Jon lines

[Braunbehrens]

I've been asked to make a post explaining why jon lines are bad, but I'm hesitant to do so because of the earlier unpleasantness.

Still, to answer a few specific point O-ring made in his last post, or maybe more accurately, expand on them.

Cold water is one more reason not to use a jon line. It is colder to flap in the breeze than to drift in the current.

Bad visibility is another reason not to use a jon line. As soon as one person let's go he's out of sight and unlikely to find his way back.

As for jon lines being used as a crutch instead of poor buoyancy control or worse having a balanced rig, yes, that is a major reason, but not the half of it. What's far worse is that even with good buoyancy skills the diver is usually not neutral at the jon line and should he get blown off will be up the creek as well.

The argument that "it's done a certain way around here" is TO ME not valid. I will do the dive if I deem it safe enough. If it isn't, I simply won't dive. I don't really care that the locals do something I feel is unsafe.

I think jon lines add a lot of risk. IMO an unacceptable amount. However, everyone is free to take on as much risk as they want, of course.

There are really 3 scenarios. One a jon line is not needed at all, because there is no current. Two, there is current but the dive can be done doing drift deco. Three, drift deco is not possible.

I am saying that in 1 and 2 drift deco is safer, and 3 means that I'll be seeing the sights above water.

I'll probably get crucified again for this....go ahead.

 

[O-ring]

Braunbehrens once bubbled...
I've been asked to make a post explaining why jon lines are bad, but I'm hesitant to do so because of the earlier unpleasantness.

Still, to answer a few specific point O-ring made in his last post, or maybe more accurately, expand on them.

Cold water is one more reason not to use a jon line. It is colder to flap in the breeze than to drift in the current.

Bad visibility is another reason not to use a jon line. As soon as one person let's go he's out of sight and unlikely to find his way back.

As for jon lines being used as a crutch instead of poor buoyancy control or worse having a balanced rig, yes, that is a major reason, but not the half of it. What's far worse is that even with good buoyancy skills the diver is usually not neutral at the jon line and should he get blown off will be up the creek as well.

The argument that "it's done a certain way around here" is TO ME not valid. I will do the dive if I deem it safe enough. If it isn't, I simply won't dive. I don't really care that the locals do something I feel is unsafe.

I think jon lines add a lot of risk. IMO an unacceptable amount. However, everyone is free to take on as much risk as they want, of course.

There are really 3 scenarios. One a jon line is not needed at all, because there is no current. Two, there is current but the dive can be done doing drift deco. Three, drift deco is not possible.

I am saying that in 1 and 2 drift deco is safer, and 3 means that I'll be seeing the sights above water.

I'll probably get crucified again for this....go ahead.

I just think that "they do it around here" is more valid for certain people. Where do you do most of your diving? The only reason I ask is that if you were to get on a boat up here and say, "Hey, Cap'n, I am going to intentionally NOT come up the anchor line, but am instead going to make a free ascent to 70' and shoot a bag. Then, I want you to track me and send a chase boat so that I can be picked up after my deco. Ok?", you would not be diving.

I understand the arguments about chartering our own boats and doing it our way, but it is VERY hard to pull that off due to scheduling (instead of 1-2 members of the team needing to be available on a given weekend to dive with me, now I have to find enough to fill the boat) and weather (little teeny boats can't go out up here very often...the seas can get pretty snotty) coupled with distance (all our decent wrecks are at least 2 hours offshore - hard in a little boat). Believe me, we have talked about it...to the point that we actually sat down and talked about everyone chipping in and buying our own Zodiac...

 

[GearHead]

Braunbehrens once bubbled...
There are really 3 scenarios. One a jon line is not needed at all, because there is no current. Two, there is current but the dive can be done doing drift deco. Three, drift deco is not possible.

I am saying that in 1 and 2 drift deco is safer, and 3 means that I'll be seeing the sights above water.

I'll probably get crucified again for this....go ahead.

Do you really see those as the only three scenarios out there?

Let me throw a hypothetical situation your way:
(I hope you don't consider this crucifixion)
You're planning a trip to dive a wreck, a spectacular wreck, and the boat ride out there is long and hard. When you get to the site, the wreck is hooked and a strong, constant current is observed. There is no chase boat, and drift deco is not an option.

