The present invention relates to a stake structure for maritime use comprising a supporting member secured in the sea bottom and a stake member which is rigidly but releasably connected with the supporting member and which extends from a point below water level and to a point above water level .

Several different stake structures for maritime use are known, as e.g. stakes for bathing jetties, navigation marks, boat bridges, pound nets and the like. In waters where ice formations may occur a part of the year, a common feature for many such stake structures will be that they ought to be taken up and brought ashore during the winter time in order to avoid damage and possible also fractures due to the actions from the ice which will make the stake structures totally unusable. Often such stake structures are made of wood. Before such stakes may be used bark must be removed, the stake must be tapered and trans¬ ported to the cite where they are to be used. Then the wood stakes, after having been made ready, have to be transported from ashore and to the position of use where they must be beaten down into the sea bottom. Such work is heavy, time-consuming and heavy equipment is ne¬ cessary. After the stakes have been beaten down the further equipment, as e.g. navigation marks or nets are arranged and the wooden stakes remain erected until there is a risk for beginning of ice formations. At that time it is necessary to withdraw the wooden stakes, transport them ashore and store them during the winter time at storage places arranged therefor. This work, as well as the beating down of the stakes is heavy and time-consuming.

Stake structures will, in particular when they are to be used as fishing stakes, often remain as long as possible on the places where they are installed in order to extend the season and the use of the stakes as much as possible. Accordingly, it is often necessary to take up the stakes rapidly at the beginning of the ice formation. In many instances a part of the stakes will be left because ice formations prevent further work as regards the taking up of the remainder of the stakes. Such stakes may be regarded as lost. Due to all these circum¬ stances such stake structures have in average only a short lifetime which makes their use expensive.

Furthermore, wooden stakes generally are in danger of decomposi¬ tion and destruction due to external actions e.g. fouling, rot, ship-

worms etc.

It is the object of the present invention to avoid the drawbacks referred to above by providing a stake structure of the kind stated above which rapidly may be demounted, when ice formation starts and which easily may be remounted after the ice has disappeared and which has a long lifetime. Furthermore, it is intended that the stake struc¬ ture should reduce or eliminate the problems arising due to the exter¬ nal actions.

According to the present invention this object is achieved by means of a stake structure which is characterized by the stake member having a density which is greater than the density of water, the stake member and the supporting member being mutually connected by means of a fle¬ xible connecting member which allows separation of the rigid connection between the stake member and the supporting member. Hereby it is made possible in a simple way rapidly and cheap to demount and remount stake structures which remains the winter over on the bottom or, in any way, at such depth that no risk for ice forma¬ tion exists and which, accordingly, may be used year after year.

It is a further advantage of the stake structure according to the present invention that the stake structure may be provided with a smooth non-wooden surface which excludes the risk that objects, e.g. pound nets, which come into contact with the stake structure may be torn and which excludes the risk that the stake structure is destructed due to said external actions. When the supporting member once and for all has been secured to the bottom by being beaten down, buried by flushing or in any other way the stake structure may rapidly and easily be erected or remount¬ ed. By the erection or remounting of the stake structure only a single vessel is necessary with a winch and a diver which has to guide the stake member in order to provide the rigid connection together with the supporting member and to connect the flexible member.

By the erection, the stake member is lowered and the diver guides the stake member and connects it with the supporting member and then he connects the stake member and the supporting member by means of the flexible connecting member.

By demounting the stake structure, it will only be necessary from the vessel to lift the stake member to such a height that the stake member is separated from the supporting member and then the stake mem- • ber is allowed to sink down upon the sea bottom upon which it, due to

the flexible connecting member, will remain immediately adjacent the supporting member and connected with the supporting member by means of the flexible connecting member.

By remounting, a diver will be positioned on the bottom in order to secure a wire from the vessel to the stake member resting upon the bottom, then the stake member is lifted and the diver then guides the stake member so as to connect it rigidly with the supporting member. Now the stake structure is remounted and this will under normal con¬ ditions result in that a considerable greater number of stake struc- tures may be established per day compared with usual stake structures which has to be beaten down into the bottom.

Moreover, the stake member itself may easily be exchanged in case of tearing, simply by demounting the flexible connecting member and totally remove the teared stake member, whereafter a new stake member may be erected as described above.

