CA1309303C - Ship bottom form - Google Patents
Ship bottom formInfo
- Publication number
- CA1309303C CA1309303C CA000529311A CA529311A CA1309303C CA 1309303 C CA1309303 C CA 1309303C CA 000529311 A CA000529311 A CA 000529311A CA 529311 A CA529311 A CA 529311A CA 1309303 C CA1309303 C CA 1309303C
- Authority
- CA
- Canada
- Prior art keywords
- ship
- elements
- ice
- centre line
- guiding
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000003643 water by type Substances 0.000 claims abstract description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 21
- 238000001816 cooling Methods 0.000 claims description 6
- 239000007787 solid Substances 0.000 description 7
- 230000008901 benefit Effects 0.000 description 6
- 230000002349 favourable effect Effects 0.000 description 5
- 238000010276 construction Methods 0.000 description 3
- 230000003292 diminished effect Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 230000001133 acceleration Effects 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000009533 lab test Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
Landscapes
- Hydraulic Turbines (AREA)
Abstract
Abstract:
The invention relates to a ship intended for operation in icy waters, the hull of which comprise a generally horizontal bottom part and a bow portion that breaks ice downwardly. In order to achieve an effective guiding of broken ice chunks to the sides without increasing the draught of the ship noticeably and without impairing its seaworthiness, at least two but preferably three or more list-like guiding elements are arranged one after another on the bottom part of the ship on both sides of the centre line, which elements are obliquely arranged with regard to the centre line.
The invention relates to a ship intended for operation in icy waters, the hull of which comprise a generally horizontal bottom part and a bow portion that breaks ice downwardly. In order to achieve an effective guiding of broken ice chunks to the sides without increasing the draught of the ship noticeably and without impairing its seaworthiness, at least two but preferably three or more list-like guiding elements are arranged one after another on the bottom part of the ship on both sides of the centre line, which elements are obliquely arranged with regard to the centre line.
Description
1 30~303 Ship Bottom Form This invention relates to the design of the bottoms of ships adapted for operation in ice-filled waters.
A considerable part of the adverse effects on the forward movement of an ice-breaking ship operating in icy waters is due to the frictional work that broken chunks of ice exert on the sides and the bottom of the ship. By directing at least a large proportion of the ice chunks away from the drive channel, under the edges of the solid ice sheet, this friction will decrease. At the same time this also gives rise to the advantage that the propellers of the ship are protected from the broken ice,~and that the forward movement of ships following the ice-breaker in the drive channel is made easier.
Many different ships' hull designs have been produced in order to direct chunks of ice away from the underside of a ship. For example, in Canadian Patent No. 1,253,746 a ship is described in which a wedge-shaped plow, extending from the bottom of the stem line and diverging in the direction back-wards, removes the ice chunks far beyond the reach of the propellers of the ship, and to a great extent forces them below the edges of the solid ice field. The drawback of such a solution is, however, a poorer seaworthiness and larger driving resistance in open water conditions in comparison with a conventional ship's hull. A stationary, massive plow construction also permanently increases the draught of the ship and decreases its displacement.
Another way of directing ice chunks away from under the bottom of a ship is shown in German Application Publication DE
2112334, according to which a vertically projecting, relatively high plow structure is fitted to the bottom of the ship. This structure is intended for cooperation with a twin-stem ice-breaking bow that collects about 50 % of the ice in front of the ship into a channel formed between the two stems.
~*~
.i'3;'~.L?~
1 3nq30~
Under these circumstances, the plow structure must provide proper sideways transport of about half the amount of ice chunks broken by the ship, and consequently, must have a great vertical height and must be of an extremely rigid construction. Such a plow structure considerably increases the forward moving resistance of the ship, firstly, because the twin-stem configuration provides inferior ice-breaking qualities, secondly, because there will inevitably be ice cloggings in the channel between the stems, and thirdly, because about half the ice to be broken is collected into a narrow channel and forced downwards, against its natural buoyancy, and then is forced sidewards. Further, the vertically high plow structure provides a permanent increase in the draught of the ship. Because of the considerable height of the plow structure, strong water currents will occur at the outer sides of the plow elements and at their lower edge. These water currents are likely to suck chunks of ice back against the bottom of the ship.
Canadian Patent N0. 1,276,508 discloses a ship bottom with plow elements that are foldable into cavities. Thereby the forward moving resistance of the ship in open water is reduced, the seaworthiness and maneuverability of the ship is improved and the draught of the ship with the plow folded remains "normal". The drawbacks of this solution include a considerable forward moving resistance in ice conditions and strength problems, because the impact of ice chunks against the plow causes high loads. It is also difficult to provide existing hulls with such an arrangement.
