Cave Line for Diver Alert Marker Deployment. Less than Ideal?

[rakpix]

i bought a new spool for my 6 foot diver alert marker. the spool came with 150 feet of #24 braided nylon line, and i am considering replacing said line with something else. when i started cave diving i purchased a couple pounds of #24 braided nylon, but i think a different line might be more appropriate for SMB deployment. my ideas being

1) braided line kinks.

unlike twisted line, braided line will kink as you wind it back onto the spool. this forces you to alternate direction as you ascend. not a huge deal, but it still takes up some mental bandwidth during the most important phase of the dive. as this line will be deployed in the water column, and only make contact with the smooth metal surfaces of the snap and double ender, i don't think the added abrasion resistance of braided line is necessary.

2) 150 feet might not be enough.

the diver alert marker has a maximum lifting force of 52 pounds. the test strength of #24 braided nylon line is upwards of 250 pounds. even when you take off 25% of that strength for the figure-of-eight knot in the end of the line, that still leaves us with a test strength of 180 pounds, way more than could ever be exerted by buoyancy. i can spool almost 500 feet of #9 braided nylon line onto the same size spool, while maintaining a test strength of 80 pounds. even when you take off 25% of that strength for the figure-of-eight knot in the end of the line, that still leaves us with a test strength of 60 pounds.

3) white may not be the most visible.

we use white line in cave diving because it 'pops' against the unlit cave background. even when lit only by the corona of a HID head, white line is easily visible. in open water, however, pale colors can easily blend into the background. in a worst case scenario: you have been blown off the wreck/reef by a ripping current, you are in mid-to-poor visibility water, you have no visual reference ... a colored line would be easier to see. elsewhere in marine systems, ResQ orange has been established as the most visible against seawater in day or night.

has anyone tried different lines for deploying a bag? what about different materials (polyester, dacron, kevlar?) what other considerations can you think of when choosing a line for open water use? discuss ...

 

[Jim Lapenta]

Braided line also does not unravel when it gets wet. It does not kink enough when rolled up to matter. And for SMB deployment why would you need more than say 75-100 feet of line? I see 500 feet forming one heck or a bird's nest. I am in the process of re spooling a couple of mine. I am taking off the 100 feet of #24 nylon and the 150 feet of number 18 and replacing both with #36 line. Don't need any more than that for wrecks and surely not for SMB deployment. Most SMB's are deployed at a max depth of 50 feet or so. I'll put 75 on just to be sure. More than that I'm using the reel.

 

[Chris Brown Tech]

Braided line also does not unravel when it gets wet. It does not kink enough when rolled up to matter. And for SMB deployment why would you need more than say 75-100 feet of line? I see 500 feet forming one heck or a bird's nest. I am in the process of re spooling a couple of mine. I am taking off the 100 feet of #24 nylon and the 150 feet of number 18 and replacing both with #36 line. Don't need any more than that for wrecks and surely not for SMB deployment. Most SMB's are deployed at a max depth of 50 feet or so. I'll put 75 on just to be sure. More than that I'm using the reel.

If you shoot a bag down here in the Gulf stream Jim, you need to pop it from the bottom otherwise you will be a mile away before you get shallow enough to shoot a spool.

Just ask one of my instructors who found this out for himself when he did a 200' dive and couldn't find the shot line in the milky viz. By the time he realized it was a no hoper, he was already a mile down stream. Boat didn't see his bag and he was 4 miles away when we picked him and his buddy up

To the OP - #24 line is fine in the tropics. All I ever use.

FWIW we use 150' for backup smb & spool deployment 100' or shallower, 400' of line for anything down to 250'. 300' and deeper is a 600' reel. Again due to current, the line often goes diagonally to the surface, sometimes even in an S shape!

 

[TSandM]

Sounds like a small reel might be better than a spool, if you're having to shoot that deep.

I have found that yellow line is fabulously visible here in Puget Sound's murky waters -- much better than white.

 

[Jim Lapenta]

If you shoot a bag down here in the Gulf stream Jim, you need to pop it from the bottom otherwise you will be a mile away before you get shallow enough to shoot a spool.

Just ask one of my instructors who found this out for himself when he did a 200' dive and couldn't find the shot line in the milky viz. By the time he realized it was a no hoper, he was already a mile down stream. Boat didn't see his bag and he was 4 miles away when we picked him and his buddy up

To the OP - #24 line is fine in the tropics. All I ever use.

