Author Topic: Navigation Lights  (Read 351 times)

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des

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Navigation Lights
« on: May 08, 2017, 02:48:09 »
I am having a problem with the COLLREGs in relation to horizontal positioning of some navigation lights for my current project.

I am building a model loosely based on early (1960's) AHTS vessels built for OSA - the Offshore Supply Association, based in Germany and the UK.  There is no shortage of photos of these ships, thanks to a gentleman in Germany who has put together data sheets of many of these ships, with photos.  If you are interested, take a look here - http://
http://www.ddghansa-shipsphotos.de/osaregister.htm

Unfortunately, none of these photos come with detailed dimensions, so I have referred to the COLLREGS to determine light position requirements so that I can properly build my masts with lights in the correct places.

ANNEX I to the Collregs, Rule 3 - Horizontal Positioning and Spacing of Lights, para (a) states as follows -

"When two masthead lights are prescribed for a power-driven vessel, the horizontal distance between them shall not be less than one-half of the length of the vessel but need not be more than 100 metres. The forward light shall be placed not more than one-quarter of the length of the vessel from the stem."

I have never seen any AHTS or other offshore platform support vessel, actual or photos, with the main mast located so far aft as to comply with this requirement.  Indeed, many modern AHTS's only have a single mast, with the fore "masthead" light actually being located on the wheelhouse roof.

Can anyone please tell me how the rules are applied to these vessels so that they comply with the Rules.

Des.
« Last Edit: May 08, 2017, 14:10:01 by des »

Volker

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Re: Navigation Lights
« Reply #1 on: May 08, 2017, 23:53:49 »
Why don't you follow one of the prototypes? There must be reasons not to follow the rule.

In Rule 1 Application contains the following statement:
(e). Whenever the Government concerned shall have determined that a vessel of special construction or purpose cannot comply fully with the provisions of any of these Rules with respect to the number, position, range or arc of visibility of lights or shapes, as well as to the disposition and characteristics of sound-signalling appliances, such vessel shall comply with such other provisions in regard to the number, position, range or arc of visibility of lights or shapes, as well as to the disposition and characteristics of sound-signalling appliances, as her Government shall have determined to be the closest possible compliance with these Rules in respect of that vessel.

Perhaps this is the reason you are looking for?
Regards, Volker

des

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Re: Navigation Lights
« Reply #2 on: May 09, 2017, 14:18:00 »
Yes - that would cover it.  Thanks Volker.

As to "why not just follow one of the prototypes",I guess that comes from my engineering background - as well as building a model I like to understand why it is the way it is.

Des.
« Last Edit: May 09, 2017, 16:52:46 by des »