Learn Spanish (Latin America): Ellos están por desatar el amarre y soltar el gancho. - They are about to untie the mooring and release the hook.

While van a desatar just means 'they are going to untie' (a general future plan), están por desatar adds a strong sense of imminence. It translates to 'they are about to untie', meaning the action is pending and will happen at any second.

Why isn't the word por repeated before soltar?

When two infinitives are linked by y and share the same preposition, you usually drop the preposition before the second verb to avoid repetition. The single por naturally applies to both desatar and soltar.

Could I use dejar instead of soltar here for 'release'?

Not quite. Soltar specifically means to physically release your grip, let loose, or unfasten something that is held (like a rope, a hook, or a dog). Dejar means to 'leave' something somewhere or 'allow' something to happen, so it wouldn't make sense for unhooking physical equipment.

I know atar means 'to tie'. Is desatar related?