Tuesday, 16 August 2016

Steel-work on Sickle - Part 1

(Boat Sickle - posted by Alan)

(Retrospective post for Tuesday 16th August 2016)

Section near right hand front cut out and replaced.
This was our first visit to Stockton Dry Dock to actually look at work in progress on "Sickle".  When we were up just over two weeks ago, Graeme was still in the preparation as assessing stage, but now things were really starting to happen.

Basically when "Sickle" was first rescued around a decade ago now, the family restoring her put large amounts of effort, (and money), into replacing the bottom, and quite a lot of plate-work at the rear end, including long sections of side, and the counter and uxter plate, (the bit that sits above the propeller).  However whilst they had also thoroughly cleaned and painted steel forwards of this, in fact not a lot of replacement work had been done on the front of the boat.  Last year's survey had revealed most of the problems to be in this area, and this would now be the main focus of this programme of works.

Three things in particular were true.....

New steel let in on right hand side and being pulled in to shape.
Firstly when "Sickle" was converted to an ice-breaker in 1942, large amounts of additional internal steel had been added, not part of the original boat.  In particular long girders were supported by brackets along the hull-side, running through to brace the large ice-ram that was originally added to the front of the boat.  This extra steel-work  had remained in place ever since, so during her period as a largely unloved maintenance boat, rain water had continually run down and over and around these additions.  Furthermore the various muck and mud that no doubt regularly sat in the boat, probably trapped this water in more.  The end result was that the worst corrosion was around this additional steel-work, and much of the outside plating of the boat was now heavily thinned out at these points.

Repair to right hand side viewed from outside
Secondly the entire bow of the boat had been rebuilt as part of the ice-breaker conversion, to make it double thickness, with additional plate on the inside, between the knees.  Where the boat was corroded around the area of the front bulkhead, this extra layer would need to be cut back, to allow inspection and the required repairs in the outside layer of steel.

Right hand side shaped, and tacked in place, awaiting full fixing.
Finally, anyway, 80 year old boats regularly suffer around the knees, as water gets between the knee and the side of the boat, and corrosion builds up, trying to force the two apart.  There is a view amongst the specialist repairers that the boats built by W J Yarwoods at Northwich suffer more in this respect than those built by Harland and Wolff at Woolwich, because Yarwoods used less rivets on the knees, and as Harland and Wolff ones the two parts are joined in more places, maybe water can penetrate less.  Either way, "Sickle" now had significant corrosion in the hull sides around the leading knees, that were not tackled by her previous owners.

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