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Old 29-07-2017, 19:04   #61
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Re: Leopard 46 lost in French Polynesia - stunning rescue pictures

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Originally Posted by Jim Cate View Post
...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...
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There are probably modern units which do scan faster?
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Old 29-07-2017, 19:11   #62
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Re: Leopard 46 lost in French Polynesia - stunning rescue pictures

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Does anyone cruising there use Google Earth -> KAP imagery to double-check things like this?
Yes, I run sas planet side by side with opencpn, its seriously awesome. I also use navionics, my belief is you can't have to much information.
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Old 29-07-2017, 19:15   #63
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Re: Leopard 46 lost in French Polynesia - stunning rescue pictures

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Originally Posted by Kenomac View Post
You've been sitting on front of your desktop too long. Google Earth out in the middle of the pacific? I doubt the reef had a cell tower.

Their former insurance company got this one right, however unexpected stuff does happen even to people well prepared. They sound very resilient, hopefully, this will just be a setback.
Hi Ken , you download all the imagery in advance so it can be used off line. I have approx 50gig of downloaded imagery, its a real game changer.
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Old 29-07-2017, 19:26   #64
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Re: Leopard 46 lost in French Polynesia - stunning rescue pictures

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There are probably modern units which do scan faster?
It's not really the scan speed that is the issue, it is the distance in front of the vessel that they can see. If you can only see 100-150 feet ahead then when you calculate the reaction time you'd need when travelling above say 3 or 4 kts it really does no good. Even if you could make a turn you would need a full-time sonar operator to call for the turn. Good tool, but it isn't useful on passage.
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Old 29-07-2017, 19:34   #65
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Re: Leopard 46 lost in French Polynesia - stunning rescue pictures

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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

https://www.gofundme.comhelprescuethetribe
Excellent post. I to screw up, I try not to but still do. It's difficult and unjust to judge from our armchairs but this dosent mean we can't learn from events like this.

I know that complacency creeps into my cruising and this thread is a good reminder to have a look at myself and the way I manage my cruising.

Im a believer in electronic charts but I use multiple sources as sometimes they vary. Electronic charts and hardware are relatively cheap and power draw is minimum therefore I have at least two options running at anyone time.

One of the reasons im not replacing my old plotters with new is im liking the ability to have multiple sources on tablets etc, you can have open cpn, isailor and navionics all on the one device if you choose.
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Old 29-07-2017, 19:41   #66
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Re: Leopard 46 lost in French Polynesia - stunning rescue pictures

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Originally Posted by Cormorant View Post
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.
+10
I thought cross reference with another data set was essential in these waters.
If not GE then pencil & paper.
Easy to get in "island time mode", she'll be right mate we've got navionics.
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Old 29-07-2017, 19:43   #67
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Re: Leopard 46 lost in French Polynesia - stunning rescue pictures

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Originally Posted by mbuckely View Post
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

https://www.gofundme.comhelprescuethetribe
But by the grace of God go I.
It can happen to anyone. It is still useful to understand what happened, learn from it and be better prepared. That is one of the advantages of forums like CF.
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Old 29-07-2017, 19:49   #68
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Re: Leopard 46 lost in French Polynesia - stunning rescue pictures

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Originally Posted by lateral View Post
+10
I thought cross reference with another data set was essential in these waters.
If not GE then pencil & paper.
Easy to get in "island time mode", she'll be right mate we've got navionics.
How will you be cross referencing with paper and pencil? Using even older paper charts than the electronic ones, often on a completely different datum, isn't going to help a lot.

Understanding what charts offer you and what they don't and then navigating conservately based on the risks. If it's a new area I always do a sanity check on satellite vs e-charts before arrival. That helps to evaluate what level of trust to have in the charts. In this case it would not have had much affect.
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Old 29-07-2017, 19:50   #69
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Re: Leopard 46 lost in French Polynesia - stunning rescue pictures

This might be a good time to call Navionics and explain this to them and maybe some of these accidents will stop.
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Old 29-07-2017, 21:02   #70
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Re: Leopard 46 lost in French Polynesia - stunning rescue pictures

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Originally Posted by ranchero76 View Post
There are probably modern units which do scan faster?
The limiting thing is the speed of sound in water. The sonar emits a ping (carefully collimated into a beam and carefully aimed somewhere ahead of the boat). Then it waits patiently until the echo returns before emitting the next ping. The speed of sound in water is around 1500 m/s or 5000 ft/sec, so for a target 500 feet away, it takes around 0.2 seconds for the round trip. A scan is made up of dozens or even hundreds of pings, so assembling the data takes a while.

