Any more info on Lost Marbles rescue off Puerto Rico

[Don C L]

Originally Posted by donradcliffe

The article gets a bit weird--they used a VHF radio to call mayday, and their messages was picked up by a 650 ft ship, which then took 6 hours to come to their position--huh?

Hmm, not sure why its weird, I was on a boat where we called for assistance and a freighter came for us.... can't recall exactly how long it was but it was at least six hours, and it did take a while for them to jockey around for us in the wind. We weren't sinking though.

[belizesailor]

Originally Posted by billknny

I thought catamarans did not sink?

My read of the article was they were rescued from a capsized hull. If one hull flooded, it might not sink, but would be easier to capsize.

"...three survivors from a capsized vessel..."

[LoudMusic]

Originally Posted by Don C L

Hmm, not sure why its weird, I was on a boat where we called for assistance and a freighter came for us.... can't recall exactly how long it was but it was at least six hours, and it did take a while for them to jockey around for us in the wind. We weren't sinking though.

Via AIS I've seen ships in that size range doing anywhere from 8 to 19 kts. At that top end speed that's 105 nm. Seems entirely plausible for it to take 6 hours.

[LoudMusic]

Originally Posted by belizesailor

My read of the article was they were rescued from a capsized hull. If one hull flooded, it might not sink, but would be easier to capsize.

"...three survivors from a capsized vessel..."

What does it mean to be capsized? Does the vessel have to be turned 180 degrees onto its top? Or 90 degrees? Or simply taking water into its primary hold over the side of the boat?

[donradcliffe]

Don't confuse anecdotal information on long range VHF transmissions under rare tropospheric ducting conditions with reliable VHF communications. Under normal atmospheric conditions the maximum VHF range a sailboat with a masthead antenna at 50 ft talking to a large ship with antenna at 150 ft would be less than 25 miles--a ship less than 2 hours steaming time away. If the family was able to talk on the VHF to a ship that was 6 hours away they were very lucky indeed. Talking that far on a handheld while they were clinging to a capsized boat with its mast in the water would be a true miracle.

[boatman61]

Over this side of the pond we do Mayday relays which means if I pick up a Mayday I write down the info I have then broadcast it on ie 'Mayday Relay.. vessel in distress.. Position etc' before heading in their direction.
Other faster vessels may recieve the call and arrive quicker than me at say 3 to 5kts depending on conditions. Or a shore station with long range can pick up the call and co ordinate the rescue.
Theres many reasons for delays.. including ******** who ignore the Mayday.

[hpeer]

Elsewhere I’ve read from supposedly reliable sources it was a Prout Snowgoose catamaran that had a leak, possibly a thru hull that turned into a cracked hull.

Not sure how that happens but that it was a cat seems pretty certain. That makes the reports of a “capsize” suspicious.

[LoudMusic]

Originally Posted by hpeer

Elsewhere I’ve read from supposedly reliable sources it was a Prout Snowgoose catamaran that had a leak, possibly a thru hull that turned into a cracked hull.

Not sure how that happens but that it was a cat seems pretty certain. That makes the reports of a “capsize” suspicious.

Earlier in this thread Sunfish75 provided the same information. Multiple reports would seem to make it more believable.

http://www.cruisersforum.com/forums/...ml#post2646283

[Don C L]

Originally Posted by donradcliffe

Don't confuse anecdotal information on long range VHF transmissions under rare tropospheric ducting conditions with reliable VHF communications. Under normal atmospheric conditions the maximum VHF range a sailboat with a masthead antenna at 50 ft talking to a large ship with antenna at 150 ft would be less than 25 miles--a ship less than 2 hours steaming time away. If the family was able to talk on the VHF to a ship that was 6 hours away they were very lucky indeed. Talking that far on a handheld while they were clinging to a capsized boat with its mast in the water would be a true miracle.

You have a good point and as I think of it now, it was many years ago, we had a 90' mast and the ship was an RFA (Royal Fleet Auxiliary - British Navy) freighter so it may have had more height than you mention. My memory of the event could be skewed.
edit: you know, you're right, in piecing it back together I realize it couldn't have been 6 hours between the time we made contact and the time they showed up, more like half that perhaps, it was dark... I guess it only seemed like 6 hours.

[Valmika]

Originally Posted by LoudMusic

Via AIS I've seen ships in that size range doing anywhere from 8 to 19 kts. At that top end speed that's 105 nm. Seems entirely plausible for it to take 6 hours.

As others have said in the thread. The question was if they could reach the freighter by VHF most feel it would have been less than about 25 miles away. I think I would chock this up to reporting not being entirely knowledgeable of marine issues and procedures

[foufou]

It is also possible for transmission to be 25 miles but the route to the distressed vessel to be much longer because of land mass needing to go around

[hpeer]

Back in the late 70’s I was in the USCG Reserve having just come out of 4 years in aviation. I was in Atlantic City and we picked up a May Day from a guy off Mauntauk, NY. That’s close to 100 miles. No intervening stations could hear him so we took the call and coordinated the response. After an hour or so the situation changed and a more local station took over and we lost contact.

I can’t explains it but I lived it.