The object of the invention is to create a novel, more efficient and less harmful arrangement for directing broken ice chunks to the sides, away from under the bottom of an ice-breaking ship being otherwise designed for highly effective ice breaking, that is, ice breaking with minimized energy consumption. A further object is to create an arrangement, which does not cause any substantial increase in the draught of the ship and which is easy to make strong in relation to the load caused by the impact of broken ice chunks. An object "~ ;, i~
3 1 3 " 9 3 0 3 of the invention is further to create an arrangement, which is easy to install when modifying existing ships.
According to one aspect of the invention there is provided a ship intended for operation in icy waters, the hull of which comprises a generally horizontal bottom portion and a bow portion designed for effective ice breaking, in which ship said bottom portion is provided, at both sides of a longitudinal centre line of the ship, with a plurality of consecutively arranged list-like guiding elements for sideward removal of broken ice chunks, said elements being arranged obliquely to said centre line and having a height measured perpendicularly to the horizontal bottom portion such that the sum of the average heights of the list-like elements on one side of said centre line does not exceed 120% of the limit lS value of the ice-breaking quality of the ship.
The term "generally horizontal bottom part" generally means a completely flat bottom between the sides of the ship, but the term does not exclude the possibility of forming the bottom of two parts arranged at a small angle relative to each other along the longitudinal svmmetry plane.
In the following disclosure, the concept of the limit value of ice-breaking quality means the thickest ice a ship is able to break during continuous advancement. This feature is mostly the basis for planning a new ship, and for every existing ship a strict value for this feature is defined. A
bow portion which breaks ice favourably means a bow that mainly breaks the ice by means of downwards bending, for example according to Canadian Patent No. 1,253,746. When the angle of the stem line to the water line plane is small in the lowermost part of the stem line, the velocity downwards of the broken ice chunks will be reduced before they meet the plow or guiding surfaces in the bottom of the ship.
In the invention, at least two but preferably a greater number of list-like guiding elements are arranged on the bottom of the ship, on each side of the symmetry plane, which . ~ -3a 1 3nq ~ 03 elements guide chunks of ice that the bow has broken to the sides away from the underside of the ship. According to known technology, one single plow element guides the broken chunks of iC2 to the sides. According to the present invention, several guiding elements arranged one after another perform this guiding procedure. This makes it possible for some of ~.j r, ~
4 1 3"~q303 the chunks of ice to slide below the edges of the forwardly positioned elements, i.e. the vertical height of the guiding surfaces may be considerably lower than is the case when one single element must guide all the chunks of ice away from the underside of the ship. When the chunks hit the first guiding surface, they receive a lateral component of motion, which assists the operation of the guiding surfaces arranged more rearwardly.
The benefit of the invention is hereby based on the fact that the draught of the guiding elements may be considerably smaller than before. The advantage of minimizing the total draught is of first-rate importance, especially for river ice-breakers. Many other benefits are, however, derived from the arrangement of the present invention. The small vertical lS dimension of the guiding elements also considerably diminishes the generation of harmful water current below the edges of the guiding surfaces. These turbulent water currents, which are likely to bring chunks of ice to the wrong side of the plow element, are due to the overpressurized state in front of the plow in comparison with the rear of the plow. The impact that the chunks of ice direct against the guiding element is considerably stronger when there is just one guiding element meeting the chunks. Moreover, the momentum of the impact is a lot greater when a guiding element of large vertical extension is used. The invention also has the advantage that the constructional and strength problems encountered during the construction of hulls are more easy, simple and economical to solve than in the known technology. The physical properties of the elements are especially important when turnable guiding surfaces according to Canadian Patent No. 1,276,508 are used.
In accordance with the present invention, it is possible to arrange the guiding elements more favourably in the bottom of the ship than in the known technology. When just one plow element is used, the front edge of this has to be both pointed and essentially closed. According to the present invention, no single plow element has to take care of the complete removal of the chunks of ice alone, so for example the forward ~W
1 3nq3~r~,3 elements may be placed closer to the bow of the ship, even partly in the actual bow portion, so that a rather wide gap can be between the opposite guiding surfaces. Opposite guiding surfaces may also be placed at different longitudinal levels so that a gap may be formed between the elements in the longitudinal direction, which gap allows a non-turbulent water current to the rear of the guiding surfaces. Chunks of ice that move with the water current will encounter another guiding surface later on.
