Understanding climate
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Freshwater plant aboard Statsraad Lehmkuhl. (Thomas Spengler)

Drinking the Sea

While water levels aboard continue to plummet, Emma looks in to how to make fresh water at sea. 


Written in quarantine, published later.

We have been living under quarantine now for five days aboard the Staatsraad Lehmkuhl, anchored in Suva harbor. I suppose there are worse places to be. We have a nice sea breeze, tropical sunshine, and the green Fiji hills surrounding us.

Five days ago, one case of Covid-19 was found aboard, then two cases, then six. Additionally, the stomach flu is circulating around the crew and trainees. Surprisingly, these afflictions are no longer our biggest challenge. Our current challenge is water.

It might be surprising that water would be a problem in the middle of the blue Pacific, but it is. While we are surrounded by saltwater, our ship’s freshwater reserves, which we need for drinking, showering, and washing our hands, are running dry.

Every day we meet at 15:30 for the captain’s briefing and he reports to us the previous days excessive water usage.  It’s jarring to hear how many liters we now have left per person. 

Freshwater has historically been a big problem for sailors. In the days of pirates, a ship would fill caskets with water when they were in port. They added alcohol to the water to prevent algal growth. This water-alcohol concoction was called grog (coincidently, the same nickname that the USP students call Kava). But the One Ocean Expedition did not rely on grog as their water source as they crossed the Pacific for 36 days to get from Chile to Tahiti. So where did the water come from? 

The water has to go through the four tubes, each with a membrane for the osmoses processing. (Photo: Thomas Spengler)
The water has to go through the four tubes, each with a membrane for the osmoses processing. (Photo: Thomas Spengler)

How to make water?

These days, ships convert sea water into fresh water using an onboard reverse osmosis system. Reverse osmosis is a process where high pressure is used to force the water molecules in seawater to move across a semi-permeable membrane while the sea salt and other particles stay behind.

The water that has crossed the membrane is freshwater that we can use. On a normal day at sea, the Staatsraad Lehmkuhl’s reverse osmosis system can produce up to 20 tons of fresh water!

Unfortunately, the location of our anchorage is not suitable for our water treatment procedure. Due to heavy ship traffic and city runoff the water in the bay is quite polluted and would not be up to the strict Norwegian standards that this boat is held too, even after treatment. So, as we can’t make our own water here in quarantine.

One option is that our ship goes back to the dock in Suva, and we fill up with local Fiji water. While this water is safe to drink, it does not meet the standards we are held to and would require flushing the entire water system aboard. Another option (and I would say by far our favorite) would be to leave Suva harbor for cleaner seas that would allow us to make our own fresh water.

The captain mentioned in one of our daily briefings that, given that we seem to have our Covid situation under control, the Staatsraad Lehmkuhl might get permission to raise anchor and leave our quarantine post early.  We are all hoping that we will soon get to set sail!