Putting SideScan into Perspective
2013 Jun 10
Finding objects with your SideScan is a relatively easy task, but how do you put what you have discovered into perspective, and ultimately fish these Points of Interest (POI)? Are you left with a single dot with a number next to it on your GPS screen, and a vague memory of what the POI looked like?
DrDepth’s SideScan Mosaic version is the tool to help you put things into perspective, along with some other very basic little tricks.
Step 1: Record several parallel lines of an area you are interested in and put them into DrDepth like the image below.
Step 2: But how big are these POI’s? Are these anthill size humps or is that circular object on the right an old tyre, are those little twigs / branches lying on the bottom, who knows? Lets take that little rectangular object in the top right and measure it in DrDepth, and then place a 21ft bass boat next to it. Now all of a sudden that ‘little rectangular object’ turns into a building foundation that could fit six 21ft bass boats side by side! That is a substantial slab of concrete.
Step 3: Now place that same scaled bass boat to our first image and it’s actually quite hard to spot something as big as a 21ft bass boat. This really puts things into perspective. The combination of structure, in the form of breaklines/edges, vehicle tracks, humps and holes in this mosaic is just mind blowing. Not to mention the cover, in the form of old gum tree laydowns, brushpiles, building foundations etc.
Step 4: So how do we approach these potential hotspots? Planning is the key. In this example here I have created 20ft range rings (x3 = 60ft) around the boat icon. I have used 3 rings because 60ft/18m is a very easy cast, even with a light plastic.
I have placed the boat in a position and heading (by rotating the boat overlay) so when I make a cast to those two +30ft laydowns ahead of me, I will be able to keep my bait in the strike zone all the way down the length of the timber rather than just a short bump from the side as it comes over it. A waypoint can be made here, but remember to give it an icon that you will know is not the POI, but the approach point.
If you are unsuccessful there, you have another opportunity to target the large laydown at your 10 o’clock position off the bow. Or the timber on your starboard side right next to the boat, just perfect for a little drop shot.
Once the timber has been targeted thoroughly you will move forward by 40ft or so and target this huge hump ahead of you. At this point your boat will be in 24ft of water and you will be targeting a hump that comes up to around 21ft. Ever watched KVD casting like a machine to a spot that seems to be in the middle of nowhere and all of a sudden that big cranking stick just loads up, time after time? These are the type of humps he is targeting.
And unless you have a detailed and accurate perspective of this hotspot, you will be wasting your time.