Illumination device When sailing it is known in order to know that a sail, in particular a head sail, has the correct angle in relation to the wind to arrange a couple of decimeter long cotton threads (trim treads) in the vicinity of the front edge of the sail and a distance up on this and furthermore somewhat distant from each other height-wise. When the threads are parallel the flow conditions of the wind/air of the front and back side of the sail are as desired in order to achieve maximum pulling force for the sail. Since the sails are light and thin also the thread on the side facing away from the boat can be seen.

The draw back with the above described simple but practical device is that at bad weather it may be difficult to see the trim threads and then i particular the thread on the side of the sail facing away from the boat. This is of course also conditions at dusk and darkness and the described device then becomes impossible to use and the adjustment of the sails is more instinctive, which inevitably leads to less optimal adjustments in average and thereof resulting time losses.

The object of the invention is to supplement the above device so that this can be used also at bad weather and even in darkness.

The above object is solved with an illumination device so arranged that the sail in level with the trim threads is illuminated from the lee-side. In this way the thread on the lee-side of the sail (that at the same time is the front side) will throw a shadow on the sail that is easily seen from the boat below while the other thread on the wind side (the rear side, that is the one facing the boat) will be clearly visible against the sail illuminated from the other side.

Advantageously such an illumination can be achieve by an illumination device being arranged on a front mast stay or even in the front edge of the sail itself and includes two illumination means one for port and one for starboard and that there is also a switch device that either lights the port or starboard light respectively.

Advantageously the switching by the switch device may take place with remote control via infrared light. This may either be achieved by means of a remote control handled by a suitable person, alternately one can consider that continuous infrared light is directed towards the illumination device that is provided with a corresponding receiver at or for each one of the separate lights that are also so connected that the light that is illuminated is off while the other one is lighted, resulting in that for most normal cases it is the light on the lee-side that is lit.

Advantageously also the activation of the illumination device may at this take place by means of infrared light, that is the illumination device is lit first when its remote control is switched on. In this way an automatic shifting may be obtained as well as a switching depending on if the sail blows out in the port or starboard direction and furthermore a switching off and on of the illumination device without this needing any mechanical switch maneuverable from the outside. This also provides a larger freedom of choice as to the location of the illumination device. Alternatively the step wise switching may take place with infrared light pulses. One can also consider that the light source illuminated by a continuous infrared beam is switched off in order to secure that the light source on the leeside is the one that is lit, this since the illumination from the wind side can be blinding and may illuminate the wind side of the sail to such an extent that the trim thread ca not be seen at all on the lee- side.

In an alternative embodiment one can consider that the illumination device comprise a position-switch reacting to the inclination of the device and thereby the inclination of the mast or boat and that lights the illumination that is the lowest and thereby on the lee-side. At week wind or an efficient balancing of the wind forces however the front stay on which the illumination device and the sail are fastened may be turned somewhat due to the forces on the sail so that since the front stay being inclined backward the illumination on the lee-side becomes higher than the one on the wind side, which would give a faulty lighting and off- switching. This alternative embodiment can however be used if the boat is inclined comparatively much, or if it is arranged on an essentially vertical (in rest position) mast that in addition has little tendency to turn. By arranging the means or switch sensible to the inclination vertical with the boat in a non-inclined position the reliability in lighting the correct side of the sail is further increased at this variety.

Preferably the two illumination means or light sources are arranged on arms so that one does not risk to be blinded by direct light from the light source that at present is lighted Preferably the illumination device in itself consists of antenna-like arms with light emitting diodes in the outer ends. These antenna-like light diode holders are then more or less flexible in order to allow individual adaption to thread location etc. By the use of light emitting diodes it is also possible to use batteries and by using intermittent feeding of the light emitting diodes the need of battery change becomes almost non-existent. For the switching off and on of the light emitting diodes one may of course consider a mechanical switch but one may also consider a light sensitive switch that switch on illumination when for instance darkness occurs. Advantageously the illumination device can be snapped or clamped on the front mast stay.

Since the illumination device is so light one can also consider that the same may be fastened to the sail itself. In this case one can also consider the illumination device to be constituted by two separate illuminations, that are either fastened to the same or different locations on the sail.

Alternatively one can consider only to arrange one light source in a hanging pendulum that depending on the inclination of the mast and the influence of the wind always will hang on the lee-side of the sail. Since this device is mobile however the risks that it becomes entangled or with time moves too sluggish when the bearing has been sustained to weather and wind.

Further advantages and characteristics of the invention are apparent from the patent claims and from the following description of a preferred embodiment. Here fig. 1 depicts the front end of a sail boat provided with a device in accordance with the invention seen from the side, fig. 2 the invented device seen from above in a larger scale, and fig. 3 the same invented device seen from the side in the same scale as in fig. 2.

In fig. 1 is shown the front end of a sail boat 1, where a head sail 2 has been provided with two trim threads 3 and 4, one on each side of the sail. The sail 2 runs in its front edge in a channel in the front stay 7 of the mast 6. On the front stay 7 an illumination device 8 in accordance with the invention is fastened by means of two flanges 9 that extend rearward form the battery part 14 of the illumination device and grips snap like over the front stay 7 of mast 6 without preventing the sail from being raised or lowered. The illumination device 8 includes two light emitting diodes 10 and 11, fastened in the outer ends of flexible arms 12, 13 of aluminum tubes or profiles, in or on which the leads to the light emitting diodes 10, 11 are arranged. The arms 12,13 are with their inner ends rigidly cast in the battery part 14, at which the two arms can constitute each end of a common profile or tube extending straight through the battery part. In the battery part is arranged an electronic unit that pulses the current to the light emitting diodes in order to prolong the useful time of the batteries. In the battery part is further arranged a switch-circuit that feeds current to the diodes one at a time or to non of them. The switch circuit is controlled by remote control and the battery part therefor also includes two photo diodes so directed that they can be reached by light beam from a remote control in the cockpit of the boat or corresponding. The reason for having two photo diodes is that one is always shadowed by the sail.

The battery part is further provided a lid that is salable watertight, which lid however only need to be removed when the batteries need to be exchanged.

If so should be desired one can even consider allowing the illumination device to slide on the mast stay profile and at the same time be fastened to or connected to the sail so that the illumination device is pulled up at the same time as the sail. This may facilitate if one wish to have the threads and the illumination device higher up than what is comfortable or safe to reach.

At the use of the device in accordance with the invention this is mounted on the front stay with the snap device and the arms are adjusted so that they illuminate the intended area 15 of the sail were the two trim thread are fastened. The device is switched on and during the sailing the current is switched manually by means of the remote control to the arm situated on the lee-side.

Even if the invention above has been described adapted for a head-sail one can also consider to use it for other sails.