AU733741B2 - Boat hull - Google Patents

Description

Regulation 3.2 -1-

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT APPLICANT: ASD MARINE SERVICES PTY. LIMITED NUMBER: PO 6829/97 FILING DATE: 16/ 5/1997 Invention Title: BOAT HULL The following statement is a full description of this invention, including the best method of performing it known to me/us: BOAT HULL OUTLINE OF THE INVENTION This invention relates to a boat hull and in particular to a hull for use with shore landing ramps. There are many applications where barges are the preferred method of transporting articles as normally they have a relatively shallow draft for a large carrying capacity and thus can be useful where there are no established wharfs and in other inshore and other coastal duties.

Generally landing barges -have had substantially flat hulls with an opening ramp, usually at the bow end. This enables the barge to be driven up close to a beach or the like until its ramp is beached and then by dropping .the ramp the contents of the barge can be readily moved to the shore.

Whilst this arrangement is satisfactory in as much that it keeps the propeller or propellers away from the shore and it does enable ready loading and discharging of the contents it nevertheless means that the vessel because of its wide flat bow is generally unsatisfactory in any form of sea or weather.

Further such constructions have had propulsion disadvantages as when it is required to remove the barge from the beach the propeller is operating in an astern mode which is normally less efficient than its forward mode and should the bow have become embedded, either because of a tide change or because of D:\WP51\SPEC\ASD.CAP May 14, 1998 the weight of the material which has been loaded into the barge, then difficulties can occur.

Also the use of a forward ramp has generally obstructed visibility from the wheel house and, where there is a sea, particularly where there is a head sea not only can there be general shuddering through the barge but spray being formed by the barge can also act to limit the visibility for the helmsmen, and water damage the deck cargo.

The object of the invention is to provide a barge which minimises:previous disadvantages and which can be viable as far as deck: space, dead weight and total lane length are concerned.

o The invention, in its broadest sense, is a barge including a conventional boat bow and an essentially V-shaped hull provided with keel devices (pods) on either side of the hull to the same depth as and adjacent the keel of the hull a transom slopes back from the keel to the stern of the hull where a loading and unloading ramp is provided.

In order that the invention may be more readily understood we shall describe one particular form of barge made in accordance with the invention in relation to the accompanying drawings in which: D:\WP51\SPEC\ASD.CAP May 14, 1998 Figure 1 is an isometric projection of one particular form of hull; Figure 2 is a hull body plan; and Figure 3 shows three different views of a cavitation plate used with the invention.

In this embodiment of the invention, as can be seen from Figures 1 and 2, the hull 10 below the waterline is of a shallow V-shape over much of its length with a transom sloping up to a.square stern. 12 while having a relatively conventional bow 11.

S As can be seen from Figures 1 and 2 the V shape of the hull is flat in the floor area. The pods 13 are attached to either side of the hull 10 adjacent the waterline and extend a essentially the length of the V shaped portion of the hull being that part of the hull which constitutes an effective keel 16.

The pods 13 which, as illustrated, may be relatively pointed both at the forward end 14 and the rearward end extend downwardly to the level of the keel 16 of the barge, the lower end of which itself may be flat, the lower ends 17 of the pods are also flat so that when the barge is in ground contact it will be effectively stable and supported by D:\WP51SPEC\ASD.CAP May 14, 199a at least one pod and the keel or, where the beach is relatively flat, on the surfaces of each of the pods and the keel.

The actual shape of the pods can be varied but it is of course desired that they produce minimal resistance to forward motion, at least.

The hull is driven by propellers 20 located at the rear 15 of each pod 13 and these propellers are associated with cavitation plates 21 which maximise effective immersion and operation of the propellers even in very rough water, and when the vessel is rolling. Whilst not specifically illustrated: in Figure :1 the stern comprises or includes a loading ramp which is pivotally connected to the hull and can adopt a position where it extends outwardly onto the shore.

The ramp, practically, can be effectively identical to known loading ramps and the actual form of connection, the sealing and the operation of the ramp will not be further discussed herein.

The wheel house, which is not illustrated in the drawings, is preferably near the bow so that for normal operation the helmsman has a clear view and even when the barge is going D:\WPS1\SPEC\ASD.CAP (ay 14, 1998 astern can preferably be of a sufficient height to enable accurate directing of the barge.

