Whilst Beal & Petzl go along with the leave 3 days approach, Singing River suggest 7 days. I remain troubled by not having a good set of references on how long the virus can last on different surfaces at different temperatures, in mud / earth, darkness / light and at different levels of wetness / soaking etc. (What other variable have I missed?) The government state
However, studies of other viruses in the same family suggest that, in most circumstances, the risk is likely to be reduced significantly after 72 hours. see
https://www.gov.uk/government/publications/covid-19-decontamination-in-non-healthcare-settings/covid-19-decontamination-in-non-healthcare-settings .
But my basic take is you need to use disinfectant or above 60C if you want to turn stuff around swiftly.
It has just crossed my mind that perhaps we should follow the prescient comment of one President Trump and look for a solution involving shining an intense light within the rope?
It's all a little bit tricky. Some of the cruise ship samples detected virus after 17 days! But it isn't clear whether that was viable virus, or just detectable fragments. It also is not yet known what is the required viral load to cause an infection (and how variable that will be between people and contact methods)