GB2266683A

GB2266683A - Ice-beaking ship

Info

Publication number: GB2266683A
Application number: GB9309491A
Authority: GB
Inventors: Peter Jans; Karl-Heinz Rupp; Jens-Holger Hellmann
Original assignee: Thyssen Nordseewerke GmbH
Current assignee: Thyssen Nordseewerke GmbH
Priority date: 1992-05-09
Filing date: 1993-05-07
Publication date: 1993-11-10
Anticipated expiration: 2013-05-07
Also published as: PL298848A1; JPH0672385A; KR930023232A; NO931650L; GB2266683B; GB9309491D0; FI110596B; FR2690892A1; RU2062245C1; CA2095871A1; CN1039689C; NO931650D0; KR100250780B1; SE9301587D0; PL171265B1; FI932046A0; CN1081152A; FR2690892B1; SE507652C2; FI932046A

Abstract

For the improvement of the manoeuvrability of an ice-breaker, the foreship P of which is formed in pontoon-like manner with an obliquely forwardly rising underside which carries ice-breaking means at its sides, the ship's hull R is equipped on both sides over the entire length of the ship with balcony-like sidewalls 1, 1' of which the lower sides 2, 2' of the balcony drop away obliquely downwardly and lie at the level of the line of flotation SWL in such a way that on turning of the ship they break away the ice edges. Furthermore, the lower side of the bows is broader in the region of the ice-breaking means than the line of flotation of the following hull of the ship, in order to provide a clearance between the ice edges and the ship's hull. <IMAGE>

Description

2266683 Ice-breaking ship The invention relates to an ice-breaking ship

with the features set forth in the preamble of claim 1.

Ice-breakers of this kind have become known through the German patent application 41 01 034 and have waisted recesses projecting at both sides into the ship's hull adjoining the pontoon-like foreship.

Furthermore,in this known ice-breaker.the balcony-like sidewalls adjoin the said recesses and extend up to the stern of the ship.

The waist-like recesses admittedly result, with an appropriate dimensioning of their depth and length, in a small turning circle radius when the ship is travelling in a turning circle, and thus good manoeuvrability, they require however considerable design interference in the structure of the ship's hull and thus increased costs.

Furthermore.the said recesses disturb the flow of the water along the ship's side which has a disadvantageous effect on the resistance, in particular during straightahead travel in ice-free waters.

The invention is based on the object of overcoming these disadvantages and accordingly of further developing ice-breaker of the initially named kind so that it requires no complicated constructional structures for the ship's hull, and furthermore has no elements which hinder the flow.

This object is satisfied in that the balcony-like sidewalls extend over the entire or almost the entire length of the ship's hull, have no form of recesses directed towards the ship's interior and extend substantially parallel to the longitudinal axis of the ship; in that furthermore the breadth of the underside of the bows at its starting point at the base of the ship corresponds-to approximately the spacing from balcony pedestal to balcony pedestal and from there is enlarged continuously in the forward direction until it reaches the width of the underside of the bows in the region of the line of flotation; and in that the spacing from balcony breastwork to balcony breastwork, and thus the width of the upper deck, is larger than the width of the lower side of the bows in the region of the line of flotation.

With these measures, in addition to the named advantages, surprising effects are achieved in that the ice-breaking or cutting means arranged at the side edges of the bows act, as a result of their outwardly directed angled position relative to the longitudinal axis of the ship, to improve the track keeping during travelling in a broken ice-channel and to improve the willingness of the ice-breaker to turn when travelling in an arc.

Previously constructed ice-breakers are able to break the ice with their bows or stern (actively). In order to obtain a turning ability these icebreakers were constructed with a lens-shaped line of flotation, i.e. without or with only a short parallel center part.

As a result of this shape and the resulting irregularly broken ice-edge and also in part as a result of further improvements in the layout of side projections at the bows, and eventually also at the stern, these icebreakers can travel in turning circles with the aid of their rudder forces.