The engines of the barge, which may preferably be diesel or other internal combustion engines can be located in each of the pods and the propellers 20 extend from the rear of the pods in such an arrangement that they do not extend below the lower surface 14 of the appropriate pod.

This arrangement is best shown in Figure 3 where the propellers 20 are shown to have a blade diameter which is less than the depth of the pods 13. Also shown is a cavitation plate 21 which is. located.-above the propeller and is attached, to the hull by plate supports 22.

In, this- preferred embodiment of the invention the cavitation plate 21. is arcuate in shape and its lower rear edges preferably extend downwards to a height 0.7 of the propellor diameter above the base of the propellor. This height however can be varied.

The cavitation plates also extend a substantial distance forwardly of the propellers about each pod, and preferably to a distance a minimum of four times the propeller diameter.

It will be seen then that the barge of the present invention has certain inherent advantages over more conventional barges which are essentially shallow bottomed.

D:\WP51\SPEC\ASD.CAP May 14, 1998 Firstly, the barge of the invention has a properly formed bow and its movement through water under most sea conditions is substantially more satisfactory than is the case with more conventional barges, and, because the helmsman is located near the forward portion of the barge there is no obstruction of visibility.

Further because of the ship shaped bow formation the amount of spray which is passed over the body of the barge is minimised.

S When> the barge comes. into. shore the helmsman can gradually:. back it onto shore by virtue.of the shape of its sloped.

transom. The propellers are however protected from damage as they are located above the pod bases':and the transom commences S a sufficient distance aft of the -rear of each pod such that the keel and pods will ground in sufficient water to operate the propellers.

The ramp can then be lowered the barge emptied or loaded and the ramp again closed.

0a When it is necessary to move the barge from a grounded position it will be seen that the propellers are acting in their more efficient forward mode and their performance is further enhanced by the cavitation devices. They are also located in a position where there is little likelihood of damage to the propellers, before the barge starts moving by D:\WP51\SPEC\ASD.CAP HaY 14, 1998 debris being picked up from a shallow bottom to the propellers as they are spaced from the bottom by the space in between the lower surface 14 of the pod.

As mentioned earlier the viability of landing barges depends upon various parameters and we have found that barges having the construction of the present invention are in fact more economically viable and are more flexible than similar, conventional barges.

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*55 555*5 We have found that it is generally not necessary using the barge..of the present invention to: use: ballast, as is. often required in flat bottomed barges or, if .ballast is used this can be:minimised and can often be provided by .locating fuel tanks and. fresh water tanks to enable transfer of :the liquids Sin these to provide effective ballast trim adjustments.

The barge of the invention also has an improved righting moment relative to more conventional barges and this permits heavier on deck loads to be carried. It is believed that in most applications this increase would be of the order of 8- Thus the efficiency of the barge is greater than has previously being the case.

D:\WP51\SPEC\ASD.CAP May 14, 1998

Claims (9)

1. A barge including a conventional boat bow and an essentially V-shaped hull provided with keel devices (pods) on either side of the hull to the same deptheas and adjacent the keel of the hull; a transom slopes back from the keel to the stern of the hull where a loading and unloading ramp is provided.

2. A barge as claimed in claim 1 in which the ramp is pivoted along its lower edge.

3. A barge as. claimed in .claim 1 in which a.deck- house is provided at:,the adjacent the bow of the :bar.ge..:

4. A barge as claimed in claiml which is driven by propellers extending from the rear of each pod.

5. A barge as claimed in claim 4 in which the propeller blades have a diameter less than the depth of the pod.

6. A barge as claimed in claim 4 in which an engine is located within one or more of the pods.

7. A barge as claimed in any preceding claim in which any propeller is provided with an cavitation device which is arcuate in cross-section and is located between the o:\WP51\SPEC\ASD.CAP May 14, 1998 upper extent of the propeller blades and the hull and is affixed to the hull.

8. A barge as claimed in claim 7 in which the cavitation device extends forward of the propeller a distance of approximately four times the propeller diameter.

9. A barge as claimed in claim 7 in which the lower edges of the cavitation device extend downwards to a distance which is approximately 0.7 of the propeller diameter above the base of the pod. A barge substantially as hereinbefore described.with reference to the accompanying drawings. Dated: 15 May 1998 ASD MARINE SERVICES PTY. LIMITED By its Patent Attorneys A Tatlock and Associates 9 *999 9 94999 9 D:\WP51\SPEC\ASD.CAP AT May 14, 1998