Roro or ropax ship having two two-stroke drive engines

Abstract

The invention relates to a RoRo or RoPax ship (10) having two slow-running two-stroke engines (20, 20') which are offset transversely to the longitudinal axis of the ship and are each connected to a stern-side ship propeller (40, 40') by means of a propeller shaft (30, 30') in each case, the propeller shafts (30, 30') each being arranged at an acute angle to the longitudinal axis of the RoRo or RoPax ship (10) so as to be directed outwards in the direction of the stern, characterised in that the two-stroke engines (20, 20') are arranged one behind the other in the longitudinal direction of the RoRo or RoPax ship (10), the width occupied, in a direction transverse to the longitudinal direction of the RoRo or RoPax ship (10), by the two-stroke engines (20, 20') arranged one behind the other in the longitudinal direction of the RoRo or RoPax ship (10) being less than twice the width of a two-stroke engine (20, 20').

Description

[0001] RoRo or RoPax vessel with two two-stroke propulsion engines

[0002] The invention relates to a RoRo or RoPax vessel with two slow-speed two-stroke engines arranged offset transversely to the longitudinal axis of the RoRo or RoPax vessel, each connected by a propeller shaft to a ship's propeller arranged at the stern. The propeller shafts are each arranged at an acute angle to the longitudinal axis of the RoRo or RoPax vessel, pointing outward toward the stern. The invention thus relates to a seagoing vessel designed for the transport of rolling cargo with or without passengers, which, when carrying rolling cargo with passengers, is also referred to as a RoPax ferry, combi-ferry, or combi-carrier.

[0003] A RoRo vessel of this design is known, for example, from the Ark Dania. This vessel features a two-stroke propulsion engine system consisting of two MAN 8S40ME-B9 engines, arranged directly next to each other and symmetrically to the ship's longitudinal axis. The two propeller shafts located at the rear are oriented at an acute angle to the ship's longitudinal axis, outward toward the stern, i.e., deviating from the ship's longitudinal axis and toward the side. The disadvantage of this vessel is its very wide engine bay, which severely constricts the vehicle deck in the center of the ship, significantly impairing the flow of loading and unloading.

[0004] In addition, there is the problem that operators of RoRo or RoPax vessels face technical challenges in reducing emissions due to the climate targets set by the UN Maritime Organization IMO, for example through the use of climate-neutral fuels such as green ammonia or green methanol.

[0005] For example, in 2015, the RoPax ferry "Stena Germanica" was converted, at considerable technical and financial expense, so that its two four-stroke diesel engines could operate in dual-fuel mode, using both marine diesel and methanol, thus complying with the stricter environmental regulations that came into force on January 1, 2015. In addition, the "Lindanger" class of tankers was introduced in 2016. These tankers are powered by a dual-fuel two-stroke engine, which is more advantageous in the field of marine propulsion, powered by methanol. Market-ready two-stroke marine propulsion engines already exist for the use of methanol and ammonia. The use of such fuels in four-stroke engines is technically significantly more demanding, and market readiness lags behind that of two-stroke propulsion engines.

[0006] Although Mitsui OSK Lines is known to have plans to build a RoPax vessel with a two-stroke propulsion engine, this is only a ferry for domestic voyages, for which the international safety regulations of the IMO under SOLAS, such as the Safe Return to Port requirement for redundant propulsion, are not mandatory. A fundamental problem is that, for example, RoPax vessels (unlike tankers) require two redundant propulsion systems for fail-safe reasons, but these require a lot of space.

[0007] The object of the invention is therefore to create a RoRo or RoPax vessel with a propeller drive having two two-stroke engines, the construction of which requires only a small amount of work and material, wherein the drive should only require a small amount of space within the RoRo or RoPax vessel.

[0008] This object is achieved according to the invention by the RoRo or RoPax vessel having the features of claim 1. The subclaims represent advantageous embodiments of the invention.

[0009] The basic idea of ​​the invention is to create a RoRo or RoPax vessel with a two-stroke propulsion system based on a twin engine system slightly offset one behind the other in the longitudinal direction of the vessel, with the two shaft trains and the propellers integrated into the system. This measure makes it possible to minimize the space required across the width of the RoRo or RoPax vessel.

