"as close behind him as the shuttle is to a woman's bosom when she throws the woof across the warp and holds it close up to her..."
See in text (Book XXIII)
The terms in this simile all refer to the act of weaving fabric. A “shuttle” carries thread for weaving; “woof” and “warp” both refer to the thread’s position in a fabric. Like the way a weaver carries her cloth close to her chest, Ulysses follows Ajax.