Boat hull with outboard drive and outboard drive for boats

[0001] The present invention relates to a boat hull with an outboard drive unit for at least one propeller, said drive unit comprising an underwater housing extending down from the outside of the hull bottom, and an at least substantially vertical drive shaft being rotatably mounted in said underwater housing, extending through an opening in the bottom of the hull and driving, via a bevel gearing enclosed in said underwater housing, at least one at least substantially horizontal propeller shaft mounted in said underwater housing

[0002] The invention relates also to an outboard drive unit for boats for driving at least one propeller, comprising, firstly, an underwater housing in which there is rotatably mounted a drive shaft, which is substantially vertical in the operating state of the drive unit, and said drive shaft being drivably coupled via a bevel gearing at a lower end to at least one propeller shaft mounted in the underwater housing, and, secondly, a gearing housing joined to the underwater housing and comprising a second bevel gearing, via which the upper end of said essentially vertical drive shaft is drivably coupled to a substantially horizontal shaft, and mounting means for mounting the drive unit with the underwater housing on the outside and the gearing housing on the inside of a boat hull.

[0003] Previously known outboard drive units of the type presently in question, which have a leg or underwater body extending down from the underside of the hull bottom, have been mounted in two different manners. In one case, the leg is rigidly joined to the engine and extends through an opening in the hull bottom, with a rubber bellows or the like forming a seal between the leg and the edge of the surrounding opening. The pushing forces of the propeller are taken up by the engine and the engine mounting. In the second case, the leg or the underwater housing is fixed to a plate which is screwed securely, or fixed in some other manner, to the bottom of the hull. In this case the entire propeller force can be taken up by the hull or a portion can be taken up by the hull and a portion by the drive unit mounted on the inside of the hull, i.e. the engine and transmission.

[0004] Common to both alternatives is that the mounting work is relatively complicated, due to the fact that a significant mounting work is required for making the hole, fitting and fixing both from the outside of the hull bottom and from the engine compartment on the inside.

[0005] One purpose of the present invention is to achieve a boat hull with an outboard drive unit of the type described by way of introduction, which permits maximally rapid and simple mounting of the drive unit in the hull and where essentially all the work after fitting of the drive unit in the opening in the hull bottom can be done from above, thereby making it possible to avoid physically tiring up-and-under work.

[0006] This is achieved according to the invention by virtue of the fact that the opening is so dimensioned that a housing portion joined to the underwater housing is insertable from below through the opening to a position on the inside of the hull, that the bottom of the hull is provided with a well surrounding said opening and extending up into the interior of the hull, said well being made with an inwardly directed peripheral flange, which, with an elastic insert on each side, is held tightly between a mounting plate rigidly joined to the underwater housing and/or said housing portion and a screw-down plate fastened to the mounting plate, said plates having shapes adapted to the opening and to the peripheral flange.

[0007] The flange and the screw-down and mounting plates may have a non-circular shape and be provided with profiles fitted to each other so that they can only be mounted in one manner relative to each other. The screw-down plate can be provided with peripherally spaced through-bores for screw-down bolts and the mounting plate may have corresponding threaded bores for these bolts. After fitting the underwater body in the well with associated elastic elements abutting against the underside of the flange, all that is required is to put the screw-down plate in place from above with the second elastic element between it and the flange and to tighten the screw-down plate against the mounting plate with the aid of the bolts.

[0008] An outboard drive unit of the type described by way of introduction is characterized, according to the invention, in that said mounting means comprise a mounting plate rigidly joined to the underwater housing and/or the gear housing, a screw-down plate and elastic inserts for clamping the drive unit against a peripheral flange in a well in the bottom of a boat hull, with the mounting plate and an elastic insert on one side and the screw-down plate and an elastic insert on an opposite side of the flange.

