If you already have a Seekey, you may try this out on the illustration of lanterns above.
Arrange the filters side by side. Hold the Seekey close to your eye, or in front of your binoculars, and close the other eye. Move the Seekey in order to look alternately through the red and the green filter.
Red is only visible through the red filter.
Green is only visible through the green filter.
White is on the other hand visible through both the red and the green filter.

To detect buoys and marks at a distance
Arrange the filters side by side. Move the Seekey rather fast in order to alternately look through the red and the green filter over and over again.

Different coloured things will now appear to have a twinkling effect and will be easy to find. This works best with red things in blue or green surroundings. Even a person with a normal colour vision will have an advantage using the Seekey at long distances or in hazy weather.

See more on the chart
A great deal of the safety information is printed in red. The "twinkling effect" method works very well also in this case.

Much of the information in the charts is printed with thin lines and small symbols. In this case it is especially difficult to tell the colours apart without the Seekey.

Some maritime links


The Swedish Sea Rescue Society

Seekey supports
The Swedish Lighthouse Society

Identify navigational lights in surroundings with other disturbing lights, e. g. from ashore
Fixed lights and leading lines you will find using the filter with the colour opposite to the light you are looking for. Alternatively look alternately through the filters, as described above.

Often it is difficult to detect other ships against a background disturbed by other lights. E. g. when approaching a harbour or in fairways close to populated areas. At such occasions the Seekey is very useful as you often and regularly check for approaching green or red lanterns.

The different red-green colour vision is also called colour blindness or colour deficiency.

Comments from Seekey customers

- I want to take the opportunity to tell that the Seekey works well for my sailing friend who has a colour problem. The red buoys turn obvious and the method of elimination does the rest.
Eva Nordström, Editor.
(Sweden)

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…as soon as I opened the packet I put it to the test around the house, and I was amazed with the results. It was rather like wearing a pair of spectacles for the first time and seeing the world un-blurred!...
…took it along to Dover harbour, close to my house, one night. Amazing! Port control lights and buoys, previously with the colour indistinguishable to me at a distance, lept out and were obvious! I can't wait to take the Seekey sailing…
Richard Diedo
(UK)