Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Vessel
The invention relates to a towboat, as indicated in the introductory part of
claim 1. By "towboat"
is meant every kind of towboat which is constructed and equipped for towing,
hauling and
rescuing boats and ships and other seagoing structures.
Background
Vessels are in general designed and built for specific purposes. Thus, most
vessels are made as
special purpose vessels, such as ferries, fishing boats, fish carriers, tigs,
supply boats, fireboats,
boats for oil pollution service, etc., each having special structures and
specifications.
Simple combination-vessels are also known, for instance boats having holds
that can be used for
different purposes or in different ways. However, the development of
combination-vessels has
been limited. An example of an existing combination-vessel is a ring net
vessel, which can be
used as a trawler.
Towboats have been built over the decades, having a low freeboard, high engine
power and
special demands concerning stability. A conventional towboat must have a
towing hook or a
towing point positioned an adequate distance in front of traditional rudders
or propellers. This is
necessary in order to achieve good turning ability when using the rudder.
Towboats can be
equipped with different propulsion systems, both conventional, ASD, and so-
called "tractor" and
escort-boats. Such vessels have not been used for purposes other than towing,
and in some cases
fireboats and icebreakers. The special demands on stability etc. have made it
difficult to modify
towboats to enable them to be used for other purposes, in periods when they
are not used for
towing. Thus, nowadays towboats are purely special purpose vessels, having
relatively high
operating costs.
In GB patent application 2.071.580 - (Van Balen), a vessel is described, which
must be
characterized as an early version of what now is called a "service vessel for
offshore work". The
main feature of this vessel is that the shaping of the sections at the
waterline is such that they can
be extended to increase the draught, if it is to be used as an open sea
towboat.
The known vessel can be used for open sea towing, but can not be used as a
towboat or as a fish
carrier, because it is too big, it does not have a towing hook, which a
conventional towboat
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needs, and furthermore, the distance between the rudder and a possible towing
point is too short
in relation to the distance between the towing point and the bow, among other
things.
In Norwegian patent publication 132.896 - (Pran) there is also described a
vessel for offshore
work, towing in open sea and anchor handling. A relatively small tank and a
larger hold is
suggested. In combination with container load on the deck, this results in
poor stability.
Object
The main object of the invention is to provide a towboat that can be used for
other tasks,
possibly simultaneously. The purpose of this is to arrange a vessel that has
satisfactory properties
for several tasks. The switch-over from one task to another should be possible
with a minimum
of readjustment and a minimum of time delay.
In particular, it is an object to develop a towboat, which is suited for
transport of living fish,
possibly with simultaneously towing, and which possibly is provided with
equipment for
counting fish, delousing fish and similar. It should also be possible to adapt
the vessel for other
purposes, such as ice breaking and in connection with deployment of oil booms
and/or sucking
up pollution.
The invention
The invention is stated in claim 1. Further preferred embodiments of the
invention are indicated
in claims 2-7.
A vessel according to the present invention can funciton as a fish carrier
function and as a
towboat. This can be acheived by utilizing the tank volume to obtain better
stability. By filling
the tank with water or with water and fish, or possibly other fluids a stable
ballast can be
acheived in novel manner.
Such a vessel can, alternatingly or simultaneously, be used for towboat
operation and as a fish
carrier. When used as a towboat, one will provide as most mass as possible by
filling the tanks to
the maxumum with water or water and fish, or other fluids.
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Fish carriers and towboats of today have high downtime. With the vessel
according to the
invention, it is possible to use the same vessel for both purposes, and
possibly others, without
lengthy preparation.
By filling the tanks with water, or possibly with water and fish, the weight
is increased and the
freeboard is lowered. This again results in higher effective pull and higher
otter-effect when
towing. Besides, the stability is increased, which allows for a bigger engine,
which results in a
higher pull ("ie bollard pull").
Another, and a substantial advantage, is that in rescue operations, for
instance when pulling off
ships that have run aground with a tugboat, one gets substantially increased
mass and hence
increased pulling force.
Alternatively, the vessel can be arranged with fixed ballast, so that the
demand on stability is
fulfilled also with empty or partially empty tanks.
Example
In the following, the invention is described in further detail, with reference
to the drawings, in
which:
Fig. 1 is a side elevation view of a vessel according to the invention, which
is arranged with
an engine room at the stern and a hold midships,
Fig. 2 is an equivalent view of an alternative embodiment, which in addition
can be used as
an icebreaker and a firefighting vessel, and
Fig. 3 is an equivalent side elevation view of a further embodiment, where the
engine room
is positioned midships in connection to the hold and with a double rudder
propeller
unit ("tractor")
In Fig. 1 a vessel according to the invention is shown, in which a hold 11 is
arranged midships.
At the rear end of the hold 11, an engine room 12 is arranged with a single or
a double
propulsion engine 13. At the forward end of the hold 11 there is space 14 for
day room, ballast
tanks or similar. A hydraulically controlled hatch 15, 16 is arranged at the
bottom of fore and aft
of the hold 11, for filling and evacuation of the same. The hold 11 can
possibly be divided into
multiple separate parts.
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The vessel has a bow thruster 17 and also an additional side thruster 18
arranged in the hull, in
front of a propeller 19 and a rudder 20. Between the stern and a deck house 27
there is arranged
a deck 21, possibly with coaming and hatches 39.
At the rear end of the deck house 27 there is arranged a towing hook 22 and a
towing block 23.