[0012] In the figures, 1 designates the bottom of a boat hull, which can be cast fibreglass reinforced polyester plastic. The bottom 1 of the hull is made with an opening 2 which is surrounded by a vertical well 3, extending up into the interior of the hull. The well 3 is preferably cast in one piece with the bottom 1 and is provided with an inwardly directed, peripheral flange 4, which, in the example shown, has a substantially triangular cross section.

[0013] The well 3 with the flange 4 forms mounting means for a propeller drive unit generally designated 5, which, in the example shown, has an underwater housing 6, in which two concentric propeller shafts 7 and 8, respectively, have rotatably mounted individual propellers 9 and 10, respectively. The underwater housing 6 is joined to an upper gear housing 11, in which a horizontal drive shaft 12 is rotatably mounted.

[0014] The shaft 12 is intended to be coupled to a power plant (not shown). The shaft 12 drives, via a bevel gearing comprising bevel gears 13 and 14 enclosed in the gear housing 11, a vertical shaft 15, which in turn drives, via a second bevel gearing having bevel gears 16, 17 and 18 enclosed in an underwater housing, the propeller shafts 7 and 8 counter-rotationally. In the example shown, the propellers 9 and 10 are pulling propellers disposed forward of the underwater housing 6, in the aft end of which there is an exhaust port 19.

[0015] Between the underwater housing 6 and the upper gearing housing 11, there is, in accordance to the invention, a mounting plate 20 fixed, which can be cast metal, e.g. aluminium, or moulded fibreglass reinforced plastic. The plate 20 is, as is the well 3, preferably oval in shape in horizontal projection. The plate 20 has furthermore a conical upwardly facing lateral edge surface 21 and the flange 4 has a corresponding conical downwardly directed lateral edge surface 22. By providing the plate 20 and the well 3 with a shape which is non-circular, together with inclined lateral edge surfaces 21 and 22, controlled alignment of the drive 5 is achieved relative to the bottom 1 of the hull, when the drive 5 is mounted from below into the well 3, as illustrated in FIG. 1.

[0016] Before the drive 5 with its mounting plate 20 is inserted into the well 3, there is placed against the lateral edge 21 of the plate 20 a ring 23 of elastic material of e.g. rubber, with a circular cross section and oval shape adapted to the flange 4 and the lateral edges 21, 22 of the plate 20. A screw-down plate 24 with a downwardly facing conical lateral edge surface 25 and an opening 26, which the gearing housing 11 can pass through, is placed with an intermediate second ring 27 corresponding to ring 23 towards an upwardly facing conical lateral surface 28 of the flange. The screw-down plate 24 is then screwed tightly against the mounting plate 20 with the aid of bolts 30 disposed in through-bores 29 in the screw-down plate 24. Said bolts 30 can be screwed into threaded bores 31 in the mounting plate 20, compressing the elastic rings 23 and 27. The thicknesses of the mounting plate 20 and the screw-down plate 24 are so adapted to each other that, when the screw-down plate is screwed securely to the mounting plate so that the facing surfaces 32 and 33 of the plates are in contact with each other, the elastic rings 23 and 27 are compressed to a thickness corresponding to a thickness corresponding to the ring radius before being mounted. By virtue of the described design and dimensional relations, the orientation and mounting of the drives will be completely controlled.

[0017] The propeller pulling force is transmitted via the plates 20 and 24, the rings 23 and 27, the flange 4 and the well 3 to the boat hull. The engine, possibly with reverse, is thus freed from the propeller pulling force and can therefore be mounted on relatively soft vibration-damping pads. The transmission of vibrations from the drive to the hull is damped by the elastic rings 23 and 27, of which the lower ring 23 also serves as a seal preventing the penetration of water into the well 3.

[0018] The invention has been described above with reference to an embodiment with two separate elastic rings 23 and 27. It is also possible within the scope of the invention to use elastic elements on other side of the flange, forming a continuous unit, for example by means of a membrane, which joins the elements to each other. The definition “an elastic insert on each side” in the attached claims shall be interpreted as referring either to interconnected or separate elastic inserts.