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Rough Science 5 Zanzibar: Ellen McCallie's diary: To the lighthouse

Updated Wednesday, 9th March 2005

The team are tasked with constructing a lighthouse to warn passing ships of the treacherous reef below. Ellen and Mike need to make a light that will be visible from the sea.

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Ellen Copyrighted  image Icon Copyright: Production team

Day 1

A lighthouse. Wow, this is hard to imagine. What’s it going to look like? I think of lighthouses as huge, made of brick or stone. Ours has to be bright, yet portable. Hum…I better just move ahead with the light source.

Light source, basically something that burns brightly. Oil burns. The more of it we burn at a time, the brighter it will be. Plus, we can devise a way to use mirrors to direct and concentrate the light so it goes out to sea and not inland.

On Zanzibar, there are a lot of choices for oil - castor bean, various palms and nuts. Given the fact I’ve got to collect, extract and purify the oil in basically two days, I’m going to try coconut oil. Plus, coconuts are big and there are a lot of them around, so if we need tons of oil to keep the lighthouse going all night, it’s more likely to be possible…fingers crossed.

As it turns out, collecting the coconuts was great fun. Plenty were underneath a group of coconut palms, plus I got to climb some coconut trees. Climbing trees is one of my favourite pastimes.

With 50 plus coconuts, I started dehusking the coconuts, cracking them open, and then grating them using this really cool grater with a built-in bench to sit on. In homage to Tom Sawyer, within minutes a wonderful group of six volunteers sat down to join me. Instead of taking days, we turned 50 coconuts into grated pulp in a matter of hours.

Day 2

The workshop is pretty tense today. I’m not sure why. People keep coming up to me, seeing all this grated coconut in buckets of water and asking, “where’s the oil? Where’s the oil? We need oil by the end of the day.”

"the situation was making me pretty nervous"

The situation was making me pretty nervous. I couldn’t think. I was getting really worried and self-doubt started. What happens if there isn’t any oil in the coconuts? What happens if I can’t figure out how to purify it? And, maybe there won’t be enough time - a lighthouse won’t work without a light source.

Then, I walked away for about 3 minutes and thought, “Do your thing, woman. Figure this out! Ignore the doubters. It’s 10 am on Day 2. Plenty of time. Plus, coconut oil is used all over the world because it is plentiful in coconuts and relatively easy to extract. Think about it slowly and methodically.”

So, coconuts are fruits, basically the seed of the coconut palm. They have a buoyant watertight husk that helps them float for long distances. Inside the nut is the embryo, which is the young plant ready to grow, and the coconut “meat” and water, which sustain the young plant until it lands somewhere and starts to grow. The coconut ‘meat’ is full of oil, which makes it energy rich and perfect to support a young plant until it can develop leaves big enough to make its own food. It’s the oil from the ‘meat’ that I want.

We grated the coconuts and washed it in water over and over. The problem was that I expected the oil just to float to the top, like oil does in salad dressing. The oil and water didn’t separate easily. This threw me for a loop. I tried squeezing the grated meat through cloth and then letting it separate - no luck. Finally, I pour the water-oil-meat mixture in a pan and set it on the fire. Water will evaporate well before oil. I’ll get to the oil…

Turns out I’d used way too much water. Perhaps it wasn’t needed at all. Once the water evaporated off, I was left with this oily, goopy coconut “meat”. I fried it some more and it was like cooking bacon - I was left with a pan of fried coconut ‘meat’ surrounded by oil. I collected the oil, squeezed more out of the coconut ‘meat,’ and repeated the processes endlessly for the rest of the day. By evening I had enough oil to burn for a week.

Day 3

I used coconut fibre and other plant fibres to make wicks. The wicks have to allow for capillary action, so oil keeps moving up the wick. The goal when making lamps and candles isn’t to burn the wick per se, but to turn the oil (or wax in the case of candles) into a vapour and then burn the vapour. A little bit of the wick burns in the process.

Using a biscuit tin, I made 20 wicks, which hung into the oil in the tin. We had lots of discussions about its safety. Would heat or pressure build up in the tin? Given the set up, we felt we were fine.

Mike and I created a mirror and glass shield to protect the flames from the wind—we hadn’t taken wind into account earlier…whoops!—and to direct the light.

One thing I never expected was that lighting the wicks would be so hard. Because the oil has to evaporate to start the process, lots of heat has to be added, so striking a match and touching it to a wick isn’t good enough. The trouble is the matches we have are about as good as sea water for lighting fires. The lighters are better, but not great. Add the wind on top of this!

It took me about 30 minutes to get the ‘birthday cake’ lit. (It looks like a birthday cake to me, except I’d need a bunch more wicks for my birthday.)

What a sight! As Jonathan and Kathy ran the lighthouse from shore, Mike and I headed out in a boat to enjoy the view without worries of running into the island.

Note: As it turned out the island already had a floating lighthouse that we didn’t know about. Several weeks later the lighthouse broke loose and ended up in the tiny bay right in front of our workshop. Thus, we brought a lighthouse to Bawe Island, and it sent one back to us!

 

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