]

Re: Two depthfinders on one boat?

I'm not sure if this will help you, but I have a Humminbird 571DI and 581HDDI that I can run at the same time. I have to run them on different frequencies, but there isn't interference,,, and I have the ducer's mounted 2' apart...

I have 1 sonar at the helm and the other on the engine cover (doghouse). I swap back and forth with one is running DI, and other times both running "fish" mode,,, or the 581 GPS and the 571 DI or fish mode.

It was kind of a gamble as I couldn't get a concrete answer if the sonars were shooting all frequencies at all times, or only the selected frequency, but the ones I have only shoot the frequency that's selected.

 

[sutor623]

Re: Two depthfinders on one boat?

I hear ya. Yea I guess that is always an option. I guess I could run the from units 2d at 83khz and the DI at 800, and the rear unit I could run the 2d at 200 kHz and SI beams at 455khz. Definitely an option. Any other ideas? Dan how do you like your DI?

 

[fishrdan]

Re: Two depthfinders on one boat?

Also.... When I called Lowrance tech support, they said their sonars shoot all the frequencies, all the time. I'm not sure if that's true, but that' what they told me.... I didn't get a good answer from Humminbird either, but rolled the dice as I liked the features of their sonars, compared to the Lowrance's in my price range.

For DI, I use it on big reservoirs devoid of a lot of structure, so it wasn't the "cats meow" that I thought it was going to be. I've run DI at the same time as traditional sonar, compared the screens, and while DI is clearer, traditional sonar was close to DI at what I was looking at. I ran over a couple of submerged trees and they showed up much clearer, but traditional sonar was still picking it up.

The biggest issue I see with DI is that the boat needs to be "stable" or DI isn't going to show a clear picture. DI takes thin slices of the water column to create the DI image, and if the boat is rocking, all of the slices won't be from directly below the boat,,, some from 5-10' fore, others 5-10' aft. SO the image is going to be all scrambled up. "My problem" with that is, I don't usually fish in blue-bird conditions. Wind and choppy waters is good for where I fish, but not good for DI.

 

[sutor623]

Re: Two depthfinders on one boat?

I'll tell you what, DI can be a great tool with some finnicking. I like the Blue screen the best. It really helps me distinguish structure vs. fish vs. structure and fish. You must also stay moving while using it to be accurate, and set your chart speed to the speed you will be going when using it. But I have found that in most cases 2D is still worth it's weight in gold. Check out these awesome sites!

Mid-summer panfish revealed by Humminbird Down Imaging

Humminbird Side Imaging Forums

 

[sutor623]

Re: Two depthfinders on one boat?

Im looking for another awesome explaination on DI that I had once seen. If I can find it, Ill show you how you can use it to distinguish not only what is directly under the boat, but how far out to the side certain objects are. Doesnt work as well as Side Imaging, but still a great product!!

 

[dingbat]

Re: Two depthfinders on one boat?

It was kind of a gamble as I couldn't get a concrete answer if the sonars were shooting all frequencies at all times, or only the selected frequency,.

You can not ring
multiple frequencies unless you have a multi-element transducer. Then again, the "other" frequencies will not interfere with the frequency the unit is trying to read.

 

[sutor623]

Re: Two depthfinders on one boat?

My newer 898si the capability to change between 83khz and 200khz or both. And for the SI signals you can choose 455 or 800khz, so to use two units would work well. Honestly when I am castnetting off of the bow Id like the narrowest, tightest band that I can get so I know the bait is actually right under me.

 

[dingbat]

Re: Two depthfinders on one boat?

My newer 898si the capability to change between 83khz and 200khz or both. And for the SI signals you can choose 455 or 800khz, so to use two units would work well.

All transducers produce a secondary, lower frequency (wider beam, lower resolution) as a side affect of the primary frequency. The 83 kHz signal is the side affect of the 200kHz signal. So you get two frequencies without using a multiple frequency pulse generator as you would using 200/50kHz unit. Clearly a cost saving move.

I suspect that 455kHz is a secondary emission of 800kHZ, but I don't know that for sure.

I'm saving my pennies up for a Garmin GSD 26

 

[sutor623]

Re: Two depthfinders on one boat?

DIngbat, the 455 and 800 are the side imaging frequencies, and you can only use one of the other at any given time. With the 83 and the 200, for the 2d, I think you are right. Bummer!

The GSD is a super nice unit. You being a salt water guy, having high speed accurate 2d sonar is a must. Plus fishing really deep water with a 200khz ducer is almost useless. Us freshwater lake and river guys drool over structure scan and side imaging I must say though, being able to choose which frequency your ducer emits, as the garmin can, is pretty incredible. Nice being able to control the spread regardless of how deep you are.

That being said, dingbat how can I get another humminbird and eliminate crosstalk with bit units o at the same time? Impossible?

 

[sutor623]

Re: Two depthfinders on one boat?

As an add on, I can get accurate bottom reads at 35 MPH with this unit. But I can only see schools of fish at around 15-20MPH.

 

[dingbat]

Re: Two depthfinders on one boat?

For me, depth is a secondary concern. I'm most concerned with the top 100' of water. Easily handled with 200 kHz and 1kW head unit.

Not sure what you mean by "Control the spread"? Being able to tune frequencies in sonar is the equivalent of tuning in a station in on a radio. Tune out the static and noise for clarity

Your unit has issues at speed because of its slow PRR. I have no problems picking up individual objects at 40mph

 

[sutor623]

Re: Two depthfinders on one boat?

I think my issue is more with cavitation bubbles at higher speeds but not sure. What is the PRR speed on the Humminbird units vs. the higher end units?

 

[dingbat]

Re: Two depthfinders on one boat?

What is the PRR speed on the Humminbird units vs. the higher end units?

my unit has variable pulse length (0.1 to 3ms) and a max. PRR of 3,000 per minute.

HB doesn't give performance spec in that detail but I read somewhere they used a 1,500 PRR. That's half the resolution at speed.

Cavitation would show up as surface clutter.

 

[sutor623]

Re: Two depthfinders on one boat?

my unit has variable pulse length (0.1 to 3ms) and a max. PRR of 3,000 per minute.

HB doesn't give performance spec in that detail but I read somewhere they used a 1,500 PRR. That's half the resolution at speed.

Cavitation would show up as surface clutter.

Sweet. I took your advice for starters. Im going to see how it works out.