Home Blog Port Trousers: How to Alter the crotch (by Artesane)

Port Trousers: How to Alter the crotch (by Artesane)

3 March, 2017
Port Trousers: How to Alter the crotch (by Artesane)

Once again, the wonderful team of Artesane share the second part of the trousers adjustments with us! Thanks so much!

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Now that you can alter the legs of a trousers pattern in your sleep, let’s focus on altering a more difficult area : the crotch.

1/ BEFORE STARTING

MATERIAL

Material needed :

  • Your trousers pattern (front leg and back leg)
  • Pattern paper or Kraft paper (cardboard)
  • Pens in different colours
  • tape
  • scissors

HOW IS MADE THE CROTCH OF A PAIR OF TROUSERS ?

pattern port trousers alter the crotch

The crotch of a pair of trousers is the curved seam that goes from the waistband center front to the waistband center back. It is made of two parts : the rise (the less curved part) and the curve.

You can alter the rise or the curve, or both at the same time. However, we recommend starting by altering only the rise of the crotch as it’s easier to adjust and most of the time, it’s enough to modify the few issue you might have with the inseam, seat or waist area.

WHICH SOLUTION FOR WHICH PROBLEM ?

pattern port trousers alter the crotch 2

The crotch line will determine the fit of a pair of trousers. And a crotch line not adapted to your body specificities might create some issues in the following areas : seat, waist and inseam.
But don’t worry ! To each problem there’s a solution.
 
THE SEAT
 
1/ Your behind is very round (it’s too tight) : you need to widen the curve of the crotch in the back. Moreover,  if the waist tends to go down when you sit, you need to add length to the crotch at the back.
2/ Your behind is flat (there are some lines under the bottom) : you need to shorten the crotch length at the back.
 
THE WAIST
 
3/ Your belly is round (there are some lines around the belly) : you need to lengthen the rise of the crotch at the front.
4/ Your waist is very small (there are some lines just below the waist in the back) : you need to shorten the rise at the back.
 
THE INSEAM
 
6/ The inseam is too tight (There are horizontal lines) : you need to widen the curve at the front.
7/ The inseam is extremely tight (it cuts the legs and the waist) : you need to lengthen the crotch at the front and the back.
8/ The inseam is too wide (it’s too loose) : you need to shorten the crotch line at the front and at the back.
 
THE CASE OF THE ARCHED BACK
 
5/ If your back is really arched, there’s a chance your trousers waist will gape at the back. You need to shorten the crotch line at the back in a specific way that we’ll explain at the end of this post.
2/ LENGTHEN OR SHORTEN THE RISE OF THE CROTCH LINE (front and back at the same time)
 
Some of the issues (nº7 and nº8) need to alter the crotch length a few cm at the front and the back. In theses cases, you’ll apply the following method (that you need to apply on the front piece and the back piece).
LENGTHEN THE RISE
pattern port trousers alter the crotch 3
1/ Cut your pattern piece along the hip line.
2/ Place a piece of paper below the pattern pieces. Determine how many cm you need to add and add them between the two pattern pieces (make sure the pieces stay parallels).
3/ Tape the pieces to the paper and redraw the curves of the crotch and the side.
SHORTEN THE RISE
pattern port trousers alter the crotch 4
1/ Cut your pattern piece along the hip line.
2/ Determine how many cm you need to remove and overlap the two patten pieces (make sure the pieces stay parallels).
3/ Tape the pieces to the paper and redraw the curves of the crotch and the side.
 
3 / LENGTHEN OR SHORTEN THE RISE OF THE CROTCH LINE (only at the back or the front)
 
Some of the issues (nº3 and nº4) need to alter the crotch length a few cm only at the front or the back. In theses cases, you’ll apply the following method to the front piece or the back piece.
LENGTHEN THE RISE
pattern port trousers alter the crotch 5
1/ Draw a line perpendicular to the grainline at the point of the dart. Cut along the line starting from the crotch but stoping before the end. 
2/ Determine how many cm you need to add and spread the pieces according to the cm needed.
3/ Tape the pieces and redraw the crotch line.
 
SHORTEN THE RISE
pattern port trousers alter the crotch 6
1/ Draw a line perpendicular to the grainline at the point of the dart. Cut along the line starting from the crotch but stoping before the end.
2/ Determine how many cm you need to remove and overlap the two patten pieces
3/ Tape the pieces and redraw the crotch line.
4/ WIDEN OR SHORTEN THE CROTCH CURVE
WIDEN THE CURVE
pattern port trousers alter the crotch 7
1/ Trace a line parallel to the grainline at the deepest of the curve. Cut along this line. 
2 / Place paper under the pattern pieces and spread the pieces apart according to the cm you need to add.
3/ Tape the pieces and redraw the crotch line.
 
SHORTEN THE CURVE
pattern port trousers alter the crotch 8
1/ Trace a line parallel to the grainline at the deepest of the curve. Cut along this line.
2/ Determine how many cm you need to remove and overlap the two patten pieces at the crotch.
3/ Tape the pieces and redraw the crotch line.
 
5/ THE CASE OF THE ARCHED BACK
pattern port trousers alter the crotch 9
If you have an arched back and your trousers gape at the back waist, you need to alter the length of the crotch. But we’ll modify it directly from the waist.
1/ Determine how many cm you need to remove (maximum 2 cm). 
2/ Lower the waist line on the crotch side.
3/ Redraw the waist line with a lsightly curved line instead of a straight one.
Now hopefully, you’ll be able to alter the legs or crocth of any trousers pattern to fit you perfectly ! 
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