mapping deadhenge: the way to Deadman Reef

[DiveNav]

Hi,
we completed the mapping of deadhenge; see image:

We plan to release this site this month.

Alberto (aka eDiver)

 

[beachcitiesdiver]

Sweet Alberto! Very nice image! Makes Shaw's Cove look wee-bit.

 

[Robert Phillips]

The angle looks wrong. The original layout (done with compass and line) was set to the connect to Shaw's Cove. The angle should be about 15° to the SE.

 

[DiveNav]

The angle looks wrong. The original layout (done with compass and line) was set to the connect to Shaw's Cove. The angle should be about 15° to the SE.

Hi Robert

2 thinghs: a) the map above is in "true northing", and b) GPS these days is quite accurate .... we dove the site, went to the first end point connected a line to a sausage ... ascended and took GPS coordinates ... descended and repeated the process for the second end point. Yes, given the current we might have not been exactly on the vertical of the 2 points, but we were not far off either.

You are welcome to repeat the experiment yourself and pass along your GPS coordinates. Maybe we could do it together ... so I will finally be able to dive with the famous Robert Phillips

Alberto (aka eDiver)

 

[Robert Phillips]

Being that I laid the line myself, I could have been off a few degrees but as you said, not by that far off.

How accurate is your GPS? Four, five, or six decimal places? Even a variation of 5 meters plus the drift of your sausage when depth and current are factored in could put you off from the actual location by at least 5-6 meters (no math wiz here so take that for what it's worth!)

The intent of the builders was to eventually connect Crescent with Shaw's cove and the compass heading was checked a few times before the line was set.

I'd be happy to dive the site with you and check my own sanity. I am having a great deal of cognitive dissonance trying to rationalize the rocks moving after being put in place, but it has been several years since Deadhenge was started!:shocked2:

 

[Rainer]

Sorry about the ignorance, but what is Deadhenge?

 

[DiveNav]

....How accurate is your GPS?....

In this case I used a basic handheld unit DD MM.mmm

.....Even a variation of 5 meters plus the drift of your sausage when depth and current are factored in could put you off from the actual location by at least 5-6 meters (no math wiz here so take that for what it's worth!)

I agree ... we tried to keep the line under tension as much as possible to minimize drift

.....I'd be happy to dive the site with you and check my own sanity. .....

Let's do it.
We could reverse the process now ..... start from a known gps coordinate at the surface and drop down vertically .... to see if the rocks are there or not
We could also attach a sausage to both end points .... keep them well under tension .. and then check alignment at the surface

 

[DiveNav]

Sorry about the ignorance, but what is Deadhenge?

It is a man made (actually made by Robert and his friends) underwater structure (a bunch of rocks - more or less in a straight line) starting somewhere in crescent bay (33 32.657N 117 48.264W according to my GPS) pointing toward deadman reef and ending with the "diver memorial" (located at 33 32.645N 117 48.282W according to my GPS).

I happened to be there during one of their "constructions dive" ... it was funny to see them "walking" on the seafloor carrying around those big rocks

 

[Doug Charney]

Building a henge, are we? That's a fantastic idea!!!

Sorry, I couldn't help myself!

 

[Robert Phillips]

It is a man made (actually made by Robert and his friends) underwater structure (a bunch of rocks - more or less in a straight line) starting somewhere in crescent bay (33 32.657N 117 48.264W according to my GPS) pointing toward deadman reef and ending with the "diver memorial" (located at 33 32.645N 117 48.282W according to my GPS).

I happened to be there during one of their "constructions dive" ... it was funny to see them "walking" on the seafloor carrying around those big rocks

My contribution was laying the line for the builders and I think I added two small stones (while not walking across the sea floor).

While I know the original builders, they prefer to remain anonymous and I can't take credit for their feats