The invention is based on the concept that ice-breaking means are not only provided at the bows and at the stern but rather extend over the entire length of the ice-breaker at the sides of the ship. This ice- breaker in' accordance with the invention thus has ice-breaking means all around it, i.e. at every position of its line of flotation.

With the aid of the transverse forces generated by the control members (rudder) this ice-breaker is in a position of being able to break ice with the sides of the ship both in the foreship region at the inner side of the curve and also in the midship region and in the stern region at the outer side of the curve. This ability is independent of the transverse forces of the control members, and also of the inclination of the lower side of the balcony and of the ice conditions such as ice thickness and ice strength. Previously constructed ice-breakers have a frame rake angle of 00 up to a maximum of approximate 250 measured from the perpendicular. This frame rake angle is too small with adequately thick ice to break ice during travel in a curve via the ship sides with the aid of the transverse forces of the control members. The abovementioned low frame rake angle should essentially only serve to reduce the forces exerted on the ship by the ice during ice-nipping.

Several embodiments of the subject of claim 1 are characterised in the subordinate claims.

In accordance with claim 3 a layout of the lower side of the bows is proposed which has proved to be particularly favourable for the breaking of a straight ice-channel, whereas the layout of the lower side of the bows in accordance with claim 4 makes it possible to easily Center the ship in its ice channel.

In accordance with claim 5 the sliding off of ice-floes from the iCebreaking means either into the channel between the lower side of the balcony and the balcony pedestal or beneath the lower side of the bows is to be made easier.

Claims

Claim 6 has the purpose of deflecting ice-floes which have reached the

underside of the bows towards the sides in order to protect the propulsion and control members at the stern of the ship from contact with the ice and to increase their efficiency and to protect them from damage.

Claim 7 aids the requirement of claim 1 that the spacing from balcony breastwork to balcony breastwork should be larger than the width of the lower side of the bows in the region of the line of flotation, since with this measure the spacing from balcony lower side to balcony lower side in this region is enlarged.

With the measure of claim 8 the turning behaviour of the ship is indirectly improved because the breaking off of the edge of the ice is intensified through the swashing movements by the inclined lower sides of the balconies, in particular when travelling in a turning circle.

In the drawing the subject of the invention is explained more precisely with respect to several variants. There are shown:

Fig. 1 a ship's hull laid out in accordance with the invention with a continuous flat lower side of the bows in the transverse direction and substantially straight side edges, Fig. 2 a ship's hull laid out in accordance with the invention with a shallow lower side of the bows in the transverse direction and outwardly arched side edges, Fig. 3 a ship's hull laid out in accordance with the invention with upwardly kinked side surfaces in the transverse direction along the side edges of the lower side of the bows, in each case seen in perspective view with several cross-sectional lines distributed over the shipslength being drawn in.

In all figures the same parts are designated with the same reference numerals.

The ship's hull of the ice-breaker is designated by R from which in all figures the starboard side is shown with a plurality of cross-sectional lines distributed over the length of the hull. As a result of these lines it can be seen that the sidewalls of the ship are formed in the manner of a balcony, with the balcony extending over the entire length of the ship and also over the stern region, and, apart from a minor broadening of the foreship towards the ship's bows, extending parallel to the longitudinal axis of the ship.

Furthermore it can be seen that the balcony breastwork 1, 11 stands approximately vertical, that the lower side 2, 21 of the balcony which adjoins it is directed at an angle of approximately 300 obliquely downwardly and that the balcony pedestal 3 which adjoins the lower side of the balcony, and which at the same time represents the sidewalls of the ship's hull and merges into the substantially planar ship's base 4, likewise stands essentially vertically.

TIe foreship designated in general with P is of pontoon-like shape, i.e. the underside 5 of the bows extends approximately transverse to the longitudinal central plane of the ship and extends on both sides of this plane and rises obliquely from the base 4 of the ship to the bows.

