Author Topic: Sidescan speed?  (Read 4221 times)

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Offline nicko_cairns

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Sidescan speed?
« on: November 05, 2014, 08:38:32 PM »
Hi guys,

My mate with a Lowrance is getting sidescan readings at 15 knots+ where I can only use mine at 6 knots. Do I have the transducer installed incorrectly? What speeds can you guys scan at? Any tips to improve mine? It’s an older 798cisi unit.

Thanks!


Offline Bob B

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Re: Sidescan speed?
« Reply #1 on: November 05, 2014, 10:27:41 PM »
Mounting and boat hull are key factors in high speed SI readings.....Not the brand of unit.
You can get good SI readings at high speed if you have "clean" water across the face of the transducer.  It doesn't work in turbulent water (air bubbles block the signal.)

My brother gets SI readings at WOT on his old Tracker PT17......He has it mounted a little lower than I do.

With some bass boat hulls, the transducer is completely out of the water when on plane.

If you drop it lower, you will be a little more susceptible to hitting something with it.
**Looking for the one that makes it all worthwhile**

Offline nicko_cairns

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Re: Sidescan speed?
« Reply #2 on: November 06, 2014, 12:09:06 AM »
Mounting and boat hull are key factors in high speed SI readings.....Not the brand of unit.
You can get good SI readings at high speed if you have "clean" water across the face of the transducer.  It doesn't work in turbulent water (air bubbles block the signal.)

My brother gets SI readings at WOT on his old Tracker PT17......He has it mounted a little lower than I do.

With some bass boat hulls, the transducer is completely out of the water when on plane.

If you drop it lower, you will be a little more susceptible to hitting something with it.

Thanks Bob, this has changed my fishing life! first thing I'll be dropping that sucker lower!! I'll post pics of the current configuration first...

Offline Humminbird_Greg

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Re: Sidescan speed?
« Reply #3 on: November 06, 2014, 12:43:02 PM »
Please do so Nick as before and after install pics along with some screen snapshots of the results would be great information for others.

Keep in mind that even if you can get the transducer in that magic position that allows good Si readings at 15 knots (17mph), the level of detail that will be displayed will decrease.  The faster you go the less detail will be there as the Si sonar will not be able to ping every square inch as it can at slower boat speeds.  As an example: many years ago I installed an Si transducer on one of the company boats.  I was not trying for high-speed Si operation and the attached picture shows that I just got lucky.  I’ll also add a pdf file showing two screen snapshots (from an ole’ 987 unit) showing the same sunken barge and logs at very different speeds, so you can see what speed does to the Si sonar detail level.
Greg Walters at Humminbird
gwalters@johnsonoutdoors.com

Offline nicko_cairns

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Re: Sidescan speed?
« Reply #4 on: November 06, 2014, 12:59:27 PM »
Thanks Greg, anything past about 6-7 knots (8 MPH) isn't readable on my unit, so I'm guessing the transducer is far too high, I usually go pretty slow, 4 knots at a guess and troll two lures to find spots. I'm looking for large structure though, so I don't need perfect precision, and speed would help cover more ground. I'll definitely post the pics before I change the height and I'll post the results afterwards.

Thanks again.


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