How to set up Humminbird SI settings

This is a repost from the Humminbird site from Blackie. I beleive this would make a very good sticky for the Humminbird forum. Most new users and old don`t know how to set up there si units to work properly.

The rule of thumb is slower the chart speed the better detail but in order to keep structure in it’s true perspective you must correlate the chart speed with the boat speed and the range that you have set. If a an underwater object such as an old silo that is perfecrly round and you have proper settings, then it will appear nearly perfectly round on the SI screen. I say nearly because objects very nearly under the boat get somewhat distorted as they must make room for the water coulumn to be displayed. Otherwise if your chart speed is too slow for the speed you are traveling, the object will appear elliptical. Being Taller (Paralell to your track). If your chart speed is too slow for your boat speed, the object will appear elliptical wider ( perpendicular to your track). the amount of distortion is proportional to ratio.
On my bow unit, My chart speed stays on 2 @ 60 feet . (approx 1MPH) On my console unit usually 5 for a speed of approx 3mph 150 . One way to check to find the optimum ratio is to pick your favorite range. Let’s say 100 feet and set your chart spped at 5. If you are using both sides and your SI SCREEN IS SQUARE, the an object that appears on to of the screen, should move off the bottom when you have traveled 200 feet. Trave 3 mph and time how long it talks for the object to traverse the screen. Since you are traveling 1.467 feet per second per mile that means you are traveling 4.4 feet per second at 3 MPH. 200/4.4 = approx 45 seconds that it should take. If it takes longer your chart speed is too slow for the other settings. if it moves over screen to in less tha 45 seconds then you ratio is wrong the othe way.
Best way to set it is: Leave your boat speed at 3 mph, and leaave your chart speed at 5 : Now instead of 45 seconds say it took only 55. Then 4,4 x 55 = 242. the 242 / 2 = 121. Now set your range at 120 speed at 3 MPH and chart speed 5 and you have round circles and square squares. The numbers are arbitrary. so don’t use the numbers above if they don’t fit your unit.

AS for the sensitivity it’s best to use the old trial and error method. If you know there is brush, adjust the sensitivity until it becomes the most distinct.

Which frequency setting do you generally use? The SI can be set to 455kHz and 800kHz.

Any preference? I could be wrong, but I think you are supposed to get more detailed returns but less distance from the 800kHz.

Anyone get better results from one or the other?

Mike

I have the 797cSI so I don`t have the choice of which frequency to use, I only have 455khz.

As far as I know I have not heard using the 800khz limits distance of return. That is set by the operator for SI. It seems most say the 800khz is more detailed then the 455khz. With the new 4.5 update my 797 screen is very sharp and clear, objects really jump out at you especially fish. I can`t wait to get in someones boat running the 997 or 1100 SI with the update in 800khz, it has to be simply amazing.

My “to do” list for the next trip is growing…but I’ll add the 800 vs 455 kHz side imaging performance to the list, as the 800 kHz is available on my 997.

I have read that some people are getting varying results, simply based on the physics of higher vs lower frequencies. Plus, it seems that the 800 kHz doesn’t quite read 180 degrees, but its close.

Intersting info at this link: http://forums.sideimagingsoft.com/index.php?topic=79.0

I was just wondering if anyone has toggled between the two frequencies and what where the findings….

Mike

I have moved back and forth with my 997 between 455 and 800. I also asked Mark Gibson at a seminar earlier this spring about it. I cannot remember exactly what he said, but for shallow water, he recommended the 455.

The image quality on 455 is considerably better than when I try 800, so therefore…… well, I use the 455.

The reason I stay with the 455, is that when I switch to the 800, it is too bright. Almost a white out on the screen. I’m sure you can make adjustments to lean the image down, but that would also require remembering the wholesale changes you make, and trying to get back to where you were, should you decide that you still dont like the 800.

I also told Mark, that I understand the reasons for the factory defaults, but it would be nice if there was a shortcut button to the owners default settings, so you could make wholesale changes, and if you didnt like them, you could just hit your user default button and be right back where you were to begin with.

I’m sure Jasons settings are different than mine, and mine are probably different than somebody elses. The biggest thing about getting set up with side imaging is getting your settings adjusted to where you are comfortable with the images

Reddog have you tried the new SI enhance mode. Puts all you settings right at the bottom of the screen really easy to adjust. It stays there until you hit exit. I will run mine with enhance up most of the time I can adjust on the fly for changes in depth etc if I need to.