Humminbird Side Imaging Forums
Images, Snapshots and Videos => General Pictures and Screen Captures => Topic started by: ZEUS on January 27, 2010, 11:37:21 AM
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Pics below of a small work barge 25m length. Compare the normal sounder to the down scan. Thank you humminbird for the upgrade to 987Cx!! In the down image you can see the square wheelhouse at the stern and the mast near the bow and can almost make out the gunnels on the wreck.
(http://i723.photobucket.com/albums/ww235/karlt/S00160.png)
The second image shows the mast on both sides as I steered down the length of the wreck.
(http://i723.photobucket.com/albums/ww235/karlt/S00161.png)
Best wishes
Zeus
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Hello Zeus and welcome to the forum!
Wow! Nice picture, but it looks like you were in some choppy waters when taking the shot.
Keep them pictures comming!
Regards / Harry
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It was relatively calm for the sea but not flat like a lake.
Although the ground speed was less than 2 knots due to the current the boat was doing 4+ knots through the water.
I do not know if this makes any difference.
Do the sound waves get 'bent' as they travel through the water?? Instead of going straight down and back up they go down and back in a distorted 'V' pattern.
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It was relatively calm for the sea but not flat like a lake.
I believe you that! There's quiet a difference between a "calm" sea and a calm lake. The streaks in the picture is something I get if our Lake is "stormy", hehe.
Although the ground speed was less than 2 knots due to the current the boat was doing 4+ knots through the water.
I do not know if this makes any difference.
It doesn't make a difference. What counts is the speed over ground to set the chartspeed in relation to the boat speed to get a unstretched / unshrinked picture. The faster you go, the faster should be the chart speed. Since you got a sister to my 981, here's a thread about boat speed / chart speed settings.
http://forums.sideimagingsoft.com/index.php?topic=242.0 (http://forums.sideimagingsoft.com/index.php?topic=242.0) [/quote]
Do the sound waves get 'bent' as they travel through the water?? Instead of going straight down and back up they go down and back in a distorted 'V' pattern.
No, the sound waves travel with 330 m/s and you gotta have a real fast boat in real deep water to outrun the sound waves. The key to get a undistorted picture is getting the transducer set in the right angles in all three dimensions + power output + right settings as mentioned above.
For me it took a while and a lot of trial and error to get the set up OK and I'll do it again when I'll get my boat back into the water in spring, 'cause I have to dismount the transducer for an overhaul of my underwater ship.
Keep them coming!
Harry
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Wrong
The speed of sound in water at 0 oC can be calculated as
c = ((2.06 109 N/m2) / (999.8 kg/m3))1/2
= 1435.4 (m/s)
where
Ev= 2.06 109 (N/m2)
and
ρ = 999.8 (kg/m3)
hendrik
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Uuuups!
Thanks for correction Hendrik, I really forgot about that there is something to think about speed of sound waves.
So Zeus, you gotta have one hell of a boat to outrun them sound waves in water.
Regards / Harry
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(http://www.snelleboten.nl/files/dsc06772_123.jpg)
Sorry for the Garmin plotter
(http://www.snelleboten.nl/files/dsc06771_277.jpg)
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:o :o
Who the hell took these pictures of my gardener's hell of a boat???
;) / Harry
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Let me wipe the drool from my mouth! Holly cow! That is absolutely beautiful!
Robert
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Wow!
Does it touch the water or just fly over top of it?
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Nice pics, Zeus.