In the latest Maritime Advocate, Douglas Lindsay puts forward a strong hypothesis as to the ultimate cause of the Stellar Daisy’s rapid sinking, recalling an earlier case and postulating that a systemic flaw in attitudes to speed of loading and unloading might gradually exacerbate pre-existing weak spots in hulls.
Lindsay said that the case reminded him of the loss of the coaster Rema some years ago, having loaded stones in Berwick-upon-Tweed for Thames discharge. “The normal practice in that trade was to load on the rising tide and sail immediately around high water, the berth being partially drying at low water.”
However, the Rema did not sail immediately, instead laying over on the berth for a tide and then sailing in early evening. It was a calm clear night with virtually no sea state, when somewhere off Whitby with just the watch officer awake, she suddenly put her bow under, stood on her nose and went down in no more than a minute, bow first and still at her full sea speed of around nine knots. The whole crew were lost.
Lindsay was asked to look into this loss. He said that it became clear that the ship had sprung a leak from sitting on the drying berth at Berwick. “Loading is by a fixed arm and the ship moves up and down under it to distribute the cargo along the length of the hold. Over time, a little hard hump had built up directly under the loading arm”. Lindsay observed that normally this would not matter because the loaded ships sailed immediately. Rema, however, did not, and almost certainly as a result she had strained herself drying out on the lump sufficiently badly to have opened up a leak into her hold. The lump was dealt with directly after the ship was lost.
Lindsay said that the worst conditions in which to spring a leak are in calm weather. “Silently the ship fills up and settles deeper in the water until the reserve buoyancy point is lost and she goes down like a stone”.
Only if the watch officer happens to notice that the freeboard is decreasing will the leak be detected. “This is what happened to the Rema, in the dark and I suspect is what happened to the Stellar Daisy”, said Lindsay.
Lindsay observed that ore carriers in his day had holds built almost like hoppers, to keep the cargo’s centre of gravity at a reasonable height so that the ship’s behaviour in a seaway was reasonably normal. This left a lot of space around the holds for ballast or void spaces. “Fill those up in a loaded ship and it wouldn’t take long for the ship to lose all reserve buoyancy”. In other words, there would be no need for the water ingress to mix with the ore and cause a gravity shift; just getting into the voids around the holds could be enough, if all buoyancy then vanished.
“For the Stellar Daisy to develop a list and flop over suggests that she had got virtually to the point of no buoyancy when something tipped her a little to one side. Free surface would do the rest, with the mass of water rushing downhill and giving the loss of GM a little added dynamic push”, said Lindsay.
He added that it was “a well-known part of the trade that loading operators can be fairly unsympathetic about finicky loading plans designed to reduce strains on a ship’s hull”, adding that “an elderly hull could be very susceptible to cracking from some unfair strains being put on it. Or it might just have been corrosion. A smallish leak would take some time to fill the void spaces of a hull as large as the Stellar Daisy’s, but it would do so with an inexorable certainty to the vanishing buoyancy point.”
Lindsay warns that “there is no substitute for the officer of the watch being alert to everything that is happening to and with the ship he has charge of.” email@example.com