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Rough Science 2 Carriacou: Mike Leahy's diary: Sun and sea

Updated Monday 28th January 2008

Setting out to use the power of the sun means the Rough Science team have to abandon wood for metalwork...

Day 1

Although Programme 5 hasn't quite begun it leaks out that J would be making distilled water using a solar furnace because no fires are allowed. Ellen will be helping us. This may be a problem for her. Whilst I'm happy not to use virology in Rough Science challenges, she always uses botany. Rather than use her as simply a helper (which would definitely cause grief) what should we do?

Solar furnace = maths, a reflective surface
Botany – > glue perhaps and maybe string

Generator = magnets, wire, movement
Botany – > insulator, glue, lubricant, springs?

Q. What do you need to charge a car battery?
A. A 12-volt car battery is normal. This is actually made up of six cells, each giving a maximum voltage of 2.2V. This means that a car battery usually has around 13v when fully charged. To recharge a battery from say 10.5V to 13V we would need to generate a potential difference (pd or voltage) of at least 13.5 volts. That's easy with no load but we would need that sort of voltage while making a current of 2amps or so.

To understand current and voltage think of water, maybe or a hose. Current would be the amount of water coming out of the hose. Voltage would be the pressure at which the water comes out. If you were to pinch the end of the hose, the water would come out more quickly and under more pressure.

However, you would not increase the amount of water flowing therefore you would have increased the voltage but not the current. Of course, electricity doesn't just pour out of a wire in the way that water pours out of a hose, unless it finds a conductor. One way it may escape is by a 'short circuit'. This is when electricity finds an easy route. It always tries to do this so we use insulators to channel it to where we need it without it escaping down a piece of metal by accident.

Q. OK, so if we make a current of maybe 1-10A and a voltage of over 13V we are there, right?
A. Well, not really. Simple things like bulbs will work on alternating current. This is what comes through our sockets at home. It is called alternating because the current moves in two directions, backwards and forwards and in doing so gives off energy as heat or light.

A battery requires direct current to be charged. In a car a diode or series of diodes (electrical one-way valves) convert alternating current into direct current. We don't have diodes. We can design the generator to produce direct current using a commutator and brushes but there will be power losses.

So if we can make 13+ volts and 1+amps direct current, we're there then.

That little lot would be difficult enough to do. It would work but there is still at least one problem: if the generator slows down so that it produces less voltage then the battery will force current the wrong way.

If this difference is small there would be no real problem but should the generator stop completely and the comutator remains connected a sort of short circuit would result. This would allow the battery to force current around the fragile electrical circuit with no check. Car batteries can deliver lots of current so our rather delicate wire would heat up and eventually set fire or melt – > full on melt down of our generation plant.

Q. What can we do?
A. This one's tricky. It's my turn to make more coils and construct a 'solenoid' which only connects the charger to the battery at about the right voltage but without a volt metre we would have to estimate this using a bulb. I'll come onto solenoids later - they are often blamed for car breakdowns but are pretty useful. In the meantime we have also got to worry about over-charging the battery.

If the solenoid assembly doesn't work we would need to use a mechanical device to disconnect the generator when it isn't turning.

I finally become comfortable with the generator idea. A final twist will be that we use the generator as a motor. It reminds us that a motor is effectively a generator.

I wake to the forecast 30.9°C 89% Relative Humidity. Yesterday, wind speed was 6mph whereas today it will be 25mph. Thank God. Yesterday was so humid and still. I'm so sick of insect bites and slimy repellent. Filming is easier now but I'm just about ready for the UK again. Sun cream and sweat dribbling into my eyes have lost their novelty value.

Tools

Tools not put away - "I've seen it around somewhere" = Quote of the series.

As a result of no vice I drove a drill into my hand last series. This time, in one day I draw blood five times. My right hand is shaking and swollen. I didn't used to hurt myself this much when I was a mechanic.

In addition to a lack of vice the others rarely put anything back. Every time I want a hammer (we only have one) or a sharp saw it's missing from the tool box. I suppose I'm often guilty but each time a tool is finished with it appears to be dropped and left there.

Materials

OK - Rough Science is usually a 'wooden world' (and not just the hamming up). G-clamps are OK, wobbly work benches, hand drills are fine. As soon as you move to metal everything gets harder. Drilling takes more time, filing is harder, hammers need to be just the right size. Sad as it sounds there is the correct hammer for every job and we don't have them. Worse still sprung stainless steel (like I used for the commutator) is almost impossible to drill, even with a good drill bit.

