Cruisers Forum
 


Join CruisersForum Today

Closed Thread
 
Thread Tools Rating: Thread Rating: 3 votes, 5.00 average. Display Modes
Old 03-07-2013, 14:18   #286
Registered User

Join Date: May 2010
Location: New Plymouth, NZ
Boat: Steel Swain 36 Cutter
Posts: 51
Re: Schooner Nina - MERGED 3 THREADS

It turns out getting position from an Iridium phone can be inaccurate unless there is a gps receiver built in or interfaced to it. 10 km errors are common but east west positions could be much, much greater than that. That is why they are now searching further west. Let's see what they come up with today.

Iridium accuracy references...

First Reference....
https://en.wikipedia.org/wiki/Iridium_Communications
Tracking transceiver units[edit]
Without an extra global navigation satellite system, receiver tracking is difficult, but not impossible, as the position of a mobile unit can be determined using a Doppler shift calculation from the satellite. These readings however can be inaccurate with errors in the tens of kilometers.[33] Even without using Doppler shifts, a rough indication of a unit's position can be found by checking the location of the spot-beam being used and the mobile unit's timing advance.
The position readings can be extracted from some transceiver units and the 9505A handset using the -MSGEO AT command.[45] In the past, Iridium has used this method of tracking to block service to U.S. embargoed countries, such as North Korea and other politically unpopular regions, such as Northern Sri Lanka. It is also used to stop geographically bounded plans from being used outside the designated area.
The Iridium Extreme phone introduced in 2011 has a GPS location service embedded in the device, which the user can use to locate themselves or include in SMS messages. It can also be used to provide advanced services like Geo-fencing. A red emergency button on the top of the unit can be pressed to send the unit's position to emergency rescue agencies or other number pre-programmed by the user or distributor.

Second Reference....
NAL - Network Reference - Iridium Subscriber Unit
The Iridium network makes calculations of the geographical location (geo-location) of an ISU each time a call is placed. The technique employed to determine the geo-location of an ISU is based on measurements of the ISU and satellite propagation delay and Doppler frequency shift. These measurements are used to estimate cosines of spherical angles that identify the ISU's location relative to the satellite by the gateway. The Iridium geo-location process proceeds as follows:
The ISU sends the satellite an uplink geo-location burst, saving the delay and Doppler corrections needed to send the message.
When the satellite receives the uplink geo-location burst from the ISU, it measures the time and frequency offsets of the burst relative to its time and frequency standards.
The satellite then responds with a downlink burst, which the ISU uses as an acknowledgement that the satellite has received the previous uplink geo-location burst.
When the downlink burst arrives, the ISU checks to see if it is satisfied with its estimates for the timing and Doppler. If so, it then transmits an uplink ACCHL message to the satellite that includes the propagation time and Doppler frequency offsets that were used by the ISU during the last geo-location uplink burst. If the ISU did not receive a response, or if the ISU is not satisfied with the accuracy of the exchange, the ISU will repeat the process again at step 1.
The Iridium network can locate an ISU to within 10 km only about 78% of the time. The location accuracy can be much higher; however, the information is not available to commercial users. The so-called error ellipse can have a large eccentricity with the major axis oriented in the azimuth dimension and the minor axis oriented in the radial dimension. The position of the ISU in the radial dimension relative to the satellite can almost always be determined to within 10 km with just one measurement. Errors in the azimuth dimension relative to the satellite are largest along the satellite's ground path and tend to increase with distance from the satellite. Geo-location errors in the east-west dimension, therefore, are sometimes more than 100 times greater than in the north-south dimension.
__________________

__________________
opusnz is offline  
Old 03-07-2013, 15:04   #287
Registered User

Join Date: Jun 2013
Location: Melbourne
Boat: Lyle Hess 32
Posts: 38
What great news about the message and as Cherie says shame on Iridium.

It appears from other posts that Iridium may be able at least to tell when the last connection to the network is for an Iridium phone. Has the State dept asked them when the last connection was and if there are any other stored messages. Also who is recipient 2?

