3 stitches and 2 rows per inch in double crochet
To fit 38-inch chest
Chain 68 stitches.
Double crochet in the 3rd chain from the hook and in each chain across. Turn.
Chain 2 (counts as first double crochet here and throughout), *skip next 3 stitches, 3 front post double crochet in next 3 stitches, working back post double crochet around the 3 skipped stitches; repeat from * across until 4 stitches remain, skip next 3 stitches, double crochet in last stitch. Turn.
Until piece measures 18 inches, ending on a right side row. Fasten off.
Work same as front panel.
With right sides together, seam front and back panels at the shoulders and sides using mattress stitch. Leave openings for neck and sleeves.
Join yarn to neck opening and work double crochet evenly around. Join with slip stitch and fasten off.
Join yarn to sleeve opening and work double crochet evenly around. Repeat for second sleeve.
Weave in all ends and block to measurements.