This will feature Lofting, its use and some of the history behind the "Black Art" of the Loftsman.
It was all started a long time ago with a wise old owl in the hayloft of the barn (only joking)
The Mould Loft at the Leith Shipyards of Henry Robb (one of two) date unknown.
(From the Loftsman collection)
The “Black Art” of the Loftsman, is even to experienced boat builders and to those who would love to build there own, something which tends to confuse and for some a skill to be avoided at all cost. Only due to the fact that it is so little understood and somewhat mystified.
So what is a Loftsman, and what is Lofting, or as I like to refer it “The Geometry of Shipbuilding”. So many people have asked me that and when you start to tell them, they just get a glazed look about them, most haven’t got a clue and that includes a lot in modern day shipbuilding as well.
The term Loftsman is still found in some shipyards and of course in the aircraft industry, and in the automotive industry it was referred to as a layout draughtsman.
To quote someone from somewhere,
"The shape of a ship's hull, whether it is slim and graceful or full and bulky, is the very essence of its character. This form determines the power required to drive it; it reflects directly the ship's speed; it determines the quantity of payload and the comfort and habitability within the ship; more important, it largely establishes the limits of safety and stability as well as the motion of the ship among waves."
Could not have put it better myself!
In our times nowadays the work of the Loftsman in a shipyard is carried out by no less than four different departments, being that the lines and the surface are done on computer aided design (CAD) you have the surface designer, and then all the plates and steel are produced by the CADCAM dept, then the Dimensional Control department look after the build accuracy of the ship and then they also have planning/quality departments who now do a lot of what the shipyard Loftsman did as part of his every day work.
It really is amazing to think that it now needs the combined efforts of four different departments to produce what the Mould Loft used to produce all as part of the job, always said that loftsmen were under valued and of course under paid!!!!!!!.
So I guess that’s progress for you. Every shipyard had of course slightly different ways of doing things, but the aim was the same for them all.
But it really is the most interesting of jobs for anyone who can, get there head around the basic building block of a ship or boat and in my humble opinion it was and still is the most important and skilled work in the shipbuilding process. (But then I would say that)
But dont just take my word for it, as descibed in his book Ironfighters, Outfitters and Bowler Hatters, the Author G.O'Hara tells pretty well how and what loftsmen did as part of the shipbuilding process in the yards of the Clyde from around 1950 to mid 1970's and (Reproduced in its entirety with the kind permission of the author.)
"Loftsmen balk at their collective synonymity with the 'black squad'. Detached and isolated between the drawing office and the shop floor in that what they do and what they made wasn't part of a ship, they nevertheless are an essential and intergral part of the traditional shipbuilding process. Loftsmen are responsible for taking the dimensions, scantlings, and details from drawings and plans,. Translating this information into templates, battens, ordinates, cutting sketches, profiles, margins and other data, whereby steel plates and sections can be identified, cut, shaped, prepared, rolled, formed, flanged and 'set-out' into the primary elements required for ship construction, including the incorporation of additional surplus for weld shrinkage, overbending and cutting allowances.
The summation of skills required for this painstaking job encompass a high threshold of interest, a three-dimensional 'seeing eye', virtually total comprehension of the subsequent fabrication, erection and launching operations, plus diligent dexterity in the art of measurement. All in all a fair spectrum of capability! Not surprisingly these high levels of aptitude were identified as the prime job specification elements required by respective yard managers, chief draughtsmen, fabrication and berth managers, for prospective loftsmen. This senior caucus took a high level of interest in the appointment of the head loftsman with more than a passing interest in the performance of his underlings. If the loftsman didn't get it right first time, then the downstream trades of platers, welders, caulkers and shipwrights would be involved in either considerable costly time consuming re-work, or scrapping of incorrect fabrications.
A blue collar profession who were part of the shipwright department, loftsmen fared better than their fellow ironfighters with almost white collar working environment. This 'perk' was not reflected in their collective adoption of office working apperal of collar and tie. Modesty, underwritten by conformity, resulted in nondescript sartorial anonymity. The donning of the traditional ubiquitous Clydeside garb of boilersuit underneath a working jacket, usually on top of a collarless shirt virtually hidden by a woollen faded tartan scarf. There remaining visible attire was topped by a worn-out, sweat-stained bunnet, with heavy duty boots as the habitual footwear.
The wide range of functions carried out by loftsmen, extended from the mundane setting out of the simplest superstructure feature, to the brain-racking traumas of comprehending a stern frame with twin screw propeller boss, bulbous bow, or a long sheered upper deck with flared fo'c'sle.
The loft carried an inordinate responsibility for the good name of the company. Traditional Clyde shipbuilders were aware of this burden from the inception of the industry. The warmest, quietest, driest, brightest, most spacious building in every yard was uaually the loft. This was necessary for essential temperature and humidity control, thus ensuring that the timber floor, incorporating the scrieve board on which the hull and deck lines were drawn full size, as well as all the wooden templates and battens, were kept dry and did not rot, warp, shrink or expand due to temperature differentiation. Any solace bestowed on the industrious occupants was a grudged benefit, often grudgingly regurgitated by polemical shipyard managers when annual wage negotiations took place!
