Rhumb line

In navigation, a rhumb line, rhumb, or loxodrome is an arc crossing all meridians of longitude at the same angle, i.e. a path with constant bearing as measured relative to true or magnetic north.

A rhumb line is, together with the Great Circle Arc and an isoazimuthal, one of the three lines that can be drawn between any two points on the earth's surface.

Introduction

The effect of following a rhumb line course on the surface of a globe was first discussed by the Portuguese mathematician Pedro Nunes in 1537, in his Treatise in Defense of the Marine Chart, with further mathematical development by Thomas Harriot in the 1590s.

A rhumb line can be contrasted with a great circle, which is the path of shortest distance between two points on the surface of a sphere. On a great circle, the bearing to the destination point does not remain constant. If one were to drive a car along a great circle one would hold the steering wheel fixed, but to follow a rhumb line one would have to turn the wheel, turning it more sharply as the poles are approached. In other words, a great circle is locally "straight" with zero geodesic curvature, whereas a rhumb line has non-zero geodesic curvature.

Rhumb Line (board game)

Rhumb Line is a two-player abstract strategy board game by Martin H. Samuel, played with glass pieces on mousepad-type material, using placement and point accumulation to win. The game board and instructions have a nautical theme, based in part on the concept of the rhumb line and historic games played by sailors.

Rhumb Line II is a 50-page note pad travel version played with a blue and a yellow pen. An iPhone app version was produced in 2010.

Components

Objective

The goal of the game is to out-navigate the opposition and achieve victory by placing nuggets on the board to build and/or block point-scoring "rhumb line" combinations of radii, arcs and spirals.

Gameplay

The Rhumb Line game board consists of a compass rose with 32 marked points with a score-keeping "ladder" on either end.

Players choose either Officer yellow or Sailor blue and use 16 same-color pieces + 1 score-keeper each. Officer (yellow) starts and players take turns placing their pieces, one at a time, on any empty point, building on those already on the board, to complete and/or block point-scoring combinations.