In the example, these parts are arranged approximately midships. In a
conventional boat type,
they can be arranged between the rudder stock and midships. Approximately at
the centre of the
deck 21, in longitudinal direction, astern of a hatch, there is arranged a
towing bridle 24 over a
winch 25 with a bobbin winder 26. With such equipment, the vessel can be used
as a towboat in
an ordinary manner, if the vessel has the required stability in regard to the
pulling force (bollard
pull).
The deck house 27 has a companionway 28 leading to the engine room 12, through
a passage 29
that is on the side of the hatch of the hold 11. The passage 29 can, for
instance, rise up to the
level of the rail, while the lower part is recessed below the deck, in the
hold 11.
On the opposite side of the hatch of the hold 11, there are arranged two
channels 30 for air inlet
and exhaust discharge, respectively, the latter leading to a funnel 31
protruding up and out from
the deck house 27. Inside the deck house 27 there are arranged pumps and other
equipment for
handling cargo, for instance living fish. Above the deck house 27, there is
arranged a crane 32,
an automatic sorter 33 and a light boat 34.
In front of the deck house 27 is the superstructure 35 of the vessel, with its
wheelhouse and crew
facilities in a known manner. The vessel has rubber fenders at the bow and at
the stern 36, 37,
and a bulbous bow 38.
This example of an embodiment or the invention can be modified in different
ways, as will be
apparent from the following. In these Figs 2 and 3, the same reference numbers
are used for
equal or corresponding elements and parts as in Fig. 1.
Fig. 2 shows an alternative embodiment with an icebreaking bow 40, a water
cannon 41 on the
top of the superstructure 35 for firefighting, and a cloak 42 under the towing
bridle 24. The cloak
42 has an entrance door 43 for access down to the engine room 12.
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Hence, this example has the advantage of a still greater range of uses, as it
can be used
alternately, and with short switch-over time, as a towboat, a fish carrier,
ice breaker and a fire-
float.
Fig. 3 shows an embodiment with a propulsion machine 50 arranged midships in
an engine room
51, and with a double rudder propeller unit 52 extending downwards. The engine
room 51 can
have the shape of a shaft. Below the forepart of the vessel, there is arranged
a combined foil and
docking support 53, and under the stern a skegg 54.
With this propulsion system, the towing line 55 can be inserted in the stern,
below a towing
bridle 56, and further onto the towing winch 25. The towing hook 22 can in
this case be moved
astern because the turning characteristics, which are required on a
conventional towboat, are not
necessary due to the location and type of the propeller.
The vessel can also be formed with other types of propulsion units than the
illustrated double
propeller unit 52, for instance a propulsion unit of the Voith Schneider-type.
Alternatively, a
diesel-electric aggregate that gives electricity supply to an electric motor
below the stern, can be
arranged in the engine room 51. Other propulsion systems may also be of
interest, such as
waterjets and integrated electric engine propellers.
With a so-called ASD-solution with two propellers astern, it is possible to
have a towing winch
in front of the superstructure, with a towing point at the bow.
This vessel can be constructed to have a small freeboard when the hold 11 is
filled with water, or
possibly also contains fish. This contributes to good stability, which is of
particular importance if
the vessel is used as a towboat in this situation: In this way a vessel is
obtained, which can be
better utilized, without downtime and with minimal preparations when
alternating between
different jobs. If the vessel has been used as a fish carrier for
transportation of fish, for instance
from a net cage to a fishmanger, and the hold 11 has no water, water can
quickly be filled into
the hold 1 l, so that the boat enters a towboat configuration. This may also
take place when the
vessel is on the way between two job locations.
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A particular advantage of the vessel according to the invention is that it can
be used for at least
two substantially different purposes simultaneously. Previously, two different
vessels where
built for such purposes.
Compared to a fish carrier, the extra costs will mainly be the costs for
fenders, towing hook,
towing winch and some additi~nal engine power. Since both towboats and fish
carriers
nowadays have lengthly downtime and seldom can be used effectively, the
exploitation ratio can
be substantially enhanced due to the invention. In practice, this vessel can
tow and transport
cargo simultaneously. This is a development that can have a large utility
value beyond the
economic aspect. It will for instance be possible to have more vessels
available, strategically
located at selected places along the coast, which can tow fish farms when
algal problems or ice
problems makes it necessary to move net cages at short notice.
Regarding emergency preparedness, it will be a great advantage for costal
areas to have more
vessels available nearby, which can be brought into action at shipwrecks and
similar. The vessel
according to the invention can then be used both for towing and drainage, as
pumping facilities
can easily connected to a suction hose and the hold can provided room for
sucked fluid. In this
manner, a new type of rescue vessel is obtained. By furnishing the vessel with
fire extinguishing
equipment and a ice breaking bow as shown in Fig. 2, the range of use will be
widened further.
Both amendments will imply relatively low additional costs.
In conjunction with the deck house 27, different types of equipment for
processing fish can be
arranged inside or outside, such as counting equipment, sorting equipment,
delousing equipment,
cleaning equipment, RSV installation, aeration plant and similar. Moreover,
there can be
provided additional drainage pumps for emergency pumping or drainage of oil
spillage, or
drainage of wrecked boats.
The deck area and the hold can also be used for transport of oil booms, for
deployment in
polluted sea areas, and for equipment for suction of oil from oil booms.
Furthermore, the vessel according to the invention can be equipped with
facilities for rendering
ballast water harmless, for instance by radiation treatment, including ballast
water from ships
and other marine constructions.
