Releasing rope wrapped around your prop

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However, if you have 2 tubes each with a one way valve at the the end furthest from you, one to allow breathing in and one to allow breathing out, you end up with a crossflow of air moving one way only i.e. fresh air down one tube, into the lungs and stale air out of the other.

[/ QUOTE ] Don't think that will work at an acceptable depth because the air is at atmospheric pressure and the water pressure on the chest/stomach will prevent lung expansion. I suffer from this more than most because I have heart and lung problems.

Long time ago, I made a simple pump powered system for diving down two or three feet and enabling me to stay down for a while. This had a small low-pressure compressor which fed air down past the mouthpiece and exhausted through a one-way valve close to the mouth. The air pressure was then the same as the water pressure at that depth and gave a continuous fresh air supply. It kind of worked, but my heart/lungs were too shot by then.

I have cleared a rope-fouled prop from under a shaft drive mobo by diving down holding my breath some 30 times and hacking it off, but I was knackered and couldn't do it now. I've also dived down to clear a snagged chain and ended up with an ischaemic attack in the brain.

As a solution for mobos, I would now go for outdrives because I can lift the props close to the surface and clear them from the stern or a dinghy.
 
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OK, you can't breathe in and out through the same tube if it's longer than about 18", 'cos you will be "rebreathing" as we in the anaesthetics business call it. However, if you have 2 tubes each with a one way valve at the the end furthest from you, one to allow breathing in and one to allow breathing out, you end up with a crossflow of air moving one way only i.e. fresh air down one tube, into the lungs and stale air out of the other

[/ QUOTE ] Slightly simpler is to breath in through your mouth, and out through your nose.

I appreciate your system was designed to work with unconcious people - which has different needs. It was also designed to work at very shllow depths.

An additional problem arises as depth increases over 1m to 2m - it becomes very difficult to expand your lungs sufficiently to breath in, since you're trying to expand against increasing water pressure, and the air, still at 1atm isn't helping!
 
Prevention better than cure?

I'm assuimng that everyone has a rope cutter fitted to their propshaft?

We've had some spectular graunching noises as we've been going along only to see shredded rope bits appearing from under the stern.....
 
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Slightly simpler is to breath in through your mouth, and out through your nose.


[/ QUOTE ] I think I would want to do that the other way around and be able to see.
 
I assumed it would be one of those masks with a built-in snorkel tube enabling breathing in the other direction. However, either way, I would get severely fogged. Maybe I'm just a heavy breather or the water is colder.

No way is the wrong way if it works and suits you.
 
Wow - great answers.
As a newbe boat owner this is all helpful. I guess that since I will be in the med, cold insn't a problem. Most of the rope entanglements are in the marina with the "lazy lines". I am not thrilled about diving in the murk of the marina as most seem to expel from heads straight out into the marina.
Interesting that no-one has tried the back pack thing - I am not sure I wish to be the first - and in any event I can't find it now on the Net.
I do have an Ambassador AM15 rope cutter on the shaft but have no idea how big a line it will cut
A knife will have to be big and sharp as the mooring lines are sometime 20+mm thick.

Thanks everyone for their input

TudorDoc
 
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I've also dived down to clear a snagged chain and ended up with an ischaemic attack in the brain.


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Wow! Had to look that one up.

I didn't say anything much about the cold because I assumed everyone knew what cold was. But seriously that's a killer too, don't forget you've got to get back into your boat, it's possible you couldn't even climb up a boarding ladder if you push it. There's few extra factors to the cold that has to be thought about.
1) Water more than a little way down can be far colder than the surface
2)There's water all over your head, you'll lose heat far quicker than if you're just swimming.
3) The pressure of "just taking a little longer" to do the job, you are after all under pressure to free your boat up, you wouldn't be in the water in the first place if it didn't matter.
4)Lack of proper equipment, dry suits and all that stuff takes a lot of room.
5)In many situations there won't be anyone who can help you.

All of these consipre to leave you hypothermic.