Programme 5 is hard for me. Even before we start I have to make a generator. In the first series it took me, J and Vanessa three days to make a generator. This time it needs to be done in one day, only by me, but thankfully I wasn't filmed too much because it would duplicate series one. Hard work though.

Ellen walks up to me with a piece of wood. "I want to cut this down the middle but can't find the saw". "OK," I reply, "get out of the way for a sec." I place it in a window, right down in a corner and break it with a knife hand strike. Cool!

By the end of the first day the generator is working and I've found a good way of gearing it. Not much filming - nothing original been done but the foundations are there.

Day 2

Can't get the solar furnace out of the factory door. Wait around for an hour while trying to film - frustrating but all too common. Today the mosquitoes are really biting. My hand has swollen up from the cuts and bangs and I'm finding it hard to do anything because it's so stiff.

I would have liked to give the coil of the generator 1,000-1,500 turns but there isn't enough wire - 250 turns have to suffice, which means turning the generator much faster. To add to my problems we can't find many magnets because so many have been lost. This combines to make the generator very weak.

On the plus side the electromagnetic switch works really well. In order to set it to battery voltage I use the 12V car battery and adjust the switch so that it just connects at 12V. It's a rough and ready adjustment but with about 1,000 windings the switch will fly across at around battery voltage. Cool!

In order to try the switch on the generator I spin it really fast. Nothing! I try spinning it even faster using a coil of string like a lawnmower. All looks good until the generator blows apart. A spring has come loose. It's impossible to realise how difficult it is to make this sort of stuff without glue, tape, a welder and a local hardware store until you try.

I decide to chill out for a bit. The mosquitoes are still biting, the directors are whingeing and it's beginning to rain. I look out of the window. A booby suddenly dives into the sea and catches a fish. It is beautiful here but after six weeks I'm ready for home. In the meantime, I'm going to make the best of it though. If only I could find more wire and magnets.

Cool! Sandra found the map that I thought I had lost. Thank goodness.

The scientists are getting on fine now and have been for some time. The production team are falling apart though. Kate now refuses to work with David so when David's crew (Derek and John) are working Steve has to direct or Kate won't play ball.

My little issues are with David today. As the day drags on I try to get more power out of my generator knowing that sat outside the lime factory is an old SIIA Land Rover. It has already been filmed and has a dynamo under the bonnet. It spins OK and there is no reason to assume that it won't work. The hypocrisy is that we are working with new state of the art magnets, new wire, bearings and a brand new car battery but we can't use a rusty old Land Rover dynamo which was genuinely found on site - typical Shulman fudge although he's sure to think of some absurd reason to explain himself.

As the afternoon progresses, work on the dynamo doesn't. There is lots of well meaning advice, some good (from Kate funnily enough), some wacky (from Jonathan) and some obvious (from Angie). One way to get more volts is to put more windings into the generator coil, but there is very little wire and Kathy wants what's left anyway. Eventually, I find some off-cut and manage to increase the number of winding from 250-517. Great, more than double but putting the generator back together was quite a problem involving much frustration.

After a while I call Kate over. I know that I can generate current but without bulbs it will be difficult to check it. J offers use of his electronic thermometer which is basically a simple volt metre. I connect it up and it works. There seems to be lots of power. Kate comes over and I spin the generator as fast as I can. The needle on the volt metre twitches then something flies out of the generator followed closely by a second projectile. The commutator has struck the front bearing housing. This wouldn't have been so bad if I could have drilled it and secured it with screws but I couldn't because the metal was too hard to drill.

Consequently, the two parts of the commutator come adrift. It takes me half an hour to fix it before a second try. In comes Kate ready for success. This time things go well until the extra windings of the coil start to unravel and get tangled up. Third time lucky? Well it looked like it but we still have no idea what the generator is really putting out.

Day 3 will be very short due to filming constraints. I have two tasks. 1. Set up the generator on a big wheel. 2. Use it as a motor. I sneakily check out the improved generator and find that when turned by hand it only gives 3V-4V. When I turn the generator much faster it tends to fall apart. I decide to set the stuff up anyway. There isn't really any way to see whether the thing works or not when it comes to charging the battery. Angie complains that people will know from the number of turns that 12V isn't possible. I retort that the number of windings isn't the only concern. For example, the strength of the magnets is important. So she goes one step further into bullshit territory by saying that her friends who supplied the magnets would know that 12 volts isn't possible. I can see why she will probably end up being a management consultant because she is so good at convincing herself that she is right.