In ice-laboratory tests, the function of the invention has been found very good. It has been proved that the guiding performance of four guiding surfaces arranged one behind another is almost equal to one ice plow, when the vertical height of the guiding surfaces is 1/8 and the height of the ice plow is 1/2 of the limit value of the ice-breaking quality. The solution according to the invention, however, offers a considerably smaller driving resistance both in open water and in ice-filled conditions. At the same time the draught of the ship is considerably reduced.
In a preferred embodiment of the present invention, at least a part of the guiding elements, preferably those arranged afterwards, together with corresponding elements on the opposite side form a sharp-edge diverging rearwardly as a list-like plow. It can be ensured in this way that the drive channel is efficiently cleaned of chunks of ice. The outer surface of the guiding elements is preferably vertical to a horizontal plane, so that the guiding of the chunks of ice is made as efficient as possible. The inner surface of the elements, however, preferably forms an inclined surface with respect to the bottom of the ship. This is a favourable embodiment both in view of achieving a non-turbulent water current, and with respect to constructional considerations, in view of achieving a strong structure. Further, this arrangement facilitates removal of the ship when it has become jammed upon a bearing layer of solid ice. The guiding elements should preferably have a longitudinal extension that reaches to the sides of the ship, in order to guide the chunks ~",.i,BJ
6 1 3nq303 of ice deeply enough under the solid ice field. The vertical height of the guiding elements may be freely altered according to the desired level of ability to remove chunks of ice. In general, the height of the elements may be lowered if the number of elements is increased. When the heights of the elements taken altogether are 50-120% of the limit value of the ice-breaking quality of the ship, the best results are generally achieved. When a ship is designed for moving forward with a low speed, a fair result may be achieved with guiding elements having a total height of only 20% of the limit value.
The guiding elements are arranged obliquely with regard to the symmetry plane of the ship. The angle between the element and the symmetry plane is preferably 15...45. When two guiding elements form a plow between each other, the angle between the sides of the plow accordingly is 30...90.
In one embodiment, cooling tubes from the cooling system of the ship machinery are placed within the guiding elements.
This is an efficient arrangement for achieving the desired cooling, because there is a strong current of cold water around the elements. A further advantage is that the heated guiding elements produce a thin layer of water between the ship and the solid ice field when the ship has become jammed.
The removal of the ship is then made considerably easier.
The outer surfaces of the guiding elements should preferably be made concave. The acceleration in the lateral direction of ice chunks that are guided along these surfaces are then made almost constant, and the guiding action is likely to succeed better. In one embodiment, the guiding elements are made turnable in to the hull of the ship, as described in Canadian Patent No. l,276,508. In this way, the draught of the ship may temporarily be reduced, and the maneuverability and the seaworthiness in open water conditions is improved.
In connection with the guiding element according to the invention, air-bubbling openings according to Canadian Patent No. 889,081 may be used, in order to diminish the drive ~ .:
~ L~ ~
1 3nq3~3 resistance of the ship.
Preferred embodiments of the invention are described in the following with reference to the accompanying drawings, in which:
Figure 1 is a schematical side view of a ship's hull according to the invention;
Figure 2 is a bottom plan view of the hull of Figure l;
Figure 3 is a bottom plan view of another embodiment of the invention;
Figure 4 is a bottom plan view of a third embodiment of the invention; and Figure 5 shows, in a sectional view, the guiding elements of Figure 2 in the plane A-A.
In the drawings, reference numeral 1 relates to the bow portion of a ship, which bow has a configuration that breaks ice favourably. In a favourable embodiment, the configuration of the bow in horizontal sections is round, and the angle a of inclination between the stem line and a horizontal plane is, at the ice-breaking zone and below this, at most 40, preferably at most 18. The sides 6 of the ship are vertical or inclined in a direction upwards and outwards, and they are preferably attached to the horizontal bottom 2 of the ship with roundings. The bottom 2 may also be formed of two parts so that the parts form a small angle between each other along the longitudinal symmetry plane or centre line 5. Reference numeral 4 relates to the constructional water line plane of the ship.
On both sides of the centre line 5 at the bottom 2 of the ship, a number of guiding elements 3 are arranged in succession and are placed obliquely at an angle b with regard to the centre line. The angle k is between 15 and 45.
According to Figure 2, the guiding elements 3 are arranged symmetrically on both sides of the centre line 5 so that a number of sharp-edged plows are formed one after another at the bottom of the ship.
