nautical technology 165
traditional two side rudders, it was also less vulnerable to collision and gave better
overall control of the vessel with a bar attached to the tiller at a 90º angle. The helms-
man handling the bar could stand higher and watch the action of the ship. When the
tiller was too long, the helmsman could not see and had to rely on commands called
to him from the quarterdeck (Gertwagen, 2004: 555).
That being said, fourteenth-century Catalan wrecks attest to the persistence of
older traditions and the creation of hybrid types. The Cultip IV carried two lateen
masts and stern quarter steering oars. The Les Sorres X carried one lateen mast but also
stern quarter steering oars, both with sternpost rudder. Belonging to local, coastal
and riverine shipping, these vessels may reflect the owners’ trial-and-error experimen-
tation with new inventions (Hamelink, 2004).
The great galleys, also influenced by the introduction of the cocha, adopted the
stern rudder without straightening the stern. Instead, a special stern rudder was devel-
oped to suit curved stern posts. Whereas on Genoese galleys stern rudders were fitted
with a tiller (as on the coche and carracks), on Venetian galleys the rudder shaft ended
simply in a circular or a spherical knob. Most probably the Venetian galleys had rudder
tillers which were removed when not needed. Mediterranean shipbuilders, however,
left the traditional two-side rudders to supplement the stern rudder. We await the
results of the research on the graffito found on the internal part of the bow of a
fourteenth-century Venice lagoon galley, representing a trireme with only a stern rud-
der on a straight stern. On the other hand, exactly such a rudder is depicted in the
iconography of a late-medieval Byzantine galley (Gertwagen, 2004: 559; McManamon,
D’Agostino and Medas, 2003).
Until the late thirteenth century, the lateen sail was predominant on both
Mediterranean war galleys and merchant ships. With the increase in ship size from the
late twelfth century, the yards of the sails, carried from the thirteenth century on two
big masts, could weigh up to 6.5 metric tonnes. The three-masted lateen-rigged ships
that required many men and a complex block-and-tackle system were correspondingly
heavier. When the cog/cocha was introduced into the Mediterranean, its square sail
was adopted in this region from the early fourteenth century. It was carried on one
mast and served for all kinds of weather, the expanse of canvas being enlarged or
decreased at need by the use of bonnets. Added lifts made hoisting the sails easier. A
more complex system of ropes allowed better control of the sail. A bowline prevented the
forward edge of the sail from curling away from the wind. The square sail allowed
the vessels to weather a storm astern better than the lateen sail, however, only when
there were carrying winds; to improve the cocha’s maneuverability, a lateen mizzen,
whose purpose was to improve bite on the helm and steering, was introduced close to
the stern. It was rarely handled at the same time as the mainsail, so there was no increase
in crew. This improvement, together with its hull form, enabled the cocha to make
round trips between the Mediterranean and the Atlantic and northern Europe. The
first evidence of the two-masted cocha in the Mediterranean appears in a Catalan
contract of 1353 (Gertwagen, 2004: 554–555).
In lateen-rigged ships, the sails had to be changed according to the wind force; in
large ships, this required a greater number of sailors than the average crew size of an
equivalent square-rigged ship. Indeed, the replacement of the three-masted lateens
by a single main square sail led to a reduction by half of the number of crew respon-
sible for managing the cocha: one man per 10 tons, compared to one man per five