Thats  awsome too see 

Thank you for the sounder shots and the explanation with them these sorts of things are a great educational tool and are much appreciated.

 Interesting mate, cheers 

 Awesome!

When was this picture taken, wouldnt mind diving that ledge!!

 thanks

very interesting !

 As someone who was both a diver and a fisherman--who dived on his own snagged pro pots for years--- it was always interesting to compare what you were seeing on the sounder with what you actually saw--I learnt a lot that way. I find your use of A-scope interesting. A-scope is not new, IIRC it was introduced in the early nineties on the pro gear we were using. We all  tried it, most discarded it. Summary of opinion  seemed to be that it may have had some value on the huge areas of general flat ground out in the 20's ( 40m or so) south of Gero and off Dongara  where it all looks much the same--some blokes reckoned they could pick up differences, instead of just running them off in a straight lines, which was the traditional way. Ground like that is more cracks and crevices and little holes, than ledges.  The ground is different off Kalbarri, where I mostly worked.  Try just running them off in a straight line up here and you'll go broke quickly.

When I bought my last crayboat, the previous owner ( from Dongara) had it set up for A-scope, for working as described above. But they were looking at the tails on the a-scope, not that  echo on top, as you drop off the ledge. That is interesting, although I can see it anyway on the conventional picture--the green on top corresponds with where the red drops suddenly then fills in with green and yellow above--classic ledge.  

Bottom lock on the Raymarines ( and Lowrance and Simrad, from what I've seen) is not the same as bottom lock on the JRC and Simrad, and Furuno, stuff we used to use. With them, it was a dead straight line, and you were looking for stuff that popped above it--deadly for deep water fishing off here. Game changer. These new machines are different, doesn't seem to work the same.

thanks for posting.

ill grab those Crays for you if you want them  

 Great info, strange water temp though. Seems like it's reading air temp on a hot day.. 

Thanks for posting mate - those jigs seem to be working a treat!

 Excellent read, looking forward to future posts,  like Ranmar it definately helps you understand the bottom when you have dived on it for years.

 Thanks for sharing. Thats pretty subtle bottom. How do you reckon you would go finding that ground without the pots marking it for you?

  Thanks for sharing. Thats pretty subtle bottom. How do you reckon you would go finding that ground without the pots marking it for you?

It looks to be just over a metre  high? You will get longer strokes when you come off broken sandy bottom onto reef, and if there is actully a ledge there, rather than a hard rock face with nothing under it, you get that distinctive flare of colours, as he is demonstrating on those shots--it will often seem to undercut the red on the echo, very distinctive. I haven't saved a lot of screenshots on my new sounder, but I have one that shows it a bit. coming up from 17 fathoms   onto 15 fathoms, you can see the ledge on the outside edge on the bottom LHS of the shoot. As it rises and the strokes get longer there is a mixing of colours , the red is shot through with others colours--this is the echo being bounced around and coming back a bit slower and weaker.

this isn't a really good example, it can be a lot more pronounced, even at well over 40 metres, although the effect does diminish as you get deeper, and it becomes more a matter of just the longer strokes. In this case , if you are showing enough screen to get a second or even third echo up, you will see the second echo tails get longer, as the first echo does, and the third echo might actually almost disappear. Unless the lump is just dead hard rock, in which casethere will be a strong third. Most users these days won't be showing enough screen to see this, particularly if they are just looking for fish.

Thanks for taking the time to post up your explanations Son and Ranmar

 thanks for the post, great reading 

West coast: regarding finding the ground without the cray pot indicators. The pic with the crays is a seperate lump that is about 0.4m high off sand bottom. I found this while travelling about 17kn with a normal 600w transducer. It comes down to how good you are at distinguishing what is worth stopping on and what is not. As someone that has had to find their ground through trial and error, I am constantly refining this art! Once you have this dialled the rest is easy.  I will get some good screenshots on examples, I could write a book on the topic as it gets rather in depth. A lot of what you read in the sounder tutorials books won’t help you on a typical day on the WA ocean, maybe on a lake. 

 I could read this stuff all day and not get bored 

 Maybe you should do a video tutorial showing what to look for and so forth. Definitely worth doing a bit of homework to get your sounder working to its capasity. Just got a new one myself so learning how to read it . Not that easy if your technologically disadvantaged like some of us. Reading is one thing but watching is another. I myself learn more from visual stuff tan reading 

Bit of work there...cheers for the write up very interesting.

I love nothing more than a day on the water...Most of the fun and effort is learning and operating my Furuno, these threads get me itching even more for the next mission.

Agreed Brocko!
I might look into some videos, if anyone has anything in particular that has always confused them or they want covered let me know here or PM. I enjoy analysing & explaining the images people have on their screen!

 I love your post but I am very surprised you are not zoomed in. I only look at about the bottom 8 metres so I get more detail in the picture.

Crano, when zoomed obviosuly you cant see the top of your screen. Looking at the top of the screen is a good way of distinguishing whether your sounder flare up was genuine or some interference / bad reading. A lot of the time your sounder will show a great school, but if you look at the top of your screen sometimes you notice there is a lot more clutter in the same vertical strip as the flare up. Then you know it was an error and to continue driving. Or you can waste time looking for it yelling at the sounder. I also dont use bottom lock because you cant distinguish false flare ups, but for a different reason. You can tell a lot with how your sounder is reading by looking at the top of the screen.

 I see where you are coming from. On my sounder if I get some random stuff like that it tends to be in a vertical strip so is easy to ignore.I do not bother with bootom lock either as I feel you are missing some detail.

I love that you back up your readings with gopro footage and are not just assuming stuff. I dive the places I fish and have had a drop camera for about 12 years and find this a great help in interpreting what you see on the sounder.

Fair call also! Yeah i normally get the full strip also, like in the above pic, but sometimes the bottom half of the image is identical, only the top has the giveaway. Definitely missing detail with bottom lock!