Close encounter - with a submarine......

It gets complicated!

The equation has to include layers (at various depths), oceanographic fronts, sound channels, pressure, salinity, temperature, strength of signal, frequency, ambient noise, biological noise, various traffic noise/signatures, reflected signal strength (if active), passive one way loss, active two way loss, aspect, speed and I think we have already mentioned the acoustic tiles for own signature reduction and active sonar absorption. :eek:

And I almost forgot.... the Doppler effect.
 
Last edited:
I believe that if you are In say 105 metres then your display will show 5 metres. it does on my NASA Clipper up to about 110 metres.
 
bikedaft said:
i had one maybe encounter, elecrocompass auto pilot on, in loch long, not far s of coulport, when boat did a 90 deg turn to port, then a 180 to stbd, then resumed its original course. all i can think of is a large lump of ferrous material under the boat. that wasn't there when i followed the exact track the next day. its deep enough there.
Click to expand...

Magnetic Anomaly Detection was used to sink a U boat for the first time about 1943. The prototype magnetic mines date back to WW1.

Bit worrying if all the Russkis needed in the cold war to take out our submarine fleet was a few bits of a yachts auto-pilot allied to first half of the twentieth century technology.

Although I did hear that the Swedes captured a Russian sub off Karlskrona in the 1980s when a group of junior officers disobeyed orders and moved a few buoys in the middle of the night.
 
Submarines are the top gun in a military arsenal.

Their rules are few... they will position themselves under a vessel to proceed undetected if they can... a sail boat could be such an opportunity. In peace time, they will be mild in their approach; I would hate to see what they will do in war.

They have also had contact with ships propellers while doing so. Damage is not too bad if held to the conning tower area. It is quite the business...

Heard many stories years ago....:D
 
JohnBuch and I have seen them at night off Sannox, and were politely warned off by them on Ch16. It's a favourite tesing area for subs and their "towed array operations", presumably because of the measured "miles", although I doubt if they're used much these days.

We changed our sail plan and tacked instead up the Kyles of Bute in pitch black conditions using the echosounder to tell us when to turn.
 
Is THIS close enough then?

Apart from somebody falling in, not much excitement. No Polar Bears - just 24hrs of sunshine...
Superb.jpg
 
MM5AHO said:
Didn't Drum once have a sub surface beneath her? I heard that story, but don't know if its true.
Click to expand...

No she got scraped by the snorkel of a diesel electric submarine somewhere around the Mull of Kintyre.
 
Drum was doing the CCC round the Mull race, late '80's when they ran over something in the water putting a long gash (approx 15 foot long) in the hull. They were able to fetch up past Giha and into crinan, straight into the boatyard and out for repairs. Had they needed to tack, they'd have sunk.
The navy claimed ignorance and that they must have hit something else
Arnold Clark (who owned the boat) allegedly then said to them, do you want the lens from the top of your periscope back then?
Damage to Drum was quite extensive, but the periscope of the sub was bent, putting it out of commission for months, just after the equipment at Barr & Stroud Anniesland for making periscopes had been decommissioned.
The story of the damage etc came from an RN submariner who later became a sub commander who sailed on the clyde.
why didn't it detect the 80' boat beating up wind in a force 4-5?
They didn't expect it to be there at that time ..... so much for listening out for whale farts in the pacific!
 
more sub stories

1: windsurfer off largs in the early 80's was arrested for wave jumping the wake of a sub coming up river. He passed between the after deck and the top to the rudder. Deatails should be in the court records for that time or an old local paper from largs

2: sunday racing off kip in an X99. One of the channel markers was a turning mark and we were going around it as a sub was coming up river passing vert close to the mark. The police chase boat came over and was giving us some lip (which was duly returned) and we claimed that we coudn't tack as the pole was set for the hoist. Put them off ong enough to get around, hoist and scoot off down wind. Must have been less than 20m from the sub ... and got a round of applause from the submariners on the conning tower.

The subs and other navy boats on the clyde were (prob still are) always really good at avoiding race boats and being considerate to yachties. Faslane used to offer ratings to crew boats during clyde week & i remember one being surprised to find that it was sat water...
 
There are many!

I resisted mentioning the sinking of the Antares because of the horrific loss of life and the distress to the families of the Trawler-men.
I also remember the incident with Drum and many others.

This all begs the question…. just what are the new procedures / SOP’s & EOP’s to avoid future incidents such as these?
 
Collision avoidance

Old Glow In The Deeps said:
I resisted mentioning the sinking of the Antares because of the horrific loss of life and the distress to the families of the Trawler-men. I also remember the incident with Drum and many others.

This all begs the question…. just what are the new procedures / SOP’s & EOP’s to avoid future incidents such as these?
Click to expand...

The MAIB report into the sinking of the Antares and the tragic loss of life is here. I believe that the more widespread use of SubFax Broadcasts covering the entire West Coast of Scotland, not just the Firth of Clyde, arose out of the report's recommendations. It makes sobering reading...

May the Skipper and Crew of the Fishing Vessel ANTARES rest in peace.
 
snowleopard said:
I had what I believe to have been a very close encounter about 3 years ago. Crossing from the Chenal du Four towards Plymouth at night the depth gauge went down to 4 metres for an hour or more. At one point it jumped back up to the usual 80+ for a few minutes then went back to 4, finally returning to normal a few miles south of the Eddystone.

I have heard that subs hide under the sonar or radar signature of yachts. I can think of no other explanation.
Click to expand...


Most likely to have encountered a Thermocline under the boat. That would account for the anomaly.

Most interesting thread chaps.
 
Started to think about boats (i.e. submarines) and whales.

If one had an electroacoustic transducer glued to the hull below the water line - say, shoving out about 100 watts or so - would that have an effect on the sub below, or act as a warning to whales ?
 
You must log in or register to reply here.

Share this page

Top