Search patterns... help!
- Thread starter Zept
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I'm not sure whether our bottom is markable. Calling it a 'bottom' is kind of generous, because it's liable to become suspended in the water at short notice. I think it's probably too soft for that strategy.
I like the idea of a contracting circle. I found that swimming round in ever-increasing circles, getting further from my buddy while getting increasingly frustrated, was not a good situation. Working my way back to the centre would have been more comfortable.
I'm going to go back and try again in a couple of weeks, hopefully.
On the plus side, we did find the fancy new snorkel that one of our divers had lost a couple of weeks earlier. I would rather have found our missing diver, but at least he'll be happy!
Zept
I like the idea of a contracting circle. I found that swimming round in ever-increasing circles, getting further from my buddy while getting increasingly frustrated, was not a good situation. Working my way back to the centre would have been more comfortable.
I'm going to go back and try again in a couple of weeks, hopefully.
On the plus side, we did find the fancy new snorkel that one of our divers had lost a couple of weeks earlier. I would rather have found our missing diver, but at least he'll be happy!
Zept
ikan bilis
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wouldn't a contracting circle raises the possibility of your reel entangling something since you haven't actually explored what's within the "big circle"?
seaangel
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What about a grid type pattern? We were taught my recent Stress and Rescue to do a grid pattern, starting away from the center where the victim was last seen working toward there going in a long the short sweep. You need a reciprocal compass, and a bouy or marker.
Mark the point of the last seen victim .
Use the reciprocal compass heading of the course starting at one end and working toward the other end.
Overlap the sweeps slightly.
This requires a team, two divers to search. A third person if shore is close enough on shore can mark each sweep with a marker or bouy.
We did ours in the lake here that has a very silty bottom and a deep drop off 5ft from shore. We did not use someone on shore but did our sweeps using 270 and 90 degree headings. We found the dummy diver within 5 minutes. Visibility was fairly good about 10ft. We had no real current but there was a mild surf and some surge as thunderstorms were brewing south of us and moving our direction.
Good luck and don't give up it can be done.
Mark the point of the last seen victim .
Use the reciprocal compass heading of the course starting at one end and working toward the other end.
Overlap the sweeps slightly.
This requires a team, two divers to search. A third person if shore is close enough on shore can mark each sweep with a marker or bouy.
We did ours in the lake here that has a very silty bottom and a deep drop off 5ft from shore. We did not use someone on shore but did our sweeps using 270 and 90 degree headings. We found the dummy diver within 5 minutes. Visibility was fairly good about 10ft. We had no real current but there was a mild surf and some surge as thunderstorms were brewing south of us and moving our direction.
Good luck and don't give up it can be done.
Sure does...
Competent gas management obviates the previously voiced concerns with expanding patterns.
Rick
There are many search patterns that use lines or some other reference. The NOAA manual has a good section on this if I remember. The PADI search and recovery manual is not bad either. I think an expanding squar in a current would be entertaining to watch. What did your instructor have to say about the whole thing?
...circular searches using a reel are good for covering a small area comprehensively, but squares are better for the exercise we're doing. I can see advantages to the square -- no special equipment required, keeps the buddy team together -- and I want to master it... or improve my success rate, anyway!
The currents we are dealing with are not strong. On the first day we were drifting about 1m for every 20m we travelled... the problems had more to do with our attempts to compensate than the current itself. I think (hope) that if we take a few seconds to assess the conditions on the bottom before we begin searching, we should be able to do better.
I don't have a date for the next session, but hopefully it will be soon.
Thanks everyone,
Zept
The currents we are dealing with are not strong. On the first day we were drifting about 1m for every 20m we travelled... the problems had more to do with our attempts to compensate than the current itself. I think (hope) that if we take a few seconds to assess the conditions on the bottom before we begin searching, we should be able to do better.
I don't have a date for the next session, but hopefully it will be soon.
Thanks everyone,
Zept
I've used this technicque on a silt bottom, in about 4-5 ft visibility.
It works for me.
1) drop a 60 lb cement block with surface foat and line, at the start of your search area. Keep it taught
2) (lay a reference line) clip onto this line about 6 inches above the bottom and reel out a straight line restiing on the bottom, to the max diameter of your search area (I wouldn't go over 100ft). Set reel on bottom.
3)(sweep line) clip on a second line and reel at 3 feet above the bottom or higher is you have the visibility or high obstructions (trees rocks etc).
Reel out the distance you can scan and starting at the reference line sweep your circle. (two divers arms length apart on the line can sweep about 8-10 feet wide area, field of view is about 12-15 feet) Swim about 3-4 feet off the bottom so you don't disurb it. You'll know when you've completed a sweep when you come back to the reference line. You can mark your progress by placing a stick in the silt by the refence line.
4) Reel out another 8-10 feet , move the stick and start another sweep. There is an intentional over lap, to insure popper coverage before moving on.
Switch places with your buddy on ever lap after completing a full circle. The guy on the outside has to swim farher and slightly farther.
Keep the line tight
Mike D
:blfish:
It works for me.
1) drop a 60 lb cement block with surface foat and line, at the start of your search area. Keep it taught
2) (lay a reference line) clip onto this line about 6 inches above the bottom and reel out a straight line restiing on the bottom, to the max diameter of your search area (I wouldn't go over 100ft). Set reel on bottom.
3)(sweep line) clip on a second line and reel at 3 feet above the bottom or higher is you have the visibility or high obstructions (trees rocks etc).
Reel out the distance you can scan and starting at the reference line sweep your circle. (two divers arms length apart on the line can sweep about 8-10 feet wide area, field of view is about 12-15 feet) Swim about 3-4 feet off the bottom so you don't disurb it. You'll know when you've completed a sweep when you come back to the reference line. You can mark your progress by placing a stick in the silt by the refence line.
4) Reel out another 8-10 feet , move the stick and start another sweep. There is an intentional over lap, to insure popper coverage before moving on.
Switch places with your buddy on ever lap after completing a full circle. The guy on the outside has to swim farher and slightly farther.
Keep the line tight
Mike D
:blfish:
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