Yacht ashore on the Cornish coast.

[wonkywinch]

Two different AIS transponders switched on at the same time?

The pings are 8 hours apart.

 

[garymalmgren]

Yeah. This is a real strange one.
Twilight Zone?

 

[chriss999]

Smuggling or other nefarious activities?

 

[ylop]

Smuggling or other nefarious activities?

Seems much more like a data glitch and a single occupant falling overboard.

 

[oldmanofthehills]

Seems much more like a data glitch and a single occupant falling overboard.

Sadly yes, particularly as the skipper was open about likely passage as we knew about it half a pontoon away. Smugglers are kind of polite but less informative. As Border Force knew of projected arrival if the skipper was actually alive they could soon track him

 

[MontyMariner]

Looks like someone hit "reverse track" on the autopilot

The boat picture shows wind vane steering gear, I don't think they have a reverse track function

 

[KevinV]

The boat picture shows wind vane steering gear, I don't think they have a reverse track function

I saw that too, but the track looks awfully straight for a wind vane, but then the track seems to be in some doubt as per other posts above.

 

[dombuckley]

Very sad. AIS track is odd. Left Roscoff on the morning of the 12th heading slightly W of N, at 20:46 that evening is a bit over 1/3 of the way across the channel, then the next update approx 6 hours later is 10nm back in the direction of Roscoff. From that point the updates continue in the original direction.

I did wonder, but it would have to have been 2 x near-exact 180 degree wind shifts 6 hours apart. Odd that there are no AIS pings during that 6 hours.

The vessel was on windvane steering. A low-pressure system came up the channel on Saturday, turning winds N'ly for a time before the SW'ly re-established itself. So the yacht, while appearing to be jilling around in a circle over the ground, was actually on a constant port tack broad reach the whole time.

Positions on Cat B AIS are not relayed directly to MRCC. They rely on being within range (8-10 miles) of either a shore station or a vessel with satellite-capable Cat A AIS (i.e. a commercial vessel), hence interruptions to such data are quite usual.

All suggests, unfortunately, that the skipper parted company from the vessel not long after departure.

 

[wonkywinch]

I saw that too, but the track looks awfully straight for a wind vane, but then the track seems to be in some doubt as per other posts above.

My guess is he set the autopilot to track at 90 degrees to the shipping lane although it's not a TSS at that location and the rule for that is to steer 90 degrees not track/COG 90 degrees to the lane as the intention is to allow the tidal stream to affect all vessels together.

It appears an autopilot was following a COG or drift compensated direct to waypoint. It's just too straight to be anything else especially as his SOG was quite low and he would have been more affected by the channel flood & ebb streams.

 

[wonkywinch]

I've had another look at the track of Misty Blue. At the point when Marine Traffic picks him up again at 1018UTC on the 13th his COG is approx 020 with a wind of 160 degrees at 8 knots, so 40 degrees starboard from his astern on a broad reach.

At 1124, the vessel adjusts course to approx 315 heading roughly towards Dodman Point. The wind would now be right behind him so the sails would possibly need to be set for the run, eg wing on wing? Was any adjustment needed that took him outside of the cockpit and therefore exposing risk of MOB?

 

[dombuckley]

I've had another look at the track of Misty Blue. At the point when Marine Traffic picks him up again at 1018UTC on the 13th his COG is approx 020 with a wind of 160 degrees at 8 knots, so 40 degrees starboard from his astern on a broad reach.

At 1124, the vessel adjusts course to approx 315 heading roughly towards Dodman Point. The wind would now be right behind him so the sails would possibly need to be set for the run, eg wing on wing? Was any adjustment needed that took him outside of the cockpit and therefore exposing risk of MOB?

Don't forget, that is track over the ground. The tide turns in that area at around HWDover -2, would have been just about that time on 13/6. She was only doing about 4 knots, so spring tides would have induced a significant cross-track movement without any alteration of heading

 

[wonkywinch]

Don't forget, that is track over the ground. The tide turns in that area at around HWDover -2, would have been just about that time on 13/6. She was only doing about 4 knots, so spring tides would have induced a significant cross-track movement without any alteration of heading

But tides are smooth sinusoidal changes, not angular. Here is our track last year from Alderney to Needles. A constant heading out of Alderney with the current sweeping us gently.

 

[penberth3]

But tides are smooth sinusoidal changes, not angular. Here is our track last year from Alderney to Needles. A constant heading out of Alderney with the current sweeping us gently.

View attachment 194932

An excellent illustration. Almost a perfect sine wave!

 

[MikeBz]

…. but only if you have enough samples, otherwise it will be a series of straight lines between samples…

 

[fredrussell]

Cap’n Sensible’s standards are slipping. 34 posts in and he hasn’t swooped down from on high to wrap the knuckles of ‘the speculators’. Must be on a delivery trip.

 

[wonkywinch]

Cap’n Sensible’s standards are slipping. 34 posts in and he hasn’t swooped down from on high to wrap the knuckles of ‘the speculators’. Must be on a delivery trip.

You like speculation? Try this thread - https://www.pprune.org/accidents-close-calls/666472-plane-crash-near-ahmedabad.html