GB2360744A

GB2360744A - Boat support arm

Info

Publication number: GB2360744A
Application number: GB0100915A
Authority: GB
Inventors: David Vernon Edwards
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-04-01
Filing date: 2001-01-12
Publication date: 2001-10-03
Anticipated expiration: 2021-01-12
Also published as: GB2360744B; GB0100915D0; GB0007956D0

Abstract

A boat 10 has a u-shaped arm 1 pivotally connected to its hull at or near the stern such that the arm can be rotated between a position above the hull and a position below the hull. The arm comprises two side beams and a cross beam with the free end of each side beam being pivotally connected to the hull. In the position below the hull the cross beam is positioned below the propulsion members and rudder. The arm may be pivotable through 200{ and may be locked in any position throughout its range of movement. The arm may also be provided with fittings to support a load (4, Fig 3). The arm may be moved by means of winched ropes or cables, motorised shafts or hydraulic pressure.

Description

2360744 BOAT GROUNDING DEVICE This invention provides a device which

allows a boat to take to the ground and which can be used also as davits. 5 The application of the device is of most use to power boats having propellers and rudders unprotected by keels or skegs and which, if the boat were to take to the ground, would be likely to sustain damage. It is usual to have unprotected propellers on power boats capable of planing speed because permanent protection such as keels or skegs creates drag and impairs performance. However the invention is not limited to power boats and may be applied to yachts, where the advantage of staying upright, when dried out, is useful.

The problem of damage to propellers and rudders by grounding is often solved by the use of stemdrives mounted on the transom. The propellers and stem gear can be tilted upwards. However such an arrangement normally requires the engines to be mounted just inside the transom at the stem of the boat and this prevents this space being used for an aft cabin. Furthermore, stemdrives can be more costly to maintain than shaft drives.

According to one aspect, the present invention provides a boat having at or near its stem a generally U-shaped arm pivotally connected to the boat hull so that the Ushaped arm can be rotated between a position generally above the hull and a position generally below the hull.

According to another aspect, the present invention provides a boat having at or near its stem a U-shaped arm which comprises two side beams and a cross beam, the free end of each side beam being pivotally connected to the boat hull so that the U-shaped arm can be rotated from a position in which the cross beam is generally above the hull to a position a position in which the cross beam is generally below the hull.

2 According to a flirther aspect, the present invention provides a boat comprising:

a hull; at least one propulsion member and/or rudder at the stem of and below the hull; and a U-shaped arm which comprises two side beams and a cross beam, the free end of each side beam being pivotally connected to the boat hull at or near the stem so that the U-shaped arm can be rotated from a position in which the cross beam is generally above the hull to a position in which the cross beam is generally below the hull and beneath the propulsion member(s)/rudder(s).

As mentioned above, the invention is not lin-fited. to power boats and may be applied to yachts, where the advantage of staying upright, when dried out, is useful.

The U-shaped arm is suitably connected to the side of the hull so that the arm can be rotated from a position above the hull where the arm lies forward of the vertical line passing through the pivot point to position below the hull where the arm lies forward of the vertical line passing through the pivot point. For example, the arm may be pivotable through about 200.

Preferably locking means are provided to retain the arm in its positions above and below the hull, and also to retain the arm in one or more positions between the extreme positions above and below the hull.

Typically in one intermediate position the arm is in a position beyond the stem but above the waterline, and in another intermediate position the arm is in a position beyond the stem but below the waterline.

The U-shaped arm may be provided with fittings to support a load to be lifted from or lowered on to water or a quay or pontoon. The arm may be raised or lowered by ropes or cables attached to the arm, which are handled manually or via hand-operated or powered winches or pulleys. Alternatively the arm mat be raised or lowered by a 3 motor or motors acting directly or indirectly on shafts which act as the pivot points for the arm.

Typically the present invention provides a device which provides protection to the propellers and rudders when operating in shallow water and allows grounding of the boat without damage to propellers and rudders. When not being used for that purpose, the device can be rotated out of the water to form a davit of known form and use, and also for other purposes described below.

Boats have a tendency to broach in a following sea, that is for the stem to begin to overtake the bow as the boat slews sideways. It is not uncommon to trail a sea anchor or heavy warps over the stem to reduce broaching. The device, the subject of this invention, may be used to reduce the tendency of a boat to broach, by providing the advantages of a sea anchor which, additionally operates in a push mode as well as a pull mode.

The berthing of boats in a marina is normally charged by the length of the boat including all overhangs such as davits and bathing platforms. With the rising cost of marina berthing, it is advantageous to be able to keep the overall length to a minimum consistent with the facilities of the boat. Most davits have a fixed overhang. The device the subject of this invention can be rotated to an inboard position with the tender hanging from the device, if the guard rails are set back or removable. Overall length and berthing charges can be reduced accordingly.

It is usually much less expensive to moor a boat on a swinging mooring in a harbour than alongside a pontoon in a marina. However some swinging moorings are in relatively shallow water with the danger of the boat taking the ground. This mitigates against using this type of mooring for a boat with unprotected propellers. However, the present invention would allow the cost saving associated with swinging moorings.