At least two, and preferably three or a greater number of such guiding elements 3 are provided, one after another. In 1 3~97)07' the lateral direction, these guiding elements have an extension generally to the side surface 6.
In Figure 3, an alternative arrangement of the guiding elements 3 is illustrated. The guiding elements 3' situated nearest to the front are arranged at a distance from the centre line 5 so that quite a large gap 10 is formed between the two opposite elements. By this arrangement, one may place the guiding elements closer to the bow 1 of the ship. At the same time, the strain that the broken ice directs against these elements is favourably diminished. The vertical height of the elements 3' is growing in the direction backwards in a preferred embodiment. The guiding elements 3'' are arranged at different levels in the longitudinal direction so that a gap is formed in the longitudinal direction between the elements 3 " located at opposite sides of the centre line 5.
By means of this arrangement, a fluent flow of water is achieved to the inner side of the elements. By this means, the flow of water beneath the sides surfaces of the elements 3'' is diminished, as well as the sliding of ice chunks to the inner side cf the elements. The gap between the guiding elements 3 " is small enough not to allow large amounts of ice to pass through this gap; it is however preferred to arrange a pair of guiding elements 3 that are connected to each other behind the leading guiding elements 3''.
In Figure 4, an embodiment is illustrated having elements with curved side surfaces. By means of this arrangement, the acceleration of the ice chunks in the lateral direction is made more or less constant, i.e. the force effect between the ice chunks and the guiding elements is constant along the whole sliding surface. By this means, the sliding of ice chunks beneath the guiding elements is also better controlled. In the case of the curved guiding elements according to Figure 4, the angle k is calculated from the beginning and end points of the side surface of the guiding elements.
Figure 5 shows a sectional view of the guiding element 3 in the plane A-A (Fig.2). The outer side 7 of the guiding .Y~, s.L
1 3n,9303 element 3 is arranged in a vertical plane, or mainly perpendicularly to the bottom 2. The inner side or inner surface 8 is, to the contrary, preferably arranged to form a sloping surface with regard to the bottom 2. This is a favourable arrangement in view of the water currents, because turbulence is diminished in this way. The vertical extension k of the guiding surfaces should be dimensioned so that the sum of the heights _ of the elements arranged one after another is at least 20%, and preferably at least 50~, of the limit value of the ice-breaking quality of the ship. The heights _ of different guiding elements are not necessarily the same. In view of the constructional strength, it is favourable to arrange the guiding elements so that the strains that the ice chunks directed to different elements are mainly of the same class of magnitude. To this end, the heights _ of the elements situated at the front of the ship should be lower than the height of the elements at the rear. As stated above in connection with the guiding elements 3', the height _ may be arranged to increase in the lateral direction. The sum of the heights _ is hereby calculated according to the vertical height at the middle part of each element.
In one embodiment, tubes connected to the cooling system of the ship's machinery are arranged in space 9 between the outer side 7, the inner side 8 and the bottom 2. This is a favourable arrangement for the cooling system and the guiding elements 3 are, at the same time, advantageously heated. If the ship has become jammed on a solid ice field, a thin layer of water between the guiding elements and the solid ice is produced in this way, which layer of water favourably diminishes the friction.
The invention is not limited to the embodiments described above,~ and various modifications and variations are feasible within the scope of the attached claims.
s,,~
: ,. i f _ . "~ .
A considerable part of the adverse effects on the forward movement of an ice-breaking ship operating in icy waters is due to the frictional work that broken chunks of ice exert on the sides and the bottom of the ship. By directing at least a large proportion of the ice chunks away from the drive channel, under the edges of the solid ice sheet, this friction will decrease. At the same time this also gives rise to the advantage that the propellers of the ship are protected from the broken ice,~and that the forward movement of ships following the ice-breaker in the drive channel is made easier.
Many different ships' hull designs have been produced in order to direct chunks of ice away from the underside of a ship. For example, in Canadian Patent No. 1,253,746 a ship is described in which a wedge-shaped plow, extending from the bottom of the stem line and diverging in the direction back-wards, removes the ice chunks far beyond the reach of the propellers of the ship, and to a great extent forces them below the edges of the solid ice field. The drawback of such a solution is, however, a poorer seaworthiness and larger driving resistance in open water conditions in comparison with a conventional ship's hull. A stationary, massive plow construction also permanently increases the draught of the ship and decreases its displacement.
Another way of directing ice chunks away from under the bottom of a ship is shown in German Application Publication DE
2112334, according to which a vertically projecting, relatively high plow structure is fitted to the bottom of the ship. This structure is intended for cooperation with a twin-stem ice-breaking bow that collects about 50 % of the ice in front of the ship into a channel formed between the two stems.
