Mariners Compass drafting

I started drafting Mum's mariners compass quilt. I have never made one before, and I am daunted at the prospect of doing such an involved pattern. I've read a few books about how to do them. Even in my collection of quilting magazines, there is a pattern or two in there, but drafting from scratch - not an easy thing to do.

I think I mentioned before that Mum selected the quilt Wild Fire, machine pieced and quilted by Alice Bessler, North Powder, Oregon, as illustrated in Stellar Journeys Flying Geese & Star Quilts (author Gail Garber). Wild Fire isn't a traditional mariners compass. I knew I would have to draft from scratch - but I didn't expect the challenge that I had. Making large templates is hard when you do not have a large compass, or a decent sized protractor. It became clear to me that I would have to resort to maths from my school days!

First step for me was to use the original design as inspiration, then work out a modified design that would sit within a 45 degree wedge. From there I had to work out how many sections I needed to divide that segment into. The circle diameter will be 40 inches (the radius is 20 inches). I drew a 20 inch square. After selecting one corner to be the centre of the circle, I made a 17 inch square from that point - so it sat within the 20 inch square. On the 17 inch line I marked off increments based on right angle maths, using Excel.

Here's a picture of the calculations.


The formulas used (in row 5) are as follows:
B5: =TAN(A5*PI()/180)
D5: =ROUND((B5*$A$2)*16,0)/16 [custom cell format 0 #/##]
E5: =ROUND((B5*$A$2)*8,0)/8 [custom cell format 0 #/#]

Cell $A$2 is 17 (the size of the internal square).

After marking off those points on the 17" square lines, I then drew a straight line from them, out to the 20" line, then back to the quilt centre.

Okay - so this sounds really technical, and probably will not make a lot of sense. Hopefully the draft pattern will make it clearer. You can see some of the numbers written on the left hand side those relate to the rounded measurements from Excel.


The arcs were created by holding the ruler at the "zero" point, placing a pencil at a set measurement (e.g. 20"), then carefully moving the ruler an inch or so along, being very careful to keep the ruler fixed at the "zero" point. Yes, painstakingly drawing the arcs "freehand".

I then divided up the wedge into sections based on what was pleasing to my eye, and continued drafting from there.

The process was repeated for another 45 degree wedge (right beside the one I just did). So now I have 1/4 of the pattern done. This 1/4 forms the base pattern.

From there the pattern has been copied onto pre-ironed greaseproof paper. Pre-ironed because it shrinks with heat, and greaseproof paper because freezer paper isn't locally available.


I am currently paper piecing the first quarter of the design. Here's what I have done so far.