Using sonar for seach & rescue

[Mike M (Sask)]

I need some help guys. We had a friend in a truck go through the ice. Unfortunately they have not been able to locate him yet. The situation is this: Water is 12' to 15' deep, visability is approx. 2', the truck went in open water and has been located, very light current but it would tend to push him under the ice. Divers will not go under the ice. I do have an underwater camera and portable finder. What we have planned is a search of the open water with sonar from a small boat. The other idea was to use sonar through the ice. Does anyone know how to and how reliable a portable finder will work through the ice? Also if anyone knows with a 15 to 20 degree transducer what amount of the bottom you are actually seeing?

Thanks in advance.
Mike M (Sask)

[Mike M (Sask)]

Anybody?

[Jesse-WI]

I've seen several examples on TV of shooting thru ice with your transducer. They cleared the snow away, if present, poured a little bit of water on the ice. They then placed the transducer on the wet spot and everything worked fine.

Jesse Fletcher

[Mike M (Sask)]

Thanks Jesse
Does anyone have an idea of the size of the transducer angle at 12' to 15'. A 20 degree transducer I believe.
Thanks
Mike M (Sask)

[BGunn]

This link will show you coverage:

http://www.fl8.com/tips/tip6.html

[GENETRON]

HOPEFULLY THIS INFORMATION WILL HELP YOU. GENETRONS ARE USED BY MANY LAW ENFPORCEMENT AGENCIES FOR BODY RECOVERY PURPOSES AND WE HAVE PERSONALLY HELPED IN MANY SEARCHES THROUGHOUT THE COUNTRY. SO THIS INFO MAY HELP YOU.

1. THE TRANSDUCER CONE ANGLE IS APPROXIMATELY .3 FOOT OF BEAM WIDTH FOR EVERY FOOT OF DEPTH ON A 20 DEGREE TRANSDUCER. WE WOULD NOT USE A NARROW BEAM TRANSDUCER FOR THIS KIND OF WORK.

2. THE BODY IN COLD WATER WILL SINK AND NOT FLOAT DUE TO DECOMPOSITION AS FAST AS IT WOULD IN WARM WATER.

3 IF THERE IS CURRENT THE BODY MAY GO AN INCREDIBLE DISTANCE!!!!!!!

4.THE CLOTHING WORN ALSO MAY ADD TO BOUYANCY OF BODY.

5. THE BODY IN COLD WATER IS GENERALLY IN A FETAL POSITION CREATING A GOOD SONAR TARGET.

6. DO NOT IN ANY WAY JEAPORDIZE ANY LIVES. THIS MIGHT SOUND CRUEL BUT YOU MAY HAVE TO WAIT FOR ICE OUT AND WARMER WATER IN ORDER FOR MOTHER NATURE TO DO ITS WORK ON THE BODY WHEN THE WATER WARMS.

7. REMEMBER THAT IF THERE IS CURRENT THE BODY MAY BE MANY,MANY MILES FROM THE POINT OF SUBMERSION!!!!!! WE HAVE SEEN 20 TO 30 MILES IN SOME INSTANCES.

8. WE USE OUR WIDE BEAM TRANSDUCER ,72 DEGREES, TO INITIALLY TRY TO FIND THE BODY. THE BEAM WIDTH ON THAT IS ABOUT 2.3 FOOT OF BEAM WIDTH FOR EVERY FOOT OF DEPTH COMPARED TO THE .3 FOR THE TRANSDUCER YOU TALKED ABOUT. IF YOU HAVE NO CHOICE GO WITH WHAT YOU HAVE.

IF WE CAN BE OF FURTHUR HELP FEEL FREE TO CONTACT US. 701-298-0900 DICK KNUTSON GENETRON

[Dave in Mpls]

Mike-

Using a 20 degree transducer, your coverage will be 4.23 feet (1.29 meters) at 12 feet and 5.29 feet (1.61 meters) at 15 feet.

