This article is adapted from a chapter in the Book - "The Canterbury Wreck - A Diver's Guide"
Hi.... although not strictly sidemount related, I wanted to cover a subject very dear to one of my great passions in diving - wreck diving. Wrecks provide an amazing array of diving experiences from creating artificial reefs that attract and aggregate marine life to the wonders of penetrating and exploring the inside of a wreck.
When you undertake your entry level Wreck Diving Specialty Course, one of the key skills that you will learn is to correctly lay a guideline. Despite this, you will see and hear of experienced wreck divers performing penetration dives without using a guideline. Are these experienced wreck divers being complacent or foolhardy or is there a reasonable explanation for not using a guideline in all circumstances when diving wrecks?
Let's start with the statement - "The use of guidelines in overhead environments such as wrecks and caves is widely held as the principal method of ensuring that a diver can successfully navigate a penetration route and return to their exit in limited or no visibility by following the guideline out".
While the above statement is true, it is a mistake to rely upon guidelines as the only method of navigation for wreck or cave diving. Guidelines are not infallible. They can be inadvertently cut on sharp edges of the wreck. They can also be cut by other divers who may become entangled in your line. This means that a good wreck/cave diver will also employ other methods of navigation in addition to, or in some carefully evaluated wreck diving cases, instead of a guideline.
Note - This explanation applies to Wreck Diving only and is not valid for Cave Diving where a continuous guideline must be used in all circumstances.
Also, most wrecks offer a number of potential penetration routes through the ship involving different entry and exit points making the recovery of a guideline impractical. This is not to say that guidelines cannot or should not be used. This is up to the diver and dive team to determine. What I can say is that many wrecks can be very effectively navigated with careful attention to using progressive penetration, planning a route, noting carefully the orientation of the wreck throughout the route, back referencing features of the wreck as you complete the dive and noting the exit points along the route. If you are to enter or explore an area where you are uncertain of the route, then a spool can be used along with a strobe from a known point with clear access to an exit.
The following are some alternative or (guideline) complementary methods of navigating a penetration route on a wreck:
- Knowledge of the wreck – Researching the wreck you are diving via books, local knowledge etc. is vital in planning your dives on the wreck. Knowing where you are in the wreck, the depth of your compartment or deck, the direction the wreck faces, the wreck’s orientation; upright, on one side or the other, inverted. Holes in the vessel allowing ingress or egress be they, as built doors and hatches, purpose cut exits, or those resulting from damage during sinking or subsequently.
- Lines of the wreck - (for visual and/or tactile navigation). The wreck is man-made and built to allow human beings to live and move through the vessel. It has decks, passageways, doors, hatches, bulkheads, deckheads, girders, scuttles, and railings. These can all be observed, noted and used for visual or tactile (feel) methods to navigate, even in reduced visibility.
- Way-point strobe lights - these can be used at waypoints during a planned penetration to provide a highly visible reference to your exit. A waypoint might be a change in deck, direction in a passage or entry into a new compartment.
- Progressive penetration - when you are new to a specific wreck or moving into a new part of the wreck you should plan to progressively penetrate the wreck and build/document your knowledge over a number of dives. This could mean creating a conservative plan to explore a new section using a guideline to navigate into and exit from this section.
Ultimately, each diver and dive team should ensure that they are qualified, trained, equipped and mentally prepared for their dives. This includes developing a plan for each dive that incorporates the appropriate techniques to ensure that they safely penetrate the wreck.
If you would like to learn more about Wreck Diving or the Canterbury Wreck in Northland, New Zealand, check out our book "The Canterbury Wreck - A Diver's Guide" and our courses - "Wreck Diver Specialty" or "Wreck Adventures Course".