My sister lives in her pool in the summer. And when they go on vacation, she is in a pool or at the beach, not just every day, but several times a day. That means she needs a LOT of swimsuits. She likes tankinis – the two piece construction means no hassle to pull down for the bathroom or to remove when she gets dressed again. But she doesn’t love clips in the back. They are hard for her to reach around and fasten. So she looks for tankinis that have no clips. She also likes interesting, designer level styling, especially ones that allow good arm movement. That’s not an easy task when she doesn’t want to spend over $30! I suggested she make them herself (which is what any “normal” sewist would think of first!) But when I showed her my Princess Tankini pattern, she wrinkled up her nose at the back clip. This is my sister’s favourite tankini. I call this the peek-a-boo back. She challenged me to hack (modify) my pattern to look like hers. Challenge accepted. 

This suit has an interesting two piece peek-a-boo back  and no clip of course!  Just pull it on and you are good to go. I also love the detail in the front strap. The back strap continues over the shoulder and ends with another peek-a-boo area on the front, so there are no shoulder seams.

To draft this from the Princess Tankini pattern you need to change the two piece back into one piece. First, remove the allowance for the turn under for the clip (1″ or 2.5 cm) on the top back piece. Next, join the top and bottom pieces of the back along the seam between them,  overlapping them as if they were sewn. That means overlapping by two times the seam allowance of 1/4″ (6 mm) so 1/2″ overlap total (12 mm). Extend from this new top edge (dotted line)  to the bottom hem, in 1/4″. You won’t need a centre back seam – your back is now one piece and will be cut on the fold of the fabric. Yes, that changes the DoGS a little but that will not matter in this case..

Raise the back up from it current location to a point much higher on the back, almost to the shoulders.  I raised mine 7′ (17.5 cm) from the original. That allows enough room to draft the peek-a-boo back. You can scoop our the armhole area too to make it more of a racer style back.

Let’s look at the front now because we have to allow for that in this part of the draft as well. Decide where on the front you want the break to be. Cut along this line keeping the line at right angles to the edges of the strap. Move this short section of front strap to the back and attach it to the back piece, once again overlapping by 1/2″ 912 mm) to compensate for the seam allowances. Smooth out the curves on the strap if you need to. 

One last thing before the drafting of the actual peek-a-boo shape. If you are going to use any type of binding for the edges, you need to remove the elastic allowance from the edges. That includes the armhole and neckline edges. if you are happy to use elastic and turn over the edges as you normally do, then there is no need to remove the 3/8″ (1 cm) allowance I put in the original pattern.  Now you can draw the peek-a boo shape on the modified back piece.  Make each of those lines curved so the peek-a-boo really shows. Allow about 1.5″ (3.7 cm) overlap at the sides. Mark each piece where one piece overlaps the other. Here is the pattern I came up with. The strap looks really long – that’s because it also has part of the front strap included.  

The two pieces separated look like this. Notice the markings where the two parts overlap each other to create the peek-a-boo. Also note that the bottom straight edge (on the left piece) will be part of the original back. There is no seam here – it was easier to draft without the rest of the suit pattern piece in the way.

Here is what the modified pattern pieces look like with the top piece in grey. That’s the top piece and you can cut it out of the same fabric, or a piece of power net or sheer mesh or even stretch mesh for a more see-through look. If you an find a piece of firm stretch lace like this one, go for it. Our Art Nouveau Stretch lace would fill the bill. Be wary of non-stretch laces – this piece does need to stretch. Cut 1 on the fold of each piece. Assemble the internal bra as you normally would, shaping the top edges of the bra lining in the font and lower back piece to the same shape as the main pieces. The top (grey) back piece does not and should not have lining.

The edges could be finished with cover hem binding strips or use fold-over elastic which we happen to carry in a lot of colours. Ours finishes out to 3/8″ wide (10 mm) . The first edges to finish off are the ones indicated below with the pink lines. These edges do not need any other elastic  as they are not areas that require any further elastication.

Once those pink edges have had the finishing binding applied, overlap the top back piece over the bottom back and stitch them together to hold them temporarily.  Now you can complete the tankini and finish the edges around the neckline and the armhole.  The binding should have a narrow strip of Filpar elastic tucked inside as you are zig-zagging it on the suit. If you find the Filpar a touch too wide for the fold-over, you can skinny it down by cutting some of the width off (don’t worry – it is one piece of siliconized rubber so it will not fray)


If you worry about where to end the binding on the neckline area, here’s as good a spot as any – just down a few inches from the back shoulder area. Don’t try to join it in the peek-a-boo area – it will not co-operate with your efforts!

I do hope you will give this Tankini Back Hack – the peek-a-boo back a try on your next swimsuit. if it is too late for this summer, it will be ahead of time for your winter vacation in the sun. I must be off – I have a tankini to make!

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