Notwithstanding the new skill plateau that was quickly reached by all the steelwork trades, as a result of the wholesale adaptation of welded prefabrication methods, the responsibility for faultless geometry still remained with the loftsmen; whereas the empirical erstwhile method adopted for steel shipbuilding had been single frame----single plate erection sequence----utilising a greater combination of the individual skills of shipwrights, platers and loftsmen.
This method was a throwback from the times of wooden shipbuilding, when the keel was set out straight and true on the declivity slipways. Transverse ribs were erected at right angles to this keel using ropes and guy wires to retain them in tempory position, until the planks that formed the hull were attached longitudinally to these frames. Steel hulls duly replaced those made of wood. Timber frames were substituted with rolled sections, called either zed-angles or bulb angles, which were riveted to the shell or hull plating of the vessel.
This ancestral, laborious method of ship construction allowed the loftsmen the luxury of setting and fairing the steel frames in conjunction with the skills of the shipwrighs and platers. The more difficult task of fitting the steel plates, which were on over 50% of a ships hull, three dimensional shaped profiles, was initially undertaken by using the ships framing as a carcass to provide a solid full-size template for accurate measurement, thus preventing undercutting of the plates dimensions. This additional skilled operation gave birth to the new steel work trade of plater.
The onset of prefabrication with its hoped for reductions in cost and duration, removed the comfort of the loft being able to lift and verify difficult ship-shape profiles from the building berth. After dimensional scrutiny this information was passed to the plater to form the developed profile of such plates in the plating shop.
This new method effectively killed-off the need for shipwrights and in so doing elevated the standing in terms of technical competence and practical application of the loftsmen. Fabrication shops were added to every shipyard that now used welded methods of ship construction. Each shipyard had its own quirk to assist unit building techniques. These varied from the wholesale building of ship sections, usually upside down utilising the flatness of the deck, hold or tank-top plating which provided a sound working datum, to staggered splicing of shell or bulkhead plating that used the continuity of frames to provide sunsequent location aids for the next adjoining section. This subtle transition of shipbuilding technology was bourne totally on the competence of loftsmen assisted by the practical dexterity of platers, whose collective skills could fashion two-dimensional drawings into real fabrications.
The high quality of prefabricated ship sections, repetitively produced with consummate ease by loftsmen along the Clyde, inured shipyard management into another niche of self-induced complacency.
This traditional and adaptable method of steelwork development works very well, has worked very well... and will continue to work satisfactorily. A trite maxim that endorsed post-war thinking on most facets of ship construction (as proclaimed by ironfighters and outfitters)... but this edict was being expounded by managements.
Messer-Sicomat A.G. of Greisham, West Germany, revolutionised post-war shipbuilding and all other metal fabrication industries in the same dynamic all conquering style, as the Lincoln Welding Co of the U.S.A. had achieved with electric arc welding earlier this century. The introduction of 'one-tenth scale' profile burning of virtually every plate component, reduced the traditional workload of the template loft overnight. Where the loftsman was previously reliant on his ability to measure correctly, he now had to acquire a draughting dexterity of flawless accuracy that would enable him to make one-tenth full size sketches on special transparent plastic sheets. These sketches would be optically traced by a 'magic-eye' connected to multiple-head burning nozzles, mounted on a cross-rail above a table containing the plates, which would be profile burned to exact size and shape in a fraction of the time previously taken, using laborious tape and chalk line marking off followed by hand burning.
These machines, including tables, burning-heads operating console and magic-eye were not cheap! They cost tens of thousands of pounds in the late 1950's, but if they had cost millions they would still have paid for themselves in a relatively short space of time. This nascent technology was accepted unilaterally by management, drawing office, planning office, template loft and most of the platers and burners whose erstwhile jobs this new machine replaced. The process was so high-tech and successful in its day, that virtually every shipyard worker (including welders) whose shipyard invested in these machines boasted to there mates about what these Sicomats could do. Here was an example of management investing....and ironfighters responding....if only the Germans hadn't invented the machine first (sic)
The natural progression from profile burning was the wholesale use of jigs and fixtures, to assist the set up and fabrication of prefabricated ship units. Used extensively in virtually every UK manufacturing industry except shipbuilding, this technological advantage was never really applied on the Clyde until more than half the industry had vanished! Traditional shipyard managements weaned on a cocktail of semi-aristocratic arrogance, infused with autocratic self belief, propounded 'If we didn't think of that idea first...its not a good idea!' Such quasi-philosophical technical myopia would have been moderately funny...if they were referring to the inclusion of a' la carte menus in the shipyard canteen... (if the yard had a canteen).
Unfortunately, selective comprehension of methods and practises deployed in foreign shipyards was exactly the attitude emergent Japanese and European shipyards needed to assert their ever-increasing commercial advantages. The author goes on to tell a great history of shipbuilding and its demise on the Clyde in Scotland. (It is a must read for anyone with an interest in shipbuilding)