Shipwrecks are not static, unchanging places. As age, tide and corrosion take their toll things settle into the seabed. Prior to photography, and more recently photogrammetry, the changes would go unrecorded. But as those of us who dive the SMS Karlsruhe regularly, it is no longer possible to recreate this image as shot in 2012:
The deck winch, just visible near the top right of the image, has now collapsed to the seabed and taken the teak decking with it.
One Deck Gun – Two Versions
Regular readers will remember that the combined model of the F2 and YC-21 salvage barge remained a work in progress, with a single dive with the Heart of Gold covering a lot of ground but leaving the midships of the F2 lacking detail.
A few weeks ago two more dives were completed on the F2 and the build of the model is running as we speak. During the dive it was apparent that the deck gun had moved quite a bit. With the first set of data processed into a point cloud and aligned with the exist model the F2 now appears to have two deck guns:-
The upper of the two gun turrets was scanned in November 2016, and the lower turret recording the (as was) position of the gun in April 2017. At some point in the 6 months between scans, things have settled.
Gravity is clearly winning the battle here, with the deck gun now much closer to the seabed than it previously was.
Movement – Which Model?
When the model finally finishes building it will be possible to measure, but for now we will have to remain patient and wait for Photoscan to do its thing.
All of this leaves one burning question: Which version do I build?
The historical variant with the gun turret more or less in its rightful place?
The current version?
For low long will the current version be valid? The gun is not yet on the seabed, so more movement may be forthcoming?
There is no wrong answer here, but as a diver orientation tool the model should reflect what the diver is most likely to see on their dive – right?
The model finished processing, and in the end the decision as to which gun position to include was irrelevant. This is a big model and for online viewing its necessary to reduce the detail, otherwise no one will wait for it to download…not even me! Here’s the final build: