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Old 29-07-2017, 16:31   #46
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Re: Leopard 46 lost in French Polynesia - stunning rescue pictures

Heck even a Volvo race boat can hit a reef or island ! How professional do you need to be ? At least it wasn't a shipping container in the middle of nowhere a thousand miles from any help
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Old 29-07-2017, 16:35   #47
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Re: Leopard 46 lost in French Polynesia - stunning rescue pictures

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Google Earth out in the middle of the pacific? I doubt the reef had a cell tower.
GE2KAP does not require cell service. It's something you can use and store the charts months or years before you cruise an area. Try it sometime.

The key is that, as in the above example of the Navionics charts looking a lot like the GE images, if the lat/long coordinates are off for Navioncs, say, indicating that everything is shifted a few hundred yards one way or the other, GE can cross-check the accuracy of the coordinates.
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Old 29-07-2017, 16:39   #48
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Re: Leopard 46 lost in French Polynesia - stunning rescue pictures

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Anyone navigating in not-well-charted waters should seriously consider investing in 'forward looking sonar' ....read that as having a 'depth finder / fish finder' with the forward-looking capability transducer. Same for having the now extremely cost effective 'broadband' radars that have wonderful continous close-in (~200 foot) 'resolution' yet with no personal radiation hazards & drawing less power than a couple incandescent lights. No matter the cost or size of your craft, depth and/or surface radar target alarms set for alerting shallows are priceless tools, day or nighttime. And in this MAYDAY case, having a deep cycle battery dedicated (...hardwired... 'float') to the VHF, and the critical lighting in particular, is always strongly advised. Sure, using 'charts' with data dating back to the 1800's is risky at best, and of course, it also helps to even realize that inaccuracy. A little pre-trip research goes a long way. Be aware even USA coastal waters have geodetic survey bottom contour data dating pretty far back. Many decades of heavy weather & shifting sands can really distort that 'dated' bottom picture (...and is not always highlighted by NOTAM's BTW). Another good example of why standing-off until higher tide, especially after viewing the intended passage situation during low tide, is a darn good way to go. While I feel terrible for what this so serving family went through, being totally blunt, "complacency can kill." Fortunately they were experienced, strong & clever enough to cope, especially emotionally to hold together under great stress. Kudos folks, plus to all those assisting.....
Forward Looking Sonar is of little or no use in the this case. The reefs come out of extremely deep water very quickly in the South Pacific. We use our FLS all the time in close in anchoring situations, but it has no use while on passage.
We do the opposite of you on the tide thing. I prefer to hunt around at lower tide and rising. Its easier to see things and if you hit anything the rising tide will help you off. In the reef strewn SP it is much more important to have the sun at a level for visibility than to worry about the tide, which is generally small.
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Old 29-07-2017, 16:57   #49
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Re: Leopard 46 lost in French Polynesia - stunning rescue pictures

Navy Davy... Totally agree! Stuff happens, eh..?!! Shipping containers as worldwide flotsam, who would have ever thought....huge waterlogged logs ('deadheads') were the fear in the day, sir.
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Cormorant.... WOW software..!!! For an old dude like me, it is incredible what is now out there for everyone to access so easily nowadays. For free in many cases no less! Is a very far cry from what it took to float along way back when, especially in the middle of the night. Just being able to download the latest NOTAM annotated charts onto your PC is huge....again, 'for free.' Better yet, get those NOTAM's on-line real time now. For one having been 'land-locked' for a few decades now, where we are at today is staggering by comparison.
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Old 29-07-2017, 17:15   #50
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Re: Leopard 46 lost in French Polynesia - stunning rescue pictures

Why don't the navigation software developers use the millions of boats out there to improve the product. If the software recorded the travels and findings of the boats they were on then sent that back to the developer when possible and a few comparisons made with others to ensure the info wasn't from one dodgy boat then we would have better information. A bit of internet is cheap for more accurate info.
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Old 29-07-2017, 17:22   #51
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Re: Leopard 46 lost in French Polynesia - stunning rescue pictures

You would have to be happy with the accuracy of the images Leaseonlife posted. Is that the actual reef they hit?
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Old 29-07-2017, 17:32   #52
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Re: Leopard 46 lost in French Polynesia - stunning rescue pictures

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You would have to be happy with the accuracy of the images Leaseonlife posted. Is that the actual reef they hit?
Only an educated guess, based on the secondary blog ("outside of Avea Bay"), and their pictures do match a normal fringe reef in that area, not a single standalone reef somewhere. As Jim Cate mentioned, getting the lat/lon of the accident would help clearing things up.
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Old 29-07-2017, 17:35   #53
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Re: Leopard 46 lost in French Polynesia - stunning rescue pictures

