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Thread: Dual Beam and Dual Frequency Transducers

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    RBW Member RonVA is an unknown quantity at this point RonVA's Avatar
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    Dual Beam and Dual Frequency Transducers

    I am looking to purchase a new fishfinder/echo sounder. Most of the diving we do here is on the reefs with a top between 10-50m with the seabed as deep as 65m, although we have some wrecks as well, deepest one at 65m.

    When looking at the Garmins there is a choice between a dual beam (80/200 kHz, 45/15 deg angle) or a dual frequency ( 50/200 kHz, 40/10 deg angle) transducer.

    Apart from the difference in angle, and that the resolution of the 80/200 is good to about 300m (900ft) while the 50/200 providing a good response down to 500m (1500ft) (which is somewhat irrelevant for my diving) I can find little back on other relevant differences between the two.

    What is the difference between a dual beam and dual frequency transponder, which one is best for diving purposes, any experiences?

    Thanks
    Ron

  2. #2
    Reads fine print (mostly) Skipbreather has a brilliant future Skipbreather has a brilliant future Skipbreather has a brilliant future Skipbreather has a brilliant future Skipbreather has a brilliant future Skipbreather has a brilliant future Skipbreather has a brilliant future Skipbreather has a brilliant future Skipbreather has a brilliant future Skipbreather has a brilliant future Skipbreather has a brilliant future Skipbreather's Avatar
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    Re: Dual Beam and Dual Frequency Transducers

    They are BOTH dual frequency AND dual beam. My understanding is the terms are used somewhat interchangeably. The different frequencies are better suited to specific beam widths.The lower (80 / 50 kHz) freqs have wider beams but lower resolution. The 200 kHz beams are very narrow but will always have a higher resolution. An example of how this might be used in the real world: The wide beam might see the wreck (at the edge of its coverage) when the narrow one might not, but the narrow beam will give you greater detail to decide what’s down there. If you also fish, the wide beam can detect fish farther off the side of the boat, but the narrow beam will be more likely to tell you if it’s a school of small fish or one large predator. The sounder on my boat has the ability to display both pictures on a split screen. I’ve read about some newer sounders (brand names escape me at the moment) that use software to blend the pictures.

    One factor may be an influence on you choice. If you have other devices that communicate w/ your boat’s electronic package via sonic signal (usually in the lower frequencies), you would want to avoid choosing a sounder that operates too close to that frequency to avoid instability and interference when both devices are in use. Example: My Raymarine sounder’s lower freq is 50 kHz. I also have a device that attaches to one of my downriggers to send both speed and depth of the bait. It operates at 80 kHz. Had I chosen to use a sounder w/ 80 kHz as the lower freq, I’d have problems.

    Hope this helps.
    Last edited by Skipbreather; 30th January 2010 at 15:49.

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    RBW Member madhooshah is an unknown quantity at this point madhooshah's Avatar
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    Re: Dual Beam and Dual Frequency Transducers

    I think this is one of the best transducer for fishfinder

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    RBW Member Packhorse is a glorious beacon of light Packhorse is a glorious beacon of light Packhorse is a glorious beacon of light Packhorse is a glorious beacon of light Packhorse is a glorious beacon of light Packhorse is a glorious beacon of light Packhorse is a glorious beacon of light Packhorse is a glorious beacon of light Packhorse is a glorious beacon of light Packhorse is a glorious beacon of light Packhorse is a glorious beacon of light Packhorse's Avatar
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    Re: Dual Beam and Dual Frequency Transducers

    Dont forget the 455/800khz down scan transducers. They can give very detailed pictured of what the bottom looks like.

    I recently purchased a Simrad NSS7 with 80/200 455/800 transducer. You can have a split screen showing 2 different frequency displays or you can over lay them.
    Of course the higher frequencies are depth limited.

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    Re: Dual Beam and Dual Frequency Transducers

    Quote Originally Posted by Packhorse  View Original Post
    Dont forget the 455/800khz down scan transducers. They can give very detailed pictured of what the bottom looks like.

    I recently purchased a Simrad NSS7 with 80/200 455/800 transducer. You can have a split screen showing 2 different frequency displays or you can over lay them.
    Of course the higher frequencies are depth limited.
    I appreciate this is a bump from a spammer (not packhorse, the one before), but thought I'd add a comment...

    Be careful of what you believe from the sales material. We bought a Humminbird (can't remember the model sorry) which featured a side imaging transducer and software in the unit which give - just like the website samples promise - a razor sharp image of a wreck's profile.

    Provided the wreck is 30m or shallower. And you're stationary. And the ocean is glassed off. Important to realise that the demos were all typically done on calm, shallow lakes with minimal interference.

    What you get in real life in the ocean is typically much, much less exciting.

    You can switch to lower frequency for the deeper sites but even that seems to be extremely noisy and loses bottom very easily. All in all it's been pretty disappointing compared to the Furuno on our other boat which is simple, very simple in feature set but locks solid to the bottom and just keeps working.

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    RBW Member fullytek is an unknown quantity at this point fullytek's Avatar
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    Re: Dual Beam and Dual Frequency Transducers

    I own a hummingbird with side imaging and I have come back with some pretty nice images down to around 150 feet when conditions were perfect.
    The technology is incredible. The execution is pure shit. The user interface is confusing and complicated. You constantly have to adjust side and down imaging range ( not a simple task when operating in rough conditions ). Programing a set of gps numbers is a chore. Changing names on way points takes far to much effort.

    The product support meterials included with the unit are lacking even the basics

    This will be my last hummingbird product

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