Clearing a rope around the prop.

[longjohnsilver]

Has anyone used a re breather? basically used in the offshore industry on helicopters.
in the event of a chopper ditching - sinking/capsizing between our lifejacket was a ebs and you put in the mouth piece and nose clips took a deep breath flicked the valve a blew into a bag basically. - as we only used 20% ish of the oxygen we breath this system allows you to stay under water for quite sometime allowing you to escape through a window.

jon

It's a very specialized piece of kit only to be used after proper training. And it's very expensive. I can't imagine anyone using it to clear a prop or clean a hull.

 

[jon and michie]

Training is a must but if you know how to use a snorkel it is the same - I have had to do this training every 4 years - I wouldn't recommend cleaning a hull for a long period of time but to clear a prop I would say it would be fine - the kit has now be replaced now with a compressed air system so the old one should be slightly cheaper.
that said you could just use a snorkel with a long piece of tube attached cheaper still

Just a thought though
Jon

 

[longjohnsilver]

you could just use a snorkel with a long piece of tube attached cheaper still



Just a thought though
Jon

Don't think you can. Have you tried it? Pressures are against you as well as constantly inhaling foul air.

 

[Shuggy]

I've cut ropes off someone else's prop on a mooring at their request using a snorkel and a bread knife. The ungrateful sod never even thanked me! So if you're the owner of a Moody called [xxx] you owe me a beer...

 

[jon and michie]

Don't think you can. Have you tried it? Pressures are against you as well as constantly inhaling foul air.

ok lets agree to disagree

simple answer if in doubt get Shuggy to do it

 

[Montemar]

If you inhaled through the tube and exhaled through your nose then would that not solve the foul air problem? Should be OK until confusion sets in.
What is the pressure problem?

 

[DougH]

If you inhaled through the tube and exhaled through your nose then would that not solve the foul air problem? Should be OK until confusion sets in.
What is the pressure problem?

Attach two snorkels together then go into a swimming pool in the shallow end and lay on the bottom and attempt to breath through the extended snorkels.

You will find it more difficult to breathe even at such a shallow depth.

Due to the fact that the water pressure increases with depth and puts increasing pressure on your chest/lungs you would not be able to work and breathe under a boat.

Remember you are in a higher pressure than you would be at the surface but you are breathing air at surface pressure.

 

[jon and michie]

right maybe this will help with what I was trying to explain - https://www.youtube.com/watch?v=FPL7hXp6B1Q
At the 36/37 seconds in to the video you will see the guy swimming underwater with the ebs on - this is quite comfortable to do - better with a pair of goggles so you can see better
jon

 

[SandgroperWA]

Use a serrated edge knife rather than a sharp knife. A hacksaw works well.

 

[Cheery]

If you inhaled through the tube and exhaled through your nose then would that not solve the foul air problem? Should be OK until confusion sets in.
What is the pressure problem?

I have a mask with a valve in it which means I can breathe out through my nose. However if someone had an ordinary mask, depending on the depth and pressure, the length of tube would need to be less voluminous than the breathers lungs. If that makes sense?

 

[longjohnsilver]

right maybe this will help with what I was trying to explain - https://www.youtube.com/watch?v=FPL7hXp6B1Q
At the 36/37 seconds in to the video you will see the guy swimming underwater with the ebs on - this is quite comfortable to do - better with a pair of goggles so you can see better
jon

So you're not talking about a rebreather, rather a life jacket, or in diving terms, a ABLJ. Maybe ok for a few seconds, possibly a minute, but little or no warning before you black out underwater. At least then you won't have to worry about ever cleaning the hull again.:ambivalence:

Maybe when you're next in the swimming pool give your extended snorkel plan a go, and then report back here as to how it went. Then see if you disagree.

 

[jon and michie]

So you're not talking about a rebreather, rather a life jacket, or in diving terms, a ABLJ. Maybe ok for a few seconds, possibly a minute, but little or no warning before you black out underwater. At least then you won't have to worry about ever cleaning the hull again.:ambivalence:

Maybe when you're next in the swimming pool give your extended snorkel plan a go, and then report back here as to how it went. Then see if you disagree.

The life jacket has a re- breather attached in the middle - it acts like a 3rd lung

http://survitecgroup.com/products/shark-lap-jacket

Jon

 

[longjohnsilver]

The life jacket has a re- breather attached in the middle - it acts like a 3rd lung

http://survitecgroup.com/products/shark-lap-jacket

Jon

It's not a re-breather. It's a bag of air. Short term emergency use only. Are you a troll? If anyone takes your views seriously they will almost certainly end up dead.

 

[jon and michie]

It's not a re-breather. It's a bag of air. Short term emergency use only. Are you a troll? If anyone takes your views seriously they will almost certainly end up dead.

