Study of Typical Cypriot Small Craft Of Medieval
Ata Atun
An
International Conference on Small Craft Related Sciences and
Engineering
1618 November 2006 BodrumTÜRKİYE
Study of
Typical Small Craft of Medieval
*
Abstract
The design concept of one of
the sailing boats of our voyaging ancestors has no fixed bow or
stern [1]. This concept of at least three thousand and five
hundred years old, may open up a new era in the form of sailing
boats and fishing boats, propelled by wind.
There are no forward and aft perpendiculars and the keel
itself turns in to perpendiculars at both ends. The curvature of
the keel is absolutely symmetric at amidship [1] and both
sections are in duplicate hyperbolic shape, touching each other
on the tip of xaxis.
Transversely the cross section is symmetric at centerline
and both halves are in identical semi elliptic shape, crown
downwards. The mast is placed right in to the geometric center
of the boat, longitudinally and transversely. The sail is in
rectangular form. There is no fixed rudder and an oar shaped
flat plank with a widening tip [2] is used as a rudder. Block
coefficient, Waterplane area coefficient, Midship section
coefficient, Longitudinal prismatic coefficient and Vertical
prismatic coefficient of this boat reveals very interesting and
interrelated ratios. [3]
Keywords : Bow,
stern,
1.
Introduction
Three thousand five hundred years
old boat of an amazing ancient design. The design concept reminds the early cars
with no reverse gear. Sailing ahead with this boat needs no maneuvering at all
times.
The peculiarity of this
boat is its doubleended shape. That is to say, there was little or no
difference in the shape of their bow and stern [4]. As long as ships were
steered by oars or by oarshaped rudders hung over one side near the stern there
was no reason to alter this doubleended design.
2.
Design
Longitudinal Cross section 
The boat is symmetric longitudinally
and transversely.
Main mast is located right in the
center of the symmetry in both directions.
The keel is not straight even
partially and is in the shape of two semi hyperbolas touching each other from
the lowest allowable x coordinate at the bottom of the vertical axis of
symmetry [5].
The keel on the tip of the bow
raises
Longitudinal Metacenter is
The design and stiffness values are
below.
KL =
KB =
KG =
KM_{L}=

The boat is propelled by wind
naturally and the rudder is not in a fixed place.
The rudder is in the shape of an ore
but rather more wider and thicker in size. Usually its place is to the post side
of the stern part at that specific sailing position. [7]
A thick rope knot is fitted to the
port sides of each end for the purpose of sliding in the rudder, according to
the direction of wind and sailing.
The rudder has no effect at all on
heeling or tilting. Thickness of the sides plank is around
The size ( width
x thickness) of the :
Deck planks
: 20 x
Bottom planks
: 15 x
Freeboard planks
: 20 x
Bulwark planks
: 15 x
Post size : 5.5
x
Post spacing :
Ribs are of 3 pieces and their
average lengths of each rib is
Design values 
Although the average speed of the
boat looks like around 6 knots per hour and the maximum speed 9 knots per hour,
according to the coefficient of form, it should be around 1525 knots, if not
capsized.
The sail area is
3.
Coefficients of
Form
[10]
a)
Block
Coefficient (C_{B})
Displacement
Volume,
Ñ
:
Depth to the Breadth, T
:
Water Line Length,
L_{WL} :
Water Line Breadth,
B_{WL} :
C_{B} =
Ñ (L_{WL}
x B_{WL}
x T)
=
C_{B
}=
b)
Waterplane Area
Coefficient (C_{A})
The water plane area, A_{WP }
:
Water Line Length,
L_{WL }:
Water Line Breadth,
B_{WL} :
C_{A} = A_{WP} /(L_{WL}
x B_{WL})
=
= 0.68

c)
Longitudinal
Prismatic Coefficient
(C_{P})
Displacement
Volume,
Ñ
:
Area of immersed Midship, A_{M
}: 1.265 m^{2}
Water Line Length,
L_{WL }:
C_{P }=
Ñ /
(A_{M }x L_{WL})
=
=
d)
Midship Section
Coefficient (C_{M})
Area of immersed Midship, A_{M}
:
Depth to the Breadth, T
:
Water Line Breadth,
B_{WL} :
C_{M
}= A_{M} / (B_{WL}
x T)
= 1.265 / (2.14 x 1.15)
=

e)
Vertical
Prismatic Coefficient
(C_{VP})
Displacement
Volume,
Ñ :
The water plane area, A_{WP }
:
Depth to the Breadth, T
:
C_{VP} =
Ñ
/ (A_{WP} x T)
=
= 0.78
4.
Conclusion
This ancient boat is very seaworthy
and speedy. Although the boat is not
stiff and the tilting or heeling is non stop, I believe the capsize possibility
is very low. [11]
After checking the coefficients of
forms, the speed turns about to be around 1525 knots. [12]
The results of the Block coefficient
and Water Plane area coefficient satisfies
the empirical formula C_{A} = C_{B} +
Every rope connected with the rudder
rigging was to have its purpose, the strains nicely calculated and so arranged
that practically all tension was taken from the rudder post when the boat was
under way. [14]
Since the Egyptian warships had a
stout metal ram at their bows [15], this proves the use of nails made of metal,
probably soft iron, in the construction.
5. References
[1] PhillipsBirt, D., A
History of Seamanship, Jarrold & Sons Ltd., Norwich, UK, 1971,
pp. 59
[2] Mondfeld, W. zu., Historic
ship Models, sterling Publishing
pp. 128
[3] Atun, A., Unsalan, D., Ship Construction for Merchant Marine Officers,
[4]
[5]
[6] Atun, A., Unsalan, D.,
Basic Ship Stability,
[7] Güleryüz, V. H.,
[8] Johnstone, P., The
Archaeology of Ships, Henry Z. Walck, Inc., NY, 1974. pp.10
[9] PhillipsBirt, D., A
History of Seamanship, Jarrold & Sons Ltd., Norwich, UK, 1971,
pp. 36
[10] Atun, A., Unsalan, D., Ship
Construction for Merchant Marine Officers,
[11]
[12] Atun, A., Unsalan, D., Ship Construction for Merchant Marine Officers,
[13] Atun, A., Unsalan, D., Ship Construction for Merchant Marine Officers, Near
East University Press,
[14] Culver B.,
[15] Cornwell,