Midline Swimsuit Pattern Sewalong [part 4] – Swim Bottoms

Swim bottoms come together as quickly as the swim top. Before you cut out fabric please review sizing guidance on page 8. Most bodies will not fit a straight size for the bottoms. I recommend you grade between your waist and upper thigh circumference. Brace yourself for some more food related instructions.

This first step has the unfortunate nickname “crotch seam sandwich”. The order here is very important! Pin the crotch seam with these layers:

1. Swim Bottoms back (right side up)
2. Swim Bottoms front (wrong side up)
3. Swim Bottoms lining front (right side up)
4. Swim bottoms lining back (wrong side up)

Sew a standard zig zag stitch at 1/2″ seam allowance on the crotch seam sandwich seam. Trim seam allowance down to 1/4″.

Moving past the crotch we will knock out some side seam sandwiches. The order here is very important! Pin the following stack along the side seam:

1. Swim Bottoms lining side panel (right side up)
2. Swim Bottoms lining front (wrong side up)
3. Swim Bottoms front (right side up)
4. Swim bottoms side panel (wrong side up)

Sew a standard zig zag stitch at 1/2″ seam allowance on the side seam.

Repeat for the opposite side seam, following the same order as before. Trim side seam allowances down to 1/4″.

Moving along in food comparisons we are now encountering some back side seam burritos. Do you believe in magic? Good, lets proceed. Things get weird here and might be confusing, but you can do it. If between the photos and illustrations you are still unsure please click through the Midline Swimsuit Instagram highlight reel until you find the video demonstrating this step.

Be careful to note the order. For the perfect back side seam burritos stack:

1. Swim Bottoms lining side panel (right side up)
2. Swim Bottoms lining back (wrong side up)
3. Swim Bottoms back (right side up)
4. Swim Bottoms side panel (wrong side up) – this piece should be wrapped around the rest of the pieces to complete the burrito.

I’m sure that was crystal clear, but just for fun let’s break down that side seam burrito again. I like to start by butterflying the side seam, keeping the lining side panel right side up and the main fabric side panel flipped right side up on the opposite side of the seam.

Next I lay the rest of pieces flat.

Then I flip up both layers of the swim bottoms back and line them up with the side panel. I like to stop and pin the three layers together at the side seam at this point.

Now I take the opposite side and start rolling until I see the edge of the main side panel showing up…

…And then keep rolling and pin in place to the first three layers.

And pause to appreciate that tidy burrito. Stitch the side seam with a standard zig zag at 1/2″ seam allowance.

Flip everything right side out and you now have one fully enclosed side panel and crotch seam. You are a wizard!

Repeat the same layering order/steps for the last back side seam.

Flip inside out. Admire.

At this point you should stop and try on the swim bottom. I know, I know. It’s so annoying. Do it! Everyone’s awesome body is different. Thighs come in all different shapes and that’s cool. But that also means you may want to make some small adjustments to your suit. The crotch width should be 1/2″ wider on either side than where you want the final edge to be (to account for the elastic edging). The crotch is slightly wider than normal due to the boyshort style, however, it should not be full on shorts or you may find yourself with some unwanted crotch lines (ew, tragic).

The most common adjustment was scooping out a little of the swim front fabric between the crotch and side panel. Trimming beyond that will take away bum coverage, so be aware of that. If you feel some adjustments are needed I have recommended trimming lines for the scoop on page 23 of the instructions.

Once happy with the fit trim side seam allowances to 1/4″.

I can see the finish line! You are almost there.

Smooth and pin the lining to main fabric for the waistband and legs. Use an elongated zig zag on the edge or serger to baste the layers together.

Before you cut the elastic to length mark the length (elastic list on page 6) and try it on your thigh and waistband. Are either of the areas too tight or loose? Make needed adjustments (accounting for the 1/2″ overlap) and cut to size.

Overlap the elastic 1/2″ and stitch to create loops for the legs and waistband.

Mark 12, 1/4, and 1/8 points around the waistband + waistband elastic only.

If you are unsure how to do this I have a Midline Swimsuit Instagram highlight reel that includes a classy l video demonstration on dividing an area to evenly space elastic and fabric.

Match up the pins in both pieces and pin in place. I prefer to add additional pins in between to make it easier to sew. Use an elongated zig zag stitch at 1/4″ seam allowance. It helps to hold the fabric behind the machine while you pull from the front, stretching the elastic to be flat with the swim bottom fabric as you sew.

If you have never sewn swimwear I find it helpful to watch a few YouTube videos to visualize how to stretch while you sew. This video is a few years old, but a helpful overview of how to equally divide elastic and fabric, as well as how to stretch the elastic while you sew.

For the legs we are going off road! Buckle up. We are not going to divide the elastic evenly. Whoa. The suit needs most of the stretch from the crotch to the back side seam to keep your bum snug.

Pin the elastic to the lining side of the fabric without stretching anything from the crotch to the front and side panel.

The remaining elastic and fabric is for your bum coverage. With the leftover elastic and fabric mark 1/2, 1/4 and (if you can) 1/8th points. Match up the points and pin together.

Sew an elongated zig zag stitch, centering the presser foot on the elastic. Stretch the elastic as you sew where the fabric is loose so the fabric is evenly included in the seam. You will need to pull behind the presser foot on the garment as you pull the elastic from the front.

Repeat for second leg.

For the final top stitching on the waistband and legs I prefer to use a wider twin needle (mine is just under 1/4″ wide) with a slightly elongated straight stitch. The zig zag stitch will also work great. Roll the elastic over (you may pin if desired, I like to guide it by hand) and sew the top stitching with a 1/4″ seam allowance. Pull the fabric as needed to lay flat while you sew.

Next take your suit and …wait. You are done! Virtual high five. I knew you could do it.

If you would like to share your progress or final make on Instagram: #midlineswimsuit #ginghamhivepatterns @ginghamhive

Midline Sewalong:

1. Intro + Swim Top Support – Shelf Bra
2. Swim Top Support – Sports Bra
3. Swim Top
4. Swim Bottoms (you are here!)