The sequence of events that then emerges is this:

1) Nina rings Bob McD and he says basically you are going to get the weather, head south and heave to. We know from footage on YouTube where David describe's heaving to transAtlantic that he does so under at least Trysail.

2) The "anything for Nina" message is sent but Bob, from recollection cannot get through.

3) At some point within 2 hours of that Nina blows out her Trysail and perhaps Storm Jib as evidenced by this new message. That leaves her unable to remain hove to and she therefore begins to run off downwind at 310 degrees and 4 knots.

Assuming that Nina did in fact heave to as suggested - and past evidence shows that David had previously used this tactic - then the loss of her storm sails has probably rendered her unable to remain hove to and hence the 310/4 knots message.

Every vessel has different behaviour when hove to - some require sail aft, others sail forward and aft and this changes as wind speed increases. It is unlikely that she could remain hove to however without some sail aft.

Does any one know whether she lay to a parachute sea anchor when hove to or whether she carried a drogue or parachute? I'm also interested in the questions suggested about the EPIRB.

Just thoughts.
__________________

__________________
Pelorus32 is offline  
Old 03-07-2013, 15:04   #288
Registered User
 
Friend of Nina's Avatar

Join Date: Jun 2013
Posts: 211
Click image for larger version

Name:	image-3598260210.jpg
Views:	265
Size:	268.2 KB
ID:	63566



Click image for larger version

Name:	image-313958724.jpg
Views:	246
Size:	260.2 KB
ID:	63567



Click image for larger version

Name:	image-3766822818.jpg
Views:	247
Size:	263.5 KB
ID:	63568



Click image for larger version

Name:	image-3366251584.jpg
Views:	222
Size:	212.8 KB
ID:	63569
__________________
Friend of Nina is offline  
Old 03-07-2013, 15:12   #289
Registered User

Join Date: Jun 2013
Posts: 14
Re: Schooner Nina - MERGED 3 THREADS

Here is the same text as above with the proper link.

Quote:
Originally Posted by katc.com
UPDATE: Father says text message proves yacht survived storms
Posted: Jul 3, 2013 12:18 PM by Dwayne Fatherree
Updated: Jul 3, 2013 12:19 PM

A Lafayette businessman whose daughter is aboard a missing yacht off the Australian coast says a text message was received from the crew of the boat after it passed through rough storms last month.

Ricky Wright said he learned Wednesday morning that a satellite phone was used to send a text message to a meteorologist from the 70-foot schooner Nina after it had passed through two storms in early June. According to the message, the schooner had damaged sails from the high winds but was still making headway at 4 knots per hour.

Danielle Wright, 18, is one of the people missing on the Nina. Prior to today's information, the boat had not been heard from since June 4, when it was about 370 nautical miles west-northwest New Zealand.

Ricky Wright said the message was not delivered when sent. Because of privacy laws, it took weeks for the U.S. government to authorize the satellite phone carrier to release the message.

"My prediction is they are making 3 knots, and the storm pushed them north of where they thought they would be," Ricky Wright told KATC Wednesday morning. "The main search area was south of where they are."

The Rescue Coordination Centre New Zealand (RCCNZ) suspended the search for the on Wednesday as bad weather hit the search area reducing visibility. They are using the down time to reassess the search effort.

Along with Danielle Wright were five other U.S. citizens -- three men aged 17, 28 and 58 and two other women aged 60 and 73 -- and a British man aged 35.

The boat, which was built in 1928, left Opua, New Zealand, on May 29, headed for Newcastle, Australia.

Ricky Wright said there were two major storms two days apart, one a rainstorm and the other a wind event. The storms tore the boat's storm sails, limiting its ability to make speed and maneuver as it worked against the currents.

"To put it in perspective, it's like sailing from the Mediterranean to the Bahamas," Wright said. "Everyone follows the same course along the trade winds. They are doing the same thing, just against the prevailing winds."

