Having spent some time teaching in the pool, most of our ADIs have had plenty of practice at teaching the basics.  In this forum we started to look at some of the lessons that are taught in open water without a specified pool training session.  First up, we look at the simulated decompression and line laying lesson that is detailed in Sports Diver lesson SO3.

When was the last time you used these skills yourself?

We started this forum with a show of hands as to who had done any line laying since they did the lesson as part of their own SD training.  Not many hands went up, so if you’re in that position make sure you brush up on the skill before attempting to teach this lesson.  Have a dry run of line laying making sure you are confident will the key points that need to be demonstrated.

I promise I will add some useful photos showing the key elements for line laying that should be a good refresher.

The links below show the skills (unfortunately not all in one), the final tie off isn’t strictly needed for the BSAC lesson but it a useful bonus element:

This video is okay, but they miss the secondary tie off and a lock and a loop on the final tie-off. https://www.youtube.com/watch?v=wioZGY4INbY

This video does not skip the secondary tie off, but the final tie-off is not executed correctly (substituting a loop for a lock). https://www.youtube.com/watch?v=a29YHCaByuA

Hand placement is incorrect in both videos as well, and neither demonstrates team roles and positioning, which I argue is one of the most important points of the lesson.  No mistakes are made in the following video, but it doesn’t show anything clearly and doesn’t work well as a teaching aid. https://www.youtube.com/watch?v=hlDo2-M9vGE

Planning and executing a decompression is more familiar for most people, but again, if its been a while make sure you give yourself a quick refresher before attempting to teach it.

Pre-lesson considerations

There are two SD theory lesson that should be taught before attempting this lesson; ST3 – Equipment and Techniques and ST4 – Deeper Diving.  Having completed this theory the student should understand why line laying and decompression diving are useful skills to learn.  If you start the lesson with a discussion of why you are doing the lesson, the student should be able to answer.

This lesson can be taught with 2 students at once, but it is easier to teach one on one unless water conditions allow a relatively long dive.  Both you and your student will need some specific equipment for this lesson:

  • spool or reel with sufficient length for line laying (50m+)
  • knife or line cutter, its good practice to always carry a knife or line cutter but essential when working with line
  • slate or wetnotes for recording your deco plan
  • DSMB in case line laying needs to be abandoned

The task loading in this lesson can mean students go through significantly more gas than they normally would, don’t be tempted to let students go in with a partially full tank.

Consider the students previous experience, students should have used spools or reels in some of the earlier SD lessons, but it they might not have used both.  Do you need to incorporate a short demo in how to use either?

Line laying dry demo

The dry demo is essential for this lesson, this is the first time the student will have attempted any line laying.  If you’re teaching at Capernwray the picnic benches near the diving bell give a good mix of points you can practice tie offs, ranging from a simple post to small boulders.  Key points to cover in the demo and student practice are:

  • the primary tie off – make sure it is secure by passing around fixation point and passing spool or reel thought end loop, the direction of travel should be away from the loop so it tightens as line is let out.  The line can be wrapped around the fixation point a few times to ensure it is secure.  The fixation point could be the end of the shot line if you are confident it wont be pulled.  If a large rock is used then pick one that widens and attach below the maximum width so the line cant be pulled off.
  • reeling out line and positioning of line layer and buddy – the reel/spool should be held away from the body at arms length to avoid entanglement and line should be kept taut.  Buddy should be positioned slightly behind the line layer on opposite side of the line and follow with hand making an OK around the line.
  • secondary tie offs – after reasonable distance or any change of direction the line should be looped around another attachment point.  Loop around the fixation point, then go under the incoming line and around it.  You can go over under but this is more likely to pull up as the line tightens.  Stay consistent with the direction you wrap the line as it will make it easier to undo in zero visibility.  The buddy following should trace the line with fingers to move past the attachment point.
  • reversing route – buddy should be positioned ahead of the line layer, line layer should slowly reel in the line keeping it taut.  Reverse the process at secondary tie offs.
  • detaching and storing reel – reverse process at primary attachment point, lock reel or spool and stow.
  • discuss communication between line layer and buddy particularly at tie off points.  Remind students of the importance of maintaining buddy skills and monitoring each other through out the dive.  Discuss and agree additional signals relevant to the lesson.

It is useful to practice the skill a few times and at least once with gloves which make handling the reel/spool and line more difficult.

If you only have short spools then demonstrate how to join two spools together.

When handling line, carrying a knife or line cutter is essential in case of line entanglement.  Students may not be that familiar with using them so this is a good opportunity to show them.  If you have any scraps of line you can get them to practice cutting with the line cutter on their kit.

Simulated decompression advanced planning

Students need to be able to plan and execute simulated decompression.  Give the student the actual requirements of the dive, ie max depth and time, then ask them to plan decompression and gas requirements as normal including a deeper longer plan, this should be a no deco dive.  Ask them to make a second plan at deeper depth that will take them into decompression.  The decompression can be planned on dive computer or tables.  Some dive computers will only show no-deco time and not show actual decompression requirements, so its useful to make sure they can plan properly on tables.  Tables can also be a really useful back up if your computer fails.  The dive plan including the decompression requirements and the longer deeper plan should be recorded on a dive slate / wet notes for reference on the dive.

When the student presents their plan, its a good opportunity to discuss signals that will be used to communicate going into deco and managing the ascent.  They can be repeated in the SEEDS brief as a reminder.

The student is going to lead the ascent so it is also worth discussing how they will time the ascent.  Most beginner computers only display minutes so the ascent may take longer if they have to wait for the minute to tick over to begin counting.

This is also a good opportunity to bring in additional learning in the form of gas planning.  Do the students know their SAC rate?  Do they know how to calculate the amount of gas they need to carry out the ascent including the decompression stops and factor in reserves?

SEEDS brief

Safety – recap the need to carry knife or line cutter.  Remind students that good B&T is essential (+/- 0.5m is expectation) as reduces risk of entanglement and reducing visibility.  Discuss awareness of snag hazzards.  Remind to hold reel at arms length to reduce entanglement risk.  Warn of task focussing and the importance to maintain good buddy monitoring.

Equipment – basic plus dedicated reel/spool, knife/line cutter, computer/timer and slate/wetnotes.

Exercise – brief ascending and descending shot lines, including positioning relative to the shot line and using it as a visual reference.  Recap expectation of line laying, a short demo from instructor and then student line laying.  Recap expectation of ascent and deco management.

Discipline – remind of buddy positioning on line laying element and importance buddy monitoring throughout the dive.

Signals – recap signals relevant to line laying and deco eg stop, attach line, let out line, let in line, fixation point, deco, ascent to stop etc.

Diving the dive

The actual dive will need a shot line to go up and down and many points that you can practice line laying with.  My personal suggestion is the shot line on the cesna plane at Capernwray.  The shot line is in 12m and you can lay line towards the Murphy or towards the African Queen.

Demo line laying then hand over to the student to practice all elements.  Watch for them monitoring the dive and their buddy and prompt if necessary.  Watch out for task focusing and fast gas consumption.  The student should maintain buoyancy +/- 0.5m throughout the dive.