Voltage depends on the number of windings in the coil, the cross sectional area (CSA) of the wire, the strength of the magnets, the length of the coil or armature that passes across the magnetic field. Finally, the speed of rotation has a large effect. It can be seen from this that Angie has got a bee in her bonnet but that she is wrong.

I've wasted another day on a challenge that has been attempted in the first series. I can get power but whenever I try to get enough to charge the battery by modifying the generator or turning it faster things go wrong. I don't fancy my chances for tomorrow.

Day 3

AM

We still have bugger all time to do the website stuff and are still working through lunch hours. This should be a good programme though. The solar furnace is particularly impressive.

The insect life here is really beginning to bug me. Today it's little flies that deliberately fly into my eyes. The Deet burns my face.

Frustration carries on. I can't use a bit of wood because David wants if for a museum or something because Kathy has written morse code on it. Meanwhile he is taking tools as I am using them to make "a nice shot for a montage". At the same time Jonathan is taking wood that I am actually working on to make a parasol to protect him from the sun.

A bit from a bit and brace has been put in a drill - people here don't even know how to use tools properly. No-one charged our new cordless drill. Great. No chance of doing all the drilling I need to do after yesterday's disasters. I pick up a file and the magnets on J's voltmeter come flying towards the springs. This place is a complete disaster. Tools in the bog and scraps everywhere (none of which I'm allowed to use).

Lunchtime dynamics: comfy chairs are bagged by some of the others and like Germans they leave their towels on them to prevent others using them. I sit on one of the tool chests and after a while lay down. No sooner had I settled down to doze than David came over in need of some tools. Lovely as he is, he is also a major pain. Nice lunch though.

Did a nice interview with Kate but the camera was set up wrongly - 4x6 instead of widescreen. Programme 5 really has been a pain but the five of us are getting on well.

Another disaster: Mike B's phosphorous didn't work and he melted a pyrex jug in the process. Typical - can't melt glass when we really want to but...

Anyway, this afternoon we'll be on a boat filming. Cool!

PM

I have to re-do a piece with Kate because Derek wasn't on widescreen. No problem as it was a short one and very easy. Then I realise that I only have 15 minutes for the outtake wind-up of Sarah. Drew is also away filing with David so I have to ask Derek and John. No real problem but everything is so rushed. Anyway, I ask Sarah to film me with a final modification to the generator which should force the electromagnetic switch to work (knowing that it won't because I've stopped the Jenny). I repeatedly try to get the generator working, finally losing my temper and smashing the generator to pieces with a sledge hammer. Sarah wasn't convinced, but it was fun.

After the usual messing around we leave for the dive centre. I have a sneaking suspicion that the whole 'underwater bulb thing' is set up for the divers' benefit. After all, adding the element of being under water doesn't add that much to the challenge. In addition, the cost of this one scene must be over £1,500 which is quite high considering that we are supposedly already over budget.

We reach the dive centre for the safety talk. Of course, it is needed but inevitably it sort of ends up being a bunch of drama queens scare mongering which leads to a degree of mild hysteria. How dangerous can a friggin' car battery be? They have now incorporated a fuse into the circuit in case the bulb element blows (pointless). Angie claims that seawater has a resistance of 0.3 ohms per metre, which is absolute and total rubbish.

Anyway if the water was so conductive the electricity would take the easiest path and short between the wires by-passing the element in the first place. I used to lecture apprentices at night school on motor vehicle electrical circuits so I know what I'm talking about but here it's all about personalities. If you bullshit with confidence you are far more likely to be heard than if you quietly give honest advice.

I then told Ellen (gently) not to be so patronising and pointed out that the other scientists can spot the obvious as easily as her. As the meeting dragged on Mikey B knocked over a compressed air bottle angering Max (the self-important dive instructor) who warned him that such a mistake could blow up the whole building. Mike B replied that the bottles should be secure rather than left about to which Max retorted that it was his place so he could do what he wanted. Cool! And we are worried about a car battery.

OK, we're all paranoid now but at least we can get on with the shoot. It's a great opportunity to see Laurence again and his solidly built blue speed boat. Eight of us (the scientists, Kate, Derek and John) travel out to Sandy Island in this boat, the others taking one of the dive centre boats. We do a test of the bulb. Yes the wire glows. And then we lower the jar containing the glowing filament into the sea. Everything is fine - it still glows. More impressive is that the water hasn't forced its way in under pressure. Cool!

