Determining fish size with Side Imaging...

One thing I have learned while using SI is how to determine fish size. Crappie on SI don't reveal a large return because they are a small fish (of course) but also because of their shape. If you think about SI and how it is a thin beam that when objects are scanned they return a signal. I try to think about it this way.. Think about a water fall of smooth flowing water. If you stick a football (representing a striped bass) in the waterfall you will make a pretty big hole in the wall of water. If you stick a frisby vertically (representing a crappie) in the waterfall you will have much less of a return due to the thickness and shape. I believe the same holds true to fish size and returns on SI. The football size thick fish will return a larger round dot and cast a nice shadow in SI. The vertical frisby shaped fish will return a much smaller dot and small shadow (if any). Just something to keep in mind. Also remember to compare size to scanned distance. If you are scanning 100 feet, your returns will be much smaller than scanning at 50 ft.

Gar seem to return a long return since they are long hard fish. Catfish seem to return your biggest and brightest returns since they are long, hard, and FAT!.

Below are some examples of fish type. Most of these are confirmed by catching them. The gar images are confirmed by visually seeing them rolling all across the surface. The catfish images have not been confirmed but I feel pretty sure about them.

Striped Bass
http://i615.photobucket.com/albums/t...s/S00682-1.png
http://i615.photobucket.com/albums/t...s/S00793-1.png
http://i615.photobucket.com/albums/t...s/S01045-1.png






Gar


http://i615.photobucket.com/albums/t...ams/S00831.png
http://i615.photobucket.com/albums/t...s/S00842-1.png
http://i615.photobucket.com/albums/t...s/S00965-2.png






Crappie


http://i615.photobucket.com/albums/t...ams/S00720.png
http://i615.photobucket.com/albums/t...s/S00903-1.png
http://i615.photobucket.com/albums/t...s/S00999-1.png
http://i615.photobucket.com/albums/t...ams/S01025.png
http://i615.photobucket.com/albums/t...ams/S00707.png






Catfish


http://i615.photobucket.com/albums/t...S00320-1-1.png
http://i615.photobucket.com/albums/t...leCams/348.png



DoubleG

I useta use a program called yellowfin. I could even measure the height of stumps. I believe it was based on length of shadow and distance from boat. Lost interest.

How come you can see the Bass and catfish off the water column, but the crappie you cant. Is that because of size also? Oh yeah great shots.

Great shots and great job interpreting the return. I'm not that good myself, but can sometimes tell crappie by the shape of the school of fish.

great pictures, maybe one day I'll get a screenshot like those. Very nice. I've read where the size of the shadow generated is a good indicator of the size of the fish

great pictures

Thanks for the great pics and explaining what we're seeing. These are by far the best SI pics I have seen on any forum! Look forward to more!! Thumbs Up

Quote:

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Originally Posted by slabbandit

Thanks for the great pics and explaining what we're seeing. These are by far the best SI pics I have seen on any forum! Look forward to more!! Thumbs Up

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Yep. I like the last shot the best.

Thanks fellas... I appreciate it. These are some of my best images. I have over 1100 right now. That last one was taken with my 898 before I upgraded. It was super cold that day and I just decided to ride around and explore and found that big group of fish. I was amazed.. I need to get some cut bait and try to catch one of those big rascals this year... I am just usually too busy chasing crappie to switch to catfish.

DoubleG

On Doublegobble00's pics, what does the green arrow represent? Sometimes it's pointing left and sometimes it points to the right.

That last pic of the gar is scary. dang crappie ain't got a chance.CF

No wonder so many crappie here have "gar scars". :yikes

Quote:

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Originally Posted by slabbandit

On Doublegobble00's pics, what does the green arrow represent? Sometimes it's pointing left and sometimes it points to the right.

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The Green Arrow indicates which set of X-Press menus will be brought up when you press the MENU button. This will only show up on a split screen type View. It the second image when you press the MENU button the X-Press menus for the Di and (2D) Sonar windows will come up. In the third image the X-Press menus for the Si sonar will show when you press the MENU button once.

Thanks Greg. I did read something about it in the manual after I made this post. Tommorrow we will attempt to install my friends 998. I think I have studied the on-line manual and read enough posts that I think that we can get it done. He didn't purchase an SD card or a mapping card. I told him we need to wait and see what Lakemaster comes out with for Arkansas on the mapping card.
What size SD card do I need to pick up for snapshots and recordings? Looks like we are going to be running wire about 17 feet, what gauge wire do you guys reccomend for this? I plan on putting a 3 amp in-line fuse on the positive wire. Is this the required size fuse?

Thanks for the help,
Dave

Dave,
A 3 Amp fuse is the recommended size.
For running wire that far (you have to remember that in extending the power cable 17 feet that the actual added length to the circuit is double that = 34 feet) I would use at least a 14 AWG wire. Make sure this is a copper multi-stranded type.

For the memory card I would get at least a 4GB sized SDHC memory card. The SanDisk is recommended and you need to go with one that has a faster read/write speed - so look at SanDisk’s Ultra 2 or even better would be the Extreme 3 SDHC memory cards. Keeping Sonar Recordings to 30 minutes maximum makes it easier to review as well.

Dave,

Get the mini-blade 3 amp fuse. I use to have an inline 3 amp fuse (round cylinder type held in place with spring) but if the waves were really rough, it would lose power to my 1198. Now I rewired it with a 3 amp mini blade fuse and it will not loose power no matter how bad the waves are that day. You can get them at radio shack.

30A 12/24VDC Mini Blade In-Line Fuse Holder : Fuse Holders | RadioShack.com
3A Mini-Blade Automotive Fuse (3-Pack) : Automotive Fuses | RadioShack.com

Nice pics, good job