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Old 02 July 2009, 03:19   #1
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Grr tubes + temperatures

Hi Guys,

I've had a quick read of a few things on here but it always seems to point to a leak!

Yesterday we took the old humber out diving for the first time.
Before going out the tubes were nice and solid, they dropped a tiny bit when she was on the water, but when we came up after diving (20 mins) I would say they were 1/3-1/2 flat.....
Once home again on the trailer after 10 mins they were hard again.

Now this is all tubes so it is obviously a temperature issue... my question is- am I not blowing them up enough to start with? Its a 1984 and doesn't appear to have pressure release valves so I don't want to blow my tubes up when it gets really hot!
But at the same time is was a little hairy yesterday with 1/2 inflated tubes!
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Old 02 July 2009, 04:20   #2
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Going soft is a common problem for me. Yesterday midday - mine were very hard - by 8pm & after a 10 mile run with breeze & spray youd think they were punctured, but its all down to the temp ! The only thing you can do is infate them on the water as needed. I'd be surprised if it ever gets hot enough to burst them in the UK ( apart from maybe 1 day a year) . I've never seen it & never heard of it happening to anyone.

I'd blow them up hard after 10 minutes afloat to get them ' right'. It may not help if you have wet divers / gear on the tubes as this will cool them alot compared a dry tube in the sun. As you will know water takes the heat away alot faster than the air - is it 50x ?
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Old 02 July 2009, 04:26   #3
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I think the best you can do it to have them at a minimum useable pressure when cold, hopefully one of the tube guys will be along to confirm that this should not cause an over-pressure situation when hot.
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Old 02 July 2009, 04:53   #4
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remember when i had my first boat (black tubes) scared the bejesus out of me first time when i was going down southampton water and looked at the tubes as they were almost flat!!

they had pressure release valves which made it worse cos as they expanded they let air out to keep pressure but of course when they cooled down, there was almost nothing left!!!

Strangly the next two boats didnt have any problem at all, even in the really hot weather!!
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Old 02 July 2009, 05:07   #5
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Quote:
Originally Posted by Blackroady View Post
As you will know water takes the heat away alot faster than the air - is it 50x ?
I am no expert but I think it is 25x
I think it is the same for sound as well?

Lee
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Old 02 July 2009, 05:16   #6
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had a new black tubed rib outside on monday tubes blown up hard when inside temp 21approx took temp of tube outside too hot to touch 61 degrees .tubes are fine didnt even blow off pressure relief valves
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Old 02 July 2009, 05:40   #7
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I am no expert but I think it is 25x
I think it is the same for sound as well?

Lee
Your heat factor is correct: the thermal conductivity of water is 0.6 and air is 0.025 which is actually 24x.

The speed of sound through salt water is only 4x faster than air (at 1,560 m/s as opposed to 343 m/s).
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Old 02 July 2009, 06:06   #8
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I knew it was alot ! my guess was based on a conversation years ago when I considered getting in to diving on a more than ' i'm on holiday in a nice place' type of way. As you can tell I didn't take it far.

Hopefully it gives a good indication of how much water will cool you / the tubes compared to being in the sun / air. As Paul said tubes can be too hot to touch & are fine - a quick rain shower / bit of spray and they very soon cool of.

I'd guess if running with big divers etc then more of them will contact the water, more cooling, more divers - more water running over top of tubes , more cooling , etc etc .
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Old 02 July 2009, 06:45   #9
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thats why lifeboats are pumped up solid in the boat house ,though i suppose if you inflate a boat at a high altitude there should be more volume in it at sea level , i wondered why some of the diving clubs that come from higher altitudes have no bother ,Bradford b.s.a.c . club house is about 2000 ft above sea level ,
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Old 02 July 2009, 07:03   #10
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though i suppose if you inflate a boat at a high altitude there should be more volume in it at sea level , i wondered why some of the diving clubs that come from higher altitudes have no bother ,Bradford b.s.a.c . club house is about 2000 ft above sea level ,
I think you'll find it is the reverse.

Curious about the Club House, the town is at less than 500ft, is it well up the Pennines then?
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