[0010] At the same time, the arrangement according to the invention facilitates spatial separation of the two drive motors while simultaneously complying with leak stability regulations.

[0011] According to the invention, a RoRo or RoPax ship is proposed with two slow-running two-stroke engines arranged offset transversely to the longitudinal axis of the RoRo or RoPax ship, which are each connected by means of a propeller shaft to a ship's propeller arranged at the stern, wherein the propeller shafts are each directed outwards in the direction of the stern at an acute angle to the longitudinal axis of the RoRo or RoPax ship and the two-stroke engines are arranged one behind the other in the longitudinal direction of the RoRo or RoPax ship and wherein the width occupied by the two-stroke engines arranged one behind the other in the longitudinal direction of the RoRo or RoPax ship in a direction transverse to the longitudinal direction of the RoRo or RoPax ship, specifically perpendicular to the longitudinal axis of the RoRo or RoPax ship, is less than twice the width of a two-stroke engine.Most preferably, the width occupied by the two-stroke engines corresponds to a maximum of one and a half times the width of a two-stroke engine. According to a further preferred embodiment, the two-stroke engines are installed in a centrally arranged engine shaft, with the two-stroke engines extending vertically into the freeboard deck of the RoRo or RoPax vessel and, due to the narrow overall width of both two-stroke engines, only occupying a cargo space with a width of no more than four, preferably no more than three, and most preferably no more than two truck lanes. The width of a truck lane is typically approximately 3.00 m to 3.20 m.

[0012] According to the invention, two separate drive trains are provided, it being understood that in this arrangement, one drive train must be connected to one two-stroke engine and the associated ship's propeller by means of a propeller shaft which is longer than the propeller shaft of the other drive train connecting the other two-stroke engine to the other ship's propeller.

[0013] The propeller shafts are each arranged at an acute angle to the ship's longitudinal axis, with the propeller shafts running approximately from the ship's center outwards (towards the respective side) and deviating from the longitudinal axis of the RoRo or RoPax ship. In particular, each propeller shaft runs outwards to the side of the RoRo or RoPax ship to which the associated two-stroke engine is offset. This creates an angle between the propeller shafts which, from a hydrodynamic point of view, should preferably be kept small, particularly preferably < 5°. This can easily be achieved by designing the distance between the propellers and the two-stroke engines connected by the propeller shafts as large as possible. In particular, the two-stroke engines are preferably arranged in the ship's center with respect to the longitudinal axis, particularly preferably towards the bow, so that the influence of a - -

[0014] The propeller angle remains small. With a rigid arrangement between the two-stroke engine, propeller shaft, and propeller, it is therefore necessary in this case that the longitudinal axes of the two-stroke engines are not parallel, but also aligned at an angle to each other.

[0015] The acute angle formed by the propeller shafts to the longitudinal axis of the RoRo or RoPax vessel is preferably identical, so that the necessary offset of the two-stroke engines along the longitudinal axis of the RoRo or RoPax vessel also provides sufficient space.

[0016] According to a further preferred embodiment, the two-stroke engines have identical performance parameters, i.e., they are essentially identical, i.e., identical in construction or of the same type. Specifically, the two-stroke engines preferably have the same dimensions.

[0017] In particular, according to a further preferred embodiment, the two-stroke engines are arranged in compartments separated from one another. The compartments are specifically designed as separate engine rooms, whereby each two-stroke engine can be operated independently of the other two-stroke engine (in an emergency). In the simplest case, the compartments are separated by a bulkhead partition, which is particularly designed as a firewall. Specifically, all walls forming the respective compartment, including the ceiling and floor, are designed as bulkheads, thus ensuring a high degree of reliability of the RoRo or RoPax vessel, even with limited space requirements.

[0018] The invention will be explained in more detail below with reference to a particularly preferred embodiment shown in the accompanying drawings. They show:

[0019] Fig. 1 is a longitudinal section of a preferred embodiment of a RoRo or RoPax ship according to the invention;

[0020] Fig. 2 is a plan view of the embodiment shown in Fig. 1 at the level of the

[0021] Two-stroke engines; and Fig. 3 shows a cross-section through the previously shown RoRo or RoPax vessel in the area of ​​the two-stroke engines.

