Ellen McCallie's Zanzibar diary: The reef

Production team

Day 1

Who wrote this challenge? Who builds a burglar alarm for a reef?!?

Turns out this challenge was the brain child of Rob, one of the soundmen. Think of the scale! Our end product will be a 20+ metre floating barrier rigged up with a trip wire powered by waves! I can just imagine us trying to haul this around in the ocean to set it up. I must say, it is a classic Rough Science challenge: big, almost logical, and definitely over the top!

In terms of context, this is a pretty important challenge as well. Reefs are often unintentionally damaged or destroyed by boats when their captains don’t realize shallow reefs are around.

When I said that as my contribution to the challenge I was going get 150 coconuts, people had one of two responses. They either put their order in for their favourite curry with coconut milk or ran for cover, thinking I’d need help grating coconut to make more oil like in the lighthouse programme. (The first steps to getting coconut oil actually give you coconut milk, but that’s not the challenge for this programme.)

In any case, my real challenge was to come up with a very simple solution to getting the burglar alarm to stay afloat. Coconuts in their husk are fabulous for this as they are very buoyant. If you’ve ever husked a coconut, you know how fibrous they are and can see how much air is trapped between the fibres. This makes them much less dense, basically lighter per unit volume, than sea water, so they float.

So I built two rafts for Jonathan’s equipment from wood that almost floats. I then put a net beneath it, trapping about 30 coconuts underneath which push the raft up, so even if Jonathan’s equipment is heavy, the raft won’t sink.

Day 2

Keith, one of the cameramen, and Kate are stars! Today the three of us drilled hole after hole in the husks of coconuts—careful not to pierce the actual coconut seed, because if that fills up with water, it sinks! Then we strung them on lengths of rope which will go between Mike’s sticks to which the trip wire will be attached.

You’d think drilling a bunch of holes would be easy. Long, hard work. Lots of fun and laughter as every once in a while one of us broke through the “shell” of the coconut and coconut meat and milk went whirling everywhere!

Day 3

In terms of a team, this was the best Rough Science day! It took every one of us, working constantly on behalf of the overall challenge, to get this monstrosity going. And, up until the very end, none of us had any clue as to whether it would work at all. Usually, you get to test sections as you go or you have a feel for what’s going on overall, but not with this. We knew that rafts floated and the burglar alarm could go off, but this thing was huge! Would it work together in the ocean?

Getting the boats lined up with the reef, given the strong current—wow! That took at least 2 hours and then had to be maintained. Mike, Kate, and I jumped in to be the water-based team. Mike monitored one end as Kate and I hauled the other end, out from the boat, against the current! Kathy and Jonathan spent their time rigging the floats as they were placed in the water.

It felt like a race against time. Being out in the water, Kate and I had no idea how much time was passing, we just kept kicking against the current trying to keep the long lines of floating sticks, coconuts, rope and wire from getting tangled - serious business this was. At the same time, if we actually looked above or below water, we had to laugh. We were dragging a huge lumbering dragon through the water. Underwater, all you could see were these bobbing sticks with rocks on the end, and occasionally Mike swimming between them! On top of the water, Jonathan and Kathy were attempting to do detailed, precise work with wire on a shifting and bobbing boat. Every couple of metres something would jiggle loose and have to be re-done.

When finally everything was ready, something like three hours later, we all piled back into the boat - Mike and Kathy did some last minute in-water repairs - and held our breaths… sure, it was great looking, but would it work?

Beep, beep, beep, beep.