First of all I am not a TROLL.

The kit I have been trying to explain is a lifesaving piece of equipment that I have used many times.

If you have read what I first posted it was a mere suggestion.

You can't stay underwater with this kit for hours upon end but minutes you can as I said earlier the human body uses 20% +/- oxygen the rest is then expelled that is why the re breather that I am explaining acts like a third lung or Bag as you suggest.

So after spending a few minutes underwater come back up for fresh air and a break.

Like I have said earlier I have used this kit many times.

If you don't understand what I am trying to explain - Ask - never assume - because no one on this planet knows everything.

Jon

 

[longjohnsilver]

Ok I understand where you're coming from and apologies for the troll remark.

 

[jon and michie]

Ok I understand where you're coming from and apologies for the troll remark.

Apology accepted.

with this kit you could go a few metres quite easily the mouth piece tube is of a corrugated rubber this stops the pipe from any crushing of water pressure however there is slight pressure on the 3rd lung or "Bag" but you do get used to it.
I would in my opinion have someone on deck timing you on intervals and a line to communicate through.

the only time I would suggest to use diving equipment is if the props are way down under but as this is a motorboat forum so as a guess the props aren't going to be more than 2 metres ???

jon

 

[duncan99210]

The kit shown in the video is not in any shape or form a rebreather as known in the diving fraternity. It's an escape apparatus only, designed to give a helicopter passenger a minute or two under water. I'd be very wary of using it to try and clear a rope wrapped prop as O2 levels will deplete rapidly but the user would not be aware of this depletion: the likely first sign of too little O2/too much CO2 is blackout.
Snorkels won't work much more then half a metre of so under water as the pressure differential between the surface and your lungs is such that the lungs can't generate enough suction to pull the air down against the pressure of the surrounding water. Trying too hard to suck air from the surface at any depth risk rupturing the lungs, not a good thing. Hookah rigs are available, which use a small, low pressure compressor to deliver air to a diver via low pressure hoses and a demand valve and they are a good option if you have the space to carry them.

 

[Portofino]

Adding to ducan99210's
That piece of kit would be useless or near useless for any extended time to clear a prop .
It's "rebreather " function of the "bag" - (1* ) is kinda usefull in cold immersion -bear with me ---the shock of which causes the person to hyperventilate -taking short ,fast , shallow ,breaths .-leads to hypoxia ie lower O 2 concentration in the blood .
The brain sensors are biased to CO2 levels -it's this that's the driver if you like in the brain controlling breathing .
So to increase the CO2 levels ( in order to tell brain to inc breathing-a good thing here ) -a rebreathing bag is used -sure you rebreathing allready expelled air and at each go increasing the CO2 in the blood --,so brain can pickup this level and settle the breathing down to longer -deeper more meaning full breaths -that also pull in /exchange a better O2 transfer
Keeping you from unconsciousness for long enought to figure out an escape .---Er in theory ?
{1*-assumes "bag " has no CO 2 scrubber .}.

Snorkel -extension
As assuming you are not shock hyperventilating ie warm Med sea in summer 25 oC -then this happens as Duncan says even @ 1/2 never mind 1-2 M the pressure on your lungs compresses them so 02 transfer is significantly reduced and as said you just have not got the puff - power to exchange the gas ,even with a bigger bore pipe and so on fitted over each other while wife holds 3 M or whatever on the bathing platform .
C02 levels rise so brain thinks tell lungs to speed up - but surface area is decrease ( due to depth pressure )
Lungs cannot exchange -02 plummets - brain cannot function person -blacks out -
Not a nice place to be unconscious underwater with brain starved of 02 .
Either hold your breath and dive in (2*) Or
Get a pressurised supply of air from a proper bottle diving kit -+ regulator or as Duncan says Hookah ring .

[ 2* - holding your breath -what happens here is this --- as you metabolise 02 and make CO2 -remember its CO2 levels that rise and brain is measuring this - so eventually it tells lungs to go -ie you feel them bursting and can tell when it's ready to surface and take another breath ] so the cycle repeats itself -you stay alive and keep doing that untill exhausted or hypothermic in cold climates -but you should not pass out

Hope this all makes sence folks

 

[jon and michie]

As I said earlier.
1 it was a mere suggestion
2 in the later of my posts - it cant be used for a long period of time
3 suggest someone to keep a time you
4 not for massive depths
jon

 

[westernman]

Is there a good reason that propeller hatches are not more common? Then any rope or net wrap can be hacked at from safety in side the boat.

Something like this?

View attachment 56859

I understand that they are common on canal boats.

From various contributions, getting a rope or net wrapped around a prop seems to happen often enough. Diving to clear it is certainly not fun and is potentially dangerous.

So why don't all motor boats have a prop hatch like the above????