[0022] Fig. 1 shows a longitudinal section of a preferred embodiment of a RoRo or RoPax vessel according to the invention. In particular, Fig. 1 shows a RoRo or RoPax vessel 10 with two slow-speed two-stroke engines 20, 20' arranged one behind the other in the longitudinal direction of the RoRo or RoPax vessel 10 and—as clearly visible in the plan view shown in Fig. 2—offset transversely to the longitudinal axis of the RoRo or RoPax vessel 10. Each two-stroke engine 20, 20' is connected by means of a respective propeller shaft 30, 30' to a respective ship propeller 40, 40' arranged at the stern. It can be clearly seen that one two-stroke engine 20' is connected to one ship's propeller 40' by means of a propeller shaft 30' which is longer than the propeller shaft 30 connecting the other two-stroke engine 20 to the other ship's propeller 40.

[0023] The two-stroke engines 20, 20', which in the exemplary embodiment are two-stroke engines of the same type, are preferably arranged in compartments (not shown) that are separated from one another, so that it is ensured that an engine failure of one two-stroke engine 20, 20' cannot spread to the other two-stroke engine 20, 20' and the RoRo or RoPax vessel 10 remains maneuverable.

[0024] The propeller shafts 30, 30', which are specifically designed to rotate in opposite directions, are - as can be seen from Fig. 2 - each arranged at an acute angle to the longitudinal axis of the RoRo or RoPax vessel 10, wherein the acute angle assumed by the propeller shafts 30, 30' to the longitudinal axis of the RoRo or RoPax vessel 10 is essentially identical.

[0025] Fig. 3, which depicts a cross-section through the previously shown RoRo or RoPax vessel 10 in the area of ​​the two-stroke engines, illustrates that the width occupied by the two-stroke engines 20, 20' arranged one behind the other in the longitudinal direction of the RoRo or RoPax vessel 10 in a direction transverse to the longitudinal direction of the RoRo or RoPax vessel 10 is less than twice the width of a two-stroke engine 20, 20'. Thus, a space-saving arrangement of the two-stroke engines 20, 20' can be achieved with only a minor impact on the loading capacity with regard to cargo transport and passenger transport. In particular, it can be seen from Fig. 3 that the two-stroke engines 20, 20' arranged in the engine shaft extend vertically into the freeboard deck of the RoRo or RoPax vessel 10, but only take up a cargo space on the freeboard deck with a width of two to three truck lanes.

Claims

CLAIMS 1. RoRo or RoPax vessel (10) with two slow-running two-stroke engines (20, 20') arranged offset transversely to the vessel's longitudinal axis, which are each connected by means of a propeller shaft (30, 30') to a ship's propeller (40, 40') arranged at the stern, wherein the propeller shafts (30, 30') are each arranged at an acute angle to the longitudinal axis of the RoRo or RoPax vessel (10) directed outwards in the direction of the stern, characterized in that the two-stroke engines (20, 20') are arranged one behind the other in the longitudinal direction of the RoRo or RoPax vessel (10), wherein the two-stroke engines (20, 20') arranged one behind the other in the longitudinal direction of the RoRo or RoPax vessel (10) are arranged in a direction transverse to the longitudinal direction of the RoRo or RoPax vessel (10) width occupied is less than twice the width of a two-stroke engine (20, 20').

2. RoRo or RoPax vessel (10) according to claim 1, characterized in that the two-stroke engines (20, 20') are arranged in compartments separated from one another.

3. RoRo or RoPax vessel (10) according to one of the preceding claims, characterized in that the acute angle formed by the propeller shafts (30, 30') to the longitudinal axis of the RoRo or RoPax vessel (10) is identical.

4. RoRo or RoPax vessel (10) according to one of the preceding claims, characterized in that the angle between the propeller shafts (30, 30') is a maximum of 5°.

5. RoRo or RoPax vessel (10) according to one of the preceding claims, characterized in that the two-stroke engines (20, 20') have identical performance parameters.

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