# Useful water recovery facts



## Jim Delbridge (Jan 27, 2010)

Once drowning has begun, adult bodies tend to drop 1.5 to 2.0 feet per second.

If water current is known (or established with submerged milk cartons just under surface), then body location on bottom can be determined by simple math.

Depth of water determines how long body takes to drop to bottom.

Time to bottom determines how long current can affect motion of dropping body.

So, simple example. 40 feet depth of water. Time to bottom is 20 to 27 seconds.

So, for example, say water flow is 1 knot. (1 knot equals 100 ft per minute)

So, body should be at rest from (0.3 min x 100 ft/min) to (0.45 min x 100 ft/min) feet from point last seen above water OR 30 to 45 feet from point last seen above water.


Bodies apparently do not rise and fall due to thermals because of water pressure and Boyle's law, i.e. if the body starts to rise it will only get more buoyant as it goes up as the water pressure lessens. If a diver hits a body off bottom, then it was on its way up anyway.

Fact I didn't know, if a body sinks below 100 feet, rarely will it come back up on its own due to water pressure is 4 times atmospheric and too great for the decomposition gasses buoyancy to overcome.

Fact that's very useful, once body hits bottom it very rarely moves from that spot until buoyancy lets it rise back into moving water or it's affected by surface winds.


All "bodies found in water" should be treated as a crime scene until proven otherwise. So, it's recommended that if divers recover the body that they bag it right there and mark their location for later examination for evidence. This is not the norm, but makes a lot of sense to do. We almost always see a drowning as a tragic accident rather than foul play unless obvious trauma is present.

Drowning victims tend to either move only up-and-down or in a circle, no horizontal movement....., i.e. then don't move much from where they were seen to go down. More important to those doing recovery, they didn't move far from where they were found on bottom which is important if the stories don't jibe.

If, as a dog team, you locate a body then photograph it (if you have a camera) as you found it then back off just like you would in a crime scene to let law enforcement treat it as such. Oh yea, give your photos to law enforcement immediately on contact. Don't touch or move the body.

Source of this information was at an excellent 8-hour seminar where the instructor tried to squeeze in 40 hours into 8 hours. Instructor was Andrea Zaferes of http://teamlgs.com/
Team Lifeguard Systems.

I'm really just touching the surface of what I learned there.

I would recommend this seminar to all dive teams, law enforcement that deal with water recovery (of any kind), death investigators, and canine water recovery teams (if you can swing it...I'd do it with your call-out agency).

I'm leaving a lot out that is more pertinent to those dealing with the investigation more than dog teams. There are a lot of implications, in just what I provided, to dispute a lot of confusion seen at most water recoveries.

Jim Delbridge


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## Meg O'Donovan (Aug 20, 2012)

Thanks for posting this useful information.


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## julie allen (Dec 24, 2010)

Thanks for sharing this. Do they go into detail on water/air temps and time to rise?


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## Jim Delbridge (Jan 27, 2010)

no, because it's a bit more complicated than that. I did find this table with a google search.

WATER 
TEMPERATURE 
DAYS TO 
SURFACE 
40 degrees 14-20 days 
50 degrees 10-14 days 
60 degrees 7-10 days 
70 degrees 3-7 days 
80 degrees 1-2 days 

Part of the problem is depth to bottom is not involved, so assume all of the above is in depths less than 100 feet. Knowing your local results doesn't always work out either. In my state, this time of year, usually 3 days to floatation, but recently worked a deep lake where the bottom temperature was 39F at 90 feet deep. Body rose at 14 days.
The key is the buoyancy of the body must overcome the atmospheric pressure at depth. At 100 feet, this is four times normal and apparently body decomposition gas can't overcome that. At 90 feet it was 3 plus and at 39F decomposition took a long time to overcome that pressure.

Also, I know from experience that EtOH (alcohol) also slows down decomposition, so someone that went in the water with a high blood alcohol level will take longer to rise as well. Nothing says they went into the water on their own at that level, so even then accidental should not be assumed until proven. 

