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Old 07-09-2010, 18:51   #1
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Day Shapes

Hi to all, my question is this>>>>> I know by law we are supposed to show different day shapes to hang from a point forward of the mast at different times. I would like to know if anyone knows the "required size" of the shapes?? I have a 13mtr, 14 tonne yacht and want to make shapes for the following>> an at anchor sphere and an inverted cone shape for motorsailing and any others that I may need? Thank you oh wise ones.........Paulo.
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Old 07-09-2010, 20:25   #2
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Hi to all, my question is this>>>>> I know by law we are supposed to show different day shapes to hang from a point forward of the mast at different times. I would like to know if anyone knows the "required size" of the shapes?? I have a 13mtr, 14 tonne yacht and want to make shapes for the following>> an at anchor sphere and an inverted cone shape for motorsailing and any others that I may need? Thank you oh wise ones.........Paulo.
Big enough to be visible and distinct? My anchor ball was 12" or so in diameter (30cm). But it depends on the size of your boat:

Navregs Appendix I
Quote:
6. Shapes
(a) Shapes shall be black and of the following sizes:
(i) a ball shall have a diameter of not less than 0.6 meter;
(ii) a cone shall have a base diameter of not less than 0.6 meter and a
height equal to its diameter;
(iii) a cylinder shall have a diameter of at least 0.6 meter and a height
of twice its diameter;
(iv) a diamond shape shall consist of two cones as defined in (ii) above
having a common base.
(b) The vertical distance between shapes shall be at least 1.5 meter.
(c) In a vessel of less than 20 meters in length shapes of lesser dimensions but commensurate with the size of the vessel may be used and the distance apart may be correspondingly reduced.
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Old 07-09-2010, 20:38   #3
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Annex I of the ColRegs - The way I read it <20m = Up to you...

Convention on the International Regulations for Preventing Collisions at Sea (London 1972)

Quote:
6. Shapes
(a) Shapes shall be black and of the following sizes:
(i) a ball shall have a diameter of not less than 0.6 metre;
(ii) a cone shall have a base diameter of not less than 0.6 metre and a height equal to its diameter;
(iii) a cylinder shall have a diameter of at least 0.6 metre and a height of twice its diameter;
(iv) a diamond shape shall consist of two cones as defined in (ii) above having a common base.
(b) The vertical distance between shapes shall be at least 1.5 metre.
(c) In a vessel of less than 20 metres in length shapes of lesser dimensions but commensurate with the size of the vessel may be used and the distance apart may be correspondingly reduced.


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Old 08-09-2010, 02:28   #4
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If you assume a 20-metre(roughly 60 ft) vessel has to have shapes with diameter and height of 60 cm, then a rule of thumb to scale your shapes would be LOA in feet = diameter/height of shapes in cm. 2.5 times that is the distance between shapes (length of your tack-line).
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Old 08-09-2010, 07:26   #5
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If you assume a 20-metre(roughly 60 ft) vessel has to have shapes with diameter and height of 60 cm, then a rule of thumb to scale your shapes would be LOA in feet = diameter/height of shapes in cm. 2.5 times that is the distance between shapes (length of your tack-line).
Except a ship of >1000 feet only requires (per the ColRegs) a shape of .6 meters....so it's not a linear relationship.
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Old 08-09-2010, 09:19   #6
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If you anchor in a designated anchorage, then the ball isn't required. Most of the sailboats I've seen anchored didn't wear the anchor ball. The big yachts (mine was 45m/145') always displayed the ball.

I've seen very few inverted cone "motorsailing" day shapes. The joke in the schools is that this particular shape is on the books but never seen. While 0.6m seems very large for a 13m vessel, it's a good idea as many motorsailors will have sails up. The day shape gives approaching vessels an earlier indication as to the mode of power.
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Old 08-09-2010, 10:25   #7
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I rock the ball in non designated anchorages or anywhere where I have a few spare minutes and want to look proper. The inverted cone thing I've never used.
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Old 08-09-2010, 21:01   #8
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If you anchor in a designated anchorage, then the ball isn't required.
That's a US Inland rule - the OP is in New Zealand.
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Old 08-09-2010, 22:20   #9
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Thanks for all your answers, great as usual. I did happen to find something on Maritime NZ's website but not the relative size bit. Cheer to all my fellow sailors. Love this site...........Paulo.N.Z.
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Old 09-09-2010, 01:41   #10
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did not ever see a ball or a cone in any anchorage in the med...
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Old 09-09-2010, 13:58   #11
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Except a ship of >1000 feet only requires (per the ColRegs) a shape of .6 meters....so it's not a linear relationship.
Quite true, but then sailors don't come any bigger on 1000-ft ships than they do on 20-ft boats. While bigger shapes give better range of vis, you can only make them so big before they become unmanageable.

You mentioned a 12 in (30 cm) anchor ball - that seems like a reasonable size for a smaller vessel - any smaller would be pointless. Just doing the math, a ball-diamond-ball signal using a 12-inch base would yield a signal that's 9 feet long, so it depends greatly on what signals you will use and the length of your signal halyards.
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