Paul l.... Agree on the forward looking sonar that yes, it truly has limitations & has been very over rated in some well documented situations. Even extremely high-technology vessels 'muff it.' Yet at a SLOW approach, it is primo versus surface observations most times. (.....Beats repeatedly tossing a weighted line as in Mark Twain's day, but that DID work really well in all fairness..!!!) As concerns detecting reefs visually in advance, I did intended that boaters in unfamiliar waters (...I meant in locales never before experienced...) should stand-off, especially in the dark, IF they realize the chart depth data is questionable. Over reliance on technology & overconfidence was probably at play here. These poor folks did not obviously 'get-it'.....a situation & end result for the courts to decide & settle. Sadly, plenty of folks have noted that-that may be a very remote end-state in this area of the ocean. When your insurance in advance refuses to cover a given area, I personally would be somewhat paranoid navigating within such areas.....even in fair weather.
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Old 29-07-2017, 17:44   #54
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Re: Leopard 46 lost in French Polynesia - stunning rescue pictures

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Originally Posted by Dave_S View Post
Why don't the navigation software developers use the millions of boats out there to improve the product. If the software recorded the travels and findings of the boats they were on then sent that back to the developer when possible and a few comparisons made with others to ensure the info wasn't from one dodgy boat then we would have better information. A bit of internet is cheap for more accurate info.
They do! there are open source solutions and commercial solutions. Navionics does have a product (sonarphone ?!?) one can use to run around in a dinghy and scan the bottom. the results are then shared to navionics and visible as sonarcharts on their webpage. I have not tested any of the open source solutions, it is not a trivial task correcting for sensor offsets, tides, erroneous readings, etc.

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Old 29-07-2017, 17:48   #55
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Re: Leopard 46 lost in French Polynesia - stunning rescue pictures

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Originally Posted by sailormed View Post
Reading this it seems it is un "uncharted reef", but ONLY on Navionics charts!!!
What is the legal responsability of the chart supplier if this is the case?
I guess this is why we have to hit that button every time we start up our $2000 chart plotters. The one that says that says we wont actually rely on it for Navigation
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Old 29-07-2017, 17:52   #56
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Re: Leopard 46 lost in French Polynesia - stunning rescue pictures

I was in this bay on Huahine two days after this family hit the reef. Spoke with two of the kids for a bit. Nothing in depth. Just what happened? How's everyone doing? What's next? The family was spread out among other cruisers in the bay.

I've read all these comments, some helpful and some not so much. This is a tragic situation, no matter who or what you might ascribe blame to. Were there mistakes made? Maybe. I wasn't on board and neither were any of you commenting. My only reason for posting is to ask you to consider the family when choosing your words. If you have been offshore yourself, responsible for a boat & crew have you ever made a mistake? Taken a chance? I know I have. I'm a good, responsible, conscientious sailor but I have made mistakes and have been fortunate enough to have not suffered consequences. Just asking for a little compassion.

They don't have any insurance and they could use some help. If you can, please do

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Old 29-07-2017, 17:57   #57
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Re: Leopard 46 lost in French Polynesia - stunning rescue pictures

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I guess this is why we have to hit that button every time we start up our $2000 chart plotters. The one that says that says we wont actually rely on it for Navigation
Ive been trying to answer my own question on the "ZOC" for the area of the reef in question, but don't seem to be able to find an answer regarding Navionics.

I'm still a paper chart kind of guy

Do all the digital chart systems have "ZOC" data available ? Navionics,
C-MAP ,Anyone?.
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Old 29-07-2017, 17:59   #58
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Re: Leopard 46 lost in French Polynesia - stunning rescue pictures

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NO. its the navigators.

Please Mr taxwizz, do tell us all what the 'ZOC' is for the area of the chart under discussion here.

I'm thinking you don't understand what you are looking at.
Dear Seaslug....I do not have the charts of these waters as I do not plan to sail there. I am merely stating that if the data is available, it should be used to update all compatible data files. We are talking about life and safety.
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Old 29-07-2017, 18:07   #59
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Re: Leopard 46 lost in French Polynesia - stunning rescue pictures

RE forward looking sonar: We've used and enjoyed ours for around 20 years now. In some situations, they are extremely useful, but as Paul L points out, not in this case. They were not slowly feeling their way into an anchorage or through a pass, they were sailing at full speed (9 knots) in what they seemed to think was open water. Nine knots is on the order of 900 feet per minute. Set to max range and fastest scan rate, our Probe takes around 30 seconds to complete a scan and refresh the display. So, the vessel would have traveled around 450 feet during that time... but the reliable detection range for a wall coming upfrom deep water is somewhere around 300-500 feet under very good conditions. This means there is a high probability that the instrument would not register the obstruction before the boat struck,let alone in time to take effective measures to avoid the reef. And from personal experience, it isn't feasible to stare continuously at the screen, nor are the alarms very useful.

The fact remains that these folks were clearly sailing near the fringe reef, in the dark at high speed with only a depth gage aiding their eyes in avoiding the coral. The reported depth of 180 feet should have told them they were very near the reef no matter what Navionics said. As others have said, perhaps the insurance company was correct in their evaluation of experience.

All so sad...

Jim
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Old 29-07-2017, 18:58   #60
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Re: Leopard 46 lost in French Polynesia - stunning rescue pictures

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No lawsuits coming. Not Navionics problem. Navigator problem.
b.
I agree. It's very sad but it's navigator's problem. World ocean is huge, there no way at current state of technology to have everything correct on charts. Attempts of some to "bring everything to the court" without even trying use simple common sense is what ruins modern world.
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