In a message dated 1/31/03 5:03:28 AM, Mike Maurice writes: << In order for any 2 lights to be distinguishable as separate lights they need to be of similar intensity and separated by a distance suitable to the needed visibility. In short, they need to be at least one yard (3 feet) apart for each mile of visibility required. >> Mike's table of light separations is based on a 2 minute of arc point discrimination distance. Awo minutes of arc is equal to the range divided by 1720. While a normal young eye with 20/20 vision can easily discriminate

At 10:45 AM 1/31/03 -0500, you wrote: >In a message dated 1/31/03 5:03:28 AM, Mike Maurice writes: > ><< In order for any 2 lights to be distinguishable as separate lights they >need to be of similar intensity and separated by a distance suitable to the >needed visibility. In short, they need to be at least one yard (3 feet) >apart for each mile of visibility required. >> > >Mike's table of light separations is based on a 2 minute of arc point >discrimination distance. Awo minutes of arc is equal to the range divided by >1720. While a normal young eye with 20/20 vision can easily discriminate My table of light separations is not based on a 2 minute of arc. It is based on the following quotation from the Nav Rules, page 145, version D. "NOTE to paragraph (c): Two unscreened all-round lights that are 1.28 meters apart or less will appear as one light to the naked eye at a distance of one nautical mile." Actually it is 46 inches not 40 as I estimated. If the lights are bright enough or or one is considerably brighter than the other, this distance may not be sufficient. Don't get confused over the "unscreened" versus screened. There may not be much difference except near the edge of the screening. Capt. Mike Maurice Wilsonville, Near Portland Oregon