~*~
.i'3;'~.L?~
1 3nq30~
Under these circumstances, the plow structure must provide proper sideways transport of about half the amount of ice chunks broken by the ship, and consequently, must have a great vertical height and must be of an extremely rigid construction. Such a plow structure considerably increases the forward moving resistance of the ship, firstly, because the twin-stem configuration provides inferior ice-breaking qualities, secondly, because there will inevitably be ice cloggings in the channel between the stems, and thirdly, because about half the ice to be broken is collected into a narrow channel and forced downwards, against its natural buoyancy, and then is forced sidewards. Further, the vertically high plow structure provides a permanent increase in the draught of the ship. Because of the considerable height of the plow structure, strong water currents will occur at the outer sides of the plow elements and at their lower edge. These water currents are likely to suck chunks of ice back against the bottom of the ship.
Canadian Patent N0. 1,276,508 discloses a ship bottom with plow elements that are foldable into cavities. Thereby the forward moving resistance of the ship in open water is reduced, the seaworthiness and maneuverability of the ship is improved and the draught of the ship with the plow folded remains "normal". The drawbacks of this solution include a considerable forward moving resistance in ice conditions and strength problems, because the impact of ice chunks against the plow causes high loads. It is also difficult to provide existing hulls with such an arrangement.
The object of the invention is to create a novel, more efficient and less harmful arrangement for directing broken ice chunks to the sides, away from under the bottom of an ice-breaking ship being otherwise designed for highly effective ice breaking, that is, ice breaking with minimized energy consumption. A further object is to create an arrangement, which does not cause any substantial increase in the draught of the ship and which is easy to make strong in relation to the load caused by the impact of broken ice chunks. An object "~ ;, i~
3 1 3 " 9 3 0 3 of the invention is further to create an arrangement, which is easy to install when modifying existing ships.
According to one aspect of the invention there is provided a ship intended for operation in icy waters, the hull of which comprises a generally horizontal bottom portion and a bow portion designed for effective ice breaking, in which ship said bottom portion is provided, at both sides of a longitudinal centre line of the ship, with a plurality of consecutively arranged list-like guiding elements for sideward removal of broken ice chunks, said elements being arranged obliquely to said centre line and having a height measured perpendicularly to the horizontal bottom portion such that the sum of the average heights of the list-like elements on one side of said centre line does not exceed 120% of the limit lS value of the ice-breaking quality of the ship.
The term "generally horizontal bottom part" generally means a completely flat bottom between the sides of the ship, but the term does not exclude the possibility of forming the bottom of two parts arranged at a small angle relative to each other along the longitudinal svmmetry plane.
In the following disclosure, the concept of the limit value of ice-breaking quality means the thickest ice a ship is able to break during continuous advancement. This feature is mostly the basis for planning a new ship, and for every existing ship a strict value for this feature is defined. A
bow portion which breaks ice favourably means a bow that mainly breaks the ice by means of downwards bending, for example according to Canadian Patent No. 1,253,746. When the angle of the stem line to the water line plane is small in the lowermost part of the stem line, the velocity downwards of the broken ice chunks will be reduced before they meet the plow or guiding surfaces in the bottom of the ship.
In the invention, at least two but preferably a greater number of list-like guiding elements are arranged on the bottom of the ship, on each side of the symmetry plane, which . ~ -3a 1 3nq ~ 03 elements guide chunks of ice that the bow has broken to the sides away from the underside of the ship. According to known technology, one single plow element guides the broken chunks of iC2 to the sides. According to the present invention, several guiding elements arranged one after another perform this guiding procedure. This makes it possible for some of ~.j r, ~
4 1 3"~q303 the chunks of ice to slide below the edges of the forwardly positioned elements, i.e. the vertical height of the guiding surfaces may be considerably lower than is the case when one single element must guide all the chunks of ice away from the underside of the ship. When the chunks hit the first guiding surface, they receive a lateral component of motion, which assists the operation of the guiding surfaces arranged more rearwardly.
