Short-Blade Training Fins

Speedo / DMC Style — Crochet Replica

A pair of snug, closed-heel foot pockets with short flared blades, inspired by Speedo and DMC swim-training fins. Worked in dense worsted single crochet: sock-style pockets in the round, two-layer ribbed blades worked flat and seamed. Intermediate. Costume, display, and play only — do not wear in water. Yarn soaks, stretches, and will not propel you; wet socks on tile are a slip hazard.

Materials

Yarn (worsted weight / category 4; acrylic or cotton)

• Color A (foot pockets; classic black or navy): 180 (220, 270) yards
• Color B (blades and trim; classic yellow or lime): 200 (250, 310) yards

One-color version: 350 (450, 530) yards total.

Hook

• US G-6 (4.0 mm), or size needed to obtain gauge (fabric should feel firm, not drapey)

Notions

• 4 stitch markers
• Tapestry needle
• Scissors
• Optional blade stiffener: 2 sheets of plastic canvas, craft foam, or a plastic folder, cut to blade shape
• Optional: non-slip fabric or suede for soles; ¼" elastic for cuffs

Gauge

16 sc and 18 rows = 4 × 4" (10 × 10 cm) in single crochet with US G-6 (4.0 mm), worked densely.

Swatch in sc and measure. If you have fewer than 16 sc in 4", go down a hook. Structure depends on this gauge.

Sizes

Instructions are written for Small (Medium, Large). Make 2 fins the same.

Fit is snug, like a swim fin. If you are between sizes, make the smaller size. Foot-pocket circumference is sized to the ball of the foot.

Abbreviations (US)

• blo — back loop only
• ch — chain
• rep — repeat
• rnd(s) — round(s)
• RS — right side
• sc — single crochet
• sc2tog — single crochet 2 together (insert hook in next st, yo, pull up a loop, insert hook in following st, yo, pull up a loop, yo, pull through all 3 loops)
• sl st — slip stitch
• st(s) — stitch(es)
• WS — wrong side
• yo — yarn over

Pattern Notes

• US crochet terminology throughout.
• Foot pocket is worked in joined rounds for the cuff, then in a continuous spiral for the foot. Place a marker in the first stitch of every spiral round and move it up.
• Blade is worked in turned rows. Ch 1 at the start of a sc row does not count as a stitch. The first sc of each row goes in the first stitch.
• Work sc through both loops unless directed to work blo.
• Stitch counts appear in parentheses at the end of each row/round.
• Make 2 identical fins.
• Blade pieces are worked blo for a molded-rubber rib. Keep tension even so ribs do not flare.
• Weave ends as you go where possible.

Special Stitch

Sc2tog: Insert hook in next st, yo, pull up a loop; insert hook in following st, yo, pull up a loop; yo, pull through all 3 loops on hook. 1 st decreased.

Foot Pocket (make 2)

With Color A, ch 34 (38, 42). Join with sl st to first ch, taking care not to twist.

Cuff

Rnd 1: Ch 1, sc in each ch around, join with sl st to first sc. — 34 (38, 42) sc

Rnds 2–8: Ch 1, sc blo in each st around, join with sl st to first sc. — 34 (38, 42) sc

Cuff measures about 1¾" (4.5 cm).

Foot

Work in a continuous spiral from here. Do not join. Place a marker in the first st.

Rnd 9: Sc in each st around (both loops). — 34 (38, 42) sc

Rnds 10–33 (37, 40): Sc in each st around. — 34 (38, 42) sc

You have worked 25 (29, 32) even foot rounds after the cuff. Piece measures about 7¼ (8¼, 8¾)" (18.5 [21, 22] cm) from the cast-on edge.

Toe

Place a second marker in the 18th (20th, 22nd) st so the round is split 17/17 (19/19, 21/21).

Rnd 1 (dec): Sc2tog, sc to 2 sts before second marker, sc2tog, sc2tog (first 2 sts after marker), sc to 2 sts before end of rnd, sc2tog. — 30 (34, 38) sc (−4)

Rnd 2: Sc in each st around. — 30 (34, 38) sc

Rnd 3 (dec): Repeat Rnd 1. — 26 (30, 34) sc (−4)

Rnd 4: Sc in each st around. — 26 (30, 34) sc

Rnd 5 (dec): Repeat Rnd 1. — 22 (26, 30) sc (−4)

Rnd 6: Sc in each st around. — 22 (26, 30) sc

Rnd 7 (dec): Repeat Rnd 1. — 18 (22, 26) sc (−4)

Sizes M and L only — Rnd 8: Sc in each st around. — – (22, 26) sc

Size L only — Rnd 9 (dec): Repeat Rnd 1. — – (–, 22) sc (−4)

All sizes now have 18 (22, 22) sc.