A preferred embodiment of the stake structure is characterized in that the supporting member comprises a tubular sleeve secured in the sea bottom and closed at the lower end, the upper end of the sleeve extending to a point immediately above the sea bottom. Moreover, advan- tageously the lower end of the tubular sleeve may be closed by means of an end closure in form of a detachable pointed member which is in¬ serted in and secured to the lower end of the tubular sleeve. Then the tubular sleeve is secured to the sea bottom. This makes it possible to use the same type of tubular sleeve both when it is to be drilled into a firm or rocky sea bottom and when it may be beaten down or buried by flushing into the sea bottom. In case the tubular sleeve has been dril¬ led into a firm or rocky sea bottom it will not be requisite to close the lower end. Hereby a simple structure is achieved whereby the stake member can be a solid stake or a tube which is manufactured from any suitable material and which only is moved into the sleeve with a loose fit. Accordingly, the material may be selected so as to avoid the risk of external actions which also makes the stake structure well suited for application not only in waters where ice formations may occur but also in waters where great risk exists for the external actions to occur e.g. in subtropical and tropical waters with danger of fouling, shipwor s etc.

A further embodiment of the stake structure according to the in¬ vention is characterized in that the supporting member comprises a rod-shaped member secured in the sea bottom and extending to a point

between the sea bottom and the water surface. Thereby a greater part of the structure, viz. the partly embedded rod-shaped member, may con¬ sist of a comparatively cheap material, as e.g. wood. According to this embodiment it is necessary that the flexible connecting member has a considerably greater length than according to the embodiment described above if it is the aim that the stake member may be capable of lying upon the sea bottom. The length of the rod-shaped member is, however, limited due to the fact that the legislation in different countries may define limits as regards the permitted distance between the end of the rod-shaped member and the water surface and/or the sea bottom.

A further embodiment of the stake structure according to the in¬ vention is characterized in that the open end of the tubular sleeve is provided with covering means. Thereby it is possibly safely to prevent material which due to sea draughts move over the sea bottom from fal¬ ling down into the tubular sleeve and block it. Preferably, the cover¬ ing means may be provided with biasing means so constructed that they automatically will bias the covering means towards their position for covering the open end of the sleeve, when the stake member is removed from engagement with the sleeve.

Moreover, the stake member may be produced from steel, plastic material, concrete or combinations thereof in order to produce a smooth stake member which secures that articles which may come into contact with the stake member are not torn and which reduces the destructing effect originating from different external actions.

Even though the invention has been explained with reference to preferred embodiments it will be understood that other embodiments also are possible, even though they are not explained specifically above. For instance, the stake member as well as the rod-shaped member may optionally be made in the form of a solid structure or as a tubular structure. Description of the Drawings

The invention will hereinafter be further explained with reference to the drawing wherein Fig. 1 schematically shows a picture of an embodiment of the stake structure according to the present invention, Fig. 2 schematically shows a picture of another embodiment of the stake structure according to the invention, and Fig. 3 a picture for illustration details of an embodiment of

the stake structure. On Fig. 1 a stake structure is shown, intended to be used as fish¬ ing stake whereby a supporting member which is secured in the sea bot¬ tom 1 consists of a sleeve 2 which at the lower end thereof is provided with an end closure 3 intended to prevent material from the sea bottom

1 to penetrate through the lower end and block the sleeve. The end closure 3 may be provided in form of a detachable pointed member (not shown). Hereby it is possible to use the same type of tubular sleeve 2 both in a loose and firm sea bottom. In case of a loose sea bottom the pointed member (which substantially corresponds to the pointed end of the supporting member illustrated on Fig. 2) is inserted in and secured to the lower open end of the tubular sleeve 2. Then the tubular sleeve

2 may be secured to the bottom by beaten down, buried by flushing or in any other way. In case with a firm or rocky sea bottom the tubular sleeve 2 may be drilled into the sea bottom by means of a drill head extending through the hollow sleeve. Moreover, the sleeve 2 is provi¬ ded with an eye fitting 4 to which one end of a flexible connecting member in the form of a wire 5 may be secured.

