Smooth water transportation by means of
highly effective drag reduction system
Due to the large length of some
flat-bottomed boats, there is a
large contact surface between the
bottom of such vessels and the
water. This causes a lot of drag
during movement of the vessel
Photo of the cavity. View from the bottom. Picture was taken with a longer exposure time and
in the water. A team of TU Delft
scientists developed a solution to shows a time averaged wave profile.
reduce this drag substantially.
complicated to be applied and used.
Unique is the fact that the cavities
Moreover prior state of art is limited to
can be formed when a vessel moves
Flat-bottomed vessels are primarily
specific ship types and not suitable to
in forward as well as in backward
built for river and canal transport of
be used at all conditions.
direction. As installing this system does
heavy goods or persons. As some
not require major modifications of a
vessels are not self-propelled, they
Efficient design
vessel, this invention is more costneed to be towed or pushed by
The TU Delft invention solves existing
effective to apply than prior state of
towboats. These towboats can easily
technological problems by means of
art.
tow or push up to six such vessels. As
a simple and efficient design of the
As the system can be applied to
a result of the large contact surface
air cavities system. This air cavity
existing and newly built vessels,
of those vessels there is a lot of drag
system is a separate system that
this invention is very interesting
during transportation.
can be installed to the bottom of
for shipbuilding companies as well
existing vessels. The air cavity system
repairing companies and shipyards.
Drawbacks prior state of art
creates a number of cavities by
Fuel savings in the order of 10 till 20%
The TU Delft invention is based on
injecting compressed air. Depending
are realistic.
the principle of ship drag reduction
on the velocity of the vessel and the
by air lubrication. Isolating a part of
water depth a number of cavities in
Advantages
a hull from water by air reduces the
longitudinal direction can be selected
•h
igh efficiency at different velocities
wetted area, and thus the drag of a
to minimize the wetted area of the
and water depths
vessel. Many types of air lubrication
bottom. In order to guarantee the
• fuel savings 10 - 20%
have been suggested in the past, but
stability of a vessel with respect to roll
•m
ore cost-effective solution than
in spite of many investigations and
motion it’s possible to select a number
prior state of art
inventions, air lubrication has not
of cavities in the traversal direction.
•e
asy to manufacture, install and
been widely applied in practice on
operate
cargo vessels. The reason for this is
Forward and backward
•h
ighly functional in both forward and
that existing technologies have some
Besides controlling the number
backward direction
major drawbacks. Prior state of art has
of cavities it is also possible to
• c an be applied to existing and newly
a low efficiency in general and is too
control the length of the cavities.
built vessels
• s uitable for inland waterway
ships, barges, containerships and
cruiseboats
Ref. TU Delft OCT-13-079
TU Delft / Valorisation Centre
Mekelweg 4
2628 CD Delft
T: 015-2786751
www.patent.tudelft.nl
Photo shows an instantaneous wave profile of the developing cavity. Picture was
taken with a short exposure time.