The benefit of the invention is hereby based on the fact that the draught of the guiding elements may be considerably smaller than before. The advantage of minimizing the total draught is of first-rate importance, especially for river ice-breakers. Many other benefits are, however, derived from the arrangement of the present invention. The small vertical lS dimension of the guiding elements also considerably diminishes the generation of harmful water current below the edges of the guiding surfaces. These turbulent water currents, which are likely to bring chunks of ice to the wrong side of the plow element, are due to the overpressurized state in front of the plow in comparison with the rear of the plow. The impact that the chunks of ice direct against the guiding element is considerably stronger when there is just one guiding element meeting the chunks. Moreover, the momentum of the impact is a lot greater when a guiding element of large vertical extension is used. The invention also has the advantage that the constructional and strength problems encountered during the construction of hulls are more easy, simple and economical to solve than in the known technology. The physical properties of the elements are especially important when turnable guiding surfaces according to Canadian Patent No. 1,276,508 are used.
In accordance with the present invention, it is possible to arrange the guiding elements more favourably in the bottom of the ship than in the known technology. When just one plow element is used, the front edge of this has to be both pointed and essentially closed. According to the present invention, no single plow element has to take care of the complete removal of the chunks of ice alone, so for example the forward ~W
1 3nq3~r~,3 elements may be placed closer to the bow of the ship, even partly in the actual bow portion, so that a rather wide gap can be between the opposite guiding surfaces. Opposite guiding surfaces may also be placed at different longitudinal levels so that a gap may be formed between the elements in the longitudinal direction, which gap allows a non-turbulent water current to the rear of the guiding surfaces. Chunks of ice that move with the water current will encounter another guiding surface later on.
In ice-laboratory tests, the function of the invention has been found very good. It has been proved that the guiding performance of four guiding surfaces arranged one behind another is almost equal to one ice plow, when the vertical height of the guiding surfaces is 1/8 and the height of the ice plow is 1/2 of the limit value of the ice-breaking quality. The solution according to the invention, however, offers a considerably smaller driving resistance both in open water and in ice-filled conditions. At the same time the draught of the ship is considerably reduced.
In a preferred embodiment of the present invention, at least a part of the guiding elements, preferably those arranged afterwards, together with corresponding elements on the opposite side form a sharp-edge diverging rearwardly as a list-like plow. It can be ensured in this way that the drive channel is efficiently cleaned of chunks of ice. The outer surface of the guiding elements is preferably vertical to a horizontal plane, so that the guiding of the chunks of ice is made as efficient as possible. The inner surface of the elements, however, preferably forms an inclined surface with respect to the bottom of the ship. This is a favourable embodiment both in view of achieving a non-turbulent water current, and with respect to constructional considerations, in view of achieving a strong structure. Further, this arrangement facilitates removal of the ship when it has become jammed upon a bearing layer of solid ice. The guiding elements should preferably have a longitudinal extension that reaches to the sides of the ship, in order to guide the chunks ~",.i,BJ
6 1 3nq303 of ice deeply enough under the solid ice field. The vertical height of the guiding elements may be freely altered according to the desired level of ability to remove chunks of ice. In general, the height of the elements may be lowered if the number of elements is increased. When the heights of the elements taken altogether are 50-120% of the limit value of the ice-breaking quality of the ship, the best results are generally achieved. When a ship is designed for moving forward with a low speed, a fair result may be achieved with guiding elements having a total height of only 20% of the limit value.
The guiding elements are arranged obliquely with regard to the symmetry plane of the ship. The angle between the element and the symmetry plane is preferably 15...45. When two guiding elements form a plow between each other, the angle between the sides of the plow accordingly is 30...90.
In one embodiment, cooling tubes from the cooling system of the ship machinery are placed within the guiding elements.
This is an efficient arrangement for achieving the desired cooling, because there is a strong current of cold water around the elements. A further advantage is that the heated guiding elements produce a thin layer of water between the ship and the solid ice field when the ship has become jammed.
The removal of the ship is then made considerably easier.
The outer surfaces of the guiding elements should preferably be made concave. The acceleration in the lateral direction of ice chunks that are guided along these surfaces are then made almost constant, and the guiding action is likely to succeed better. In one embodiment, the guiding elements are made turnable in to the hull of the ship, as described in Canadian Patent No. l,276,508. In this way, the draught of the ship may temporarily be reduced, and the maneuverability and the seaworthiness in open water conditions is improved.
In connection with the guiding element according to the invention, air-bubbling openings according to Canadian Patent No. 889,081 may be used, in order to diminish the drive ~ .:
~ L~ ~
1 3nq3~3 resistance of the ship.
Preferred embodiments of the invention are described in the following with reference to the accompanying drawings, in which:
Figure 1 is a schematical side view of a ship's hull according to the invention;
Figure 2 is a bottom plan view of the hull of Figure l;
Figure 3 is a bottom plan view of another embodiment of the invention;
Figure 4 is a bottom plan view of a third embodiment of the invention; and Figure 5 shows, in a sectional view, the guiding elements of Figure 2 in the plane A-A.
