I’ve just discovered ‘Ship Nostalgia’, and am fascinated by the many posts which are critical of the ‘Northumbria’. I was closely involved with some research in the months before she was launched, and hope the following may be of interest.
A number of posters have hinted at the huge step forward in the size of this vessel, and I would like to emphasise this because everyone at the time was very aware of it! Factoring up the design from smaller tankers may in the end not have proved adequate, but little was available by way of an alternative. Computerised stress analysis was fairly well developed in theory, but was still severely limited by the computing power then available. The most up-to-date computer analyses of ship structures in Britain had only recently been completed by the Admiralty, and the British Ship Research Association (also based in Wallsend) was in close and confidential touch with them. As a result, Britain’s largest engineering consultants were engaged, in effect to try and predict the stresses within all parts of the hull. However, these predictions were restricted to the effects of static forces, ie excluding complex dynamic effects arising from the vessel’s normal environment! Seems strange, but that was where naval science was in the 1960s.
In parallel with the above research, Swan Hunter permitted BSRA to place a huge number of strain gauges at critical locations within the hull and, as noted by one poster, this may well have been the first time a control room was set aside on a vessel for the purpose of monitoring those gauges. I believe that post-launch and pre-commissioning an extensive set of tests were carried out at sea, and that in fact the strain gauge readings corresponded well with the computer predictions. That latter part of the research was published at the time by BSRSA and may now be in the public domain.
The ‘Northumbria’ was designed and built right on the leading-edge of computational analysis, and it is perhaps of interest that, simply onf the grounds of computational scale, the above research had to be done (albeit by an English company) using an American computer at a German university! The progress and outcome of that research were watched closely by the interested parties, which included both European classification societies (Lloyds Register and Det Norske Veritas).
I had the privilege of descending from the deck into the bowels of the hull for a short visit when the strain gauges were being placed, perhaps a rare instance of a ‘civilian’ being allowed close to the workface so to speak. The ‘Northumbria’ and her sisters still stagger when viewing the contemporary photos while under construction, and I can confirm that she was even more impressive when viewed from within!
(Sorry if some of the above uses some non-nautical terminology).