Winnipesaukee Forum - View Single Post - More side-scan-sonar images

Diver1111 · 09-07-2008, 09:35 PM

Hi All,

To clarify-Upthesaukee is correct. The Course (aka Heading) is the direction my boat is traveling.

In the picture referenced-"85" is 85 feet-the scanning distance I chose out from the boat, out 90 degrees from the direction of travel of the boat. A right angle. I can set this up to 240 feet per side. Hence 480 feet total scan if scanning left and right simultaneously. Hardcore commercial units can easily go 1,000 feet or more per side. However to generate larger images on the screen I will often scan one side only, thus reducing the total width of the scan BUT getting larger images on the screen.

If I am trying to locate something or just curious about an area, I will "scan wide" using both sides available to varying distances dictated by water depth. This is how I found the barge. I had an idea of where it was but no specifics, so I scanned two sides at once, made only a few passes and saw an interesting image, then moved my screen cursor (yes we have cursors) over the TOI/target-of-interest and marked it (I can move my cursor over any object, lock on to it and capture it's Lat/Lon. Then it's only a matter of navigating over the object by selecting Go To in my chartplotter-choosing the TOI just captured-and get right on it. Very useful to say the least).

If you look carefully at the green arrow in the image in question, you will see the image of a boat-my boat-just above it. This will tell you where the boat is in relation to the entire image. The green arrow says I am scanning to the right. The boat image is cut in half because I am only scanning to one side. If I was scanning left and right at the same time, the entire boat icon would appear.

Multiple passes by a TOI is Side-scan 101; Images can be badly twisted for a number of reasons-so you need to scan as many times as necessary to develop a feel for what you have. This is why I have several different Courses indicated in the images-different passes.

Hope it helps.

09-07-2008, 09:35 PM	#11
Diver1111 Senior Member Join Date: Jun 2005 Location: Exeter NH Posts: 596 Thanks: 0 Thanked 1,027 Times in 224 Posts	Answers Hi All, To clarify-Upthesaukee is correct. The Course (aka Heading) is the direction my boat is traveling. In the picture referenced-"85" is 85 feet-the scanning distance I chose out from the boat, out 90 degrees from the direction of travel of the boat. A right angle. I can set this up to 240 feet per side. Hence 480 feet total scan if scanning left and right simultaneously. Hardcore commercial units can easily go 1,000 feet or more per side. However to generate larger images on the screen I will often scan one side only, thus reducing the total width of the scan BUT getting larger images on the screen. If I am trying to locate something or just curious about an area, I will "scan wide" using both sides available to varying distances dictated by water depth. This is how I found the barge. I had an idea of where it was but no specifics, so I scanned two sides at once, made only a few passes and saw an interesting image, then moved my screen cursor (yes we have cursors) over the TOI/target-of-interest and marked it (I can move my cursor over any object, lock on to it and capture it's Lat/Lon. Then it's only a matter of navigating over the object by selecting Go To in my chartplotter-choosing the TOI just captured-and get right on it. Very useful to say the least). If you look carefully at the green arrow in the image in question, you will see the image of a boat-my boat-just above it. This will tell you where the boat is in relation to the entire image. The green arrow says I am scanning to the right. The boat image is cut in half because I am only scanning to one side. If I was scanning left and right at the same time, the entire boat icon would appear. Multiple passes by a TOI is Side-scan 101; Images can be badly twisted for a number of reasons-so you need to scan as many times as necessary to develop a feel for what you have. This is why I have several different Courses indicated in the images-different passes. Hope it helps.