Using Quickdraw in tidal areas - caution needed.

[Larry3215]

Can't help with the tide changes. But you haven't made nearly enough recordings to develop a map, so your's won't resemble the Garmin chart at all. Just to assume your chart has north at 12:00 o'clock, you will need to make multiple passes north to south or vice versus, working your way offshore to develop the correct contours. Your first drift put the contour lines left to right, then you second pass further to the right allowed Quickdraw to start blending the depth lines.

Thats true, I didnt do a bunch of scans and the depth lines going the wrong way is another issue for me when you only go one direction. It does look like it takes some overlap inorder to get good depth contours.

However,in the one area where the scans did overlap enough for the program to draw the lines in the correct direction, you can clearly see what looks like a sudden drop off. That drop off does not exist in reality. That entire shore line has a nice steady, smooth change in depth.

Here is another area I scanend on dofferent days with multiple trips through the same area - all at different tide levels. I didnt show this one originally because I dont have a detailed chart to compare it to. However, I know this area very very well. This is the mouth of Gig Harbor which is my home port. I wish I had taken more screen shots on different days, but this "chart" changes every time I go through the passage with Quickdraw on. The actual bottom contour in this area is also very smooth, gradual and even as far as depth changes and yet the Quickdraw map shows a sharpe channel and flats that do not exist in reality.