No web site but the process is fairly simple.
As "aliens" you cannot have a USCG federally documented vessel, it simply isn't allowed. That means you can purchase
the boat under NZ or British laws and register it at home, and apply for a cruising permit
here. Or, if you have a US address, you can buy it and register it with any state as a motor
vehicle. Most of our states consider a sailboat with a permanently installed engine
to be the same as a car--you buy it and register it. You will have to pay taxes
based on the residency if you are state residents (sales tax, property tax, use tax, which one varies in each jurisdiction) or if the boat remains in that state for more than a set number of days (typically 90 days, that also varies and may be as little as 30 days). Florida
, like most states, posts their vehicle registration
and tax regulations
on the web in detail.
So, first you have to decide on where and whether you are residents or domiciled in any state, or whether you want to go the "cruising permit" route
which will place shorter limits on your stay--as will any visa restrictions.
If the boat is British flagged you enjoy some odd benefits, like being able to cruise
up into the Mississippi
River without coming through US Customs
. Apparently a legacy of the treaty ending our War of 1812 against the UK.<G>