DAVIT

Abstract: Davit of the type which comprises a main arm (1) with a bearing (8) at one end adjacent the ship's deck (21) for swinging movement in a vertical plane, and a winch with a wire (12) the outer end (14) of which is adapted to be detachably connected to suspension means on a lifeboat (20), life raft or the like. For the purpose of attaining an improved curve of movement a rocking arm (2) is pivoted (9) at the outer free end of the main arm (1) and is provided with a pulley (13D) for the wire (12) at its outer free end. A tension element (43) at one end is pivotably connected (43A) to the inner end of the rocking arm (2), and at its opposite end is pivotably anchored (44A) in a basement (44) on the ship's deck (21) at a point of attachment (44A) located somewhat higher than the bearing point (8) of the main arm adjacent the ship's deck (21). The point of attachment (44A) of the tension element (43) is positioned at the opposite side of the main arm (1) in relation to the inner end of the rocking arm (2), when the davit is in its inboard position.

Description: DAVIT There are previously known various designs of davits, am others the so-called gravity davits and roller davits. This invention relates to an improved gravity davit for attaining more advantageous pattern of movement of the outer end of the davit than what is resulting from the known davit designs. An important recognition in this connection is that the known davits involve a steeply falling movement at the termina ting portion of the outboard swinging before launching of the lifeboat or the like can be started. This steep portion of th movement curve is highly unfavourable. At one hand such curve will not give an optimal outward movement of the lifeboat so a to be clear of the ship's side, and at the other hand a larger winch power is required for lifting in this portion of the movement. Other important considerations are the total buildi height of the davit above deck as well as simple manufacturing and mounting. Examples of known davit designs having a pattern of movem with a terminating curve being to some degree modified, are fo in German patent 957148. These known embodiments however, are not gravity davits-, but are based on manual force (crank handl for the outboard swinging, and besides require an initial lift of the lifeboat from a support underneath the lifeboat keel, before the outboard swinging. This is a situation which is absolutely incompatible with the gravity davit principle, whic requires that the davit shall launch the lifeboat exclusively the effect of gravity. This shall also be possible when all auxiliary machinery onboard the ship concerned, has stopped an the ship has a list. The new davit construction being defined in the claims ma it possible to attain a substantially rectilinear movement cur of the outer end with accompanying pulley over which the suspe sion rope to the lifeboat, life raft or the like is trained, along a substantial portion of the whole movement. Besides, preferred embodiments according to the invention give an advan geous curve at the initial -movement out from the stowed positi of the davit, so that a secure outward swing is attained under different conditions. Closer statements of the davit according to the invention well as the novel and specific features thereof, are found in t claims. Among the significant advantages resulting from this invention, may be mentioned: a large outboard swing combined with a low building height, small inboard swinging forces which makes possible a lower winch motor power, a reduced need for special adjustment to the individual ships, rationalized manufacturing and assembling because, inter alia, standard materials and components can be used. The invention shall be described below with reference to a exemplary embodiment illustrated in the drawings, wherein: Fig.l shows a davit in its fully inboard (stowed) position, according to an embodiment of the invention, Fig.2 shows the davit of fig.l in its fully outboard swung position (launching position) , Fig.3, 4 and 5 show a preferred embodiment according to the invention in the inboard, partly outboard and fully outboard positions respectively. In fig.l there is shown a portion of a ship's deck 21 and ship's side 22 as well as a lifeboat 20 being suspended from th davit. This is built up from a basement for the lower end of a main arm 1, for the anchoring of a tension element 43 and constitutes a support 45 for a pulley 13 from which a rope portion 12A runs to a winch motor (not shown). The basement parts can be separately attached to the deck 21 or they can be assembled to a unit. The main arm 1 and the rope 12-12A with an associated winc motor are components which are also present in known davit constructions. Important features of the davit described here, are a rocking arm 2 pivoted at 9 on top of the main arm 1, and a tension