Are you saying that you would not take a trip like this because of the possibility of strong current?

Or would you take the trip with the hope that the current won't be strong and you can do a normal hang, but because of the current, you sit on your hands and count seagulls?

Or, would you use a Jon-line?

I'm curious to hear what you think.

 

[O-ring]

Is the GUE Brittanic expedition. They were in ripping currents in shipping lanes in the Kea Channel. They used jon lines to conduct the dive due to the conditions and the danger of being blown off and drifting in shipping lanes.

They decided the dive was worth the risk...likewise, I decide some dives are worth the risk too.

 

[Pez de Diablo]

Braunbehrens once bubbled...
<snip>
Cold water is one more reason not to use a jon line. It is colder to flap in the breeze than to drift in the current.<snip>

I am not trying to be unpleasant, I have taken my civil *discussion* to PM's so as not to look like I am crucifying you for you opinion.

I bring this up in the thread as it could sway my and others decision to use a Jon line.

In my opinion this is not true, do you have any backup data to substantiate this claim that it is warmer to drift in a current than remain on an up line?

 

[Braunbehrens]

pez, when you are drifting less water passes over your suit and you cool off less. When you are hanging in a current more water passes over the suit.

Same as windchill.

The other problem is that if you have a suit problem the current will probably fill your suit with water and continue cooling you much more than if you were drifting.

O-ring. Yes, I agree with you. If the dive is worth the risk to you, then you do it.

As for me, Gearhead, I would sit on the boat. It's not worth it to me. If the current is ripping and you get blown off....it's just too dangerous IMO.

If I really wanted to do it I might take a waterproof GPS, a waterproof VHS and an EPIRB, stuff them in a watertight tube and carry them as a stage....but more than likely I just wouldn't plan the trip in the first place.

I completely understand the problems of boat operators wanting to do things their way. It is certainly a difficult situation which I am glad not to have to deal with.

 

[O-ring]

...and take the jonline out of the picture. Let's say you weren't sure if there was going to be current, but you were pretty sure there wasn't much. Would you go in with the restriction that you are supposed to come up the anchor line instead of drift decoing? Maybe you would just hang onto the bar.

What about in a recreational setting...like in North Carolina. You are doing a 65' wreck, no deco, and you are supposed to come up and down the line - doing your safety stop on the line.

Still too risky? Are you objecting to the jonline specifically or just the "no drift deco" thing?

 

[Pez de Diablo]

Braunbehrens once bubbled...
pez, when you are drifting less water passes over your suit and you cool off less. When you are hanging in a current more water passes over the suit.

Same as windchill.
<snip>

OMG I don't buy it. Not at all. The water rushing over my suit would cool me off more than drifting in the same water? You substantiate this claim by saying it the same as wind chill. Great response.

We'll agree to disagree.

Braunbehrens once bubbled...
<snip>
If I really wanted to do it I might take a waterproof GPS, a waterproof VHS and an EPIRB, stuff them in a watertight tube and carry them as a stage....but more than likely I just wouldn't plan the trip in the first place.<snip>

LOL

Where is that jug of coolaid?

While you are waiting on the boat for the rest of us, I'd like you to keep the coffee hot and fresh and if you don't mind, whip up some sandwiches and soup for us. We'll tell you all about our great dive while we eat.

 

[bridgediver]

Pez de Diablo once bubbled...


OMG I don't buy it. Not at all. The water rushing over my suit would cool me off more than drifting in the same water?

Actually pez, the water rushing over you will produce friction between the water molecules and the suit thereby creating heat so you will actually get warmer from using a jonline.



seriously though... windchill does NOT work the way described by Braun. The air and undergarments in the suit are designed to insulate the diver and keep in warmth. The dry suit can be thought of as a wind breaker (or water barrier). As long as the wind (or water) is kept away from the insulation it doesn't matter how much wind (or water) passes over said diver.
The only factor being relative temperature; for that more or less insulation may be required. The wind (or current) doesn't make the temperature colder.

Now... if you were in a strong current on a jonline naked....
bbbrrrrrrrrrrrrrr!!!


my 2 cents (canadian$)

 

[filtered]

Can someone explain how to use the spool as a jon line?