Lagoon 450 (Next Life) damaged in the Exuma, The Bahamas

[ArtM]

Originally Posted by Lagoon4us

Art, Having over the years salvaged different vessels from reef groundings/strandings etc i have to say reef and rocks have no mercy on a boats hull.

To say this is a weakness in Catamaran design is just silly.

I'm thinking that a catamaran my be more subject to this than a keel boat based on my (possibly flawed) understanding of the hull designs.

I think a keel boat would be more likely to "bump" against the reef, and at that against a relatively thick part of the hull, at which point the captain could quickly throw the engines into reverse and save the hull.

It seems from the descriptions and photos that these cats were put up ON the rocks, then repeatedly beat their bottoms against them with little or no hope of backing out before their flat bottoms were shredded like grated cheese.

[Lagoon4us]

Reef isn't always a simple slab or plateau shape, it can shoal at times and it can have individual 'bommies' in a scattered pattern, often a mono will simply lay over and grind a largish lump out of the side.

Yes you can be lucky and bump then reverse off BUT keels get caught in the gaps of coral, don't forget these cats have 2 keels, 2 rudders and 2 legs. So theres not a great deal of hope.

A lot of groundings in reef area's in Australia stem from a 180deg wind shift, usually at night putting the unsuspecting aground in a heartbeat HENCE you anchor out. We would write a course to steer on a piece of masking tape and stick it on the compass binnacle.

Screwing around starting up a plotter is enough time to allow disaster to occur, a pre-chosen compass course essential.

Also a buoy on the anchor rode allowing you to cut and run if needs be, the time from when the anchor no longer holds your boat to the time it's safely on board also can lead to disaster.

Reef and foul ground demand respect and planning.

Cheers

[downunder]

Originally Posted by ArtM

I'm thinking that a catamaran my be more subject to this than a keel boat based on my (possibly flawed) understanding of the hull designs.

I think a keel boat would be more likely to "bump" against the reef, and at that against a relatively thick part of the hull, at which point the captain could quickly throw the engines into reverse and save the hull.

It seems from the descriptions and photos that these cats were put up ON the rocks, then repeatedly beat their bottoms against them with little or no hope of backing out before their flat bottoms were shredded like grated cheese.

Don't worry ArtM, I have salvaged both a steel and timber trawlers sunk on the GBR reef.

Coral area do not respect any type hull.

Unfortunately generally few sailors spend a lot of time amongst the real GBR and mostly just visit the GBR islands because of fear of the reef.

Navigating amongst the GBR and indeed all coral areas, as well as approching unknown anchorages should only be visually with sun at the correct angle never relying on digital cartography alone.

[cwyckham]

Mr. Carnev,

It is both good and courageous that you decided to join us here. Thank you.

I work in the aviation industry. Contrary to your original post, it is in fact routine for aircraft to both navigate and land with low visibility using nothing but their GPS systems. This is possible due to the excellent quality of the mapping availble in areas around airports and due to the fact that aircraft land on a designated path, exactly like an older ILS system, but described wholly within the database of the GPS. Each of these routes is carefully tested and certified before being approved and released. So it is possible, but clearly aviation and marine GPS are two different markets with different needs and working within different realities.

In the aviation industry, we take all accidents or near accidents very seriously and work to learn from the mistakes of the past. In this case, a boat was lost due, in part, to the fact that your product was simply incorrect. It is easy to say that the skipper should always be aware of possible errors, but mariners have relied on accurate charts for centuries, and there's a reason for that. Underwater obstructions are really hard to see because of all the water on them.

Not only did your company not clearly show reefs that other companies seemed to know were there, but you actually recommended a route through the area, straight onto a reef that you should have known was there. Whether the line was dashed or solid is irrelelvent (especially since neither is standard charting practice), the label said it was recommended.

All companies make mistakes. The difference comes in how they respond to it. Making a fix to the chart is nice. Talking to the community about it is nice too. The important thing, though, is to understand the route cause and prevent further accidents.

My question to you is whether your company has embarked on a formal route cause analysis to understand how these charting errors occured? If so, would you be willing share with the community an "approved for release" version of your findings?

[Giuseppe Carnev]

How reliable are Navionics charts

While I do not mind being under the microscope if this helps improve our products, I think that putting Navionics alone under the microscope bears the danger of misleading boaters into believing that only Navionics has errors, and thus blindly trusting other charts.
As I said very openly, all charts have errors and neither Navionics nor anybody else is an exception: with over a billion features in our database, even an accuracy of 99.999% (!) leaves room for 10,000 potential inaccuracies.

Let me give you some examples of official government charts

Yellow line = Navionics chart; red line = official government chart (note the big rock missing)


NOAA: features missing; beacon on wrong side


NOAA showing a non-existent waterway in Santa Cruz Calif: they have portrayed highway 1 as a waterway!


USS Guardian aground: Panbo: The Marine Electronics Hub: USS Guardian aground, DNC chart error?

Nobody can dispute that all charts: paper, electronic, official or private have errors but it goes beyond this – no cartographers survey 100% of the waterways nor can they keep them current when natural disasters or man made situations alter them. We have chosen to tackle the problem differently through our program of community edits and the freshest data. In this way, Navionics can obtain, make and deliver changes in a fraction of the time it takes other providers.

=======================
Whether or not community edits increase safety.

I thank SCIMITAR from Dubrovnik for reporting that 3 buoys really are not there, but if he reported the same via Community Edits Navionics users that go to Dubrovnik would see it. Certainly, blogs like this one are of great value in getting the word out but timely posting of edits directly to the charts is more efficient. Those who feel that reports by locals are dangerous and should not be taken into consideration have the option of switching them off.

Let me show an example: I realize that a buoy is 100 ft away from where reported, and move it to the correct position.
As you can see in the screenshot, the official buoy is marked with an “X” in a red dot indicating that a user reports that it is not there, while buoy added in the right position is clearly marked with a “+” in a green dot.
If you query the user-added buoy, you see that it was last modified by Beppe on August 6 at 2:48pm etc. If other boaters see an error in what was done, they can move the buoy again and or report abuse.

SCREENSHOTS


With all these precautions in place, there is little tampering with the original data, which remains in a separate and protected layer, and there is no doubt as to which data is professionally entered and which is user generated. So far, out of hundreds of thousands of entries from tens of thousands of users, we have seen only two cases of abuse and in both cases we have disabled the app for that user: that person not only cannot make any more edits, but cannot use our app altogether.

[ArtM]

I think he has addressed the question, and I think it's irresponsible that you all be demanding that he admit responsibility for the accident.

All chart systems have errors. That is what he stated. All chart data is also incomplete, subject to interpretation, and not warranted as to applicability to any specific purpose.

I don't drive my car the wrong way down a street because my GPS says I should. You shouldn't drive your boat into a rock because some chart said that it was not there.

Let's just hope that the owner is appropriately insured, and will soon be sailing again. I plan to take all the lessons I can from this, including the discussion about the dangers of sailing in areas known for reefs and rock formations, but for me - the lessons about the importance of insurance and recognizing that chart data cannot be completely trusted are the major actionable lessons.

[Kettlewell]

Maybe I am misunderstanding what you are saying in this example, but if you look at the raster chart it is a red navigation light, so it would have to be on the starboard side of the channel when entering. So the raster chart is correct, and the vector charts are incorrect? But, whose charts are the vector charts? Also, that raster chart is an old edition. I'm not certain if I have the latest, but mine dates from at least 2010. See below.

[Kettlewell]

Here's the version of the chart I have on my computer right now--not certain if it is the latest edition.

[scimitar]

This is what CM93 (December 2011) have to say....

[Kettlewell]

Here's the NOAA ENC chart I just downloaded to take a look.

[donradcliffe]

This thread has wandered far and wide, but it is now coming back to the true lesson to be learned from Rolfe's loss--YOUR CHARTS, BE THEY PAPER OR ELECTRONIC, ARE NOT PERFECT!

Generally, the closer they are to major ports, the more accurate they are, but you should be aware of the limitations of your charts. Where you are pushing the limits, you should be going dead slow with the sun overhead and someone in the rigging. It was pretty obvious from the description that Next Life was traveling far too fast for the conditions--if you are feeling your way among bommies, you should be able to immediately back off if you hit, no matter what boat you are driving.

I was stuck with the afternoon sun in my eyes once in the Solomons, and after poking around the charted channel for a bit at 1-2 knots and finding rocks less than 3 ft underwater, I called for help and waited until a dinghy came out to guide me--otherwise I would have stood offshore for the night.

If you are running along a shore where there is a ledge of rocks running up from the water, but the chart doesn't show an underwater ledge, what do you believe--the charts or your eyeballs? The navigator should be looking at his/her chart, but should also be looking at your depthsounder, wave patterns, stakes, buoys, water color, and every other available input.

It doesn't matter who made the chart--I've hit bottom where CMAP showed 5 meters, I have BSB charts scanned from NOAA which showed Bermuda 8 miles off, had my position 1.5 miles off because someone changed the GPS datum to Croatia. The chart is just one input of many, and if they don't agree you SLOW DOWN OR STOP until you figure out why.

[roetter]

Originally Posted by ArtM

Rolf himself stated that he was on the lookout for the reefs, but due to some combination of sun angle, trajectory, and probably sea condition he was unable to see it. This did not result in a simple grounding, or light hull damage, but apparantly the complete removal of the catamaran's bottom - we seem to have discovered a new weakness of catamaran design!

The mystery of the line seems to have a number of interpretations, including the one you mentioned, and also that the line should not be interpreted as a direct course, but rather a general path, requiring careful navigation through the reefs in the area.

It seems that some charts show the reefs in very obvious, cartoon like style while others illustrate them as nothing more than an area of varying depth. Everyone has their favorite guide, chart, or navigation technique - yet it seems that many or most of them have been shown to be insufficient in avoid this particular wreckage.

I would like to emphasize that there was not damage to the hull during the initial grounding. All damage occurred while the boat was constantly being pounded by the increasing waves. It took over two hours of serious pounding before the first trickle of water came in. The ripped open hull happened overnight while the waves pounded her across the reef a distance of at least 50 meters with and estimated depth at full high water of about 1 foot.

Hardly a weakness in catamaran design. She held up a lot better than I expected.

[roetter]

Originally Posted by Lagoon4us

Art, Having over the years salvaged different vessels from reef groundings/strandings etc i have to say reef and rocks have no mercy on a boats hull.

To say this is a weakness in Catamaran design is just silly.

Grab a grinder and put a thin cutting wheel in it, now try cutting a sample of steel, aluminium, timber and GRP which one do you think will be sliced like a knife through butter?

The hard cold facts are that 'no boat' can be designed to strike, then pound on reef and rocks and survive unscathed.

You cannot effectively see reef with the sun in front of you and the result can be and was, in this case, calamitous BUT Rolf was lead astray by his confidence. Hence the discussion..

Cheers

Very well said.

[ArtM]

Originally Posted by roetter

I would like to emphasize that there was not damage to the hull during the initial grounding. All damage occurred while the boat was constantly being pounded by the increasing waves. It took over two hours of serious pounding before the first trickle of water came in. The ripped open hull happened overnight while the waves pounded her across the reef a distance of at least 50 meters with and estimated depth at full high water of about 1 foot.

Hardly a weakness in catamaran design. She held up a lot better than I expected.

Would a deep-keeled sailboat have suffered this kind of damage? It's hard for me to imagine it getting tossed up on the rocks in that way. Even if the keel got wedged, as previously described, it would not have been grated across the rocks like that.

A flat-bottomed boat like a catamaran, though, will happily float right up on a wave onto the rocks, and every following wave will lift her just an inch or two, each little wavelet pushing her further along to her doom.

If the boat held up for that long, then, what would be the ideal course of action? Perhaps throw out some anchors and try to stop the grinding action? Throw off balast and try to sail her out?

Or perhaps the opposite? to try to flood the crash lockers, bilges, what have you to hold the boat hard to the rocks until the tide comes to lift you away? What kind of equipment would be onboard to do that??

[nimblemotors]

Originally Posted by ArtM

Would a deep-keeled sailboat have suffered this kind of damage? It's hard for me to imagine it getting tossed up on the rocks in that way. Even if the keel got wedged, as previously described, it would not have been grated across the rocks like that.

A flat-bottomed boat like a catamaran, though, will happily float right up on a wave onto the rocks, and every following wave will lift her just an inch or two, each little wavelet pushing her further along to her doom.

If the boat held up for that long, then, what would be the ideal course of action? Perhaps throw out some anchors and try to stop the grinding action? Throw off balast and try to sail her out?

Or perhaps the opposite? to try to flood the crash lockers, bilges, what have you to hold the boat hard to the rocks until the tide comes to lift you away? What kind of equipment would be onboard to do that??

Yes things that can help others in the future.

As I understand it, the real problem was the inability to pull the boat back off the reef as quickly as possible. What can one do?
It would think a rounded keel would make this easier, vs a deep fin keel

Could one use an inflatable to lift the boat from obstructions, or at least keep it from getting pounded??