The region at which the underside 5 of the bows emerges from the base 4 of the ship is located approximately in the front third of the ship's length and the transition from the base 4 of the ship to the lower side 5 of the bows is flowingly formed.

In this region the lower side 5 of the bows has the width of the pedestal 3 of the balcony and its side edges 51 thus merge into the rounded region 9 between the balcony pedestal 3 and the base 4 of the ship. The underside 5 of the bows broadens bit by bit towards the front until it finally corresponds to the width of the balcony breastwork 11.

In the region in which the lower side 5 of the bows intersects the line of flotation, known briefly as SWL in the following, the side edges 51 are formed as ice-breaking means which together with the underside 5 of the bows break a channel with straight ice edges in the ice sheet, the continuous broadening of the underside 5 of the bows is so selected that the spacing of the side edges 51 from one another in the region of the SWL is larger by a small amount than the width of the hull R at the SWL.

In the variant of Fig. 1 the side edges 51 of the lower side 5 of the bows form a straight line in the region of the SWL, whereas in the variant of Fig. 2 they represent an outwardly arched curve.

The lower side 5 of the bows is of flat shape in both variants in the region of the SWL transverse to the ship's longitudinal axis and in the region beneath it is slightly kinked in a downward direction in order to provide a good transition to the base clearing wedge 6 which starts there and broadens in fork-like manner towards the stern, with the fork-like projections 61 merging into the balcony pedestal 3. In the variant of Fig. 3 this manner of construction is modified somewhat in as much as the underside 5 of the bows is in each case equipped at the sides over its entire length with upwardly kinked side surfaces 51 relative to its central surface. The side surfaces 511 are bounded by the edges 5111 and the side edge 51 which both merge at the base or floor 4 into the rounded region 9.

In all variants the spacing of the balcony breastworks 11 from one another enlarges fractionally from one another in the region of the foreship P, as already mentioned, and thus the width of the upper deck 7 enlarges continuously from the start of the foreship P towards the bows. In this way the spacing of the lower sides 21 of the balcony from one another correspondingly increases in this region.

All variants have in common, that the channel which the underside of the bows breaks in the ice sheet is somewhat broader than the width of the SWL of the subsequent hull R of the ship so that a clearance remains between the latter and the ice edges of the channel, which prevents the ship's hull R being trapped.

A further variant, which is admittedly not illustrated but which is of importance in the context of the invention consists in that a device known per se is additionally ased which generates a swashing movement of the ship essentially about its longitudinal central axis. In this way additional breaking forces are transmitted onto the edges of the ice by the lower sides 2, 21 of the balcony which thereby break off the ice edges and broaden the clearance between the ice edges and the hull R of the ship. In this way the ability of the ship to turn in ice is increased.

It will be noted that the expression 11kinkedll as used herein signifies two substantially flat or slightly rounded wall sections which merge into each other at a relatively sharp crease or at a relatively small rounded transition line.

