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What Three Words - For the dinosaurs here :)


Richard10002

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None of this gear can transmit a signal from underwater. 

 

An floating AIS beacon on a cord might work but would need some way of indicating that one had become caught on an underwater obstruction so the cord would need a wire in it. Maybe a bell wire would work. 

You might get mistaken for a lobster pot buoy. 

Edited by magnetman
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5 minutes ago, magnetman said:

How does it work when diving if you get caught on something? The signals won't go through water. 

 

 

 

I did mean DIVING.

 

When you surface it is possible that currents and tides may have taken you beyond where you can get back to the boat or the shore, or you may be injured and unable to swin -  not helped that you are floating with a big 'bag of air' on your back and catching the wind.

 

Its a bit like a kiddie on a lilo they can end up miles away.

You 'press the button' and lie back and wait for the Chop-Chop-Chop sound of the helo coming for you,

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Just now, magnetman said:

None of this gear can transmit a signal from underwater. 

 

An floating AIS beacon on a cord might work but would need some way of indicating that one had become caught on an underwater obstruction so the cord would need a wire in it. Maybe a bell wire would work. 

A weather balloon could work, or a 20 ft inflatable danbuoy.

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Just now, rusty69 said:

A weather balloon could work, or a 20 ft inflatable danbuoy.

 

 

We carry a DSMB (Delayed Surface Marker Buoy) which has a line longer than you are diving, The line has a 4 foot long orange sausage attached. You can fill the sausage with air and allow it to float up to the surface where it pops out and stands upright for all to see.

 

If you were to get 'caught up' (say in a fishing line or nets) then you cut yourself free with the tools that you carry for that purpose.

 

If you somehow got your gear 'hookedup' onto (say) part of a shipwreck, then your buddy would come alongside and unhook you - if your gear cannot be unhooked, the you take it off and surface using your buddies 'spare' (alternate air source)

 

All of these things have to be practiced and perfected before becoming certified, and, you never dive alone !

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1 minute ago, magnetman said:

I meant to stop the diver drifting.

How's the diver gonna swim with a dirty great anchor? You haven't though this through, have you?

1 minute ago, Alan de Enfield said:

If you somehow got your gear 'hookedup' onto (say) part of a shipwreck, then your buddy would come alongside and unhook you - if your gear cannot be unhooked, the you take it off and surface using your buddies 'spare' (alternate air source)

If I got my gear hooked up on a shipwreck, I would not be best pleased.

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Just now, Alan de Enfield said:

 

 

I'm already carrying about 50kgs of gear - please don't add anymore.

How about an inflatable anchor?

You could fill it with cement should the need arise to deploy it. 

Horror and anger. My work here is done.

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20 hours ago, Alan de Enfield said:

 

 

I predated you by a couple of years - we used imperial ,measurements, (even log tables and slide rules right up to A-level). Even when  they became more common 'electronic calculators' were banned.

 

 

I am not for one moment advocating a return to slide rules, but they did have one advantage: use of them did require a prior estimate of the answer in order to get the decimal point in the right place. This forced one to think about the numbers rather than (as with the pi - 60 something earlier) just returning the 'answer' from the device as gospel. Similarly, with people who quote spurious precision.

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2 minutes ago, Mike Todd said:

I am not for one moment advocating a return to slide rules, but they did have one advantage: use of them did require a prior estimate of the answer in order to get the decimal point in the right place. This forced one to think about the numbers rather than (as with the pi - 60 something earlier) just returning the 'answer' from the device as gospel. Similarly, with people who quote spurious precision.

 

A bit like science write up on your experiments :

Detail what your were trying to prove.

How did you go about it ?

What were the results ?

Where they what you expected ?

 

You actually almost need to know what the result will be, you are just proving that your 'estimate' is correct.

Much more thought needed than just asking Google and writing down the answer.

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4 hours ago, MtB said:

If you divide a number by itself you get 1. 

 

If you divide zero by itself you get 'indeterminate'. 

 

Therefore zero is not so much a number as a placeholder to indicate 'nothing there'. 

Arabic thinkers did a great service to maths when they invented zero and considered it a number, like any other number. In any case, indeterminate is not the same as infinity.