Boats which attain high speed by planing depend on clean hulls underwater to reduce drag. Marine fouling accumulates during the season and it is necessary to scrub the bottom to remove weed and shme in order to maintain boat performance. Boats with unprotected propellers must be hauled out for this operation. The present invention would allow drying out on a hard or other firm ground, in between tides, in order for 5 scrubbing to be done without the expense of hauling out.

It is desirable to be able to operate a boat in shallow water, for example to explore creeks, because this adds greatly to the use and pleasure to be obtained from a boat. In this respect, boats with sterndrive have an advantage. The present invention extends that facility to boats with unprotected propellers.

Getting disabled persons onboard a boat requires modifications to the boat which can be specialised and expensive. The present invention may be used for this purpose merely by the provision of a harness for a person or a wheelchair. In a similar manner physically impaired persons can be lowered into the water for a swim and recovered back to the aft deck.

According to the present invention, the device is in the form of a Ushaped arm mounted near the stem of a boat. The arm can typically be rotated from an approximate vertical upwards position to an approximately vertical downwards position, for example through about 200 degrees, or so, to form a protection for the propellers. It can also be locked at various intermediate positions to perform other functions.

One embodiment of the invention is now described with reference to the accompanying drawings in which: Fig. 1 shows the arm in place for protection of the propeller or propellers, Fig.2 shows the arm in place to reduce the tendency of a boat to broach in following seas, Fig.3 shows the arm in position as a davit, Fig.4 shows the arm in position for launching and recovery of a tender, Fig.5 is a cross sectional view of the arm, Fig.6 is a section through one of the pivots of the arm, Fig.7 shows the arrangement for rotating the arm manually downwards, Fig. 8 shows the arrangement for rotating the arm manually upwards, and Fig.9 shows the arrangement for stopping the arm at the extremities of travel.

Figure 1 shows the arm (1) rotated fiffly to it's position under the propellers. This position can be used while the boat is still fiffly waterborne and operating in shallow water. A planing hull boat will, of course, have it's maximum speed reduced to displacement hull speed, or less, when operated with the device in the grounding position. A boat with sterndrives, in the tilted position also operates at displacement speed. Low speed is desirable, in any case, when in shallow water. The grounding device is not, therefore, much disadvantage at low speed. With the arm (1) in the grounding position as in Figure 1, the boat can take to the ground with the propellers and rudders fiffly protected. The hull (10) wiII rest on the Yee of the bow forward and the full width of the U-shaped arm at the stem in tidal waters when the water level falls. With this support the boat will remain upright. Scrubbing of the hull can be done in this position between tides.

The boat can also be rested on the arm (1) when hauled out by a crane for storage ashore, thus saving the use of a cradle or other supporting structures normally provided by the boatyard. It can be seen from figures 1, 2, 3 and 4, that the arm (1) is pivotally attached to the hull (10). The arm (1) may be rotated to the position shown in figure 2. The dotted fine (3) indicates the movement of the arm (1) from the grounding position shown in Figure 1. The arm (1) acts as a sea anchor when the boat is travelling faster than the waves. When the boat is in overtaking waves, the arm (1) may tend to break the force of the wave before it hits the transom, thus reducing the tendency to broach. This action, operating as it will in pull and pusk may make the boat more seaworthy in following seas. The strength of attachment of the arm (1) to the hull (10) necessary for it's grounding purpose, is also of use in the attribute of seaworthiness just described.

6 Referring to Figure 3, it can be seen that the U-shaped arm (1) is rotated to a position where it can be used as a davit. The single arm (1) serves the same function as a pair of conventional davits. The single arm U-shaped davit is, of course, known art The dotted fine (3) indicates the movement of the arm from it's position in Figure 2. Figure 3 shows a tender, or dinghy, (4) hanging from the arm. The tender can be raised or lowered by conventional means using a winch and/or with ropes and pulleys. Alternatively, the arm may be rotated until the tender is waterbome whereupon it can be released from the am-L This method would be suitable only for calm water operation.

In place of a tender, the foregoing arrangement can be used to board a disabled person in a harness or wheelchair. This can be done by having the boat moored stem-to to a dockside or pontoon, or alternatively from another boat. With the boat clear of obstruction, a physically impaired person can be lowered into the water for a swim and recovered again back to the aft deck. The arm (1) can be rotated beyond the vertical and angled toward the bow of the boat, as shown in figure 4, thus allowing a tender, or other heavy load to be lowered directly onto the aft deck of the boat. The arm (1) can also be used for 'man- overboard' recovery.

The arm (1) may be made from stainless steel with a cross section as in Figure 5. The width of the cross section is about 30 cm for a boat of, say, 5 tonnes displacement, sufficient to provide a good bearing surface on soft ground. For larger and heavier boats, the width of the arm and the stiffening members (1 a) would be increased in proportion. In a preferred embodiment of the invention, each of the two pivots of the arm is constructed as shown in figure 6. Describing one of the pivots, the shaft (6) has a welded plate (7) at it's outboard end and this plate is bolted to the arm. The shaft is held in bearings (8) which are located in a reinforced part (9) of the hull or superstructure (10). Inside the hull or superstructure (10) the shaft (6) is splined, to which is fitted a hydraulic rotary actuator (11) shown in diagrammatic form. There is a rotary actuator on each of the two pivot shafts. Each rotary actuator (11) is connected via hydraulic hoses (12) to a valve (13) and a hydraulic pump (14), all shown 7 diagramatically. When the hydraulic pump (14) is running, for example by electrical power from the boats batteries, the valve (13) is used to raise and lower the arm (1) to any desired position. The valve (13) is fitted with a lever (15) and preferably located near the stem of the boat. Duplicate valves can be fitted elsewhere, for example at the 5 hehns console (not shown).

As an alternative, the arm may be raised and lowered manually with block and tackle fitted each side of the boat. as shown in Figure 7 and Figure 8. Referring to Figure 7, each block and tackle (16) is secured between the arm and a deck cleat (18) for puffing the arm (1) down. Referring to Figure 8, each block and tackle (17) is secured between the arm (1) and a cleat (19) provided on the coachroof for pulling the arm up. As blocks and tackle (16) is tightened, so blocks and tackle ( 17) are slackened. Similarly, as blocks and tackle (17) are tightened, so blocks and tackle (16) are slackened. When the arm (1) is at the extremities of it's travel it is desirable to have stops (18) to prevent further movement. This is particularly important when the arm (1) is at the grounding position shown in Figure 1 since it is necessary to have it locked in position and preferably assisted by the weight of the boat. For this reason the arm (1) is taken to an over-centre position as shown in Figure 1.

Figure 8 shows the arrangement of stops (18) which form part of the structure of the bearing housing assembly at the pivot points. When the arm (1) is in a vertically upward position it may be used as a support to attach an awning over the aft deck or cockpit of a boat. This feature is not illustrated in the figures. The arm (1) may be used to mount ancillary items such as radar, searchlight, aerials and the like on a removable base. The removable mounting base may be attached with bolts and wingnuts or any similar means so that the arm (1) may be rotated to it's grounding position without damage to the ancillary items. This feature is not illustrated in a figure.

The leg system can be made an ascetically pleasing part of boat design, more so than conventional davits. Many powerboats and some sailing boats have arches at or near the stem. The leg system can be made to fit into the fines of the boat in the same way.

8 In particular the arm in its upright "rest" position, typically with the crossbeam forward of the vertical line through the pivot, may be nested in a similarly inclined radar arch at the rear of the boat.

9

Claims

1. A boat having at or near its stem a generally U-shaped arm pivotally connected to the boat hull so that the U-shaped arm can be rotated between a position generally 5 above the hull and a position generally below the hull.

2. A boat having at or near its stem a U-shaped arm which comprises two side beams and a cross beam, the free end of each side bearn being pivotally connected to the boat hull so that the U-shaped arm can be rotated frorn a position in which the cross beam is generally above the hull to a position a position in which the cross beam is generally below the hull.

3. A boat comprising:

a hull; at least one propulsion member and/or rudder at the stem of and below the hull; and a U-shaped arm which comprises two side beams and a cross beam, the free end of each side beam being pivotally connected to the boat hull at or near the stem so that the U-shaped arm can be rotated from a position in which the cross beam is generally above the hull to a position a position in which the cross beam is generally below the hull and beneath the propulsion member(s)/rudder(s).

4. A boat according to any one of eh-dim 1 to 3 in which the U-shaped arm is connected to the side of the hull so that the arm can be rotated from a position above the hull where the arm lies forward of the vertical line passing through the pivot point to position below the hull where the arm lies forward of the vertical line passing through the pivot point.

5. A boat according to claim 4 in which the arm is pivotable through about 200'.

6. A boat according to any one of claims 1 to 5 including locking means to retain the arm in its positions above and below the hull.

7. A boat according to claim 6 in which the locking means also retains the arm in 5 one or more positions between the extreme positions above and below the hull.

8. A boat according to claim 7 in which in one intermediate position the arm is in a position beyond the stern but above the waterline.

9. A boat according to claim 7 or 8 in which in one intermediate position the arm is in a position beyond the stem but below the waterline.

10. A boat according to any one of claims 1 to 9 in which the U-shaped arm is provided with fittings to support a load to be lifted from or lowered on to water or a 15 quay or pontoon.

11. A boat according to any one of claims 1 to 10 in which the U-shaped arm is raised or lowered by ropes or cables attached to the arm, which are handled manually or via hand-operated or powered winches or pulleys. 20

12. A boat according to any one of claims 1 to 10 in which the U- shaped arm is raised or lowered by a motor or motors acting directly or indirectly on shafts which act as the pivot points for the arm.

13. A boat according to claim 12, in which the arm is raised or lowered by hydraulic pressure.

14. A boat according to any one of claims 1 to 3, substantially as described herein with reference to any one of the Figures of the accompanying drawings.