I'll recount a diving story:

I was (and still am) a keen yacht racer, I was an experienced diver, caver etc and well conditioned to the cold. I was taking part in the frostbite series (January) and I went down to do a scrub but realised I'd forgotton my suit. Not taken aback too much in I went with jeans and Tee shirt and did the scrub. After about 15 minutes I starten to feel really cold. By the time I'd gone for the ladder which was about 100m away I could feel myself ebbing away. I only just made it up the ladder, I would have dropped the scuba gear if I could have actually felt anything with my hands. I had to crawl along the pontoon back to my boat, fortunately someone had noticed me and helped me out. I felt sick and shaking uncontrollably and didn't warm up for hours

So take care.
 
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Sounds though its worth having a wet suit aboard.

Is it worth having a weight belt to help you stay down, or is that suicidal???

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If you wear a wetsuit it's unlikely you would get down without some weight. without scuba gear, I float at the surface nicely with a 5mm full wetsuit and 10 kilos on the belt.
 
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Sounds though its worth having a wet suit aboard.

Is it worth having a weight belt to help you stay down, or is that suicidal???

Mj

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If you are starting to play with wet suits and weight belts, some training, ether snorkeling or diving, might be appropriate.

Essentially a weight belt would only be suicidal if it is the wrong one.

You should be neutrally buoyant at the surface and then as you go down will become negatively buoyant as the wetsuit is compressed. Divers compensate for this by inflating a Buoyancy Control Device (BCD) which is ether a waistcoat afair, special life jacket or part of the backpack set being sold. Early SCUBA divers just got their buoyancy right and then finned hard for the surface.

Using a thin wetsuit with snorkel I would probably not bother with the weight belt.
 
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I've also dived down to clear a snagged chain and ended up with an ischaemic attack in the brain.

Wow! Had to look that one up.


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'Twas off the Isle of Capri that I found it.....

Fortunately transient and I can recommend the Naples hospitals. They put our NHS to shame.
 
On our first trip 10yrs ago we got our anchor snagged in Portland Harbour and had to get a diver out.

Susequently helped out another boat with snagged anchor in Alderney but it was hard work on "free" dives.

Decided its best to get training and did the PADDY course. Since had to dive about 8 times due to polythene and ropes and that is with a rope cutter.

While a rope cutter can cut the rope you are often left with a birds nest around the prop especially if it part of a fishing net.

I echo others comments dont take chance, get training and be cautious of the cold. I always use a thick wet suit!
 
got a rope snarled round the prop last week. Luckily twas in the BVIs so water nice and warm.
Took about 15-20 dives with just a mask and hacksaw to clear it.
Trouble was that there were lots of barnacles on the hull that scratched my shoulder as i was cutting away the rope.

on the last dive , had just got the last bit of rope free and looked up to see Mr shark swimming past the keel. Only 4' or so long but attracted by the blood in the water.
Didnt take me long to get out then!
 
I wouldn't even bother trying to snorkel in a wetsuit... they contain a lot of buoyancy, and as others have said above, a weight belt without training, and the appropriate ability to counter it, sounds a bit suicidal...

I personally carry a drysuit on board.... IMHO, takes up a lot less space than a wetsuit... but even then, requires careful use.... anyone who has used a drysuit will be familiar with the need to remove the air from it properly and thoroughly, especially one with built in socks... I've seen someone literally stuck in the water, as the air has rushed into the legs, and they been unable to lower them sufficiently to get the air out... and that was on the surface....
 
Very very interesting points. I'm now in the club it would seem. Happened today after a fantastic weekend sailing (gutting end to the weekend). I was almost back safe and sound too when a little moment of ridiculousness led to a mooring buoy line wrapping around my prop. I was kindly given a hand and we managed to cut the rope and moor up to the buoy safely anyway. I just have the cut mooring line wrapped around my prop now.

My thoughts/concerns; have I damaged the prop/shaft? Shall I get my speedos on and try and cut the rest of the line free (it cut fairly easy with the bread knife I used earlier to get it loose from the buoy) or fork out the money for yet another lift out (crying emoji) just to be safe? I'm edging towards trying to swim underneath at a calm, low tide, and try and cut it free?

It just doesn't look like the visibility on The Crouch is all that great.
 
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I’m so grateful to be outboard powered. I have had experience of a rope around the prop, before the 1992 RTI race, on a classic belonging to someone else. In the Medina at 1st attempt in gear on the mooring. The owner went over the side and cleared it with a knife. The drama happened on his triumphant return to the surface. He met the most unfeasibly huge Richard 3rd, floating down on the 1st of the ebb, about 2” from his nose.
 
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