Jonathan's To The Lighthouse Diary

Production team Day 1

Our challenge is to make a lighthouse for an island off the coast of Zanzibar – Bawe Island. Ellen and Mike B will make the fuel and light source for the light, while I am making the mechanism to encode a signal onto the light. Kathy will make a system to drive it all.

We decide to build a moving structure that will block out the light in a regular manner so that the light will flash a signal showing where it is coming from. As the island is Bawe I decide to send a B in Morse Code. B is dash dot dot dot.

The basic idea is to make up a wooden curved structure or shade that will move around the central light in a circle. The shade has areas removed to let the light pass through and out into the surrounding area. By varying the amount removed and the speed of rotation we can set the Morse Code letter and speed. Half the shade is made completely of thin wood; the other half has areas of this wood removed to give a large gap followed by three smaller gaps. This then gives the correct light signal for a Morse Code B followed by a pause before repeating.

Although the mechanism was not heavy, it was quite large and so we needed some bearing to move upon so that it was as easy to move as possible. I used the golf balls we were given in the trunk to make up eight ball bearings for the apparatus to move upon. I also arranged for four vertical golf ball bearings to keep the system central. These worked really well. Each golf ball needs to be drilled centrally as best as possible as a wobble creates more friction and upsets the ease and ability for the thing to rotate freely.

Production team

Day 2

Kathy and I spend a lot of today thinking about best ways to drive the whole thing. It would be nice to power the whole thing by weights (as they did in the old mechanical lighthouse 100 years ago). So we play around with various designs and machines. Make up a large geared system, use nails in the wooden pulleys to get a good grip on the rope. First test looks great but we discover that we need so much weight! Kathy continues to try out ideas and experiment and I fiddle with the mechanism to try and lower the friction in the system.

Day 3

Make up a wooden former to support the pulleys and wheels. Only get to try out a first proper test run as our boat is about to leave! So we must once again do our first test live as our final challenge! The crossing to the island was great but a little choppy. The island itself was very idyllic. Set up the equipment in the most beautiful spot with turquoise seas all around and interesting ancient coral formations on which to place the light house.

Ellen’s lamp looks great and supplies lots of light - her coconut oil is working very well.

Ellen, Kate and Mike go into a boat that will go off and pass by the island to see if the lighthouse is visible at all. Kathy and I try out the weight mechanism and we get it to work! But it’s difficult to control and time has run out to work on it any further. We do have a secret weapon though; we found out that a rubber door stop fitted to an electric screwdriver acted as the perfect wheel to drive the mechanism!

So we go for this arrangement and it works really well. They sail by and see the ‘B’ which is a really great ending …..