We then do a run through on camera. Loads of whooping and clapping - OTT as usual. We then chilled out and waited for the sun to go down a little further and repeated the whole scene. This time Paul was going to use Drew's camera (Drew being underwater) to do a wide shot of us from the other boat. This was really funny. Firstly Paul (the soundman) looked weird with a camera. A bit like a cross-dresser in a way.

Secondly, John and Derek were not to be seen in the boat by the camera so they had to lie down on the bottom. There was no way that they could fit in both lying down so John, who is a bit shorter, laid across the bottom of the boat and Derek had to go on all fours resting the side of his head on a bench. Of course, we all had to put on whoops and cheers as usual but I was genuinely laughing at the crew.

We finished in perfect time and the boats returned to Hillsborough just as the sun set behind us. The place was so laid back even the seagulls didn't bother making any noise.

It wasn't so quiet back at the hotel. One of the hotel staff, Princess, was having her wedding reception. I shut my curtain and put the Ministry of Sound Annual CD on a loud as my little active speakers could manage. As I showered I heard the door open and the sound of something being put on the kitchen floor. I knew that it was the car battery ready for a re-charge (my generator wasn't the most efficient of inventions) so I stayed in the shower. Then as I was drying myself I heard the door go again. I wasn't expecting anyone so went to look, holding my towel in front of me. It was only Steve who implored me to stay in my bedroom but I came out anyway much to the amusement of a few local girls.

After getting dressed in the smartest clothes I had (including trainers) I left the room for the reception.

"Hi, what's your name?" came a voice to my left. It was then I noticed two young girls hiding by my porch.

"Mike" I replied not indulging them with a reciprocal question.

"Are you staying here?"

"No, I'm a burglar. Of course I'm staying here."

"My name's Jesha: can we come in?"

"I'd only be too pleased but I'm going to the wedding"

"Please".

There was no way I was going to let them in but they were persistent and I was firm. "No way!"

"OK then, but do you have more drink in there?"

Now I wasn't interested in them, don't get me wrong, but I thought that they wanted my body which would flatter any man. In fact, all they wanted was my beer.

I walked over to the wedding party - very busy. The only people I knew were Reggie (our driver) and David who is getting crankier by the day as the others get at him. There is an announcement "Food is ready". All hell let loose as there was a stampede of fat women. You don't mess with fat women around here. Within minutes there was a stream of fat women leaving the party. Their hands were full, as were their bags and guts as they pillaged the food and ran. Ultimately, even poor Michelle, who was helping out in the kitchen, got no food.

Men here, like the fat women, can be animals and we had one of the randiest on our hands. He tried it on with Kathy, then Angie and finally Sarah, trying to get me to help out at each stage. Sandra was my wife for the evening.

Quote of the day from Ellen
Referring to the forthcoming wedding reception:
"I think you all will be surprised. Drinking isn't in their culture". Accordingly, there were bottles everywhere when we arrived back at the hotel.

Rest day 1

Whoops! Another hangover and today we were going on a boat trip. I'm up a little late and have to rush. Sea Terror is an old lifeboat from Scotland piloted by a clothes designer who sailed it across the Atlantic. It's a cool boat, as is its owner, who has also ridden across the Sahara. A couple of paracetamol and I'm feeling better. It's a wonderful day and we are off to Tobago Cays.

We had been gone about an hour and those not in the diving clique were at the bow slowing the boat by about half a knot. I was pointing out we were a little close to Palm Islands. One of the others replied that the skipper was probably doing this because of currents. Then with a loud crunch we came to a standstill. We had grounded. Reverse thrust and nothing. Derek, John and I decide to move people backwards to allow the bow to lift. It worked and we finally broke clear.

I got chatting to Kathy and find out that she comes from Abingdon, four miles from the village where I was brought up. We went to school in the same small town at the same time and she lived fifty yards from my school.

Rest day 2

Grenada Carnival is on. Everything is closed. Ellen, J and I go for a walk to the cross near Brunswick. The place is like a ghost town. The bakery is closed and all the other shops are closed. Two phone calls. Cool! I want to get home. It should be great. Then India. But I want to get home. Derek and John cook for us. Party time!

Been checking up on Mike B since last night. He has hidden away from the others. I can't blame him. I didn't go out with the others last night either. He wouldn't answer his door or phone. By 7pm the others noticed that he was missing. They took their time. Something's up. Hope he's OK.

 

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