Skeg

Skeg (pronounced skeg)

(1) In shipbuilding, a fin-like projection supporting a rudder and protecting the propeller(s) at its lower end, located abaft a sternpost or rudderpost.

(2) In the design of smaller boats, an extension of the keel, designed to improve steering.

(3) In the slang of naval architects (in certain contexts), a stump or branch (the after-part of a ship's keel).

(4) In the slang of the General Motors (GM) stylists, a “lower fin”, matching the upper on the rear of 1961-1962 Cadillacs.

(5) The fin which acts as a stabilizer on a surfboard.  To suffer some injury after being hit by one of these fins is to be “skegged”.

(6) In Australian slang, a surfer; a person who leads the lifestyle of a surfer (used also derisively in the form “fake skeg” of those who adopt the style an appearance without actually surfing.

(7) A type of wild plum (obsolete).

(8) A kind of oat (obsolete).

(9) In Northern English dialectal use, a look or glance.

(10) In many cultures, a slang term applied to youth suggesting slovenliness, a predilection to petty crime and other anti-social behavior; also used widely in Scottish slang for a surprising variety of purposes including legs, trousers, dirt, scotch eggs, sex and women of loose virtue.

1590–1600: From a dialectal term for a stump, branch, or wooden peg, from the Dutch scheg (cutwater), of Scandinavian origin and related to the Swedish skog and the Old Norse & Icelandic skegg (projection on the stern of a boat).  In some Nordic languages, skegg means “beard” and was from the Old Norse skegg, from the Proto-Germanic skaggiją, from the primitive Indo-European skek, kek-, skeg & keg- (to jump, skip, move, hurry).  The name of the English coastal town of Skegness is though a construct of the Old Norse skegg (beard) + -nes (headland) and was thought a reference to the geography, the original settlement situated farther east at the mouth of The Wash (thus jutting out like a beard from a face).  A link with the Old Norse name Skeggi is thought unlikely.  Skeg is a noun; the noun plural is skegs.

A gang of four Sceggs, Sydney, Australia.

The skegs of nautical architecture should not be confused with the homophone Sceggs, the acronym for students of Sydney Church of England Girls Grammar School (S.C.E.G.G.S.), seen also in the adjectival forms sceggesque & sceggish (one whose style suggests something similar to the stereotypical student of the school).  

Lindsay Lohan in wet suit, with surfboard, Malibu, 2011.  The stabilizing skeg is the black protrusion at the back of the board.

On nautical vessels, skegs where they exist fulfill a significant function but they are not an essential part of hull design.  A skeg is an external structural feature, a vertical tapering projection permanently fixed at the aft, usually close to the centre-line.  Most are located in front of the rudder and structurally can often be considered a sternward extension of the keel (the internal, longitudinal members which lend much strength of the hull).  Although in military vessels there are additional functions, the moist significant contribution of a skeg is in hydrodynamics, a skeg designed to influence the flow patterns and thus affecting the dynamics of both the rudder (which is usually in line with the skeg) and propeller(s).  The design is thus a finely tuned equation because while a skeg inherently induces drag, the way it alters the flow pattern can reduces the drag and resistance suffered by the rudder and propeller(s), essentially by transforming the turbulent characteristics of the flow to laminar at the stern.  Historically, skegs were a vital component in maintaining a course and that’s still an important consideration in smaller vessels but in larger craft, improved rudder and advanced navigational as well as stabilization technologies like thrusters have meant skegs are no longer of the same significance in maintaining directionality.

An US Navy Iowa class battleship, showing the inner set of propeller shafts wholly enclosed in a pair of skegs.  On the big ships, the skegs were designed also as load-bearing supports while in dry-dock.

In the modern age, skegs became an unusual feature on warships, a relative few so equipped and the designs varied, some with only a few of their shafts inside skegs while others encased all.  While the traditional design imperatives were shared with other ships, for navies, they also offered the advantage of affording some degree of protection for rudders and propellers against torpedo attack.  Historically, another important attribute of skegs was what they add to a hull’s structural strength, making the (inherently weaker) stern resistant to outside forces and all the last of the US Navy’s dreadnoughts featured skegs.  Their hulls narrowed towards the stern and to save weight lacked the sternpost plates the British, German and Japanese navies always fitted to their battleships and the skegs compensated for this, offering a hull with similar rigidity.

The US Navy’s South Dakota class battleships were fitted with an unusual set of skegs, the design dictated by the relatively short hull, the large outboard skegs helping to reduce the adverse effects of fluid dynamics induced by the hull’s abrupt end.

