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post #26 of Old 05-30-2007
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I think there are a couple of inaccuracies here. The red over green are all round lights at or near the top of the mast where they can best be seen which suggests actually at the top. They may be shown in addition to normal sidelights but not in addition to a tricolour.
Normally vertical lights on a vessel less than 20 m require at least 1 m separation, eg not under proper command. This arises from Annex 1 2 i (i). But 2 i says where the rules prescribe 2-3 lights to be carried in a vertical line they shall be spaced as follows.
While the NUPC lights are prescribed to be carried the red over green is arguably not prescribed rather permitted.
However one may wish to avoid such an argument should an issue arise.
The situation then is that to achieve one metre separation of all round lights would require a special mounting clear of the top of the mast to avoid a segment being obscured by the mast. This also highlights the difficulty of a singlehander showing NUPC lights.
This former would be unlikely for cost and power reasons and would offer no advantage over a tricolour.
The prospects of sidelights mounted 1-2m above the waterline being seen in any kind of sea being seen are less than with a tri. While reliability is an issue, one should remember that the power range of a sidelight is only at least 1 mile if under 12 m and 2 miles if between 12-20m
This suggests to me roll out the leds and boost the output while still saving power. If a freighter closing at say 30 knots can't see me until within a mile, I wouldn't count on him seeing me within the two minutes to impact let alone taking avoiding action.
Indeed since his lights ranges are 6 miles for masthead and 3 for sidelights assuming I saw him instantly rather than on a ten minute scan I would have 12 minutes during perhaps 6 of which it would be unclear apart from any brightening, which is uncertain, whether it was a sternlight, and 6 minutes of certainty. That isn't much as a maximum to take evasive action particularly as my bow would be wandering and the clearance would be uncertain, particularly as even if I turned 90 deg instantly it would take me 6 minutes to cover half a mile.
It would seem prudent to treat any white light at a distance as potentially a masthead light and prepare to take evasive action immediately.
When you look at the figures you see why one of the prof mariners here (I forget who) is so strong on keeping watch and the invisibility of yachts.
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