[wayne.b]

Originally Posted by hpeer

Back in the late 70’s I was in the USCG Reserve having just come out of 4 years in aviation. I was in Atlantic City and we picked up a May Day from a guy off Mauntauk, NY. That’s close to 100 miles. No intervening stations could hear him so we took the call and coordinated the response. After an hour or so the situation changed and a more local station took over and we lost contact.

I can’t explains it but I lived it.

===


There's an atmospheric condition called tropospheric ducting, usually caused by an inversion layer, which can temporarily enable long range VHF communication. That's the most likely explanation for what you observed.


Tropospheric ducting - Amateur-radio-wiki

[ka4wja]

I have no personal knowledge of this specific incident, but I do know about the M/V Jacamar Arrow, and VHF radiowave propagation...

Originally Posted by clownfishsydney

Six hours is about 120 nm for a cargo ship. We easily pick up VHF radio at the marine rescue where I volunteer from much farther than that. No reason to think that a ship (with a very high mounted aerial) and a yacht with an aerial on top of the mast could not communicate that far. If they used DSC, then it could go even further (we have picked up AIS from 200+ nm on our yacht quite regularly). That been said, very lucky to have ship listening and respond so quickly.

The Jacamar Arrow's normal cruising speed is about 12 kts...
On Thr May 31st, they were on their way from Bahamas to Brazil...
And, it can take a few minutes to plot an intercept course, etc., and sometime for a loaded 654' cargo vessel to stop / turn...
As well as the need to approach the reported capsized vessel / MOB area at a controllable but safe speed...
So, maybe figure about 5 hours at 12kts = 60 miles...(and maybe even less distance)

Also, this past week, we've had fairly good VHF tropo-enhancement propagation along the coast of Florida....not sure about near the DR, but assume they have as well...

And, while it's not unheard of for bridge-to-bridge VHF comms of larger vessels to be done at 50 miles range, it's pretty much the max range for normal / non-enhanced VHF propagation...

And, the article mentions them responding to a "Channel 16 distress call", which is rare outside of US waters, as SOLAS vessels haven't been required to monitor VHF Channel 16 in many years....(they are, of course, required to monitor VHF-DSC, MF/HF-DSC, INMARSAT-C...and, on passage few actually monitor "voice channels" anymore...)

So, the three souls on-board s/v Lost Marbles are VERY lucky that their distress call was heard!!

For some details of "Distress" calling and VHF radiowave propagation...have a look here:

http://www.cruisersforum.com/forums/...ds-146617.html

http://www.cruisersforum.com/forums/...ge-149499.html


I haven't read this whole thread, yet...gotta' go for a bit...
More later..

fair winds.

John

[ka4wja]

A couple minor corrections...and clarifications...

According to Marinetraffic, the M/V Jacamar Arrow was enroute from SW coast of Florida to Uruguay (not to Brazil)...
(I'm not a paying member of Marinetraffic....and haven't been able to see their exact track/route....maybe some else here can find this info??)

And, I assume the exact communications distance was ~ 50 - 60 miles...possibly less...but unlikely much more than that....and this is usually local/regional "tropo-enhancement", not "ducting"....

Originally Posted by ka4wja

I have no personal knowledge of this specific incident, but I do know about the M/V Jacamar Arrow, and VHF radiowave propagation...


The Jacamar Arrow's normal cruising speed is about 12 kts...
On Thr May 31st, they were on their way from Bahamas to Brazil...
According to Marinetraffic, the M/V Jacamar Arrow was enroute from SW coast of Florida to Uruguay (not to Brazil)
And, it can take a few minutes to plot an intercept course, etc., and sometime for a loaded 654' cargo vessel to stop / turn...
As well as the need to approach the reported capsized vessel / MOB area at a controllable but safe speed...
So, maybe figure about 5 hours at 12kts = 60 miles...(and maybe even less distance)

Also, this past week, we've had fairly good VHF tropo-enhancement propagation along the coast of Florida....not sure about near the DR, but assume they have as well...
(although "tropo-scatter" could be a factor, for our marine-vhf comms this is usually only going to up-to about 50nm....but not knowing the vessels' exact locations and the tropospheric weather at these locations/times, make it impossible to know for certain....but most likely to be local/regional 'tropo-enhancement"...)
This is NOT "tropo-ducting" / "ducting"....please read linked threads for detailed explanations...

And, while it's not unheard of for bridge-to-bridge VHF comms of larger vessels to be done at 50 miles range, it's pretty much the max range for normal / non-enhanced VHF propagation...

And, the article mentions them responding to a "Channel 16 distress call", which is rare outside of US waters, as SOLAS vessels haven't been required to monitor VHF Channel 16 in many years....(they are, of course, required to monitor VHF-DSC, MF/HF-DSC, INMARSAT-C...and, on passage few actually monitor "voice channels" anymore...)

So, the three souls on-board s/v Lost Marbles are VERY lucky that their distress call was heard!!

For some details of "Distress" calling and VHF radiowave propagation...have a look here:

http://www.cruisersforum.com/forums/...ds-146617.html

http://www.cruisersforum.com/forums/...ge-149499.html


I haven't read this whole thread, yet...gotta' go for a bit...
More later..

fair winds.

John

I hope this helps clarify...

Fair winds..

John