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This has led to the birth ofa new construction
industry and the establishment of fabrication
yards around the coasts of Britain, France,
Holland, and Norway. Considering oil pro-
duction platforms alone, there are, at present,
11 being installed and a further 37 in the
course of construction. It is anticipated that
up to 80 platforms will be in position by 1980.
Basically the steel platforms consist of two
parts: a jacket, so called because it wraps
around the piles which secure it to the sea
bed, and a deck structure which supports the
various modules containing equipment and
necessary services. The two parts are fabri-
cated separately, the deck structure and
modules being installed after the jacket is
PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING, 1975
Scotland for the B. P. Forties Field (Figure
1). Both jackets are of similar design consist-
ing essentially of four main tubular legs
linked by a network of tubes joined together
by nodes. Internally there are a series of con-
ductor panels which, also, serve as stiffening
panels. In all, the jacket contains some 17,000
tons of steel but the reusable flotation tanks
and stabilizing spheres bring the total floating
weight up to 33,000 tons. The jacket is erected
on the flotation tanks in a horizontal position
and is up-ended through 90°, by controlled
flooding of the tanks, when on site in the
North Sea. It is then parted from the flotation
tanks and the deck structure added. In size
these jackets are about 150m in height and
ABSTRACT: This paper discusses the application of close-range photo-
grammetry to the measurement of two types of marine structure:
fixed-base offshore platforms and ships. Examples are given, with
results, of typical applications and the value of photogrammetry in
the measurement of such structures is assessed.
RésuMÉ: Cet article est consacré à l'utilisation de la photogrammétrie
des objets rapprochés pour mesurer des structures navales de deux
sortes, c.-à-d., des navires et des plates-formes à coque submergée.
Aprés avoir exposé des cas typiques, avec les résultats obtenus par
photogrammétrie, l'auteur propose une évaluation de cette méthode
de mesurer ces structures.
ZUSAMMENFASSUNG: Der Aufsetz befaßt sich mit der
Nahbereichsphotogrammetrie und ihrer Anwendung auf die Mes-
sungen von Schiffen und unbeweglichen Objekten im Meer (z.B. Öl-
bohrinseln). Typische Beispiele sowie Ergebnisse dieser Anwendung
werden angeführt und erörtert im Lichte der Bedeutung der Photo-
grammetrie für derartige Messungen.
transported out to its location and installed on
the sea bed. In the case of a drilling platform,
the jacket has horizontal panels which serve
to locate and support the well conductor
tubes.
Concrete platforms serve the same func-
tion as a support tower for the deck modules
and the conductor wells in the case of the
drilling platform, the major difference being
that they are fixed to the sea bed by their
self-weight, not by piling.
These massive structures are now ap-
proaching heights of 300 m as development
moves into deeper waters. Each represents a
multi-million pound project of up to two
years’ duration.
Typical of the steel jackets are the two re-
cently completed by Brown and Root-
Wimpey Highlands Fabricators Limited in
measure 90m x 75m at the base reducing to
40m x 35m at the deck level.
Owing to their size, weight, and complex-
ity, the fabrication of these structures has
created a number of problems in these early
days. One of these has been to devise an effi-
cient and accurate dimensional control sys-
tem. Such a system is essential on a project of
this kind in order to ensure a fit between
components when they are lifted into posi-
tion during erection. At present, dimensional
control measurements are made by using
conventional surveying instruments and
techniques but photogrammetry is being
considered as an alternative for certain units.
One consortium (Brown & Root—Wimpey
Highlands Fabricators Ltd) has, in fact, com-
missioned a feasibility study to look at photo-
grammetry and this has been carried out by
