Shipwrecked diaries
Shipwrecked
The first challenge - the team are going to have to find a boat that's been shipwrecked...
Corals
The protection of coral is important, as it's not that sturdy. Discover what leads to formation of corals.
Jonathan Hare's diary about the challenge for the Shipwrecked programme, from the BBC/OU series Rough Science 5
Started today with the beginning sequence of us arriving at the filming location by boat. This takes a little time but is great fun. Still, I am a little anxious to get started and to see what tools and bits and pieces they have provided for us.
Day 1
My part in the first programme is to be set the challenge of making an underwater camera. We will use this at sea to investigate the reef and so it needs to be able to navigate around the seafloor. The main challenge here is to make sure that no sea water gets into the equipment. In fact this was to be a recurring problem in all the programmes.
We have a very good selection of heavy duty plastic pipes that will do really well for waterproofing. We are also given a few battery powered hand drills and some model propellers. Finally a key ingredient is a surveillance type camera and TV screen – the sort of thing that you might use at home to monitor your front door for unwanted callers.
I intend to use the battery powered handrills for propulsion using the propellers in a design that will supply the power from the motors to the props, but keep the motors completely dry at the same time. There will be two motors driving two propellers and a camera to look at where we are going. We also need a system to make sure the movable camera is not too heavy, so that it just sinks, but also not too light that it won’t go under the water! So we need to make the whole thing neutrally buoyant but also provide some means to modify this so that we can make it go up and down when we want it to.
One idea is to use magnetism to provide a waterproof coupling between the motors and the prop. The motors will be fitted into the waterproof drainpipes and the power wires all sealed in. The motor drill chucks hold a wooden disc which has two strong magnets attached to it. When the motors are powered the disc goes round making the magnets rotate. These rotate up against the flat end of the drainpipe section.
Outside (on the other side of the flat drainpipe end) is another identical wooden disc which also has two magnets. This is attached to the shaft that goes to the propeller. When the inside disc spins there is a magnetic drag that forces the outside to follow. Thus the motor power can be transferred across the waterproof gap (the plastic drainpipe end) using the magnetism.
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Content last updated: 26/01/2005