Wright estimates that the Nina is currently four or five days from making port in Australia.
UPDATE: Father says text message proves yacht survived storms | KATC.com | Acadiana-Lafayette, Louisiana
__________________
romulusm is offline  
Old 03-07-2013, 15:29   #290
Registered User

Join Date: Jun 2013
Posts: 14
Re: Schooner Nina - MERGED 3 THREADS

interesting is the final estimate from the father...

Quote:
Wright estimates that the Nina is currently four or five days from making port in Australia.
__________________
romulusm is offline  
Old 03-07-2013, 15:31   #291
Registered User

Join Date: Apr 2009
Location: Alaska
Boat: Beneteau First 456 - Radiance
Posts: 12
Re: Schooner Nina - MERGED 3 THREADS

Here is a photo of the life raft on board Nina taken a few days prior to its departure from Opua at the end of May. It looks like you have the info you need, but at least this confirms that it was there and was likely the same one.
Attached Thumbnails
Click image for larger version

Name:	liferaft4.jpg
Views:	263
Size:	315.4 KB
ID:	63573  
__________________
palagic456 is offline  
Old 03-07-2013, 15:34   #292
Registered User

Join Date: Jun 2013
Location: Melbourne
Boat: Lyle Hess 32
Posts: 38
Quote:
Originally Posted by palagic456 View Post
Here is a photo of the life raft on board Nina taken a few days prior to its departure from Opua at the end of May. It looks like you have the info you need, but at least this confirms that it was there and was likely the same one.
Interesting that looks more like a turnbuckle than a hydrostatic release. Others may know better than me.
__________________
Pelorus32 is offline  
Old 03-07-2013, 16:34   #293
Marine Service Provider
 
ternmarine's Avatar

Join Date: Jun 2013
Posts: 33
Re: Schooner Nina - MERGED 3 THREADS

I came past the Air Force Base at 9.30am this morning ( 1 hr ago) and the Orion had already taken off.

Here's hoping they have more luck today.
__________________
ternmarine is offline  
Old 03-07-2013, 16:52   #294
Marine Service Provider

Join Date: Dec 2009
Location: St Augustine, FL
Boat: Woods Vardo 34 Cat
Posts: 2,825
Re: Schooner Nina - MERGED 3 THREADS

I would have to say, I mind it very doubtful Nina does not have some type of HF receiver at least. There must be news reports, etc in the S Hemisphere reporting her missing and also perhaps on the high seas forecast??

If the phone is buggered, and not HF TX available, it would seem the only responsible thing to do would be to set off the EPIRB. They would have a flyover within a few hours and make contact via VHF or Visually and all this sillyness would be put to rest if all is well and they are simply "limping" to port.
__________________
Check out my MoJo: Facebook.com/mojomarine1
Boatguy30 is offline  
Old 03-07-2013, 17:17   #295
Registered User

Join Date: Feb 2013
Location: Port Stephens
Boat: Brooke Cutter 38
Posts: 32
Re: Schooner Nina - MERGED 3 THREADS

Even if they're unable to receive any news, they would assume that people would be looking for them by now. I'd have probably set off the EPIRB by now for that reason. But, many have the view that the EPIRB musn't be activated until danger is imminent so, perhaps this skipper has that view.

Let's hope that she's limping to port, as suggested.

Rick
__________________
rfnk is offline  
Old 03-07-2013, 17:34   #296
Registered User

Join Date: May 2010
Location: New Plymouth, NZ
Boat: Steel Swain 36 Cutter
Posts: 51
Re: Schooner Nina - MERGED 3 THREADS

I can just read "Revere" on that liferaft photo so thanks so much for that confirmation.

I agree, it looks more like the end of a turnbuckle than a hydrostatic release. It is hard to say but with the liferaft being held down by a large single strap, a hydrostatic release would make sense. It could be hidden in the view.
__________________
opusnz is offline  
Old 03-07-2013, 17:46   #297
Registered User

Join Date: May 2010
Location: New Plymouth, NZ
Boat: Steel Swain 36 Cutter
Posts: 51
Re: Schooner Nina - MERGED 3 THREADS

There is more info known to RCC NZ than shown on this forum...