However, advantages in engineering and metallurgy meant much of the functionality afforded by skegs could be achieved in other ways and skegs became unfashionable in naval architecture.  The modeling and simulations made possible by supercomputers meant hull designs could be rendered which mastered the turbulence caused by fluid dynamics so rudders and propellers were less affected so the skeg was in many cases a source of performance-sapping skin-friction drag with little compensating benefit.  Indeed, not only did this hamper performance, in some cases excessive vibration was caused, something which could only to a degree be ameliorated by changes to the propellers’ configurations.

Cadillac’s Skegs, 1961-1962

Cadillac Coupe DeVille: 1959 convertible (left) & 1960 hardtop (right).

The 1959 Cadillac’s tail-fins are the best remembered and most emblematic of the brief, extraordinary era during which the absurdly macropterous flourished.  They’re rightly known as “peak-fin” but it’s a myth they were the tallest because, measured from the ground, those on the 1961 Imperial are about a half-inch (12 mm) more vertiginous.  The attractions of the style however were fading and from 1960, General Motors (GM) began to tone them down, Chrysler later following the lead (Ford never really got involved in big fins).  Another cultural phenomenon is that because of the large number of pink 1959 Cadillacs which now exist, many assume they were a common sight when new, the things perhaps made memorable by the sight of the one owned by the admirable Jayne Mansfield (1933–1967).  However, the factory never made a pink 1959 Cadillac and in the era, it was only in 1956 such a color was on the option list and Ms Mansfield had one of those while her 1959 convertible received a custom re-paint.

An inspiration, a step in the evolution and the result: A captured German V2 rocket (left), a full-size clay mock up of a design proposal (centre) and 1961 Cadillac Coupe de Ville convertible (left).  The clay mock-up was photographed at the General Motors Technical Center (1956) in Warren, Michigan.

For the 1961 the fins further were pruned but in compensation, the design staff added a "lower fin" and these, informally they called “skegs”.  While in a sense just another of the era's many extravagances, the outgrowths could have part of something even wilder because among the design proposals which emerged from the General Motors Advanced Design Studios was one which clearly was the ultimate expression of the motif of the 1950s which borrowed so much from the aerospace industry.  The proposed fins essentially were those of ballistic missiles which for decades were an evolution from the German Vergeltungswaffen zwei (V-2), developed first by the German military with the code name Aggregat 4 (A4).  Vergeltungswaffen is translated variously as "retaliatory weapons" or "reprisal weapons" but in English use is often written as “vengeance weapons”.  Aerodynamically, presumably the proposal has something to commend it and it proceeded far enough into the selection for an expensive, full-sized clay model to be rendered but ultimately the longer though somehow more restrained skegs were preferred.

1961 Cadillac Four Window "Flat Top" sedan (Body Style 6239, left).

Compared with some of the clay mock-ups, what emerged from the production lines hinted at rather than emulated missiles but should it be though what was rendered in clay was wild, the archives of the General Motors Technical Center contain a wealth of sketches of truly bizarre design studies which didn't make the cut to reach the hands of the modelers.  Presumably, those sketches which survive are those the stylists thought deserved to be remembered and there must of been those which even the designer concluded needed to be shredded.  As the archives also demonstrate, those who criticize the fins and "bullet" taillights on the 1959 Cadillac have reasons to be grateful even stranger things were rejected.  

Cadillac’s take on the “long & slightly less long” of it: 1961 Cadillac Six Window Sedan de Ville (Body Style 6329L, left) and 1961 Cadillac Town Sedan (Body Style 6399C, right).  In the brochures, the terms “Town Sedan” and “Short Desk” both were used.

One quirk of Cadillac’s brief embrace of the skeg was there were two iterations: skeg long and skeg short.  Whether in response to dealer feedback or in anticipation of some owners preferring their Cadillac in a more conveniently sized package, between 1961-1963 a “short-deck” option was made available on certain body styles.  Offered first on the six-window Sedan de Ville (as the “Town Sedan”), an encouraging 3,756 were built so the option was in 1962 offered on the four-window de Ville Sedan (Body Style 6398 and now called “Park Avenue”) but sales dropped to 2600.  The coming of the 1963 models marked the retirement of the short-lived skegs which thus ended their brief moment as something decorative although they continued the functional role in marine architecture.

1963 Cadillac Four-Window Sedan de Ville (Body Style 6239, left) and 1963 Cadillac Sedan de Ville Park Avenue (Body Style 6398, right).