FWIW we use 150' for backup smb & spool deployment 100' or shallower, 400' of line for anything down to 250'. 300' and deeper is a 600' reel. Again due to current, the line often goes diagonally to the surface, sometimes even in an S shape!

Understood. If in that situation I would see the need for such a line. Makes perfect sense. And for that length of line I would still.prefer a larger reel with enough line of number 24 or better. And if on a 200 ft dive I think I'd like the benefits a jersey up line of 400 or more feet of sissal rope would bring to the table. :=)

Sent from my DROID X2 using Tapatalk 2

 

[cbrich]

My finger spools have a Hi-Viz Orange Dycron line on them. It's smaller than #24, so I have about 150' on a spool that is suppose to accept 125'. I would stick with braided line over twisted line any day of the week, twisted line will become a mess to deal with.

The deepest I have ever needed to shoot a bag is at 100', that was for practice. I am curious why you are needing to shoot a bag any deeper than this. If you need a visual reference, then use your computer and do a free ascent until you can safely deploy your lift bag, or SMB. An ascent without a visual reference sucks, and takes a lot more practice. If you are doing a deep dive, aka 200' or deeper, your later stops are going to be longer, and that is when a visual reference helps a lot.

 

[rakpix]

I am not considering a reel at this time. The solution needs to be small enough to fit in my pocket. I think the best solution would be something that preserves the advantages of a spool with the capacity of a small reel. I believe this is most simply accomplished by replacing the line, and would be safe because the forces involved in open water SMB deployment are much smaller than those exerted following a line during a no-viz exit from a cave.

The deepest I have ever needed to shoot a bag is at 100', that was for practice. I am curious why you are needing to shoot a bag any deeper than this. If you need a visual reference, then use your computer and do a free ascent until you can safely deploy your lift bag, or SMB. An ascent without a visual reference sucks, and takes a lot more practice. If you are doing a deep dive, aka 200' or deeper, your later stops are going to be longer, and that is when a visual reference helps a lot.

Chris basically outlined my concern. I am not imagining the need for 400 - 500 feet of line during the ascent phase of a dive where everything is going according to plan. If everything is going according to plan, I would never shoot my bag until the first deco stop, because I don't want to put more time on the deco clock by spending another 2 - 3 minutes near the bottom. I am imagining a scenario where, during the bottom phase of an open water dive, I am blown off the wreck/reef by a strong current and need to let surface support know where I am ascending. In that case, I would shoot a bag from my bottom depth, which could be 200 - 300 feet. Furthermore, there could be different currents at different depths, in which case a longer line would accomodate the current.

Again due to current, the line often goes diagonally to the surface, sometimes even in an S shape!

Actually, that raises a concern about the test strength of the line. Even if the bag itself has only 52 pounds of possible buoyancy, there could be more than 52 pounds of force communicated down the line in a heavy current. Is it conceivable that the current could drag the marker with enough force to break an 80 - 120 pound line?

FWIW we use 150' for backup smb & spool deployment 100' or shallower, 400' of line for anything down to 250'. 300' and deeper is a 600' reel.

This sounds like a good plan, and I am sure #24 braided nylon works well. However, as an example, if you could fit 400 feet of line on the same 150' spool you take on shallower dives, would that not be more ideal? Of course, this is only workable if the line is strong enough to withstand the forces of buoyancy + drag.

I have found that yellow line is fabulously visible here in Puget Sound's murky waters -- much better than white.

Where did you buy your yellow line? I have been looking at Dacron line as a possibility. However, all the information I can find on Dacron relates to fishing line, which is usually 20 - 30 pounds test. And the Dacron line sold through Dive Gear Express is not much smaller than #24 braided nylon. Edge Gear sells HOG spools with bright orange nylon line, however the line is still #24 cave line and provides none of the other advantages I am looking for.

 

[Tug]

Where did you buy your yellow line? I have been looking at Dacron line as a possibility. However, all the information I can find on Dacron relates to fishing line, which is usually 20 - 30 pounds test. And the Dacron line sold through Dive Gear Express is not much smaller than #24 braided nylon. Edge Gear sells HOG spools with bright orange nylon line, however the line is still #24 cave line and provides none of the other advantages I am looking for.

I've recently started respooling my spools with this stuff from NESS. They stock #18, #24 and #36 in a bunch of colors.

