Flood zone designations A, AE or V are considered flood zones. A does not have a base flood elevation completed, AE has base flood elevation information available. V zones are coastal high velocity zones.
Base Flood Elevations (BFE) are the key to the new flood insurance rates. Homes built before your area's flood insurance maps were created (called PreFIRM) are the ones that have been receiving subsidized flood insurance rates for decades. Generally those would be homes built sometime in the mid 70's or earlier. Those are the ones most impacted by the revised flood insurance program.
Congress did pass legislation that would cap the annual rate increases to 15% per year for primary residence owners & 25% per year on non-primary residences, but insurance rates will keep increasing on an annual basis for those properties until the owners are paying non-subsidized rates. To cover the cost of the changes to the flood insurance program, all flood insurance policy holders will pay a $25/year surcharge on residential policies and $250/year surcharge on all non-primary residences and commercial properties.
So when looking at canal front lots, ask if the owner has a Base Flood Elevation (BFE) for the property, even if it is an older one. Then share that BFE with your insurance agent to get an idea as to what flood insurance rates will run you on the property. If you pay cash you are not required to carry flood insurance, but keep in mind if you decide to sell later on, all potential buyers that are doing financing will need to carry flood insurance for the life of the loan. So if the property comes with a hefty flood insurance rate, you could limit the number of potential buyers later on.
Another thing buyers don't always consider if the other aspect of buying in a flood zone -- remodeling. Basically the National Flood Insurance Program (NFIP) requires that if the cost of reconstruction, rehabilitation, addition or improvements to a building equals or exceeds 50% of the building's market value (building, not the lot and the building), then the building must meet the same construction and elevation requirements as a NEW building under FEMA guidelines.
The 50% rule can cause all sorts of issues for a home buyer in a flood zone if the property needs extensive renovation.
Remember, a home doesn't have to be located on a canal to be located within a designated flood zone, so be sure to find out the designated flood zone of any home you are thinking of purchasing.