Although smaller cars were selling well in other market sectors, among Cadillac buyers, the decline of interest in anything smaller was confirmed in 1963 when only 1575 of the Park Avenues were sold.  Although the 129.5 inch (3289 mm) wheelbase was common to the whole Sedan de Ville range, the “short deck” models were shorter by 7 inches (178 mm) for the first two seasons and an even more obvious 8 inches (203 mm) in 1963.  Space utilization was obviously a little better but the market had spoken; fewer than 8,000 of the short-deck models sold while the standard editions shipped in the tens of thousands, the flirtation with (slightly) more efficient packaging abandoned for 1964; in the course of the following decade, the Sedan de Ville would grow another seven inches (178 mm) and gain over 400 lb (181 kg).  It should be noted that by international standards, the truck capacity of even the abbreviated models was still quite generous, able effortlessly to accommodate two sets of gold clubs, something which later became a de-facto standard in assessing the practicality of sports cars.  Jaguar used this feature as a selling point when the XK8 (1996-2006) was introduced because it wasn’t possible with all versions of the old E-Type (1961-1974).

1958 Cadillac Series 62 Extended Length Sedan (Body Style 6239EDX, left) and 1958 Cadillac Series 62 Sedan (Body Style 6239, right).

There was in the early 1960s much criticism that “full-size” US cars had become too big but the “short deck” venture was a departure for Cadillac which had for some years been making things bigger and in 1958 the company had even included the “Series 62 Extended Length Sedan”.  The Series 62 Sedan was already an impressive 216.8 inches (5.5 m) long but the Extended Length version measured an even more imposing 225.3 (5.7), the additional 8.5 inches (216 mm) all in the rear deck, creating a more capacious trunk (boot).  There can’t have been many Cadillac buyers with that much luggage and the new model didn’t gain many sales although there was a healthy industry in jokes about Mafia functionaries and other figures in organized crime grateful finally to have more space to transport the bodies.  Unfortunately for Cadillac, there were only so many Mafia hit-men and despite 20,952 of the 103,455 (excluding Eldorados and “chassis only” sales) Series 62s produced in 1958 being the Extended Length Sedan (some 20%), it proved a single-season one-off. 

For 1963, the short-deck models returned for another dismal season but the skegs were abandoned, never to return.  The fins however the design studio found harder to forsake, conscious perhaps it was on the 1948 Cadillac they’d first appeared.  Then, modestly sized, they’d been an allusion to the tail-planes used on the twin-boomed Lockheed P-38 Lightning (1939) but the fashion had passed and the fins had to go so, inch by inch, there was a retreat from the heights and exuberance of 1959 until in 1966 the fins were vestigial, a hint which for decades would be retained.

1955 Ford La Tosca.

A half-decade before Cadillac decided their customers needed skegs, Detroit had pondered the idea.  Shown in 1955, Ford’s La Tosca (named apparently after Giacomo Puccini’s (1858–1924) three act opera Tosca (1900) although the intended connection seems to have been a general sense of the “emotional and dramatic” rather than the fate of the doomed protagonist) was unusual in that it appeared not as a full-scale “concept car” but in the form of a 3/8 scale model, used to demonstrate the possibilities offered by a remote-controlled chassis, directed through the medium of radio waves.  To achieve this, rather than build custom components (as the Pentagon would have done), Ford’s engineers dipped into the corporate parts bin and wired together the regulator and relay from a power window apparatus, the electric motor used to lower a convertible’s soft-top, a power seat mechanism and a standard, 12 volt car battery.  The system worked flawlessly and, depending on the topography, La Tosca could remotely be controlled at distances greater than a mile (1.6 km).  According to Ford records, the project began simply as an “…internal exercise to show students in the Advanced Studio how hard it was, even for professional designers, to design a car” but so long did the model take to complete (the complex curves and canted structures challenging to render in what was then the still novel fibreglass) that “mission creep” intruded, thus the radio-controlled chassis.

1954 Lincoln Futura (1954) and Ford Mystere (1955).  In Detroit, these were at the time typical of what was authorized to be built as "concept cars", machines destined for the show circuit to gauge public reaction.  If they now seem rather wild, much of what never left the stylists' (they weren't yet "designers") sketch pads and drawing boards truly was bizarre.  

Stylistically, La Tosca was in the vein of the corporation’s other concept vehicles of the era such as the Lincoln Futura (1954) and Ford Mystere (1955), the trio reflecting the way the industry was applying motifs from missiles and jet-propelled aircraft such as Perspex bubble-tops, tubes, fins and exhaust nacelles.  Most of these proved to be brief, though memorable relics of jet-age aesthetics, fads although elements were easily recognizable in the 1958 Lincoln and Cadillac of course would later take up the skegs.  The remote-control concept was ahead of its time though it did find a niche in model cars and aircraft.  In the twenty-first century new versions of the technology are now mainstream with cranes, trucks and trains routinely operated from sometimes thousands of miles away although usually on mine-sites and other remote locations (experiments with vehicles on public roads are being undertaken).  Despite these advances, the industry regards the technology as transitional and intends as soon as practicable to remove human (and thus costly and unreliable) element completely, re-allocating control to an entirely autonomous AI (artificial intelligence) model which, without complaint or toilet breaks, can be worked 24/7/365.