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Scuba Blog
27
Oct
Side Scan Sonar Images of The PLM-27 and Rose Castle
We first attempted to image the SS Rose Castle, the deepest of the wrecks. It sits in about 160 feet of water and it's about 110 feet to the deck. We chose this wreck to run the device through its paces, and it delivered!
Second Scan, Rose Castle
As you can see, there is an amazing amount of detail. The bright part areas are the ship itself, while the darker area is its shadow. The black area at the bottom of the image is the side scan sonar's "blind spot", an area underneath the sonar that it can't see. As you can tell, we were fairly close to the wreck, but you can see still a lot! Of note, you can see the mooring line to the right.
Our third run was even more illuminating:
Third Scan, Rose Castle
The rigging, superstructures and even cargo holds become apparent in this scan. There was a bit of shakiness, which we attribute to some wave action topside shaking the towfish a little. I will point out on the far left, specifically in the shadow, a small piece pointing toward the top of the photo. That's the stern's 4.7 inch gun! We were stunned to see it!
(The discerning eye will note a "glitch" in the photo. The range was inadvertently changed briefly, so it has been zoomed in and placed in the proper area after the fact.)
Totally blow away already, we decided to take a run at the much shallower PLM-27, sitting 100 feet of water with only 50 feet to the deck. After taking an initial image to get everything in order, we got an amazing shot on our second run:
Second Scan, PLM 27
This was better than we could have expected. You can clearly see the superstructures, the stern gun, the torpedo hole, the derricks, and the cargo holds! There was a slight curve to the wreck, meaning we went slightly off course as we passed it, but otherwise, this image can almost be used as a map to navigate the 400 ft wreck!
On our third pass, we got a little further away, and there was yet another surprise:
Third Scan, PLM 27
Pretty much the same thing, just with less contrast, as we were further out. However, if you look at the shadow on the left side near the boat, you will see the shadow of the PLM 27's rudder and propeller!
All in all, it was a fantastic day (all of this was done in about 1.5 hours!), and after diving these wrecks for 12 years, it was great to see them from a completely new perspective!
As soon as we get the weather, we're heading out to scan the Saganaga and Lord Strathcona! Stay tuned!