element in the form of a rod 43 which connects the inne end of the rocking arm 2 to the basement or support 44. . The outer free end portion of the rocking arm carries a pulley 13D for the rope 12, the outer end of which is detachably connecte to suspension means on the lifeboat 20. The embodiments shown in the drawings distinguish themsel primarily thereby that they have an initial movement curve out from the inboard (stowed) position which is very advantageous, i.e. the outer pulley has a more steeply falling movement than circular arc, which usually is the initial movement at the kno designs. The embodiments described here, moreover has the adv tage that the movement as a whole will be quite smooth. It is common to the embodiments described that they have anchoring of the lower end of the tension element at a pure pi point which in the stowed position of the davit is located clo to the main arm than is the upper end " of the tension element. will appear from the following description with reference to t figures of drawings, the said pivot point moreover can be so positioned that the tension element crosses the main arm in th stowed position. A basement support 45 in fig.l and 2 has a projecting support member 44 at which there is provided an anchoring 44A the tension element 43. Thus the tension element will cross t main arm 1 and this leads to the above mentioned favourable movement curve out from the inboard position (fig.l), as the tension element 43 from this position will result in a somewha rising movement of the point 43A in relation to the pivot 9 fo the rocking arm, so .that the outer end of this arm will have a corresponding relatively falling movement curve. In fig.2 the is indicated an "ideal" rectilinear movement curve 50 and besi a curve 41 being followed by the outer pulley 13D on the rocki arm 2. Curve portion 41 quite closely follows the ideal line and continues with a smooth transition to the portion 42 which has also a favourable curve. Thus the movement takes place al a substantially straight line which runs at an inclination downwardly and outwardly with a sufficient slope for gravity t result in the desired outboard swinging in an emergency situa¬ tion. Advantageously the angle of inclination can be about 30 degrees with respect to the deck plane. It is obvious that during this outboard movement there is all the time payed out 8 rope from the winch by means of a brake, under manual control i a known manner. A preferred embodiment is shown in fig.3-5. Therein the lower end of the tension element 63 is anchored at 64A on a bracket 64 which itself is somewhat pivotable, namely about a bearing 66 on a support 65 having its basement for example on a ship's deck. In the inboard position in fig.3 the configuratio of the parts is in the principle similar to what is shown in fig.l, whereby the bracket 64 at 69 is in engagement with the support 65. By swinging outwards as far as to the position in fig.4, the bracket is still in engagement at 69, but in this . situation the points 66, 64A and 63A lie on a straight line, so that a continued outboard movement will result in the swinging the bracket 64 together with the tension element 63 quite as a direct extension thereof. Fig.5 illustrates the substantially fully outwardly swung davit with indications (dot-dash lines) o the preceding posisions or stages as shown in fig.3 and 4. The resulting movement curve of the outer pulley 13D consists of portions 61 and 62 which advantageously run closely to the idea line 50. By comparison of the curve portions 41 and 61 in fig. and 5 it will be seen that the latter has a steeper first porti out from the stowed position, i.e. a more secure start of the outboard movement in the embodiment of fig.3-5. » The embodiment of fig.1-2 however, is somewhat simpler wit respect to the mechanical construction and therefore is more inexpensive, and may be preferable in cases where the geometric conditions are not too strict. Although on account of space considerations the embodiment described have a substantially vertical main arm and a substan¬ tially horizontal rocking arm in their inboard position, it is obvious that the essential function according to the invention possible also with angular positions being different from these when the davit is in its stowed position. The space considera¬ tions mentioned also imply that the construcion usually should have as small dimensions as possible horizontally at the baseme on the ship's deck or the like. The geometry of the link or arm system described is very important for an optimal adjustment of the movement curve of th pulley 13D. Thus it will be appropriate to let the main arm the tension element in their fully outboard position approach each other in the outward direction, i.e. that the distance between their lower end portions is larger than between their upper end portions in this position, with