Strobe dropping?

[USMC CPL.]

Oh that's because you got the leatherneck map. All us squids ran a pool on how long it would take you to pee over the side because none of the heads were on your map.

LMAO. Nice one.

 

[geoff w]

So what I am understanding from this conversation is that commercial divers had other means to their disposal such as blowing or cutting their way into the wreck. This meant that line work (which is imported from cave diving practices) was not really as useful for their purpose. When recreational wreck penetrations began, recreational divers did not have the cutting tools or explosives at their disposal.They were forced to replicate cave diving techniques into the wreck. This may not make sense to hard core commercial divers but my question to commercial divers is if you guys did not have explosives or other hole making things at your disposal, then would you still regard the use of lines as unreliable? If yes, what option would prefer.

To those who have taken Chattertons wreck course, he talks about using multiple methods on a single dive. These would be:

Wreck line
Strobes
Progressive Penetration

What else?

Thanks for everyone's input. This has been one of the most enlightening threads to me.

We didn't talk about progressive penetration in the class. The TDI advanced wreck student manual mocks it as being unrealistic. The six key navigation methods were:

- Strobes

- Identification from research / experience as to the layout of the ship

- Magnetic compass bearings from knowing orientation during exterior survey prior to penetration

- Penetration lines

- Natural lines of the wreck - decks, passages, hallways, stairwells, depending on the type of ship, how it settled

- Exact depth - knowing your depth at various waypoints as you go in should help you get out the same way

Of course, in a total silt out or with the blackout mask on, touch navigation is essential, in conjunction with some of the 6 methods

John's advanced wreck class was outstanding, but like any certification class, it's really just an introduction to the basic techniques, skills and tactics for getting in and out of a wreck and safely back to the surface, with true proficiency left to the student to fully develop after the class

 

[Akimbo]

it isn't dental floss, it is actually fairly strong..

It's all relative. How strong is it with 3/8" deep gash?

1/2" double-braid is about 7,600 Lbs breaking... before the wreck starts eating it for lunch.

 

[PfcAJ]

It's all relative. How strong is it with 3/8" deep gash?

1/2" double-braid is about 7,600 Lbs breaking... before the wreck starts cutting it eating it for lunch.

Yanno it's possible to lay line so it's not rubbing on stuff...

 

[DevonDiver]

We just follow our umbilical out....

That experience leads me to use line on Scuba that is much closer to what a mountain climber uses than to fly a kite.

But it fails regularly?

Yet, in contrast, specific 'recreational' line laying approaches very rarely fail. Even with much, much thinner lines.

Doesn't that indicate an inappropriate solution?

 

[Tassi Devil Diver]

Whilst I have not completed a wreck penetration course (I do plan on doing one some day) the wreck penetrations I have done are mostly through trips, and generally don't enter anywhere tight or looks like it might silt up. So if laying line on through trip, do you just cut the line off on the other side an leave it there?

 

[kensuf]

That's odd. Why?

I've never seen a broken line whilst wreck diving... and that's a lot of aggressive wreck penetrations over the years.

The line has to be laid artfully and never used as a supplement for propulsion or buoyancy, of course.

What differs in your approach that leads to so many failed lines?

I'm trying to figure out the "exceeding loads" comment myself. The manufacturer rating for #24 braided nylon is over 250 pounds and #36 is over 330 pounds. What kind of forces are people putting on their guidelines???

 

[DevonDiver]

... So if laying line on through trip, do you just cut the line off on the other side an leave it there?

The most common type of wreck penetration is a 'reciprocal' - an 'in-and-out' along the same path. On reciprocol penetrations it's usual to lay and retrieve the guideline as you go.

On 'traverse' penetrations; where you exit from a different part of the wreck that you entered, it's necessary to leave the guideline in place on one dive, then recover it on a subsequent dive.

If a traverse route were done regularly, it's be prudent to leave a primary guideline in place alone that route. That's what cavers would call a permanent 'gold line'.

The only problem with permenant lines is that they're sirens for the untrained wreck divers... enticing divers to enter wrecks way beyond their competency to survive predictable hazards and situations.

I've known dive operators remove permenant lines from wrecks for exactly that reason... in the interests of safety.

Unlike many cave diving sites, it's impossible to regulate whether visiting divers penetrate without accepted training.

 

[DevonDiver]

What kind of forces are people putting on their guidelines???

I've always felt that thick lines can be indicative of weak skills.

Even in zero viz, there shouldn't be any tension put onto the line. They should be a tactile reference only... with only a "loose O" made with the fingers for contact... not gripped, pulled or yanked upon.

Having taught many wreck courses, at all levels rec-tec, the only times I observe undue tension on guidelines is from students who've yet to master fundamental skills and confined area maneuvering.

 

[stuartv]

I got a new trilam drysuit last summer. I took it to the local quarry and dived it to make sure it was "good". Then, I went to NC for a couple of days of wreck diving there.

My second dive, I was swimming through a wreck taking pictures with my new camera rig. I swam through a really big hole in a bulkhead at one point. Apparently, I was not maintaining perfect trim and I gently bumped into the bottom of the hole with the front of my thighs. I didn't think anything of it at the time (other than "oops, try and hold better trim"). When I got out, my suit was flooded. I had about a 1/4" cut in the front of my suit's thigh.

I have little experience laying line inside a wreck. Is it really so hard to imagine that a #36 line laid in a wreck could inadvertently get cut relatively easily?

ps. when I do lay line, I do generally attempt to keep it somewhat taut - as I was trained. Not piano string tight, but not saggy.