#24 Extreme Duty Dive Reel Line - Northeast Scuba Supply

 

[cbrich]

Where did you buy your yellow line? I have been looking at Dacron line as a possibility. However, all the information I can find on Dacron relates to fishing line, which is usually 20 - 30 pounds test. And the Dacron line sold through Dive Gear Express is not much smaller than #24 braided nylon. Edge Gear sells HOG spools with bright orange nylon line, however the line is still #24 cave line and provides none of the other advantages I am looking for.

Dacron is a good alternative to Nylon, slightly smaller, with the same breaking strength. Also most of the specialty lines are going to be used for fishing. Which sport is larger, Scuba or Fishing? I think that is pretty obvious which is the larger sport, so the manufacturers are going to focus on that sport.

If you want a smaller diameter line, you should look into Spectra. I have seen Hi-Viz Yellow Spectra line in 200lb test. Diameter is equivalent to 50lb mono line, 0.030".

Specs

 

[DA Aquamaster]

My finger spools have a Hi-Viz Orange Dycron line on them. It's smaller than #24, so I have about 150' on a spool that is suppose to accept 125'. I would stick with braided line over twisted line any day of the week, twisted line will become a mess to deal with.

The deepest I have ever needed to shoot a bag is at 100', that was for practice. I am curious why you are needing to shoot a bag any deeper than this. If you need a visual reference, then use your computer and do a free ascent until you can safely deploy your lift bag, or SMB. An ascent without a visual reference sucks, and takes a lot more practice. If you are doing a deep dive, aka 200' or deeper, your later stops are going to be longer, and that is when a visual reference helps a lot.

It's been addressed above - twice - but I'll give a real life example.

Coming off a wreck at 210', with a strong current (off South Florida in the gulf stream) we shot the bags from 200' before we drifted off the numbers. That's important as the bags on the surface allow the boat to locate us before we start drifting down current during the 45 minutes of decompression. If you don't shoot a bag near the boat, which is holding near the numbers for the wreck, then you are drifting down current and when you eventually shoot the bag it may be too far from the wreck to be easily seen, especially if you are now down current from the boat and the boat crew is looking up current where the wreck is at, waiting to see your bag pop up.

On one particular day we had a 3-4 kt current at depth and then a 2 kt current above about 70' that was running at a 90 degree angle to the bottom current. That did interesting things to the line and given he strength and mid water change in direction, it probably used 300' of line for a 200' shot, and I was happy to be using a 400' reel.

Even then, 400' might not be enough. For example, if I am diving up north on a 200' wreck where the visibility, seas conditions and shipping traffic could cause the boat to have to leave the wreck and/or cause the upline to fail, I might have to establish an upline from the wreck to ensure I can stay on the numbers to do my ascent and decompression. That's important as the numbers for the wreck are the first place the boat will look when it returns. High seas, fog, etc can make finding a diver doing drifting deco extremely difficult, especially when the boat won't even come looking until the other divers doing their deco on the wreck are recovered. When you add the 60-90 minute delay to the whirls, eddies and possible visibility challenges in Labrador current diving, the odds of being found quickly are not exactly stellar, and if the water is cold, you could be in pretty significant peril of severe hypothermia or death before you are found.

The Jersey reel is a little dated but still works, although many divers use 1/8" nylon line rather than 1/4" sisal since it will rot on the reel very quickly if it is not removed and dried after every diving day. Consistent with that, there are some better options available that allow enough 1/8" nylon line to be carried, but on a more compact butt mounted reel.

But failing that, I'd still like to have the option of shooting the bag and tying off to the wreck and I'd regard #24 as the minimum line weight. You've cited a 250 pound breaking strength, but 230 is a more common figure and I've seen #24 rated as low as 170 pounds. Worse that will be reduced by age and by knots in the line. So with a 100 pound SMB in a strong current and a diver or two hanging off that like a kite, #24 may not be adequate. #36 gives you another 100 or so pounds of tensile strength and is not a bad idea, but going lighter than #24 is a sure fire way to find your self on the wrong end of a broken line. The handling qualities also start to suffer with smaller diameter line and you really do not want to have an entanglement issue as you bag is launched.

I also carry a loop of tubular webbing in a pocket. If I have to shoot an upline and tie into the wreck, a small diameter nylon line is at high risk of being severely weakened or cut by abrasion. So for an emergency upline I'll tie the loop of webbing to a suitable spot on the wreck and attach the line to the webbing. It's cheap insurance.