Would you dive to clear the prop?

[LadyInBed]

Freeing the prop of net is a totally different proposition to freeing rope, net is IMO much more difficult and not attempted lightly.

Using an extended snorkel isn't to get more depth but to allow you to use what depth you can achieve without sucking water!
As I said previously, you HAVE to exhale through your nose for all the reasons previously stated.

 

[Danny Jo]

I've done it when we fouled a lobster pot line on the East Coast of Scotland (a bit south of Stonehaven, I think). No option; the line was anchoring us! Held my breath and went down with a sharp knife (on a lanyard; that bit is important!). The cold was the main challenge; . . .

I tried it in Greencastle harbour on Lough Foyle, wearing just a swimming costume and a mask. We had been towed in by the owner of the salmon net we had wrapped round the prop. I hadn't been running the engine, so it was easy enough to clear in three dives without a knife. As a kid I used to be able to manage two lengths of a 25 yard pool underwater, but I found swimming under Danny Jo's modest girth pretty scary.

When I tried to repeat the exercise under another boat which had been towed in just after us I became too cold to be effective - and that was in July. The net was well wrapped so I asked for a sharp knife on a lanyard. NEVER AGAIN! The knife, lanyard and net got tangled, still attached to the prop, with me attached to it, and for a brief moment I thought I was done for.

There was another learning point for me. The boat I tried to help was a fairly new Swedish one with a rope cutter. It transpired that the force transferred from the propshaft via the net and rope cutter to the cutlass bearing mount stripped the thread holding the mount into the hull - so the poor people needed not just a diver but a crane, boatbuilder and (I guess) holiday accommodation.

 

[lw395]

When clearing a prop, how much weight is needed to counteract buoyancy enough to make it easier, but not enough to sink. I was thinking of a short length of chain, maybe a dozen links. It would be cheap enough to be jettisoned if in difficulties. So how much weight please. I can calculate the number of links from what is available. Come to think of it all the chain on board is 8mm.

Personally, when working on the hull with scuba gear, I have found it ok to be very buoyant.
Your buoyancy holds you against the bottom of the hull, so you can work on it.
If you are neutrally buoyant and start using scrapers, saws to cut rope etc, the tool stays still and you move back and forth.
I normally pass a rope under the hull to hold on to.
I've never tried breathing through a hose, but I think it might be plausible with a shallow hull, where your lungs need only be 18 inches or so under water.
Breathing out through your nose and in through your mouth(with a dive mask on) is easily mastered, any scuba diver with facial hair does a fair bit of it I think.

 

[duncan99210]

Whilst SWMBO nor myself have had to use our dive gear to clear Rampage's prop, I have dived on other boats to sort out entanglements. If you get your bouyancy right by using your BCD, then there is no problem with the movement of the boat/prop, as you move up and down with the boat. If you try and hold yourself still in the water, that's when the hull will descend and clonk you one. If at sea, then you obviously need to be tied on to a line and if an engine key is present, take it with you.

On the topic of using a hose/tube as a snorkel to dive much more than a foot or so, the real problem is that your lungs may be ruptured by the pressure differential. Yes, I know that if you go down 10m it's only 1 bar more than on the surface but your lungs are set up to deal only with breathing with no pressure gradient. Trying to work against a gradient of even fractional parts of a bar means a much increased breathing effort and the potential of damaging the lining of the lungs.

 

[Cardo]

I've not had to do it yet, but I'd imagine it'll happen at least once once we're in the Med.
However, Tinkerbell only has a 0.7m draft with the prop protected within a skeg shallower than that. I figure I can probably manage the 0.5m worth of depth right at the stern...

 

[westernman]

I've not had to do it yet, but I'd imagine it'll happen at least once once we're in the Med.
However, Tinkerbell only has a 0.7m draft with the prop protected within a skeg shallower than that. I figure I can probably manage the 0.5m worth of depth right at the stern...

Is hasn't happened to us in the Med - despite motoring over the top of some lobster cages etc. Bu tthen we have a very deep keel in front of the prop which does a pretty good job of keeping ropes away from the prop.

If it does happen, then I will be attempting to clear if from the tender with a sharp knife tied to the end of the boat hook (which is a good 2.5m long). No diving for me.

 

[TQA]

Is hasn't happened to us in the Med - despite motoring over the top of some lobster cages etc. Bu tthen we have a very deep keel in front of the prop which does a pretty good job of keeping ropes away from the prop.

If it does happen, then I will be attempting to clear if from the tender with a sharp knife tied to the end of the boat hook (which is a good 2.5m long). No diving for me.

Knife on a pole yes but trying to do it from the tender is hard. Use snorkel gear and do it from the surface [ no diving ! ] you can see what you are doing.

 

[SamanthaTabs]

Got our scuba gear onboard, the Boss is instructor level (I've passed a couple of courses but not got much experience) so he's "it"! So far chopping something off the props has been possible at anchor or in a marina. Being only 2 up I wouldn't feel happy with him diving adrift so to speak, despite knowing how to handle the boat it's not a situation that would flood me with confidence.

 

[lw395]

Swimming goggles would be better than a mask to facilitate this, but you can still exhale through the nose while wearing a mask - just more slowly and it is more liable to fog up.

Di

I vaguely disagree.
If you have a mask on, it kind of works as a one way valve and stops you breathing in water through your nose.
Sort of!

Sax players can often 'circular breathe' very effectively, though they tend to exhale via their mouths for obvious reasons.
Some can keep a note for a long time.
Free divers are weird, they push their bodies a long way in a direction mine is not suited to going.
Training and practice....
And fitness!

 

[WestWittering]

I used to exhale through my mask to photograph fish (when diving open circuit) - the bubbles disperse without the rush of exhaling through a reg. Later, as a rebreather diver, I would use the same method if I wanted to dump the loop for either a quick dil flush or to bump my PP02 while adding O2.

A mask is not there to protect your nose from water - it is there to enable you to see under-water. Thats all.

Di