Humminbird Side Imaging Forums

General => General Discussion => Topic started by: Kokanee on December 04, 2013, 08:42:04 PM

Title: Narrow beam transducer for depth contour mapping?
Post by: Kokanee on December 04, 2013, 08:42:04 PM

Looking for info on narrower beam transducers for deep water bottom contour recording/mapping. The 20 degree cone that came with my HB598ci HD SI covers and averages too much bottom area. My past lake mapping has been under 100 feet, but lakes I want to do are up to 1,200 feet. At that depth, the 20 degree will miss a lot of detail. Before wasting mapping time and gas, I would like to find out what is available.

Web searches, so far, have not yielded much info.

Thanks for any help.

Lou

Title: Re: Narrow beam transducer for depth contour mapping?
Post by: Nitro78 on December 05, 2013, 01:59:22 AM

I get the same probem than you now i use a TM258 (5°x6°) cone but it is a 1KW tranducer, need to ask if can work on your 598HD as if less power. Results are better that 20° that i have before for that same wreck mapping more realistic!!!

Title: Re: Narrow beam transducer for depth contour mapping?
Post by: Rickard on December 06, 2013, 08:19:43 AM

Nitro,
 
The TM258 operates at 50 and 200 kHz, but the 598HD can only use 83 and 200 kHz (no hidden transducer select option can change this, as far as I know). This means the 598 can display the narrower 200 kHz result and also measure depth when using the TM258. But 200 kHz doesn't reach deeper than about 250 m. For deeper water 50 kHz must be used.
 
When time allows for it I will build my own Mill's Cross using 8 (maybe more) 50/200 kHz elements from disassembled XHS 9 SI 160T transducers. I will use it as a narrow beam "boomer" with a towfish for sub-bottom profiling. 50 kHz is high for this, but I know I can penetrate several meters with clay. I'm curious what may hide in the thick sediment layers in my waters. The same configuration can be used for deep water narrow beam depth measurments.
 
Rickard

Title: Re: Narrow beam transducer for depth contour mapping?
Post by: Kokanee on December 06, 2013, 10:32:15 AM

Nitro/Rickard,

Thanks for your experience and information. It will help me find a better system.

Lou

Title: Re: Narrow beam transducer for depth contour mapping?
Post by: newkid4si on December 06, 2013, 11:50:56 PM

Rickard

      " I'm curious what may hide in the thick sediment layers in my waters."
 
      I'll share something that I learned by accident. While reviewing a recording in HumViewer, I was looking at the 2D portion.
      The water depth was about 35', but I had the depth on the viewer set at 150'. I went over a target that had four echos.
      It ended up being a homemade sand dredge from about 50 years ago. They were used to pump sand from the bottom of
      the lake to make beaches. Welded out of heavy steel. When the divers went down, they thought it was a space ship. LOL
      Anyway, if I hadn't make the error on the viewer depth, I'm sure I would have missed it.

                    Mike