We are one of those who did not purchase the decal because we had no intention of being in US waters for several years. Well, as we all know, plans change. When we decided on the spur-of-the-moment last month to sail from Bonaire to the USVI, we were able to obtain the decal online. The actual decal was mailed to our permanent mailing address in the US, but the decal number was made available to us online after about 48 hours for processsing time.
We were required to have this decal number when we cleared in at St. John. And, yes, this decal is now required for all boats entering US waters, even those that are foreign flagged.