In the drawings, reference numeral 1 relates to the bow portion of a ship, which bow has a configuration that breaks ice favourably. In a favourable embodiment, the configuration of the bow in horizontal sections is round, and the angle a of inclination between the stem line and a horizontal plane is, at the ice-breaking zone and below this, at most 40, preferably at most 18. The sides 6 of the ship are vertical or inclined in a direction upwards and outwards, and they are preferably attached to the horizontal bottom 2 of the ship with roundings. The bottom 2 may also be formed of two parts so that the parts form a small angle between each other along the longitudinal symmetry plane or centre line 5. Reference numeral 4 relates to the constructional water line plane of the ship.
On both sides of the centre line 5 at the bottom 2 of the ship, a number of guiding elements 3 are arranged in succession and are placed obliquely at an angle b with regard to the centre line. The angle k is between 15 and 45.
According to Figure 2, the guiding elements 3 are arranged symmetrically on both sides of the centre line 5 so that a number of sharp-edged plows are formed one after another at the bottom of the ship.
At least two, and preferably three or a greater number of such guiding elements 3 are provided, one after another. In 1 3~97)07' the lateral direction, these guiding elements have an extension generally to the side surface 6.
In Figure 3, an alternative arrangement of the guiding elements 3 is illustrated. The guiding elements 3' situated nearest to the front are arranged at a distance from the centre line 5 so that quite a large gap 10 is formed between the two opposite elements. By this arrangement, one may place the guiding elements closer to the bow 1 of the ship. At the same time, the strain that the broken ice directs against these elements is favourably diminished. The vertical height of the elements 3' is growing in the direction backwards in a preferred embodiment. The guiding elements 3'' are arranged at different levels in the longitudinal direction so that a gap is formed in the longitudinal direction between the elements 3 " located at opposite sides of the centre line 5.
By means of this arrangement, a fluent flow of water is achieved to the inner side of the elements. By this means, the flow of water beneath the sides surfaces of the elements 3'' is diminished, as well as the sliding of ice chunks to the inner side cf the elements. The gap between the guiding elements 3 " is small enough not to allow large amounts of ice to pass through this gap; it is however preferred to arrange a pair of guiding elements 3 that are connected to each other behind the leading guiding elements 3''.
In Figure 4, an embodiment is illustrated having elements with curved side surfaces. By means of this arrangement, the acceleration of the ice chunks in the lateral direction is made more or less constant, i.e. the force effect between the ice chunks and the guiding elements is constant along the whole sliding surface. By this means, the sliding of ice chunks beneath the guiding elements is also better controlled. In the case of the curved guiding elements according to Figure 4, the angle k is calculated from the beginning and end points of the side surface of the guiding elements.
Figure 5 shows a sectional view of the guiding element 3 in the plane A-A (Fig.2). The outer side 7 of the guiding .Y~, s.L
1 3n,9303 element 3 is arranged in a vertical plane, or mainly perpendicularly to the bottom 2. The inner side or inner surface 8 is, to the contrary, preferably arranged to form a sloping surface with regard to the bottom 2. This is a favourable arrangement in view of the water currents, because turbulence is diminished in this way. The vertical extension k of the guiding surfaces should be dimensioned so that the sum of the heights _ of the elements arranged one after another is at least 20%, and preferably at least 50~, of the limit value of the ice-breaking quality of the ship. The heights _ of different guiding elements are not necessarily the same. In view of the constructional strength, it is favourable to arrange the guiding elements so that the strains that the ice chunks directed to different elements are mainly of the same class of magnitude. To this end, the heights _ of the elements situated at the front of the ship should be lower than the height of the elements at the rear. As stated above in connection with the guiding elements 3', the height _ may be arranged to increase in the lateral direction. The sum of the heights _ is hereby calculated according to the vertical height at the middle part of each element.
In one embodiment, tubes connected to the cooling system of the ship's machinery are arranged in space 9 between the outer side 7, the inner side 8 and the bottom 2. This is a favourable arrangement for the cooling system and the guiding elements 3 are, at the same time, advantageously heated. If the ship has become jammed on a solid ice field, a thin layer of water between the guiding elements and the solid ice is produced in this way, which layer of water favourably diminishes the friction.
The invention is not limited to the embodiments described above,~ and various modifications and variations are feasible within the scope of the attached claims.
s,,~
: ,. i f _ . "~ .
