The present invention relates to a method for the treatment of a boat bottom.

It is a well-known problem that plants and small animals attach to the bottom of boats when the boats are in water. Hitherto, therefore, boat bottoms have been provided with more or less toxic paint, which has contributed in a various degree to the boat bottoms remaining clean, without the growth of plants and small animals. A further problem is that boat bottoms on which growth has occurred are difficult to clean. This is particularly the case for plastic boats, where great care must be taken when using scraping and abrasive tools. The use of toxic substances in hull paints has been limited in recent years, due to environmental concerns.

The Swedish patent number 0502359-3 describes a method of treating boat bottoms that comprises the application of a material onto the boat bottom at least in the area that extends downwards from the waterline of the boat. The material is a plastic material that has sufficiently small and/or few pores, so that plants and small animals will not be able to attach to the outer surface of the material

This method suffers from the disadvantage that it is

relatively expensive and that it can be difficult for an inexperienced person to apply a plastic sheet onto surfaces that are curved in two directions.

The present invention solves the problem of the growth of plants and animals in a simpler manner. The present invention thus relates to method for the

treatment of a boat bottom comprising the application of a material onto the boat bottom at least in the region that extends downwards from the waterline of the boat, and it is characterised in that the material is constituted by a grease that is insoluble in water and that has a consistency such that it can be applied to the said boat bottom and remain there during motion of the boat.

The invention will be described in more detail below, partly in association with an embodiment of the invention shown in the attached drawing, where

- Figure 1 shows schematically a side view of a boat, and

- Figure 2 shows schematically a cross-section of a part of a bottom wall.

Figure 1 shows a boat 1 comprising a bottom 2, which is surrounded by water when the boat is placed into water.

Figure 2 shows schematically a cross-section through a hull wall 1 of a leisure boat.

The present method that of treating a boat bottom 2 comprises the application of a material onto the boat bottom 2 at least in the area that extends downwards from the waterline of the boat 1.

According to the invention, the material is constituted by a grease that is not soluble in water with a consistency such that it can be applied to the said boat bottom 2 and remain in place during motion of the boat 1. Figure 2 shows a cross-section of a part of a hull wall, where the hull wall comprises a supporting glass fibre layer 3 and a gel coat 4. An applied layer of grease is denoted by the reference number 5.

According to one preferred embodiment, the grease is of the type that is insoluble in water, used to lubricate machine joints and ball bearings. Such grease is called, among other things, consistency grease and ball-bearing grease.

According to one embodiment, the grease is a vegetable grease .

According to a second embodiment, the grease is a petroleum- based grease.

On the one hand, the grease must not have too low a

viscosity, such as for example paraffin oil has, because this entails the grease disappearing relatively rapidly from the boat bottom during motion through water. On the other hand, the grease must not have too high a viscosity, because this promotes growth. Grease of bee-wax type, for example, remains on the bottom, but allows growth. According to one preferred embodiment, the grease is caused to be applied to the said boat bottom by means of a brush or roller .

According to a second, also preferred, embodiment the grease is caused to be applied by spraying onto the said boat bottom 2. It has surprisingly proved to be the case that the grease remains in place even on fast motorboats throughout a

complete boating season, while it is at the same time

possible to remove most of the grease at the end of the boating season by washing the boat bottom with a high- pressure washer. A high-pressure washer discharges water, often at a pressure that exceeds 20 bar, from a nozzle.

It is desirable that grease is not applied above the

waterline of the boat. In order to prevent growth above a layer of grease that has been applied, a self-adhesive tape 6 of a plastic material is applied according to a preferred embodiment around the boat along its waterline, where the tape 6 has a width such that the growth of plants and animals is prevented around the waterline. The tape is applied before the said grease is applied. The tape 6 is removed when the boat hull is to be cleaned after the boat has been withdrawn from the water. Thus, the present invention solves the problem described in the introduction.

A number of embodiments have been described above. It is, however, possible that any suitable grease that remains on the boat bottom and on which growth does not take place, or takes place only to a limited extent, may be used.

The present invention, therefore, is not to be considered to be limited to the embodiments specified above since it can be varied within the scope specified by the attached patent claims .