Hope that helps,

Jim


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## Sarah Platts (Jan 12, 2010)

Some of the other factors I've heard affecting float times are age (adults usually float, children may not), if the adominal cavity has been ruptured or to much body damage to the skin, how much other weight the body is trying to lift (aka heavy clothing, cinder blocks, or that old logging chain)


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## Jim Delbridge (Jan 27, 2010)

Yup, not to be blunt, but if the balloon is pierced then it's harder to inflate.

Bodies can get trapped under things even if buoyant. A lot of the lakes in my area were man-made and they didn't clear out what was there before the water was. There can remnants of old buildings, lots of trees, fences (including barbed wire), etc.

I'm not going to post how many cinder blocks will hold down a body, but it takes a lot. Years ago, I created a pulley system with a submerged source and a buoy I could raise from shore to recover the source. I used a bleach bottle on the pulley tied to a cinder block. About a pint of air in the gallon bottle created enough lift to raise the cinder block. I eventually just created a different source containter on a very long line that I could tie up to something accessible by a boat.

On children, depth is much more of a factor due to atmospheric pressure versus buoyancy.

Jim


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## Nancy Jocoy (Apr 19, 2006)

I have a collection of articles from over the year but it is all bits and pieces. I think the most controversial topic is that of neutral buoyancy.

I am not sure how much time a body spends "hovering" just over the bottom of the lake or river just before it comes up but there have got to be times where it is partially suspended though many argue not. Had some searches though where the first dogs hit upstream, next dogs downstream in a channel, then after that further down the channel and the body comes up downstream in that very same channel [moving river] the next day........

As far as bodies being suspended and staying there for awhile, I gather probably not but I think there would have to be some time (though I don't know for how long) for partial buoyancy and movement underwater. In lakes it seems they come up where they went down. And also they don't seem to move in rivers until they start the floating process.


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## Jim Delbridge (Jan 27, 2010)

The presenter was solid on several facts. One being that neutral buoyancy is a myth (and these people do experiments) and that the body doesn't move once it hits bottom despite current. Once the body starts to rise again, it can again be affected by water current. What I usually see is that the body surfaces during night and is pushed along by the water current and winds on surface. Once the body is buoyant enough to rise off bottom (point of greatest pressure due to water weight), it will only get more buoyant and continue to rise.

For investigations, it's always better to locate the body on bottom as there can be evidence left by the doer if foul play is involved just like in a burial. That's why they'd prefer the body be bagged by the divers where found and then moved in the bag. That's also why they'd prefer the dive team leave some sort of marker where the body is found (along with GPS coordinates) in case further developments suggest an accident was really a homicide.

Jim Delbridge


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## julie allen (Dec 24, 2010)

Jim Delbridge said:


> no, because it's a bit more complicated than that. I did find this table with a google search.
> 
> WATER
> TEMPERATURE
> ...


Thanks Jim. I have had water hr classes and some info, but all I hear on that is it varies, and I want to find more studies done with research proving this. 
The 100' foot info I had never heard, that's interesting. Most waterways here have lots to hang up on and usually bodies don't return up unassisted.


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## Nancy Jocoy (Apr 19, 2006)

I am still not sold that neutral buoyancy is entirely a myth. I get that they are not 'hovering' at some mid-level in a lake and that as they rise they only become more buoyant, but as they are getting ready to float, they are building up gas which starts to lift them up from the surface but that process is not instantaneous. I would like to see actual studies on that.


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## Sarah Platts (Jan 12, 2010)

Julie, I've heard of the 100ft thing and had a couple of PD divers tell me that too. I think alot depends on the temperature at the depth but also how much bouyancy is produced to counteract against the pressure. Rule of thumb I've always been told if it's down that far - it's staying down.

