[UPDATED AUG 29] As noted in a response to an earlier post, the CCGS Laurier's online track shows a route rather different than expected (thanks again to Dave Woodman for alerting me to this possibility). Using sailwx.info, one can get almost hourly updates on the vessel's current location, which shows that, rather than remaining in Queen Maud gulf, it ascended the eastern coast of King William Island as far as Matty Island. Some have inferred from this that the searchers are following up on latter-day Inuit accounts, collected by Dorothy Eber, of one of Franklin's ships being in this area, but although that's possible, I'm not sure how much we can infer from this ship's tracking data. For one, the searchers have the use of two launches, the Gannet and the Kinglett, which could enable them to conduct surveys independently of the Laurier. For two, the Laurier, a multi-purpose vessel with many tasks, may well be moving in response to other needs and obligations -- servicing navigational beacons, search and rescue, and so forth.The August 19th update from Parks Canada is consistent with this; it indicates that
With the two Canadian Hydrographic survey launches, Gannet and Kinglett readied prior to arrival, the marine search began immediately with a side-scan sonar deployed from each launch. The side-scan sonar is towed from the stern of the launch vessel, offering an acoustic image of the sea floor. During surveys with the side-scan sonar, our team will systematically cover as much of the targeted area as possible.
It's a little frustrating that the update doesn't mention the exact location of the "targeted area," but it's clear that it's in Queen Maud Gulf, as they mention consulting ice charts of that area. I'm relieved to learn that this is indeed the area of their work, and that they're focusing on covering as wide of an area as possible in the available time; I'm certain that's the right approach. After all, readers will recall that, in the search for RMS Titanic, Bob Ballard's team and a rival French outfit were trolling the ocean back and forth in just such a manner; thanks to good luck (and perhaps some historical tips, or intuition), Ballard was the first to locate her.
As of August 29th, the Laurier seems to be retracing its route, which -- if indeed the launches did manage some means of operating independently -- could mean that it is returning to pick them up. Only time will tell.
Thanks as always for the updates, Russell.
ReplyDeleteAny idea of the range of the scope on each passage?
Ted, a good question. I think this will vary somewhat, depending on the width of the source beam, as well as on the acoustic shadow length, which would vary according to the depth of the water. The system shoots a beam off both sides of the boat, so the effective scope would be 2x the acoustic shadow. There's also an inverse correlation between frequency and range; if their initial scans are at lower frequency (and thus lower resolution), they could be wider. I suspect some compromise would have been made, as you'd need a fairly decent degree of detail to spot a ship, especially if you are looking for possible debris as well ... they could of course go back with higher-resolution scans of areas that show promise on lower-res, wider scans.
ReplyDeleteSo I guess the answer to your question is, we can't be sure!
A slight update: from Dave Woodman, I hear that, in general practice the two launches do not operate far from the Laurier; this is because of the significant logistical problems with establishing land-based camps or support for the launches. So if indeed they are still in the targeted search area, that would be a change from past practice.
ReplyDeleteThe latest from the Parks Canada Twitter feed:
ReplyDeleteUnderwater archaeologists complete survey for Franklin vessels. Large area covered in Arctic, no vessels found. Stay tuned.
So it's disappointing news, although the "large area covered" sounds hopeful, and their web page says that they have funding and resources to return next summer ... will keep everyone here posted with anything further I hear.