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 French naval compass - 1781 
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Lieutenant

Joined: Thu Feb 12, 2009 7:05 pm
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Post French naval compass - 1781
I am trying to reconstruct the action of 21 July 1781 fought off Spanish River (now Sydney Harbor, Cape Breton Island, Nova Scotia) between the French frigates L'Astrée (38) and L'Hermione (34) and the British "line of battle" comprising the frigate Charlestown (28), Sloops Allegiance (18) and Vulture (16), the Quebec provincial ship Jack (14) and the armed transport Vernon.

At noon, L'Hermione reported her position as:
Quote:
A midi, j'avais relevé le cap Nord au N.O. 1/4 N, une des pointes de l'entrée de la baie des Espagnols au S.O. 1/4 S.

The "standard" 64-point compass does not use "¼" unless attemping to divide the angle between two of the 64 points.

The British compass for the NW-to-North sector would be:
(64-points versus degrees):
NW = 315º
NW½N = 320⅝º
NWbyN = 326¼º
NNW½W = 331⅞º
NNW = 337½º
NNW½N = 343⅛º
NbyW = 348¾º
N½W = 354⅜º
North = 360º [0º]

Query: what are the British equivalents of "N.O. 1/4 N" [NW½N = 320⅝º or NWbyN = 326¼º] and "S.O. 1/4 S."?

Thanks


Mon Sep 20, 2010 3:23 pm
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Commander

Joined: Sat Mar 31, 2007 12:27 am
Posts: 389
Location: Australia
Post Re: French naval compass - 1781
The simplistic view is that due to the inherrent difficulties of taking accurate bearings they were using the standard 32 points and the answers would be NW by N and SW by S.

As far as I am aware, the French compass card was similar to the generality of cards until a 400 degree card was introduced at the time of the Revolution.


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Mon Sep 20, 2010 11:11 pm
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Lieutenant

Joined: Thu Feb 12, 2009 7:05 pm
Posts: 62
Post Re: French naval compass - 1781
Many thanks, Peter

If memory serves, HMS Pearl (moored in the East River, NY, in 1776) used a 128-point notation. From perusing logbooks of that era, I can only recall the 64-point notation used while sailing. I would expect on able to steer a Sloop of War or small frigate within one point of the 64-point compass although it is difficult to do on a thirty foot gaff-headed sloop in six foot seas.

Downeast


Mon Sep 20, 2010 11:37 pm
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Post Re: French naval compass - 1781
IONIA wrote:
As far as I am aware, the French compass card was similar to the generality of cards until a 400 degree card was introduced at the time of the Revolution.

Why did they decide to use a 400 degree card? So each quarter could be divided into 10?

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susan


Tue Sep 21, 2010 12:10 am
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Joined: Sat Mar 31, 2007 12:27 am
Posts: 389
Location: Australia
Post Re: French naval compass - 1781
susan wrote:
IONIA wrote:
As far as I am aware, the French compass card was similar to the generality of cards until a 400 degree card was introduced at the time of the Revolution.

Why did they decide to use a 400 degree card? So each quarter could be divided into 10?



They were obsessed with the decimal system and everything had to be related to that. I suppose 400 was the closest they could get to 360 and it gave them 100 deg per quadrant..


Tue Sep 21, 2010 12:47 am
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