The 'hovering thing' is something I'm also wondering about. If a body in 50 degree temps takes 10-14 days to surface, that's a range of time. Gotta wonder if the body is starting to lift at day 10 and then finally breaks free/pops up at day 14. So what's it doing between day 10.1 and day 13.9? I don't see it careening to the surface like a sub on an explosive blow but I do think that once the body finally develops enough positive bouyance that it will begin to rise but depending on the amount of weight the positive pressure is trying to overcome (and the object in the water weigh less than on land) then how long does it take that amount of gas to develop and pool? And if part of it is leaking out in the interium due to aquatic feeding activity or holes in the bag how much does that change things?


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## Nancy Jocoy (Apr 19, 2006)

I figure the 10-14 days is more along the lines of nature of victim and their decomp process as well as the depth of the water.......I think once they clear the bottom and start floating the process is probably very fast.......but HOW fast?...that would answer some questions. 

My own question is more along the lines of when they are not quite off the bottom before float but starting to....I know the vast majority come up right where they went in but I have seen one and know of a few where it seems they are in motion underwater in fast flowing channels in rivers . Still not great distances but one seemed to move about 75 yards during the course of a day..then he came up and snagged downstream that night. Once they are on the surface of a river they can go miles. These were independent hits over time by dogs, all of which had good pinpoint accuracy on other real bodies not just training aids.


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## Bob Scott (Mar 30, 2006)

How does OR does the fat content of an individual come into play in a drowning?
I've never been able to float without movement yet a "plump" friend of mine can fall asleep while floating on his back.
Obviously decay causes gasses that create floatation but do some take longer to sink?


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## Sarah Platts (Jan 12, 2010)

Bob Scott said:


> How does OR does the fat content of an individual come into play in a drowning?
> I've never been able to float without movement yet a "plump" friend of mine can fall asleep while floating on his back.
> Obviously decay causes gasses that create floatation but do some take longer to sink?


Good question. I know that when I was diving, just to be slightly negative in my skin (5'7", 140lbs), required an extra 15 lbs of weight. Once I put on the tank, suit, and BC it took 45 lbs to get me negative.

Funny thing is most of the drownings I've worked are children or adults at their appropriate weight. Does being excessively fat help prevent drownings by at least keeping you at or near the surface..... Interesting idea. I'll have to troll around and see if anyone has thoughts on the matter.


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## Nancy Jocoy (Apr 19, 2006)

Sarah, I was actually thinking the same thing.......a "typical" drowning victim for us is a young man in his 20s who is full of booze or a teenage boy...both usually doing something stupid..


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## mike finn (Jan 5, 2011)

Thanks for the great information. I have a question. Would a dog be usefull in locating bodies in the ocean that have drowned a 100 meters or so from the beach? We have had nine drownings at the beach here in the last few years, and it took a few days for the last kid to be found and he was a mess. Any thing we could do to shorten the time it takes to find the body would really help.


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## Nancy Jocoy (Apr 19, 2006)

It should not matter. You want a team who has trained in salt water. I know finds in 75-80 feet of water have presented no difficulties. I think a teammate once had one in 300 feet.


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## Sarah Platts (Jan 12, 2010)

Yes, you can use dogs for that. I don't think it matters if the dog has only has fresh water experience but I think what really matters is that the dog gets some exposure to dead sea life first. I know of several instances were landlocked dogs alerted on dead fish. 

