|Underwater Search & Recovery Techniques|
While these techniques have worked well for me, I am not advocating their use by others. I am not a trained professional nor a certified instructor. Much of the information is "common sense" and none of it is new, but it might help others. Regardless : Caveat Emperor
Use this information as a starting place for your own search plans and methods.
Underwater lifts can be hazardous to your health ... what goes up can often come down or a diver might rocket up with the load if entangled.
Caution is the watchword use of lines or tether in a cluttered environment can be problematic
When searching in low visibility always be aware of the risk of entanglement
No one technique can cover all requirements.What this is NOT
We are not talking Search & Rescue which has time limitations outside of the scope of these articles. Water rescues often require formal training, practice and specialized equipment. It also requires increased attention to the "rules" put in place to protect the responder from jumping in and possibly becoming a victim rather than a rescuer.
This is also not Commercial Diving, which utilizes specific training and us subject to OSHA (in the U.S.) safety regulations. Searching for automobiles in flooded drainage tunnels is NOT something the average diver is best suited for. Neither are most public safety divers. Overhead environments, low visibility and entanglements has claimed several experienced divers who attempted search and recovery without the proper training and/or surface support.
So what is Search and Recovery ? Many of the same skills and tools but there is less external pressure on the Searcher, there is more time to interview and determine the most likely location to search. There can though be pressure to perform and the risk to the searcher increases when they ignore common sense and enter environments they are not skilled in, such as fast water, low visibility, overhead environments or all of the above. If you do not feel at ease in an environment, trust your gut feeling and put the dive off until conditions meet your comfort level.
Public Safety Departments and Commercial Divers have specific safety rules intended to protect the responders from outside pressure (emotional and political) in unsafe environments. The recreational diver does not have anyone but themselves to make risk vs reward decisions.
I separate execution of a search and recovery operation into several steps. Not all steps are required and sometimes they will all occur without prior planning upon spotting something that grabs your interest. Don't let Treasure Fever make you think you can lift that 200lb mooring using your BC, or more likely that lifting that 30 lb anchor by swimming it up is a great idea. Or to forget simple math ... that chain end you want to bring up isn't too heavy ... but 30 feet of it is :-)
Planning can be from a simple "I think I'll pick that up" to years of research. Sometimes it might be "we'll try over there" other times it will involve studying nautical charts, creating a search grid and taking into account the carrying depth or bottom structure into the search plan. eg: sloping bottom might be best searched by taking the deepest grid point and searching parallel to the shore decreasing depth as your search progresses. If you know SAC rates for the searchers and fin rate you can try to fine tune the entire plan on paper before anyone hits the water. Of course the plan must be flexible but it can be a good starting point, especially when depths increase and deco obligations are an issue.
Old Events: Interview people if possible. If no observers are available research written accounts, or second hand information. All information should be treated as suspect. If searching for ship names, be aware vessel names changed often, and if captured, the ship would be renamed. This can lead to gaps in tracking by name if you miss the capture (ie: Revolutionary War) . Official documentation of sinking by an officer often was not observed by the officer, and was simply reporting what they assumed happened or were told that happened. Those locations are VERY suspect and ships reported as sunk to avoid capture by the enemy have been simply abandoned, found and renamed. Also - if you assume the fact that several sources all report the same information, track back their references. Often they all trace back to the same reference which may be in error and by sheer volume become branded as "fact".
Current Events: Interview witnesses - besides the obvious of "where is it" ask them to describe the item in as much detail as possible and also any other
relevent information, such as what else might have been lost at the same time. Take note of the items, consider the different buoyancy characteristics or
distribution pattern. For instance .. knowing the color and size of a tackle box that fell overboard with the missing tournament
grade rod and reel might id the vicinity and be more visible than the subject item.
Question the accuracy of information. People rarely have a good sense of location when on the water since there are few (if any) fixed markers for them
to use. Even shore based cues can be wrong or useless, so when they bring you to a shore spot and say the item is 200 ft over there ... ask how they
event: brand new 40hp outboard engine fell off a small powerboat in 60 ft of water, in a large bay under windy conditions. The owner went out with me, indicated "this is it" and dropped the hook in the spot. His outboard was within 10 feet of the anchor - only visible portion of the engine was a small bit of the prop hub sticking out of the mud, which I initially thought would be a beer can . Engine was recovered via surface lift and was de-watered and running by nightfall.
next: the actual Search