The present paper is the second of three papers dealing
with the reconstruction of the Hjortspringboat. Of these three papers the two first are
being presented at ISBSA 8, while the third one, reporting on the sailing
performance of the boat, will be published in the autumn 1998.
Our predecessors 2500 years ago had the experience of building a
line of still more refined boats by a team of boat building professionals. According to
the characteristics of the trees at hand, each new boat would vary.
As the philosophy of the reconstruction was to build a boat as close as possible to newest
interpretation of the excavated Hjortspringboat, and as we did not have any experience in
boat design or manufacturing, we had to use modern theoretical tools.
The employment of these tools produced at the same time new knowledge as to the standard
of boat building in the Celtic Iron Age, compared with modern standards of
"similar" boats. Furthermore the prediction of the performance, compared with
the tests, gives new knowledge regarding the validity of these theoretical tools.
A line plan of the boat, taken from Fr. Johannessens drawing was
read into a computer.
From this computer program, shapes of the boat were printed out for use by the boat
From the same program were calculated the volume of displacement and the wetted surface at
different draughts (loads).
Through tests with the middle section of the boat (part of the wood training program), the
center of gravity of the paddling crew and the boat was determined, and the static
stability was calculated. The metacenter position is that close to the center of gravity,
that the boat can't be characterized as being very stable.
As to hydrodynamics we calculated different shape coefficients.
Furthermore calculation of resistance and effective power versus speed was performed. The
calculations shows, that 1500 watts (2 hp) is required in order to obtain a boat speed of
Paddle force and efficiency characteristics were calculated.
The stress and strain characteristics of the sewing material and
the seam construction were determined by tests.
Some strength and elasticity characteristics of the boat were