relative dimension selected there is obtained advantages both with respect to th pattern of movement and to the mechanical strength. It is important to note that in all the embodiments show the tension element is shorter than the main arm. Moreover, i can be an advantageous practical design to split up the tensi element into parallel parts lying on either side of the associ ted main arm (or vice versa) in order to obtain a more balance force system. As in the known designs of davits there may also here advantageously be incorporated an auxiliary spring which has stored energy in the stowed position, for the purpose of assis ting at the starting of the initial outward movement. The course of the rope 12 can be modified in many ways, s as by locating the pulley 13C differently so as not to coincid with the pivot 9, for example at a position closer to the oute pulley 13D. The rocking arm 2 does not have to be straight, n to have a constant thickness. In consideration of available space and mechanical strength relationships also other designs this arm may be of interest. The simple rope 12-12A with pull can be strengthened by providing blocks and multiple tackle in manner known per se. The davit can be arranged as a single davit, for example for a life raft, or as a double davit for a lifeboat or the like. It can be used onboard ships as describ or on drill rigs, quays and other installations at which there a need for rafts, boats or rescue equipment which shall be adapted to be launched to and lifted from the sea respectively

Claims: AMENDED CLAIMS [received by the International Bureau on 24 November 1987 (24.11.87) original claims 1 and 2 replaced by amended claim 1 ; claims 3 - 5 renumbered as 2 - 4 (2 pages)] 1. Davit of the gravity type, comprising a substantially straight main arm (1) having a bearing .(8) at one end adjacent the ship's deck (21) for swinging movement in a vertical plane, and a winch with a rope (12) the outer end (14) of which is adapted to be detachably connected to suspension means on a lifeboat (20), life raft or the like, a rocking arm (2) pivoted (9) at the outer free end of the main arm (1) and provided with pulley (13D) for the rope (12) at its outer free end, and a tension element (63) at its one end being pivotably connected (63A) to the inner end of the rocking arm (2), and at its other end being pivotably connected to an anchoring point (64A) being higher than the main arm bearing point (8) adjacent the ship's deck (21), and being located at the opposite side of the main ar (1) in relation to the inner end of the rocking arm (2) when the davit is in its inboard position (fig.3), characterised in that the anchoring point (64A) of the tension element (63) is provide on a bracket (64) which itself is pivotable about a bearing (66) on a support (65) being anchored to the ship's deck (21), and which is adapted to be in engagement (69) with a portion of the support (65) in the inboard position of the davit, but upon swinging out beyond a certain angle it is adapted to be moved away from its engagement (69) against the support (65) and to take part in the further outward swinging in line with and as an extension of the tension element (63). 2. Davit according to claim 1, characterised in that there is provided locking means (11) for automatically fixing the main ar (1) and the rocking arm (2) in relation to each other in the fully outboard position, said locking means acting preferably between the upper end portion of the main arm (1) and the inner portion of the rocking arm (2) . 3. Davit according to claim 2, characterised in that said locking means (11) are connected to a lock (10) for the rope end (14) so that said locking means (11) enter into function when th lock (10) for the rope end (14) is released. 4. Davit according to any one of the claims 1-3, whereby for the ro e 12 in ad oute the rocking arm (2), there is provided a second pulley (13C) a the outer end of the main arm (1), preferably having an axis coinciding with the pivot axle (9) for ' the rocking arm, charac rised by a third pulley (13B) preferably mounted on the lower half of the main arm (1), and a fourth pulley (13A) mounted on upright support (65) founded on the ship's deck (21). STATEMENTUNDERARTICLE19 Amended claims are filed in view of British patent specification 391161 which is cited in the international search report. Thus original claims 1 and 2 have been combined into a new main claim, whereas original claims 3, 4 and 5 have been re-numbered to be amended claims 2, 3 and 4 respectively. The amended claim 1 is directed to the embodiment shown in figures 3-5 of the drawings. This is also reflected in adjusted reference numerals included in the amended claims.

Inventors: GAUSVIK NILS, OEEN ROALD, GAUSVIK, NILS, OEEN, ROALD
Applicants: HARDING SAFETY AS
Application year: 1987
Main classification: B63B23
IPC codes: B63B23