Best sidescan sonar on the used market?

[Jay Whitehair]

I've been doing well enough salvaging small boats, vehicles, etc to purchase a decent 22' dive boat. I am wondering if there is a sidescan sonar unit that stands out in the used market that I can install to locate things faster. High resolution, ease of use, and cheap... is that too much to ask? Let me know if anything is remarkably better than others. I sure will appreciate the insight.

Thanks!
Jay
Norwich, VT

ps - I am looking for a sonar that shows well at 100' or less depth. Maybe that opens up more possibilities? Also - what is "CHIRP"?
Thanks!

 

[FF / EMT]

JW fisher makes a really good unit.

 

[spoolin01]

You're talking about a "fish finder" type of boat-mounted unit, not a towed sonar device, right? And you want to profile the bottom, not locate bait schools or fish around the boat?

 

[Nemrod]

I have been using the Humminbird units for years now. I have found all sorts of things with them from cars off of ramps to new dive sites. You have to consider the limitations of such units, objetcs are very small, depth is a real limitation, rough water ruins the tiny images, saltwater is not as transparent as freshwater. But they work and they find fish also. The console on my Boston Whaler 19 Outrage:

The transducers:

N

 

[Jay Whitehair]

You just got me thinking a tow behind would get the best imaging? I am not concerned about fish at all. I am looking at simply bottom scanning for dropped and sunk goods. Downsides to tow behinds? I assume the imaging is better because the angle of side scan is increased?

 

[Nemrod]

The imaging is better because the "fish" rides below the waves and in clean, unaerated water. A transducer on a boat picks up cavitation noise and bubbles even at the very slow scanning speeds and it goes UP and DOWN and side to side as the boat rides through and over waves distorting or even obscuring the image. I am sure there are more reasons.

N

 

[spoolin01]

Probably a much better transducer than most middle to low end units as well. But what sort of head unit and software is needed? When you buy a boat unit, they show the display. When you buy a towed unit, they show the transducer.

 

[Nemrod]

I took this image a long time ago. It is a wreck in a freshwater lake at about 70 to 100 feet depth. The wreck is probably about 60 feet long.

N

 

[FF / EMT]

Downside to any sidescan is vegetation, i.e. seaweed

 

[greeniguana]

Downside to any sidescan is vegetation, i.e. seaweed

Or an upside. I'm a biologist, we use sonar to do submerged aquatic vegetation surveys. Works great.