Patent claims 1. Ice-breaking ship, the foreship (P) of which is formed in pontoon-like manner with the underside of the bows rising obliquely forwardly from the base of the ship, starting approximately at the beginning of the front third of the same, up to and above the line of flotation, with the side edges of the lower side of the bows having ice-breaking or cutting means (reamers) in the region of the line of flotation and the width of the underside of the bows being greater in the region of the line of flotation than the width of the line of flotation of the following hull of the ship, with the hull of the ship having balcony-like sidewalls on both sides, the balcony breastwork being approximately vertical and with the balcony underside which adjoins it being directed obliquely downwardly and with the subsequent balcony pedestal being aligned approximately vertical up to the transition into the substantially flat ship's bottom, and wherein the line of flotation extends approximately parallel and preferably somewhat outwardly of the half width of the lower side of the balcony, characterised in that the balcony-like sidewalls extend over the entire or almost the entire length of the ship's hull (R), have no form of recesses directed towards the ship's interior and extend substantially parallel to the longitudinal axis of the ship; in that furthermore the breadth of the underside of the bows (5) at its starting point at the base of the ship (4) corresponds approximately to the spacing from balcony pedestal (3) to balcony pedestal (3) and from there is enlarged continuously in the forward direction until it attains the width of the underside of the bows (5) -lo- in the region of the line of flotation (SWL); and in that the spacing from the balcony breastwork (11) to balcony breastwork (11), and thus the width of the upper deck (7), is larger than the width of the lower side of the bows (5) in the region of the line of flotation (SWL).
2. Ship in accordance with claim 1, characterised in that the enlargement of the width of the lower side of the bows (5) is so selected that its side edges (51) in each case result in a straight or slightly curved line.
3. ship in accordance with claim 1 or claim 2, characterised in that the lower side (5) of the bows is flat, slightly arched or kinked above and below the line of flotation (SWL) transverse to the longitudinal axis of the ship.
4. Ship in accordance with one of the claims 1 to 3, characterised in that the lower side (5) of the bow is in each case kinked upwardly at the side between its starting position at the base of the ship (4) until above the line of flotation (SWL) in each case in such a way that longitudinally extending side surfaces (511) arise (Fig. 3).
5. Ship in accordance with one of the claims 1 to 4, characterised in that the side edges (51) of the lower side (5) of the bows are chamfered andlor rounded.
6. Ship in accordance with one of the claims 1 to 5, characterised in that a base clearing wedge (6) is provided which is mounted beneath the line of flotation (SWL), preferably in the region of the starting location of the underside (5) of the bows with the fork-like projections (61) of the clearing wedge merging into the balcony pedestal (3) or extending in the base of the ship.
7. Ship in accordance with one of the claims 1 to 6, characterised in that the spacing from balcony breastwork (11) to balcony breastwork (11), and thus also the spacing from balcony lower side (21) to balcony lower side (21) is continuously enlarged towards the bows in the region of the pontoon-like foreship (P).
8. ship in accordance with one of the claims 1 to 7, characterised in that it is equipped with a device (known per se) which is preferably equipped with hydraulically, mechanically or pneumatically controllable means and which in the case of need generates and maintains a swashing (swaying, rolling or lurching) movement of the ship essentially about its central longitudinal axis.
9. Ice-breaking ship, the foreship (P) of which is formed in pontoonlike manner with the underside of the bows rising obliquely'forwardly from the base of the ship from a position approximately one third of the length of the hull behind the stern and extending up to and above the line of flotation, with the width of the underside of the bows being greater in the region of the line of flotation than the width of the hull at the line of flotation behind said position, with the hull of the ship having balcony-like formations on both sides, the balcony-like formations having upper sidewalls (1, 11) approximately vertically disposed and undersides which extend obliquely downwardly and inwardly from the sidewalls and merge into lower approximately vertical sidewalls which meet the substantially flat ship's bottom at transition regions, and wherein the line of flotation extends at each side of the ship approximately parallel to the longitudinal axis of the ship, characterised in that the upper sidewalls extend over the entire or almost the entire length of the ship's hull (R), have no inwardly directed recesses and extend substantially parallel to said longitudinal axis of the ship; in that furthermore the breadth of the underside of the bows (5) at its starting point at the base of the ship (4) corresponds approximately to the spacing between said lower sidewalls (3, 3) and from there is enlarged continuously in the forward direction until it attains the width of the underside of the bows (5) in the region of the line of flotation (SWL); and in that the spacing between the upper sidewalls (11, 11), and thus the width of the upper deck (7), is larger than the width of the lower side of the bows (5) in the region of the line of flotation (SWL).
10. Ice-breaking ship in accordance with claim 9, characterised in that it is substantially rectangular in plan view with the bows end being divergently flared in the direction from the stern to the bows.
11. Ice breaking ship substantially as herein described and as illustrated in any one of the Figs. 1 to 3.