Another question

[cod]

Daylight/Good visibility. Entering Braye. At what range would you expect to see the green NO1 buoy?

MINESAPINT.

 

[dralex]

Are you just trying the easy way to get all the answers to an RYA shorebased course homework?? All sounds a bit suspicious.

 

[cod]

Not exactly. But you are along the right lines. The thing is I have never come across any information re the visible range of lateral buoys. I imagine no more than 200m maybe a bit more with binos.

MINESAPINT.

 

[cod]

Come on. Somebody point me in the right direction.

MINESAPINT.

 

[powerskipper]

about 4 ish miles max on a good day with naked eye or check your col reg for light intensity and distance visible.

 

[landaftaf]

range of lights on buoys etc are determined by light intensity, height of eye and visibility ....
the prevailing visibility is classified as -
the range of a lights given on the chart or in Admiralty List of Lights & Fog Signals(ALLFS) is based on visibility being 10nm, this is referred to as the luminous range.
visibility is rarely exactly 10nm so ranges given are a rough guide.

in daytime - yes, 4 miles is a good approximation assuming the sea is smooth and vis good

 

[kidnapped]

Good Lord .... must get my eyes tested! /forums/images/graemlins/blush.gif

 

[powerskipper]

/forums/images/graemlins/grin.gif

 

[john_morris_uk]

To complete the picture(?) In daylight and good visibility I would start looking for a buoy at 2 miles and expect to see it by one mile or thereabouts. Some of the buoys out at sea are a bit bigger, but the rule seems to hold good. Nowadays if I really want to know where it is I look on the radar...

 

[Neraida]

I agree, 4 miles (ish).

 

[BrendanS]

Come out with the Pathfinder powerboat club when we do one of out wonderful annual Nitex excursions, and you'll find out for real. All gps turned off, and each leg is to a buoy or other point on preplanned bearings

You'll soon find out the distance for visibility to a lighted buoy from a rib or small craft. Much less than you'd think

 

[tcm]

not sure: white lights on boats shd show at 5 miles, red/greeen at 2 miles. Yer sposed to look at the blimmin chart which will tellyer!

 

[jimi]

I would'nt .. it might not be there

 

[cod]

I dont see what the visible range of lights has got to do with spotting this buoy in daylight.

Everytime I return from sea I pass a cardinal buoy which I bet is larger than the buoy in question and you are lucky to see that at 1M and of course you only know the range because you have it on radar.

I have just started Yacht racing and we race round 45 gallon drums painted orange. I suspect the buoy in question is slightly larger than an oil drum. However the drums are spaced at 1.5M and we do not see then with naked eye until we have sailed most of the leg. If the 4M suggested was accurate we should be able to see all the buoys clearly before we set off to sail the leg which clearly is not the case.

I still reckon 200m.

Any more offers????

MINESAPINT.

 

[john_morris_uk]

I think the post meant 4 miles visibility of a lit buoy at night.

By day, I still reckon on seeing a buoy about a mile away, although in a small boat close to the water and in rough weather that might be reduced.

 

[StugeronSteve]

I can remember swmbo asking me about this one after she had trawled all of the RYA info looking for guidance. There is no indication on the chart of the size of the buoy and, from what I remember, the approach would give the open harbour as a backdrop. I suggested that it ought to be visible from a yacht cockpit at about 1-1/2M out, but with the harbour clutter etc. I think you would need to be well inside 1M for a positive ID. However, if it's just a green painted oil can?

 

[Andrew_Fanner]

Green cone/blob against mucky green Thames Estuary with -10/-11.5 prescription, about 10m

Rather more relevant would be consideration of observer's eye height, buoy top height (or topmark if relevant) if doing a daylight search. Don't recall horizon distance 2.5m above the water though.

 

[cod]

Of course there are many variables which are not made clear in the question.

I have to say I am with Stugeron Steve and Andrew Fanner on this one. The main consideration is the background. A buoy is certainly much easier to spot in open sea than tucked inside a harbour with the background in this case the visitors moorings.

What if I revise my answer to between 1 and 3 cables depending on variables. (Size of buoy, ht of eye, sea state, background clutter, whether the observer has 20/20vision) That should cover it.

MINESAPINT.

 

[Talbot]

This is not a simple question. The three fundamental points are :

is it dark or moonlight?
Will your course allow sight of the buoy without light pollution from the island?
What is your height of eye?

On a dark night with no light pollution, the naked eye is considered to be able to distinguish a candle flame at 10 miles.

Assuming your height of eye is 2m and the light on the buoy is at 1.5m, the maximum distance you will be able to see a buoy is 3.4 nautical miles (from Norries tables) /forums/images/graemlins/laugh.gif

 

[Cornishman]

You should be able to distinguish shape at approx 2 miles and colour at approx 1 mile in the conditions you have described.