Fish finder and a Submarine...

[Seaduck]

One of my mates has a 25 foot fishing boat in which he potters around the south coast whilst trying (and failing) to hook little fishies out of the drink for fun...

He told me not that long ago that his fish finder screen blacked out and came back again after a few seconds, he swears blind he passed over a submerged RN submarine and the acoustic hull tiles of the sub blocked his fish finders sender/receiver.

I reckon he's telling sea stories but it does raise the question:

What would happen to your depth/fish finder if you where to cross paths with a submarine?

Neal

 

[arahant]

id imagine just what happened could be a likely scenario, or you wouldnt see anything if these "acoustic tiles" just asborbed the signal not bouncing it back.

In anycase tho its most likely that his fish finder just malfunctioned for a few moments.

 

[Seaduck]

I don't doubt he was making stuff up to disguise an otherwise dull fishing trip.

Any current/retired submarine techy types on here care to shed any light on what could/would happen? ... without disclosing any national secrets obviously

Neal

 

[mlines]

More likely his fishfinder threw a wobbly.

Mine does occasionally either showing no depth or immense depth which is clearly wrong at the time it shows it. Sorts itself out after a few seconds.

 

[supersparky]

Sounds like a glitch, I once crossed the pacific from Brisbane to Panama in a merchant ship with a paper tracing echosounder. It's peformance was poor so I rebuilt it, then I could see down to 5,000ft and more, but one afternoon it burnt though the paper at 300ft for a few seconds. That was a whale with a headache, or an Americal submarine.
Digital readouts will always have glitches, as the gain and swept gain will be on automatic and may not respond as you think to some events.

 

[PeterV]

Very unlikely. Nuclear submarines very rarely dive in less than about 300ft of water, and only in a few very select locations within the continental shelf. He would have to be a very long way out on his potters. This explains why the submarine bases are sited close to open water.

 

[supersparky]

The sub was about 300ft below us, the sea bottom was a mile or so below that. It could have been a whale but it was a very hard target. I was also getting a feathery continuos echo at around the 3-400ft mark day after day. Each evening it would dissapear and about one in the morning I would get a firmer echo at around 120ft. It would dissapear when the sun rose, and reappear again at 3-400ft late morning. I am told this is layers of squid, but it went on day after day.