So you have a tall slender child and want to adjust the Trinity Tee for a longer length.
Even though the Trinity Tee is quite unique in shape, lengthening,
or shortening, can be done pretty easily.
In this tutorial we are going to use the slash and spread method for lengthening.
Let's start with the back panel.
Measure down the back panel from the nape to the waist and draw a line across the width, perpendicular to the center back. (shown in blue)
Align the diagonal side of the front panel with the diagonal side of the back panel. Make a mark on the front panel where the line you made on the back panel touches. (circled in picture)
Draw a line across the width of the front panel, perpendicular to the center fold line, where you made the mark.
These two lines you just made are your "slash" lines. Cut your pattern pieces across these lines.
Next you will spread your cut to the amount you wish to lengthen the pattern. It is important to keep the edges of your pattern aligned. To make this easier I like to draw lines on tracing paper to align my pieces.
Here I am lengthening the pattern by 6 cm. Draw a vertical line to help align your pattern pieces as they are spread. Anywhere on the line draw two lines perpendicular to the vertical line and 6cm apart from each other.
Now lay your back panel pieces over the paper. Align center back with the vertical line and the edges you cut along the horizontal lines. Tape or glue the pattern pieces to the tracing paper to secure.
You will now need to redraw the diagonal side of your back panel. Draw a straight line from the underarm down to the upper corner near the hem (I have no idea what to call this!). (shown in red below)
Cut off the excess paper and viola! (cut along dashed line as shown in picture below)
You now have a new, longer, back panel.
Now it is time to do the same thing to the front panel. This is where it may take a little trial and error because if you lengthen the front the same amount as the back it will be too long.
This will not do! I found that I needed to lengthen the front panel about 1cm less than the back panel, but this will vary from size to size.
So, for consistency's sake, let's go through lengthening the front panel.
Draw a vertical line on tracing paper. Then draw two horizontal lines, making sure they are perpendicular to the vertical line. The distance between the lines is the amount you wish to lengthen the front panel. In my case it is 5cm.
Now place your front panel over the paper with the center fold edge aligned along the vertical line drawn and the edges you cut along the horizontal lines drawn. Tape or glue the pattern pieces to the tracing paper to secure.
Re-draw the diagonal side just as you did with the back panel. (shown in red). Cut off the excess paper.
Compare the length of the diagonal sides on the front and back panels. If the front panel is too long you can make a fold along the spread to take up the length. It is important to keep the center fold line aligned or your panel will be misshapen. Draw a new diagonal line if needed.
When the diagonal sides align properly it will look as it does below.
You can also lengthen the sleeves in the same manner. Keep in mind that the 3/4 and long sleeves will have a cuff in addition to the sleeve length.
Measure the distance from the underarm to the wrist. Mark a line at the midway point. This should be just above the 3/4 sleeve edge.
Cut the sleeve along this line.
On a piece of tracing paper draw a vertical line and two horizontal lines as we did before. The distance between the horizontal lines is the amount you wish to lengthen the sleeve. Align your sleeve pieces along the lines you drew and secure them to the paper with tape or glue.
Re-draw the underarm seam staying true to the curve of the pattern piece. (shown in red)
Cut off the excess paper once again, and there you go! All done.
Even though the pattern shapes are a little crazy, lengthening is easy peasy!
Shortening the pattern can be done the same way, except you will overlap your pattern pieces instead of spreading them. See the example below.
But say your child is very tall and skinny but also has wide shoulders. Or maybe they have a wide chest but have narrow shoulders. Then blending between sizes is likely a better option for you. I hope to have a tutorial for blending sizes soon; as well as lots of other modifications. It will be fun! See you then :)