 

Your argument that zero is not a number because it behaves differently under a particular usage is not valid. Even in computing NaN is not the same as 0 (failure to recognise this led to all sorts of problems at one time esp with database work.

 

For example, saying that you have zero children is not the same as saying that you do not know how many children you have!

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Slide rules are brilliant. I have a number of very good quality Faber Castell slide rules in their plastic boxes.

 

The need to estimate is a hugely undersetimated skill when it comes to maths.

 

I'm engaging with the younger of the offsprings around the slide rule. They are both clever but she is the Mensa kid so I think it might work.

 

She can already write Floccinaucinihilipilification by hand backwards with her eyes closed so that it is readable in a mirror. Antidisestablishmentarianism was done similarly after viewing the word just once. I was like "OMG".

 

I think the slide rule might be childs play for this one.

 

A good slide rule operator can execute complex calculations faster than someone with a calculator and they are less likely to make a mistake.

 

Yars ago I was able to use almost all of the functions on the rule but the old grey cells have gone somewhere else now.

 

 

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4 hours ago, Alan de Enfield said:

 

 

But conversely, any number divided by Zero is Zero

 

Wrong, I'm afraid.

Divide any (positive) number by a very small (positive) number indeed, and you get a very large number indeed.

Divide the number you first thought of by zero, the smallest positive number there is, then logically you get the largest number you possibly can, otherwise known as infinity.

 

Alternatively, you get an undefined value, whereby division by zero gives whatever number you want. That, as I understand it, is why computers return division by zero as an error.

 

Zero, however, has no units and no dimensions. Strictly speaking there is, for example, no such distance as zero metres -- it's just no distance.

 

 

 

 

 

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54 minutes ago, magnetman said:

Slide rules are brilliant. I have a number of very good quality Faber Castell slide rules in their plastic boxes.

 

The need to estimate is a hugely undersetimated skill when it comes to maths.

 

I'm engaging with the younger of the offsprings around the slide rule. They are both clever but she is the Mensa kid so I think it might work.

 

She can already write Floccinaucinihilipilification by hand backwards with her eyes closed so that it is readable in a mirror. Antidisestablishmentarianism was done similarly after viewing the word just once. I was like "OMG".

 

I think the slide rule might be childs play for this one.

 

A good slide rule operator can execute complex calculations faster than someone with a calculator and they are less likely to make a mistake.

 

Yars ago I was able to use almost all of the functions on the rule but the old grey cells have gone somewhere else now.

 

 

 

 

I had a slide rule at skool which was made from bamboo with white veneer facings. It was beautiful to use as there was none of the stiction and jerkiness that plastic slide rules suffer from.

 

Curiously the one thing you can't do with a slide rule is add and subtract. 

 

Ok that was two. 

 

But not zero! 

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31 minutes ago, ditchcrawler said:

 The COSPAS-SARSAT satellite network can detect the location of the PLB with an accuracy of 2 to 5 km. 

 

 

But if you buy one (like the one I gave the details of) it is equipped with Galileo GNSS which gives an accuracy down to 'metres', then the searchers switch to 121.5Mhz to get to within 'feet'

 

The Galileo system has a greater accuracy than GPS, having an accuracy of less than 1 m when using broadcast ephemeris (GPS: 3 m) and a signal-in-space ranging error (SISRE) of 1.6 cm (GPS: 2.3 cm, GLONASS and BeiDou: 4–6 cm) when using real-time corrections for satellite orbits and clocks.

 

 

Leatlet details.jpg

Edited by Alan de Enfield
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2 minutes ago, Alan de Enfield said:

 

 

So have I, and similarly no eye deer on its use. However, it is a requirement of the French marine authorities (or it was) that a visiting boat should have one.

Yes, I can see how a sextant could be useful for a visting uk boat across the channel.

 

Perhaps a sex tent would be a better option afterall.

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2 hours ago, Alan de Enfield said:

We have one each which we use for Hiking, Horse riding, Boating and Diving. 

They are waterproof to 1atm (10 metres) but I keep mine in a pressure resistant carrier so it will still be OK deeper when subject to higher pressures.

 

Seems a bit cruel to the horse riding under 30 feet of water ...

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