Junk Rig Calculation Tools

Work in progress, send comments and/or suggestions here

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Spar mass/strength

Calculates the mass and breaking strength of a solid or hollow spar


Input:

m
mm
mm
mm

Results:

kg
kpm

Densities from http://www.engineeringtoolbox.com/material-properties-t_24.html
Modulus of rupture from http://www.conradfp.com/pdf/ch4-Mechanical-Properties-of-Wood.pdf (mirror)

Spar angle/rake

Calculates spar angles (mast rake for example)

Graph

Fill in the two missing factors and remember to use the same unit for length and distance

Example 1: If you want to find out how much forward the top of a 9 meter mast is compared to the base with 4 degree rake, choose "Distance" and fill in "9" for length and "4" for angle.

Example 2: If you want to find out how rake there is on a 12 meter mast which top is 1.02 meters forward of the base, choose "Angle" and fill in "12" for length and "1.02" for distance.

Input:

m
m
degrees

Credit goes to http://www.1728.org/angsize.htm

Hull properties

Calculates sail area vs. displacement and displacement vs. waterline ratios


Input:

m
kg
m
m2

Results:



knots
kpm

SA/disp

Disp/LWL

Sail properties

Calculates batten lengthts for given sail area


Input:


m2

Results:

m
m
m
m
m
m
m
m
m
m (recommended minimum)
m (minimum)

Fantail calculations from http://www.junkrigassociation.org/technical_forum?mode=MessageList&eid=1060993

Johanna calculations based on http://www.junkrigassociation.org/Resources/Documents/Arne%20Kverneland's%20files/Johanna's%20sail%20plan,%20sheet%201-9.pdf

Copyleft © 2013-2014 Oscar Fröberg