SailNet Community - View Single Post - Great Lakes Boaters, Polyconic charts, mph
View Single Post
post #8 of Old 10-04-2012
Senior Member
jackdale's Avatar
Join Date: Dec 2008
Location: Calgary, AB, Canada
Posts: 9,051
Thanks: 27
Thanked 63 Times in 58 Posts
Rep Power: 7
Re: Great Lakes Boaters, Polyconic charts, mph

Originally Posted by Hartley18 View Post
Righto.. What's this then?? Looks like nautical miles (and tenths) to me:

Attachment 12380

I understand that the Polyconic nature of the chart means that lines of lattitude and longtitude aren't necessarily straight up that part of the world, but don't get me wrong, I'm happy to learn something new.
It is the latitude scale, used to measure distance on a Mercator projection.

Polyconic projections are common in the Great Lakes of Canada and the US.

ISPA Yachtmaster Offshore Instructor Evaluator
Sail Canada Advanced Cruising Instructor
IYT Yachtmaster Coastal Instructor
ASA 201, 203, 204, 205, 206, 214
As I sail, I praise God, and care not. (Luke Foxe)
jackdale is offline  
Quote Share with Facebook
For the best viewing experience please update your browser to Google Chrome