I've worked a couple of coastal drownings and the biggest issue is you have to understand the hydrology of the area in question and what the currents are doing. Partly because depending on the depth and down time you could have a long scent cone to deal with. Especially, if you can only do shoreline and not put the dog on a boat. Obviously, having a boat available is ideal but that depends on water depth, surf, and shore conditions. 
I did one search where we were only allowed to work the shoreline. My alerts were approx 1 mile from where the body was physically located stuck in a known trash gathering area off-shore which was "down stream" to our location. Afterwards, we wanted to know why the dog alerted so far down the shoreline from the recovery site and "up stream" to the water current directtion. Ended up speaking with a guy who was a walking encyclopedia of water data for the ocean in my area. He looked at my alert data and told us that it was plain as day why the dog alerted where it did and that it wasn't wrong. An hour later my head was spinning with phrases such as on-shore flow, off-shore flow, tidal changes, sand bar placement, tidal drift, on-shore wind, off-shore wind, eddy zones, counter-flows, turbulent zones, and so forth and so on. Upshot of the matter was the dog alerted correctly in the only area where, with regards to the off-shore trash gathering site, it was part of the off-shore current flowing counter (south) to on-shore current (north) did a reversal, caused by off-shore sand bars which forced the counter southbound current to be bent back toward shore, where it joined the north running shoreline current. Where the dog alerted was at the junction of this mixing bowl. In so many ways, working a river is easy when compared to the bigger dynamics of the ocean. 
Its definitely worth it but I would recommend doing some training first to get an idea of what you are dealing with. Also locate the locals who really know the water in your area and get them involved in the search process. It really helps.


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## mike finn (Jan 5, 2011)

Sarah Platts said:


> Yes, you can use dogs for that. I don't think it matters if the dog has only has fresh water experience but I think what really matters is that the dog gets some exposure to dead sea life first. I know of several instances were landlocked dogs alerted on dead fish.
> 
> I've worked a couple of coastal drownings and the biggest issue is you have to understand the hydrology of the area in question and what the currents are doing. Partly because depending on the depth and down time you could have a long scent cone to deal with. Especially, if you can only do shoreline and not put the dog on a boat. Obviously, having a boat available is ideal but that depends on water depth, surf, and shore conditions.
> I did one search where we were only allowed to work the shoreline. My alerts were approx 1 mile from where the body was physically located stuck in a known trash gathering area off-shore which was "down stream" to our location. Afterwards, we wanted to know why the dog alerted so far down the shoreline from the recovery site and "up stream" to the water current directtion. Ended up speaking with a guy who was a walking encyclopedia of water data for the ocean in my area. He looked at my alert data and told us that it was plain as day why the dog alerted where it did and that it wasn't wrong. An hour later my head was spinning with phrases such as on-shore flow, off-shore flow, tidal changes, sand bar placement, tidal drift, on-shore wind, off-shore wind, eddy zones, counter-flows, turbulent zones, and so forth and so on. Upshot of the matter was the dog alerted correctly in the only area where, with regards to the off-shore trash gathering site, it was part of the off-shore current flowing counter (south) to on-shore current (north) did a reversal, caused by off-shore sand bars which forced the counter southbound current to be bent back toward shore, where it joined the north running shoreline current. Where the dog alerted was at the junction of this mixing bowl. In so many ways, working a river is easy when compared to the bigger dynamics of the ocean.
> Its definitely worth it but I would recommend doing some training first to get an idea of what you are dealing with. Also locate the locals who really know the water in your area and get them involved in the search process. It really helps.


 Thank you so much for the detailed information. There seems to be so many variables to consider. Were you able to find the body when you searched the beach? Also were you in a boat or on shore? Once again thanks


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## Sarah Platts (Jan 12, 2010)

mike finn said:


> Thank you so much for the detailed information. There seems to be so many variables to consider. Were you able to find the body when you searched the beach? Also were you in a boat or on shore? Once again thanks


The body was recovered off-shore in an area that is a known "trash-gathering" area. There are several of these in my area and depending on where the body goes in, the dive/marine resource folks monitor the location that services that area because that's where the body will eventually end up. So instead of scouring miles of open water they just monitor these trash sites and wait for the body to show up. Which it does, eventually.

On this search, I was only allowed to work the shoreline and unable to put the dog on a boat. The body was recovered out of one of these "trash" eddies which was about 400 yards off-shore, approx 5-6 hours later, approx one-half mile away from the known drowning location. Because of current flow and wind direction, my dog's alert was approx 1 mile away where the off-shore current was bent back to the shoreline which put it in reach of my dog's nose.


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