Underwriting a Private Island
Desalination, generation capacity, dock depth, medical evacuation time. The building is the last thing that should be assessed, and usually the first thing that is.
Rashid Al-Mansouri
Partner & Senior Market Advisory
Photography: Private island seen from the air
Every private island we have been asked to assess has been presented to us photographically. Every one we have recommended has been recommended on a spreadsheet.
Water first
An island's carrying capacity is set by its fresh water, and nothing else matters until that number is established. Desalination capacity, storage volume, and — critically — redundancy. A single reverse-osmosis unit serving a ten-bedroom house is not an amenity; it is a single point of failure that renders the property uninhabitable within about seventy-two hours of a fault.
We look for two independent units, storage of at least fourteen days at full occupancy, and a maintenance record showing the units have actually been serviced rather than merely installed.
Then power
Generation, storage, and autonomy. Solar with four days of battery reserve and a diesel backup is a serious specification. Solar with no reserve and a generator that has not been load-tested since commissioning is a liability that will present itself during the first storm.
Then access
Dock depth at low water, not at high. Airstrip length, surface, and — the question that is almost never asked — whether the permit is current and whether it transfers on sale. We have seen two islands where it did not.
Medical evacuation time to a facility capable of receiving a cardiac patient. On one Caribbean island we assessed, the honest figure was four hours and eleven minutes. The client bought a different island.
Then, finally, the house
Hurricane rating, salt tolerance of the specified materials, and the practical question of who maintains it. An island house is only as good as the staffing arrangement that keeps it, and staff arrangements on remote properties are considerably harder to sustain than owners anticipate.
What the numbers looked like
On the last island we recommended, infrastructure represented sixty-two per cent of replacement cost and the buildings thirty-eight. The particulars had devoted one line to the former and eleven photographs to the latter. Our model inverted that ratio, and the price we advised was nineteen per cent below asking. It was accepted.
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