The last text from Evi to Bob McDavitt said 3.5 knots at 310 deg at 0939 local time. The "new" text message just released by Iridium says 4 knots at 310 deg about 2 hours later, or just before noon on Jun 4th.

The new info about having damaged sails and being under bare poles is significant because it shows that they must have been going down wind. This helps confirm the previous data and helps confirm that their position must have been further west, according to the weather of Jun 4.

Iridium should be ashamed of themselves for withholding such critical information.
__________________
opusnz is offline  
Old 03-07-2013, 17:46   #298
Registered User
 
Friend of Nina's Avatar

Join Date: Jun 2013
Posts: 211
Quote:
Originally Posted by Pelorus32 View Post
What great news about the message and as Cherie says shame on Iridium.

It appears from other posts that Iridium may be able at least to tell when the last connection to the network is for an Iridium phone. Has the State dept asked them when the last connection was and if there are any other stored messages. Also who is recipient 2?

The sequence of events that then emerges is this:

1) Nina rings Bob McD and he says basically you are going to get the weather, head south and heave to. We know from footage on YouTube where David describe's heaving to transAtlantic that he does so under at least Trysail.

2) The "anything for Nina" message is sent but Bob, from recollection cannot get through.

3) At some point within 2 hours of that Nina blows out her Trysail and perhaps Storm Jib as evidenced by this new message. That leaves her unable to remain hove to and she therefore begins to run off downwind at 310 degrees and 4 knots.

Assuming that Nina did in fact heave to as suggested - and past evidence shows that David had previously used this tactic - then the loss of her storm sails has probably rendered her unable to remain hove to and hence the 310/4 knots message.

Every vessel has different behaviour when hove to - some require sail aft, others sail forward and aft and this changes as wind speed increases. It is unlikely that she could remain hove to however without some sail aft.

Does any one know whether she lay to a parachute sea anchor when hove to or whether she carried a drogue or parachute? I'm also interested in the questions suggested about the EPIRB.

Just thoughts.
Thank you for your thorough thoughts. Yes. It's hard to believe an 84 yr old boat doesn't know all the ropes but appears when you take away luck and trump cards... Even she has to say "uncle " !
Feeling a bit low right now but I can never thank you guys for your insight, prayers and sailor caring!! Cherie
__________________
Friend of Nina is offline  
Old 03-07-2013, 17:50   #299
Registered User

Join Date: May 2010
Location: New Plymouth, NZ
Boat: Steel Swain 36 Cutter
Posts: 51
Re: Schooner Nina - MERGED 3 THREADS

Things have really changed the last few years. There are a lot of boats sailing offshore now without HF radios. With Iridium phones coming down in price, they get all their weather via email, internet, or text grib files.
__________________
opusnz is offline  
Old 03-07-2013, 17:54   #300
Marine Service Provider
 
ternmarine's Avatar

Join Date: Jun 2013
Posts: 33
Re: Schooner Nina - MERGED 3 THREADS

There is a series of you tube videos here;



that show very well how capable they are of sailing Nina through almost everything.
__________________

__________________
ternmarine is offline  
Closed Thread

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Merged Threads: HMS Bounty Mark1977 Cruising News & Events 571 01-08-2013 14:08
Stripped Threads on Mast voxxmd Deck hardware: Rigging, Sails & Hoisting 51 25-04-2013 08:37
Merged Threads: Cruising Madeira brine Atlantic & the Caribbean 14 19-12-2012 03:23
OpenCPN Beta Version 3.1.814 Released bdbcat OpenCPN 185 14-09-2012 08:43
Top 10 Cat Manufacturers Sand crab Multihull Sailboats 46 12-09-2012 00:49



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 23:40.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.