By narrowing the scan width you can improve the speed but at the cost of not seeing the full view of things ahead... its a tradeoff that you can make with some experience in use of the instrument, but it still isn't very useful in this role of high speed encounters with fixed objects.

Interphase, the folks who spearheaded this technology for amateur use, were bought out by Garmin who promptly stopped production of the Interphase FLS units. They have not replaced them with anything more capable or modern in terms of this application. There are a lot of adverts showing fantastic image resolution of bottom features, but even in the vapor ware there isn't talk of performance that would have aided these poor folks.

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Old 29-07-2017, 21:18   #71
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Re: Leopard 46 lost in French Polynesia - stunning rescue pictures

Wow this is horrific.
Our family has been following their blog and Zatara for a while now as we are off in 4 days to France to start our similar family adventure. I actually saw the Tanda Malika in Tahiti when I was there a few weeks back and took a photo to show my boys who were most excited about it.
The latest blog posts really left a real sick feeling in my stomach and Im not sure what to tell my boys when they next ask about the them.
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Old 29-07-2017, 21:21   #72
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Re: Leopard 46 lost in French Polynesia - stunning rescue pictures

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Hi Ken , you download all the imagery in advance so it can be used off line. I have approx 50gig of downloaded imagery, its a real game changer.
Maybe like me, they didn't know you can do this. Did Magellan know?

I consider myself to be very up to date on technology and preparedness.... I didn't know about offshore satellite imagery for open waters.
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Old 29-07-2017, 21:25   #73
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Re: Leopard 46 lost in French Polynesia - stunning rescue pictures

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Wow this is horrific.
Our family has been following their blog and Zatara for a while now as we are off in 4 days to France to start our similar family adventure. I actually saw the Tanda Malika in Tahiti when I was there a few weeks back and took a photo to show my boys who were most excited about it.
The latest blog posts really left a real sick feeling in my stomach and Im not sure what to tell my boys when they next ask about the them.
How old are the kids? Seems like at any age this could be turned into a serious learning experience. They can learn about the dangers and the need to be ever vigilant. It may allow you to set the safety-first attitude for all boat related decisions and have them participate.
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Old 29-07-2017, 21:51   #74
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Re: Leopard 46 lost in French Polynesia - stunning rescue pictures

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This might be a good time to call Navionics and explain this to them and maybe some of these accidents will stop.
A better use of time would be to install and learn to cross-reference a second or third or fourth mapping or satellite imagery system.

If it is indeed demonstrated that the Navionics chart is a little off in the area... I would expect Navionics to answer that this is perfectly normal, because their sources are not perfect, and that their maps never have been and never will be 100% complete and accurate. The same goes for every other mapping product available.

That is why they are aids to navigation only, and should not be relied upon totally... which I believe is spelled out in capital letters all over their products.

The very last thing we need is chart makers tied up in litigation over their accuracy, and held responsible for accidents related to it. That would lead to skyrocketing chart prices, a new generation of professional sailing lawyers, and most of us unable to afford either.
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Old 29-07-2017, 22:07   #75
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Re: Leopard 46 lost in French Polynesia - stunning rescue pictures

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This might be a good time to call Navionics and explain this to them and maybe some of these accidents will stop.
What have Navionics got to with it? The Navionics chart image of the fringe reef, as shown earlier in a post together with GE image, show the fringe reef in the same position in both images, out by no more than a 100 m, if that. There is no 'hidden' reef. There is no 'uncharted' reef. Let's stop with the American 'sue the bastards' mentality.

It is awful for the family, and all sympathies to them.

But it was, given the information so far, a navigation mistake compounded by a seamanship mistake. A navigation mistake for setting a waypoint so close to the island and reef. Regardless of whether they were heading for Fare or Uturoa, the waypoint should have been a minimum of 2 or 3 nm south of the fringe reef. There's no point in cutting the corner as we can only assume they were not intending to make a night entry into Fare or Uturoa? In addition, the reef-set current close to a fringe reef is strong and can easily pull you in sideways into the surf line. Stay well clear!

The seamanship mistake is for not having a better lookout when so close to the island. The chart plotter would have shown them to be close to the island and requiring extra attention. I find it hard to believe that an alert watch keeper would not have seen if not heard the surf. Did they have radar? That would have shown distance to the island if not the surf line and would have made it obvious that they were too close.

I'm sorry, but this accident is on them. Buying boats and crossing oceans does not provide training in seamanship - a fact recognised by their insurance company.

Sure as hell provides a kick up the ass to up my game and not be complacent.
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