If you lay a line from A to B, is there a way to retrieve a line from B?

[VikingDives]

If I was going to do this (and I wouldn't) I can think of a couple of methods.

The first would be to make a slippery hitch at the tie-off point. That will come loose when it becomes slack. You'd have to keep constant tension on the line, and doing a circular search would presumably negate being able to retrieve the line.

The second would be to take the end of the line and secure it to a double-ender which would then loop back to the line near the spool. The third would be to tie a fisherman's knot on the line near the spool. Both of these would require dragging half the length of the line over whatever you've tied off to and hoping your line doesn't break.

But let's say you need 60 feet/18 meters to do this search. With method 1, you've got 60 feet to reel in, with the other methods, double. Either way, you've created an entanglement hazard for yourself and others.

This all sounds like a massive S***show to me.

 

[Wibble]

Have you seen the mass of lines over a wreck when the vis isn't great and the skipper's called a "must return to shot" dive? Just laying a guideline around a wreck gets messy as there's so many things the line snags upon.

 

[Celt]

Thinking of the times this has happened to me.

Every time I've lost something -- the wreck -- I assume I can just swim out 15m/50ft and find it. Then turn left/right and go in a square search format. All to no avail. Current, inability to swim straight, drifting from the start point...

My successful searches are nearly always when I pin the end of the reel/spool on a rock/anything, swim out by 15m/50ft. Then search around in a large circle around the start point.


For a laugh, my worst example of a failed search was the largest wreck in Sussex, 35,000 tons, using a scooter I managed to get half a mile off the wreck, no matter what circles I swam in. I know that as when I finally abandoned HMS seabed and surfaced, the boat could barely be seen.

So now I stop. If I cannot see it then it's tie down a spool/reel and do a proper search with line.

The OP never mentioned grid search. He wished to go from A to B that’s a straight line, and recover the line from position B, a compass will do that without having to retrieve the line.

 

[Wibble]

If you're using a line, you're probably not that certain where "B" is until you find it
So there's always an element of searching.

 

[Gone for diving]

Buddy on the tied off end. Is one way.

I am sure there is some type of fancy pinger system but that would be overly complicated...

 

[Celt]

I am doing a circular search (semi circular)

Example, 30 min planned bottom time, wreck lying East West, and I wish to search port bow section. Drop the shot at the bow, clip my strobe and reel 20 feet up and clear of high wreckage, drop and take a bearing, head off keeping to the port side wreckage for 8 minutes. Lock my reel and swing out the port side for 8 min or reach a reciprocal bearing and reel back in. Leaves 6 minutes to find what I’m searching for and send it up.

 

[Kendall Raine]

Tie off at A with some lightweight thread. Dont put too much pressure on the line when you are laying line. When you get to B,give a sharp tug to break thread and reel up. Not ideal because you have to reel up slack line but it's doable.

In California you can tie off to small piece of kelp and break it off but not everyone is lucky enough to have kelp

Aside from other mentioned objections (e.g. pre-mature line breakage), this method means leaving line in the ocean (trash) unless the line is tied into the anchor line and so the broken piece can be retrieved when the anchor line is raised or if the weak point is the tie off enabling you to reel up all the line once broken. Not a big deal with biodegradable line like sisal, but nylon doesn't degrade.

If using nylon line other methods are better (e.g. looping around the starting point) since they don't leave trash in the ocean or require use of flimsy breakable line. There is a risk of the line snagging on a wreck, true, but that risk exists with a breakable nylon line, too. A non-biodegradable alternative is using polypro (or other buoyant line) which might help solve the entanglement risk, but might not depending on circumstances. I would never use a buoyant line in overhead-too much entanglement risk.

Reeling up slack line is not otherwise a problem provided you maintain tension on the line with one hand.

 

[inquis]

I would just go back to the anchor line after finding the object of interest (or not finding it). That's where the boat will look for me (if ascending the anchor line) or my DSMB to surface (if free ascending).

 

[stiebs]

The situation is as OP described in the post #3, It's not looking for a lost object, it's not navigating around a wreck. The skipper has dropped a shot line to the wreck, but he's missed the mark. The instruction is something like "OK, the shot is 15m NE of the stern, so when you hit the bottom, swim SW and you'll find the wreck".

There's current, its deep, and vis is only 5m, so easy to miss it, or at least waste time looking. If the dive plan is to do a free ascent with a DSMB, there's no need to return to the shot. It's a large wreck and the plan is to start the dive at the stern and end at the bow. So you don't need or want to get back to the shot.

 

[inquis]

The situation is as OP described in the post #3

Things were pretty well laid out in post #4. Of those, leaving a buddy at the anchor until the tie off is made on the wreck seems most in keeping with OPs desires. 3 tugs means come on over. This lets them ascend from wherever they want. Hopefully the skipper will see their bag.