Sonar 103 - Bottom Hardness and Speed

[@rayzar6720]

Thanks for your time doing these educational videos. Im in WA and run an axiom pro 2 with a TM 265 M/L. This is the best information on echo sounders and how to use and read the images. Much appreciated.

[@weFishAU]

Thabk you, I'm glad you are getting something out of them. I was using the Axiom Pro a while back, good unit.

[@deefa_damo]

Great info, thanks for sharing. Very cool to see a stylus sounder from the 60's - how many times did someone forget to change the paper roll?

[@weFishAU]

Thanks. LOL, they were bloody hard to read when all you had was the flashing light.

[@Camh1968]

Hi mate. Thanks very much for the structured approach you have taken here. I can tell you have spent alot of time and thought in framing this video. Regarding, the bottom structure thickness and double bottom etc. - if the bottom was solid rock for a fair depth down, what reason(s) exist to continue searching a 'double bottom' for verification? Also, what advantage in features / screen visual do you give up when manually setting the depth range to 3 x known depth? When using Contour lines to assist in tracing bottom structure, what preferred orientation do you use - 'North Up' or other? What is the ideal speed to trace bottom structure in this application? Cameron

[@weFishAU]

Thanks, you're welcome. It doesn't really matter how thick the rock is. The double bottom is formed by the ping being reflected between the bottom and the surface. If we imagine a flat rock on the bottom and a very calm surface the sound will be reflected 3 or, under ideal conditions, even 4 times. It is a bit of an art form, i'll try to include some real footage in future videos. When you set the range manually to see the bottom hardness it becomes harder to identify fish, particuarly individuals of very small schools. This is simply because we are showing more data on the screen there are less pixels available to show the fish arches. I use the double bottom technique to check the bottom hardness but I use a full screen to search for fish. I prefer North up. Some people prefer heads up but I just find that confusing. OTOH, I've been reading maps for 50 odd years. Best speed for checking bottom hardness? Depends a bit on your transducer setup and how calm it is. I can get a reasonable reading at around 15 kts in good conditions but in general, under 10 kts. You could do a slow pass over an area and take a reading. Pass back over the area a bit faster. Repeat until you see a degradation in the image. That will be how fast you can get a read in the same conditions.

[@Camh1968]

@ many thanks. Just curious to know what you do after you’ve established the type of bottom that you desire with the double bottom technique? (I.e. next steps to catch / hunt that fish)

[@weFishAU]

Look for fish if it is the type of bottom that I know to hold fish in other areas. You will often find Snapper on a rubble bottom, or perlies where you find wire weed. It is always worth knowing the bottom type where you have caught fish so you can apply that knowledge elsewhere.

[@axelohmen4138]

Thank you for work I greatly appreciate your efforts to teach this Neanderthal lol

[@weFishAU]

You're welcome, I hope it helps.

[@peterdebeer8765]

Why are they showing different depts. 2d. 3d.

[@weFishAU]

The difference is because I have one offset to show the depth from the surface and the other shows the depth under the keel plus a small safety factor.