Claims (11)
1. A ship intended for operation in icy waters, the hull of which comprises a generally horizontal bottom portion and a bow portion designed for effective ice breaking, in which ship said bottom portion is provided, at both sides of a longitudinal centre line of the ship, with a plurality of consecutively arranged list-like guiding elements for sideward removal of broken ice chunks, said elements being arranged obliquely to said centre line and having a height measured perpendicularly to the horizontal bottom portion such that the sum of the average heights of the list-like elements on one side of said centre line does not exceed 120% of the limit value of the ice-breaking quality of the ship.
2. A ship according to claim 1, in which the angle between each of said elements and said centre line is 15° to 45°.
3. A ship according to claim 1, in which at least some of said elements form, together with corresponding elements on the other side of said centre line, a pointed plow which diverges in the rearward direction.
4. A ship according to claim 1, in which front surfaces of said elements are arranged generally vertically to a horizontal plane and in which rear surface of said elements form inclined surfaces with regard to the bottom part of the ship.
5. A ship according to claim 1, in which said elements generally extend from the centre line to side surfaces of the ship.
6. A ship according to claim 1, in which the sum of the vertical heights of the elements on the same side of the centre line is at least 20% of the limit value of the ice-breaking quality of the ship.
7. A ship according to claim 1, in which water circulation tubes connected to the cooling system of the ship machinery are arranged inside at least some of said elements.
8. A ship according to claim 1, in which front surfaces of at least some of said elements are concave in the longitudinal direction of the elements.
9. A ship according to claim 1, in which said elements are pivotally attached to said bottom part so that they may be pivoted temporarily to form a continuous part of the bottom surface of the ship.
10. A ship according to claim 1, which is provided with three or more consecutively arranged list-like guiding elements for removal of broken ice chunks.
11. A ship according to claim 1, in which the sum of the vertical heights of the elements on the same side of the centre line is 50 to 120% of the limit value of the ice-breaking quality of the ship.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI860697 | 1986-02-17 | ||
| FI860697A FI74673C (en) | 1986-02-17 | 1986-02-17 | Bottom shape for vessels. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1309303C true CA1309303C (en) | 1992-10-27 |
Family
ID=8522179
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000529311A Expired - Lifetime CA1309303C (en) | 1986-02-17 | 1987-02-09 | Ship bottom form |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA1309303C (en) |
| FI (1) | FI74673C (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110053725B (en) * | 2019-03-19 | 2020-03-06 | 江苏大津重工有限公司 | Ice breaking blade for icebreaker |
-
1986
- 1986-02-17 FI FI860697A patent/FI74673C/en not_active IP Right Cessation
-
1987
- 1987-02-09 CA CA000529311A patent/CA1309303C/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| FI74673C (en) | 1988-03-10 |
| FI860697A0 (en) | 1986-02-17 |
| FI860697L (en) | 1987-08-18 |
| FI74673B (en) | 1987-11-30 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR101122512B1 (en) | Method for breaking ice, motor-driven watercraft and its use | |
| CA2228792C (en) | Icebreaking method and icebreaker | |
| KR860002189B1 (en) | Ship | |
| PL164327B1 (en) | Ice-breaker | |
| US4003325A (en) | Cargo vessel low resistance bow | |
| US11858601B2 (en) | Variable use pontoon boat system and method | |
| US4715305A (en) | Ship's hull | |
| US6007393A (en) | Surfboard | |
| US5176092A (en) | Icebreaker bow and hull form | |
| CA1309303C (en) | Ship bottom form | |
| FI85967C (en) | Icebreaker | |
| CA2150763C (en) | Small watercraft hull | |
| JPS62116385A (en) | High speed vessel | |
| KR20060072847A (en) | Barge with hydrofoil skeg formed on stern lake and hydrofoil skeg structure | |
| US20240059373A1 (en) | Variable use pontoon boat system and method | |
| EP0249321A2 (en) | Boat hull | |
| WO1996008408A1 (en) | Grass and debris exclusion plate for marine jet pumps | |
| SE462480B (en) | CREATIVE SHIPS | |
| US4215756A (en) | Apparatus for preventing damage to the flexible skirt of an air cushion vehicle, by ice | |
| US5161477A (en) | Ice going ship | |
| DE3240299A1 (en) | Ship | |
| SE1450545A1 (en) | Ice breaking device | |
| SU901153A1 (en) | Ice removing unit for ship | |
| FI74672C (en) | FARTYGSSKROV. | |
| AU764670B2 (en) | A boat hull |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |