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Author Topic: Mystery Debris  (Read 30243 times)

Ric Gillespie

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Mystery Debris
« on: July 25, 2017, 04:26:13 PM »

During the recent expedition, one of the teams came across what they believed was a piece of Norwich City wreckage at the NW tip of the island.   It's a sheet of steel reportedly measuring about three feet by four feet and one half an inch thick. There was also a second piece that was slightly smaller that you can just see peeking over a rock behind it (see photo).  If NC debris, we would have to greatly adjust our thinking about the distribution of shipwreck debris.  However, the sheet is unlike any NC debris we've seen in that the rivets have apparently rusted away and/or fallen out. Rivets on NC wreckage remain in place (see photo).   But if this thing is not NC debris, where did it come from?  It doesn't look like it would float worth a damn. 
The location (see photo) is not far from the base of the first Bushnell tower.  Is there anything in the Bushnell Survey literature that might account for such a steel plate?
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Matt Revington

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Re: Mystery Debris
« Reply #1 on: July 26, 2017, 11:36:04 AM »

The towers erected by the Bushnell would have been Bilby Towers.  I have been looking at online pictures, they appear to have been mostly metal beams, narrower bits without large plates like that in the photos.  Where the platforms are shown they look like wood planks.  The bit that is not shown in photos (that I have found so far ) is the base which might have had more substantial parts to it.
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Ric Gillespie

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Re: Mystery Debris
« Reply #2 on: July 26, 2017, 11:43:34 AM »

We know they were set on concrete pads which still exist.  I see at least two, maybe three, finished edges on the steel plate but the left edge looks like it failed, which implies that it was part of a larger structure.  Strange.
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Bill Mangus

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Re: Mystery Debris
« Reply #3 on: July 26, 2017, 02:46:51 PM »

Perhaps they scavenged something from the NC as they were building the towers?
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James Champion

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Re: Mystery Debris
« Reply #4 on: July 26, 2017, 06:07:31 PM »

The piece of metal is definitely meant for riveted construction. Welded construction on ships slowly replaced riveted construction methods in the 30's. Additionally heat and/or stress and/or corrosion have caused all the rivets to fail and have left the piece of metal warped. It can't float and could not have been carried there by birds or fish. It also appears to me too misshapen and heavy to have been transported to the island by people for any normally useful purpose. The little that can be seen of a second piece of metal with even more irregular edges reinforces this observation.

Occam's razor - It's from the Norwich City. 

Could be from near the keel, bilge, or bottom hull portions that haven't been seen by Tighar. These portions may have been up against sand or coral and less exposed to marine growth and less exposed to corrosion causing air. The second picture of Norwich City wreckage appear to be of single-row riveted-sheet to right-angle construction which would fit with lower strength upper-superstructure wall and compartment construction debris.
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Bill Mangus

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Re: Mystery Debris
« Reply #5 on: July 27, 2017, 06:30:58 AM »

I wonder if the big bit in photo #1 is part of the boiler that went missing sometime last year.  The multiple-row rivet pattern in photo #1 seems close to what can be seen of the remaining boiler in the upper-right corner of photo 2. 
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Ric Gillespie

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Re: Mystery Debris
« Reply #6 on: July 27, 2017, 07:07:16 AM »

The problem with the debris at the NW tip being from NC is its location.  It's more than half a mile and around a corner from the shipwreck.  How did it get there? NC debris does not travel northward.  There is no known NC debris on the beach, on the reef flat, or in the ocean more than a few meters north of the shipwreck. There are no natural forces (wind or water) that could move it that far without also also moving other ship wreckage northward.  If it's NC debris, someone brought it there (I sure wouldn't want that job).

Occam's Razor actually argues for the debris being associated with the only known nearby activity that involved heavy construction - the erection of the Bushnell tower.

Occam's Razor is widely misunderstood.  It does not hold that the simplest explanation is the most likely to be true.  Occam's Razor - "Entia non sunt multiplicanda praeter necessitatem" - holds that "Entities must not be multiplied beyond necessity."  In other words, "... if there are several possible ways that something might have happened, the way that uses the fewest guesses is probably the right one. However, Occam's razor only applies when the simple explanation and complex explanation both work equally well. If a more complex explanation does a better job than a simpler one, then you should use the complex one." (https://simple.wikipedia.org/wiki/Occam%27s_razor)

The Niku Hypothesis is a classic example.  It is more complex than Crashed & Sank but, as an explanation for the known facts (post-loss radio signals, Bevington Object, castaway, Seven site artifacts, etc.) it works far better.
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Jon Romig

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Re: Mystery Debris
« Reply #7 on: July 27, 2017, 05:46:04 PM »

Why would someone transport something heavy and apparently useless in a maritime environment, very likely by boat?