Regards

[Cangl]

Provided you can get a reasonable ice surface so as the transducer sits flat with no air between it and the ice good readings can be had but as mentioned above your bottom readings are covering more area then the readings just below the ice. Yes almost any LCD or flasher can be used this way but remember if the body is directly below the ice (floating)you practically have to take a sonar reading almost every square foot. The transducer cable should be able to extend its full length for coverage When doing this you might wan't to set up a grid type system and use markers, augermounds, food coloring or ski tracks. If your local search and rescue could not locate him with scuba, the sonar may prove vain be careful and do not try this alone.

[Mike M (Sask)]

Thanks for all your input Guys. It looks like we are going to give it a shot. We will attempt to shoot throught the ice, drill a hole if we spot anything and drop the camera down. I haven't acctually seem the sonar unit but it is an Eagle 3 beam unit. I understand the transducer is 30 degrees. The ice is still solid as the divers walked on it to get to the open water. The divers would not venture under the ice for safety reasons. We feel this is where he most likely will be. Current is very limited, almost nonexistant. We will be using survival suits and have ropes on us.

Thanks again
Mike M (Sask)

[Mike M (Sask)]

Hi Cangl

Just a quick question, when you refer to viewing a larger area through the ice are you refering to the depth of the ice? or do you mean the sound waves from the transducer actually bend or get distorted in some way?

Thanks
Mike M(Sask)

[Kodiak]

Try mounting a transducer on a pole with it pointing at a 90 degree angle from the pole. Insert it through a hole in the ice and shoot it parallel to the surface of the water. sweep it in full circles (like a side scanner) lowering the pole about 1 ft for each sweep. You should be able to pick up any suspended objects in the water out to the effective range of the finder. Use the narrowest possible angle beam for this method. If you dont find anything move about 100' in a grid pattern and try again. I worked at the crash of TWA flight 800 and the Navy used side scanning (although at a higher level of technology than you have at your disposal) to find bodies and wreckage. Fishfinder may be low tech but the principal is the same. Good luck. I hope you find your friend soon.

[EyeAuthority]

Always hate to hear things like this. Not sure if we can help much here but we have a Search, Dive, and Rescue team with trained ice divers. They can surely give you guys some tips or advice and if not can more than likely hook you up with some folks around the country who are very good at this type of recovery. I am not a member of this team but know most of them and know that they receive their training from some pretty good folks. Like I said, they do have trained ice divers, and they can probably offer advice etc.

I will be at work tonite from 6:00pm to 3:00am CST and you can call me and if you want, I will try to connect you with their team leaders etc.

Dave Hegg 605-882-6210

[Kodiak]

Another option is using a finder such as a Raytheon L-365 or L-470 which has side scanning transducer as an option.

[Mike M (Sask)]

Thanks again guys.

The RCMP dive team here has very limited resorces to say the least. No electronics, no cameras, etc. It took 2 days to find the truck in open water. They never did put a boat in the water. We will give a couple of these ideas a shot tommorrow and see how it goes.

Thanks
Mike M (Sask)

[LakeRat]

The body will be drifting within the bottom 2 feet of the lake for at least three weeks. It will be in the floating sediment that is difficult to see in. Find a person that is intimately familiar with the current pattern in that lake. Get something with the same bouyancy down to that level that can be tracked. Once you have the speed of the drift and track for a bit, you should be able to apply amount of time drifting and figure about where the body should be at. Then scan heavily.

[Larry L]

Sorry to hear about your friend. I lost one through the ice several years ago. About ten years ago a man went through the ice with his pick up into about thirty feet of water. I remebered it taking five days to find the body. This winter I just happened to be ice fishing with a man that was in on the search. He said that they found him with a search dog. The body had surfaced under the ice and the dog scented it though snow and 2-3 feet of ice. This sounds pretty amazing to me but I have no reason to call him a liar. The key here is the fact that the body did not stay on the bottom. This was in a lake and the body was still found some distance from where it went through.