A stake member in the form of a plastic tube 6 filled with concre- te 7 and, accordingly, having a density higher than the density of water, is produced with a length so as to extend to a point above the water level 10 and with an outer diameter adapted according to the inner diameter of the sleeve 2 in such a way that the lower end 8 of the tube 6 may be arranged with a loose fit in the sleeve 2. The tube 6 is provided with a further eye fitting 9 to which the other end of the wire 5 may be secured. At the end 11 of the tube 6 extending above the water level 10 a transversely extending rod or bitt 12 is provided. The bitt 12 may be used for securing a pound net (not shown) and/or for securing a wire from a vessel either by erecting, mounting or de- mounting the stake structure as explained above.

As a non-limiting example of the dimensions of the structure shown on Fig. 1 it may be mentioned that the sleeve 2 has a length of approx. 2 m and approx. 1,8 m is embedded in the sea bottom by flushing whe¬ reas the remaining approx. 0,2 m extends above the bottom of the sea in order to prevent material moving over the sea bottom from falling down into a sleeve 2, which is not covered. The outer diameter of the tube is approximately 1-2 cm less than the inner diameter of the sle¬ eve and the eye fitting 9 is arranged approx. 2,2 m from the lower end of the tube 6, which is a length approx. corresponding to the depth of

the sea plus 1,5 . The bitt 12 is arranged immediately adjacent the upper end of the tube 6. The length of the wire is approximately 2,3 m.

On Fig. 2 a stake structure is shown wherein the supporting member is constituted by a tubular or solid rod 13 secured into the sea bottom 1 and which extends to a point below the water level 10 and wherein the stake member 13 is constituted by a top extension 6 constructed in the same way as explained with respect to Fig. 1 viz. consisting of a tube 6 filled with concrete. Dependent on the legal provisions, the practical use, etc., the rod 13 may extend to a point shortly above the sea bottom 1 or to a point at a considerable distance above the bottom as illustrated in Fig. 2. The rod may be produced from a compa¬ ratively cheap material and is intended to be produced e.g. from wood. However, in waters where wooden structures are in danger of destruction e.g. due to shipworms, the rod 13 may be produced e.g. from concrete, plast material, steel, or a combination thereof. Moreover, this struc¬ ture makes it possible to reduce the weight of the stake member which must be lifted with respect to the bottom of the sea for remounting the stake structure. The tube 6 and the rod 13 may either have general- ly the same transverse dimensions or different transverse dimensions in order to dimension the rod 13 for a stronger load. The tube 6 and the rod 13 are mutually connected by a tubular member 14 which in any suitable way is secured at the top of the rod 13 and the diameter of which is a little greater than the outer diameter of the rod 13 and of the tube 6.

Fig. 3 shows a covering member consisting of a lid 15 which is pivotally mounted at 16 in order to automatically cover the open end of the sleeve 2 by means of a spring 17, when the tube 6 is withdrawn from the sleeve. Furthermore, such a lid 15 will secure the sleeve 2 from being filled with material which due to sea draughts moves over the sea bottom.

When frosty weather is to be expected the stake member shown in Fig. 1 is lifted free of the supporting member 2 and is lowered down upon the sea bottom 1. The wire 5 has lenght such as to allow such lifting, seeing that it is longer than the depth of the sleeve 2. Now the stake will be protected against the effects from the ice. As re¬ gards the embodiment shown in Fig. 2 the top extension 6 is lifted clear of the tubular member 14 and lowered down upon the sea bottom 1. Also in this case the wire 5 has a length such as to allow the lower-

ing of the top extension 6 because the wire is longer than the length of the part of the rod 13 projecting from the sea bottom.

In case a stake structure corresponding to that shown in Fig. 1 or Fig. 2 is to be used in waters where the risk of ice formations do not exists its use will still be advantageously. Often the stake structure will be destructed in the part provided at the water level due to me¬ chanical, chemical or biological attacks. With the stake structure according to the invention it is possible to choose a material whereby the effect of such attacks is minimized. Moreover, if the stake struc- ture has become weakened, the stake member 6 may easily be exchanged, simply by demounting the flexible connecting member 5 and remove the weakened stake member 6. Then a new stake member may be erected as described above by means of a winch-provided vessel and a diver which guides the stake member in order to provide the rigid connection to- gether with the sleeve 2 or the tubular member 14, and to connect the wire 5 between them.