Muad Dib Posted June 19, 2011 Posted June 19, 2011 ive had a 798 si for a month or so and still have a difficult time with it. When it comes to the chart speed i have heard you should match it to your mph. When i do that i feel the scroll speed is not as fast as the boat is moving. why would you want to have a slower or faster chart speed. and why isnt it automatically adjustable to the boat speed? I also had a ton of trees down off othe shore that was off of a steep drop off and for somereason the si couldnt pick up any of them. any tips or answers would be awesome! t Quote
Super User Wayne P. Posted June 20, 2011 Super User Posted June 20, 2011 Your should be trying to get images to fit on a screen that is about 3 3/4" wide. It's all about picture size to actual size ratio. When you take a picture of a person with a camera, the picture of that person is not the same size as that person. To get the sharpest images with Side Imaging and Down Imaging, set the Chart Speed at or +/- 1 of the GPS speed in MPH. Go as slow as your can when scanning objects, the longer the beams are on an object, the sharper the images will be. That applies especially for vertical objects like trees, dock posts, etc. Quote
Super User Wayne P. Posted June 20, 2011 Super User Posted June 20, 2011 Additional tip. When searching for unknown features, use around 100'-150' range setting unless you are in 50'+ deep water (longer range for that). After you find something or know of something you want a better look at, set the SI range to 3 times the depth or less. That is because the shorter the range that is displayed, the larger an object will be displayed. An example is a 12' fish. If you want to see fish that are 12" and have the SI range set to 100' then the fish will be represented on 1/100 of the SI view on one side or 1/200 of the screen width. You can choose to display either the right or left side SI scan and that will make objects appear larger also. To see trees that are laying on the bottom, it is best to scan them parallel to the trunk so they show up better as illustrated in the screen shot. When I am fishing, I usually have my SI range set to 30'-50' depending on the depth I am in. I use Side Imaging at the console with a transom mounted transducer and at the bow with a trolling motor mounted transducer. The actual screen width is 3.625" so you can do the math of how big something will look of a known size based on the SI range setting. Quote
Muad Dib Posted June 21, 2011 Author Posted June 21, 2011 thank you for your time and help wayne. as usual this site is the best. t Quote
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