[PSUBS-MAILIST] Forward scanners

[Alan via Personal_Submersibles]

Thanks Sean,
I am looking for the under $500- solution.
Alan

Sent from my iPad

> On 8/10/2014, at 11:45 pm, "Sean T. Stevenson via Personal_Submersibles" <personal_submersibles at psubs.org> wrote:
> 
> What you probably want is a sector scan sonar. This employs a horizontal beam that sweeps 360° around the boat, giving you the best situational awareness, and is easy to interpret. This would be in conjunction with a single transducer altitude indicator.
> 
> If you actually wanted to automate navigation, then a DVL (Doppler velocity log) is probably in order. This is a four beam system which gives you differential movement, but the last time I checked was $15 K or so.
> 
> I might look at a unit like this:
> 
> http://www.imagenex.com/html/881l-gs.html
> 
> Sean
> 
> 
>> On October 8, 2014 3:55:08 AM MDT, Alan James via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>> Has anyone had any experience or know anything about forward scanners.
>> I'm reading.....Without moving parts, the ForwardScan transducer is more akin to a conventional sounder that has been tipped on its side. Its effective range is about eight times the actual depth, up to about 160 feet ahead of the boat. It includes a built-in shallow depth alarm with parameters set by the user. In deep water, this is great for detecting rocks and pinnacles. Of course, if you are operating in shallow waters such as the Bahamas or portions of the Chesapeake the eight-to-one ratio begins to work against you.
>> This seems to indicate that if you are cruising 5ft off the bottom or closer in a submarine, you won't get much warning for collision avoidance from the alarm settings These would just pick up on the bottom 5ft below rather than an obstruction coming off the bottom in the distance. Can these be mounted so the angle of the beam runs parralel to the sea bed, pointing more up than down? Or do I leave as is & forget about the alarm function. Am I just as well off buying a fish finder & mounting that forward facing? 
>> Regards Alan.
>> 
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