Geophysical Prospecting, 2001, 49, 735–745 J.H. Hagedoorn – inventing the Hapa: A review of a geophysicist’s ‘other’ work and how it inspired others Theodor Schmidt* TO Engineering, Ortbu ¨ hl 44, 3612 Steffisburg, Switzerland Received July 2001, revision accepted July 2001 ABSTRACT This paper describes J.G. Hagedoorn’s work on ‘ultimate sailing’ – the combination of a manned kite and a water kite called a Hapa, constituting a minimal sailing system – and the way others have taken up his challenge to sail while suspended from a kite. Hagedoorn’s goal has not been entirely achieved, but ‘near’ and partial solutions have been reached. Kite-Hapa-sailing continues to pose a ‘Holy Grail’ type challenge to many kite-sailors. INTRODUCTION: EARLY HAPAS Besides his professional geophysical work, Hagedoorn had another scientific interest, which he pursued as an amateur. It is a field so exceptional that he was able not only to invent it and give it a name, but also to inspire dozens of enthusiasts and become known to thousands of people outside geophysics, and that with only two publications! The title of his 40-page principal monograph, Ultimate Sailing (Hagedoorn 1971), describes the subject. Hagedoorn managed to reduce the concept of the sailing boat, which usually consists of a hull, a keel or centreboard, a mast and a sail, to a simpler system consisting of a kite in the air, a line and a kind of water-kite for which he coined the name ‘Hapa’ (HAgedoorn-PAravane), liking its vaguely Polynesian sound. The components of Hagedoorn’s concept were already known. Kites have been used to propel boats for many years, beginning perhaps with the above-mentioned Polynesians and later the great thinker Benjamin Franklin, then in earnest by the Englishman George Pocock (1827/1851), who mainly undertook long journeys in southern England by means of his kite-powered carriage and who described man-lifting kites for nautical use. More recently kites have been used by members of the Amateur Yacht Research Society (AYRS) with whom Hagedoorn corresponded. His Hapa or water-kite is also not entirely original, similar devices having been used for mine-sweeping, fishing and oceanographic work. Many synonyms are in use, such as paravane and ‘chien-de-mer’ (sea dog). As early as 1845, a Dr Collodon operated a model kite-Hapa on Lake Geneva (see Fig. 1). Burgess (1939/1995) suggested sailing buoyant airships with paravanes. O.W. Neumark flew buoyant kites from motorboats, but lacked any sort of Hapa (Morwood 1961). Hagedoorn was the first to suggest coupling such a device to a manned kite, instantly forming a minimal sailing system, but still a proper one capable of travelling upwind. Air- inflated kites known as parafoils had just been invented and were used by parachutists to glide through the air a distance several times greater than the altitude from which they jumped. Hagedoorn’s concept was to equip such aviators with his Hapas, which they could fling into the water while still flying and, with sufficient wind, immediately begin to sail in this new mode, becoming ‘aquaviators’ capable of unlimited travel without even getting wet, as long as the wind lasted. The Hapa was thus not to be merely a sailing novelty or thought experiment, but a device for rescue and possible military use. In the early 1970s, Professor Jerzy Wolfe and his students at the Polish Aerodynamics Institute in Warsaw built and flew a ‘paravane hang glider’, apparently with many crashes, but I do not know whether there was any connection between Wolfe and Hagedoorn (Bradfield 1979). q 2001 European Association of Geoscientists & Engineers 735 *E-mail: [email protected]
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Geophysical Prospecting, 2001, 49, 735±745
J.H. Hagedoorn ± inventing the Hapa: A review of a geophysicist's
`other' work and how it inspired others
Theodor Schmidt*TO Engineering, OrtbuÈhl 44, 3612 Steffisburg, Switzerland
Received July 2001, revision accepted July 2001
A B S T R A C T
This paper describes J.G. Hagedoorn's work on `ultimate sailing' ± the combination
of a manned kite and a water kite called a Hapa, constituting a minimal sailing
system ± and the way others have taken up his challenge to sail while suspended from
a kite. Hagedoorn's goal has not been entirely achieved, but `near' and partial
solutions have been reached. Kite-Hapa-sailing continues to pose a `Holy Grail' type
challenge to many kite-sailors.
I N T R O D U C T I O N : E A R LY H A PA S
Besides his professional geophysical work, Hagedoorn had
another scientific interest, which he pursued as an amateur.
It is a field so exceptional that he was able not only to
invent it and give it a name, but also to inspire dozens of
enthusiasts and become known to thousands of people
outside geophysics, and that with only two publications!
The title of his 40-page principal monograph, Ultimate
Sailing (Hagedoorn 1971), describes the subject. Hagedoorn
managed to reduce the concept of the sailing boat, which
usually consists of a hull, a keel or centreboard, a mast and a
sail, to a simpler system consisting of a kite in the air, a line
and a kind of water-kite for which he coined the name `Hapa'
(HAgedoorn-PAravane), liking its vaguely Polynesian sound.
The components of Hagedoorn's concept were already
known. Kites have been used to propel boats for many years,
beginning perhaps with the above-mentioned Polynesians and
later the great thinker Benjamin Franklin, then in earnest by
the Englishman George Pocock (1827/1851), who mainly
undertook long journeys in southern England by means of his
kite-powered carriage and who described man-lifting kites
for nautical use. More recently kites have been used by
members of the Amateur Yacht Research Society (AYRS) with
whom Hagedoorn corresponded. His Hapa or water-kite is
also not entirely original, similar devices having been used for
mine-sweeping, fishing and oceanographic work. Many
synonyms are in use, such as paravane and `chien-de-mer'
(sea dog). As early as 1845, a Dr Collodon operated a model
kite-Hapa on Lake Geneva (see Fig. 1). Burgess (1939/1995)
suggested sailing buoyant airships with paravanes. O.W.
Neumark flew buoyant kites from motorboats, but lacked
any sort of Hapa (Morwood 1961).
Hagedoorn was the first to suggest coupling such a device
to a manned kite, instantly forming a minimal sailing system,
but still a proper one capable of travelling upwind. Air-
inflated kites known as parafoils had just been invented and
were used by parachutists to glide through the air a distance
several times greater than the altitude from which they
jumped. Hagedoorn's concept was to equip such aviators
with his Hapas, which they could fling into the water while
still flying and, with sufficient wind, immediately begin to
sail in this new mode, becoming `aquaviators' capable of
unlimited travel without even getting wet, as long as the wind
lasted. The Hapa was thus not to be merely a sailing novelty
or thought experiment, but a device for rescue and possible
military use.
In the early 1970s, Professor Jerzy Wolfe and his students
at the Polish Aerodynamics Institute in Warsaw built and flew
a `paravane hang glider', apparently with many crashes, but I
do not know whether there was any connection between
Wolfe and Hagedoorn (Bradfield 1979).
q 2001 European Association of Geoscientists & Engineers 735