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I think it is like this:

BOAT 7-12 m, UNDER SAIL
(M = visibility range nautical mile
cd = luminous intensity candela)

Either (1):
Green sidelight 1M 0,9cd + red sidelight 1M 0,9cd + sternlight 2M 4,3cd

Or (2):
Bicolourlight green/red sidelight 1M 0,9cd + sternlight 2M 4,3cd

Or (3):
Tricolourlight green/red/white at top of mast 2M 4,3cd

Optional ADDING under sail, together with (1) or (2) BUT NOT WITH (3):
All-round red 2M 4,3cd over all-round green 2M 4,3cd
(Never seen that on such a small boat)

SAME BOAT MOTORING
Together with (1) or (2) NOT (3):

Either (4):
Turn on a masthead light 2M 4,3cd

Or (5)
Turn off the stern light and turn on an all-round white 2M 4,3cd
(Can separately be used as anchorlight)

I have chosen (3) for sailing  and (1)+(4) for motoring.
(1) can be used when sailing if (3) fails.
Thus I totally have 5 electrical navigation lights.
And a kerosenelamp when at anchor "unsafely".

Paul


----- Original Message -----
From: "Jared Sherman" 
To: 
Sent: Tuesday, October 14, 2003 5:42 AM
Subject: Nav light colors and ranges


> With all the talk of light ranges and alternates I made the mistake of 
looking back in COLREGS and found some things to wonder over. I put it to the 
list for comment and note as usual I am not licensed to practive mathematics, 
don't accept any numbers I present as being correct.
>
> COLREGS gives examples of lamp brightness as:
> 1nm     0.9cp
> 2       4.3
> 3       12
> 4       27
> 5       52
> 6nm     94cp
>
> and for vessels under 12m requires a sidelight range of only 1 nm (0.9cp)
> and all other lights 2nm (4.3cp)
>
> for 12-50 meters,
> masthead 5nm (52cp) (20-50m oal)
> masthead 3nm (12cp) (12-20m oal)
> all others 2nm (4.3cp) including all-around lights.
>
> I note this because it would mean a sailboat 12-50m, using red/over/green 
all around lights would need a total of 8.6cp with that lighting scheme--but 
12cp with a masthead tricolor light. So here the alternate lighting saves 25% 
on power needs.
>
> For a boat under 12m it would mean 8.6cp instead of 4.3cp, actually doubling 
power consumption on the mast.
>
> Pros and cons, it would seem. And I have no idea how the lamp manufacturers 
match bulbs for this criteria, I'd expect them to use "stock" bulbs so 
perhaps with tungsten bulbs it is simply 10W vs 20W and devil take the 
details.
>
> Comments?

   

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