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Use surplus merchant ships as "Rain Boats". Modified vessels will follow tropical low pressure systems and harvest rain for needy countries.

Modify large ships with lined holds suitable for water. Equip with deployable catchment "sails" that are deployed to capture rain and funnel into the lined holds.

These vessels would follow the tropical and sub-tropical low pressure systems (ex-cyclones are an example) that produce prodigious amounts of precipitation. When full, the vessel would then proceed to locations of need around the world and offload the water through filters, so it is immediately potable.

Vessels could be refurbished and donated by appropriate donor entities. Vessels such as this would be ideal to be repainted in sponsors colours, so wherever in the world they were deployed, the sponsors message would be clear and apparent.

I envisage that it would operate as a non-profit organisation, possibly under the auspices of a large NGO.


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    Mar 16 2011: What a fabulous fresh idea! There is plenty of water from this source. We just have to get it to where it is needed. Thanks for tickling my brain with something unique. Maybe the filled ship could travel controlled by robotics under sail to predetermined ports to reduce potential pollution.
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    Mar 16 2011: Great idea, but there's also an issue of stability. Tankers strive to have completely full, or completely empty tanks, due to adverse hydrodynamical forces causing instability in half filled tanks.
    Also, as mentioned, the cost of operating a large tanker is huge, and freshwater may be better collected in other ways. However, I know that there have been ideas of towing icebergs or big floating/submerged "balloons" of freshwater from the northern hemisphere down to Africa. However, the technical and economical feasibility of such projects have not been good.
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    Feb 17 2011: The problem is that the cost of the water would be way too expensive! Just to give you an idea ...a panamax ship might cost something like USD 10 million per year to operate (crews, port costs, fuel, insurance, etc.). If you managed 8 loads of 70.000 tons per year (highly improbable you would get so much) the cost per ton would be close to USD 20 per ton (or cubic meter) of water.

    Also, every day millions of cubic meters of fresh water are "destroyed" (turned into salt water) at the mouths of rivers around the world, in many cases this water is clean enough to drink. This would probably be a cheaper fixed location to "harvest" water. But still the total cost would make the whole thing uneconomical, there are better alternatives.

    In comparison water from a desalination plant costs about USD 1 to USD 3 per ton, these are becoming more popular but still have the problem of their environmental impact (energy consumption and waste salt).

    It would be much more efficient to set up purification plants (small or large) at a water source close the location where the water will be consumed, with less transport costs you would also reduce the environmental impact of the whole operation.
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      Mar 16 2011: Thanks Jose. It is really helpful to have someone with the relevant figures to put perspective on the difficulties of implementing the solution. What if the ship were preprogrammed to run with a skelton crew and a predetermined route filling pumping stations near each harbor?
  • Feb 17 2011: Addendum: Tropical Cyclone Carlos, when it was still a deep low, dropped almost 500mm of rain on Darwin in 24 hours a few days ago. If a rain boat with a (small) 4,000 Sqm catchment were located under a tropical low such as this, it would have collected more than 2 Million Litres of fresh water in ONE DAY.