Something with a shape, or with holes in it, that makes it easy to attach a line?

Anchor.

Jon Romig 3562R
 
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Bill Mangus

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Re: Mystery Debris
« Reply #8 on: July 28, 2017, 09:31:22 AM »

Maybe not the NC crew as they were already assured of rescue and did need to go to that much effort.  No mention of it in the investigation records. 

I can see the Bushnell survey crew using something like that, though.  The plates might have helped to support a pole or beacon or light marking that end of the island.  There is mention in the Bushnell records of the crew hanging a light on the mast of the NC to help with station keeping at night.  Perhaps they needed something on that point also.

Ric, is the spot where these plates are now once much/any further inland? Has the reef eroded away underneath them?
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Ric Gillespie

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Re: Mystery Debris
« Reply #9 on: July 28, 2017, 01:07:21 PM »

Ric, is the spot where these plates are now once much/any further inland? Has the reef eroded away underneath them?

No. That end of the island is pretty much solid coral.  No sand.  It looks the same over the years.
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Matt Revington

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Re: Mystery Debris
« Reply #10 on: July 28, 2017, 01:20:06 PM »

How often have Tighar expeditions looked at that point of the island, and is it likely that they would have seen those sheets if they have been there on the reef since ~1939?  Could the sheets have been further up in the vegetation and been washed out more recently by a storm?
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Ric Gillespie

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Re: Mystery Debris
« Reply #11 on: July 28, 2017, 01:23:16 PM »

How often have Tighar expeditions looked at that point of the island, and is it likely that they would have seen those sheets if they have been there on the reef since ~1939?  Could the sheets have been further up in the vegetation and been washed out more recently by a storm?

It's not an area of interest. We've spent very little time up there.
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Greg Daspit

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Re: Mystery Debris
« Reply #12 on: July 28, 2017, 02:03:21 PM »

I think it is possible that the Bushnell tower construction crew used Norwich City Debris for some reason.  For example, a flat hard surface to use as an anvil to fix something.  Maybe used as shim at the tower base.
If there is nothing to tie to on the edge of the reef, native fisherman may have used it to tie fishing lines to at a good fishing spot.
There could be some unknown reasons we can’t think of for why it may have been moved by people.

The interesting thing to me is there are two pieces of debris very close together.
The location at the shoreline and the proximity of two pieces close together suggest something bigger may have washed up and broke apart there.
But the rivet holes suggest it was very old. At the same time its level of corrosion looks very different than the steel at the Norwich City wreck. It could have been out of the water or buried for a long time.
How could rivets erode away and leave the main piece relatively un corroded?
How could that piece have broken up without some rivets remaining?
How could a broken piece like that possibly be part of something that floated?
It’s all weird. My best guess is the pieces are from the Norwich City and were used for some purpose near that site. Rivets may have been removed by man for that purpose. After being used it was abandoned and left somewhere near the shore.
3971R
 
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Jon Romig

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Re: Mystery Debris
« Reply #13 on: July 28, 2017, 08:39:43 PM »

I think we generally agree that this debris is probably from the Norwich City. I also think that human transport to the northern point is quite unlikely, and in any case it doesn't appear to be particularly useful in the context of the search for Amelia.

What is interesting and useful is if this debris was transported north by currents, wind or waves. I think this is far more likely, and very relevant to our search:

Given all we know, it is extremely unlikely that this piece of debris - as it is currently seen on the reef - could have been moved from the wreck to this spot by currents and/or wave action. The debris is steel and would sink like a stone - it is extremely unlikely that waves would have moved it half a mile North on the reef (but not impossible I admit). Additionally, the current always (?) flows toward the south.

Thus we must conclude that the debris most probably floated to the Northern point, attached to something buoyant. Then, over time, the rivets rusted out and the rest of the wreckage rotted or corroded or was swept away.

If we accept the above, there must be times when winds and waves can move a floating object north along the reef, even against the prevailing current. Notably this could occur during a storm that might also sweep a stranded Electra off the reef.

That means that a future wide-area underwater search should look not only to the South and West, but to the North of Niku as well. All else being equal, there is a 33% chance that a floating Electra was swept North.

Jon


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Ric Gillespie

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Re: Mystery Debris
« Reply #14 on: July 29, 2017, 07:06:52 AM »

Regardless of where the debris at the NW tip came from, any wide-area underwater search for Electra debris will, of course, include the area north of where the plane presumably went into the water.
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