Next rnd: Sc2tog around, ending with a sc in the last st on Small only. — 9 (11, 11) sc

Fasten off, leaving a 12" (30.5 cm) tail. Thread tail through the remaining 9 (11, 11) sts, pull tight to close the toe, and weave in securely on the WS. (9 [11, 11] sts cinched closed ✓)

Pocket inside length is 9 (10, 11)" (23 [25.5, 28] cm).

Blade (make 4 — 2 per fin)

Work all blade rows blo for horizontal ribs. With Color B, ch 33 (37, 41).

Row 1 (RS): Sc in 2nd ch from hook and in each ch across, turn. — 32 (36, 40) sc (8 [9, 10]" / 20.5 [23, 25.5] cm)

Rows 2–10: Ch 1, sc blo in each st across, turn. — 32 (36, 40) sc

Flare decreases

Dec row: Ch 1, sc2tog blo, sc blo in each st to last 2 sts, sc2tog blo, turn. — 2 sts decreased

Even row: Ch 1, sc blo in each st across, turn.

Rep Dec row then Even row 9 (10, 11) times. — 14 (16, 18) sc

(9 [10, 11] decrease pairs × 2 sts = 18 [20, 22] sts decreased; 32 [36, 40] − 18 [20, 22] = 14 [16, 18] ✓)

Next 4 rows: Ch 1, sc blo in each st across, turn. — 14 (16, 18) sc

Fasten off after the last row, leaving a 24" (61 cm) tail on two of the four pieces (these tails are for sewing to the foot). Fasten off the other two pieces with a short tail.

Blade measures 7 (7.5, 8)" (18 [19, 20.5] cm) long and 8 (9, 10)" (20.5 [23, 25.5] cm) at the tip.

Finishing

Block

Pin each blade panel flat, stretching the tip to the full 8 (9, 10)" (20.5 [23, 25.5] cm) width. Steam-block (acrylic) or wet-block (cotton) and let dry completely. Do not skip this — unblocked blades curl.

Assemble each blade

Hold two panels WS together, matching the wide tip and the 14 (16, 18)-st edge. With Color B, sc through both layers around one long side, across the wide tip, and down the other long side. Leave the narrow 14 (16, 18)-st edge open.

If using a stiffener, cut it ¼" (6 mm) smaller than the seamed blade on all sides and slide it in now.

With Color B, sc the narrow edge closed through both layers (and catching the stiffener if used). — 14 (16, 18) sc along the attachment edge

Make 2 assembled blades.

Center spine (optional, classic fin look)

With Color B (or A for contrast), surface-sl-st a straight line from the midpoint of the attachment edge to the midpoint of the tip on the RS of each blade. Keep the line taut.

Attach blades to pockets

Put a foot pocket on. Mark the center top of the toe (12 o’clock, not the sole). Center the blade’s 14 (16, 18)-st edge on that mark so the blade points forward, overlapping the toe by about 1" (2.5 cm). The blade sits on top of the foot, not under it.

Pin through all layers. With the long Color B tail (or a new strand), sew the attachment edge to the pocket with firm whipstitch or mattress stitch, going through both blade layers and the foot-pocket fabric. Take a second pass for strength. The join must take walking stress.

Rep for the second fin.

Cuff trim

With Color B, join at the center back of the cuff. Ch 1, sc in each st around the cuff edge, join with sl st to first sc. Fasten off. — 34 (38, 42) sc

Heel pull tab (optional)

With Color B, ch 12. Sc in 2nd ch from hook and in each ch across. Fasten off. — 11 sc Fold in half and sew both ends to the center back of the cuff, just below the trim, to make a 1" (2.5 cm) loop.

Soles (optional but recommended for costume wear)

Cut non-slip fabric or suede slightly smaller than the bottom of each pocket and whipstitch in place. This is for dry indoor wear only.

Weave and set

Weave in every remaining end on the WS. Smooth the blades so they stand out from the toes. If the cuff feels loose, thread ¼" (6 mm) elastic through the blo cuff ridges, overlap the ends ½" (1.3 cm), and sew them down.

Wear and care

Slide on like a snug sock; pull the tab if you added one. Blades should project straight forward.

Spot-clean. Do not machine-wash if a stiffener is inside. Do not wear in water, on wet floors, or as actual swim training gear.

Schematic (one fin, top view)

              8 (9, 10)"
         ________________
        /                \
       /      BLADE       \
      /     7 (7.5, 8)"    \
     /______________________\
              | 14 (16, 18) sts
              |    TOE
              |  FOOT POCKET
              |  9 (10, 11)"
              |  8.5 (9.5, 10.5)" circ.
               \______________/  cuff