1.  Release upon receipt of an acoustic signal by the process of electrolytic erosion of a loop of stainless steel wire.

2.  Slant range 2,000 to 5,000 feet and up depending on water conditions.  (note:  sound travel is extremely variable in water depending on many factors).

3.  Operating depth is 0 to 1000 feet (444 psi).

4.  Topside interrogator is set to the four digit identification number of the unit underwater by pressing the increase or decrease key while viewing the unit identification number on an LCD display.

5.  Topside interrogator can be used to interrogate the battery state (high, med, low), make the release unit act like a pinger, or cause the release unit to become a transponder so that slant range can be displayed.  Other commands induce a 10 second brief erosion for testing and another command causes 20 quick pings for testing.

6.  The release unit has an external LED that flashes once every 10 seconds to indicate that the unit is on and listening and that the micro computer is fully operational.  The system can be checked out in air to give assurance that all is operational just before deployment.

7.  Four months plus four releases are obtainable on one set of 12 alkaline AA batteries.  One year plus eight releases are obtainable on one set of 12 lithium AA batteries (L91 made by Energizer price about $2.25 each).  Both of these cases use erosion link LKH-162 (160 lb max) and have a factor of two safety margin in battery energy.

8.  Underwater release receiver sensitivity equal to or better than -37 dB relative to one micro bar.  Output power from topside unit greater than 82 dB relative to one microbar at one yard (10 watts acoustic).  This is 1,000,000 times the theoretical minimum power needed for ideal water conditions at 1000 feet range (60 dB of margin). 

First picture below shows entire system including topside acoustic release interrogator (ARI-60), topside transducer (TD-60), two acoustic release units (AR-60-E) with erosion links installed (LKH-162).  

Second picture below shows three acoustic release (AR-60-E) with erosion links (LKH-162) in various stages of installation.

Third picture below shows the topside command unit, the acoustic release interrogator, (ARI-60). 

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MODEL AR-60-E RELEASE UNIT. This release is deployed underwater and contains the receiver plus a micro computer  and batteries and holds a replaceable release link with a pull pin for replacement.  (Note: This release works in ocean water and typical bay water. It will not work in fresh water since the electrolytic erosion will not occur at a fast enough rate). Size:  2.75 inch diameter by 30 inches long.

MODEL LKH-162 EROSION LINK. This erosion link is made from two loops of 0.035 inch diameter 316L stainless steel wire encapsulated in a replaceable holder. The erosion link operates by the fast electrolytic erosion of the exposed stainless steel part of its loops thereby freeing any lines passed through them. This occurs when a positive voltage is connected to it by the internal electronics. It is partially coated to restrict the intended erosion to two points at the base of the each loop to speed the release and save on battery consumption. The erosion link is replaced after each release. An O-ring is used to keep salt water out of the link connection cavity. The model LKH-162 is rated at 160 lb on-axis load and erodes in six minutes at 1000 foot depth.

MODEL LKH-262 EROSION LINK. This erosion link is identical to model LKH-162 above except that the two loops of stainless steel wire are 0.045 inch diameter.  This model LKH-262 is rated at 200 lb on-axis load and erodes in about 12 minutes at 1000 foot depth.  Its thicker wire mainly provides more strength against side loading (off-axis pull).  Its disadvantage is higher cost, more battery drain,  and requiring about twice as long to release once the command is sent.  Its erosion time might even exceed the 15 minutes of time applied by the electronics and therefore require that the release command be sent a second time.  There are some applications where these disadvantages are made up for by the extra assurance of a sturdier link.

MODEL ARI-60 INTERROGATOR.  The interrogator is used to send the acoustic signal to the release unit.  With it comes a transmitting transducer (TD-60) which is placed over the side of the boat and into the water.   First the unit identification of the release unit to be released is set using increase/decrease keys and viewed on an LCD display.  Second the specific action desired is selected.  Third the command is transmitted.  The signal takes about 15 seconds to send.  When a release command is received by the underwater release unit,  the release unit starts the erosion process which takes four to ten minutes using the LKH-162 erosion link depending on battery state and water temperature.  The release unit can emit pings while it is releasing as set by the command that was sent.  This reply ping signal confirms that the erosion is in process and could be used for tracking if a pinger tracking system is available.  Another command causes the release unit to become a transponder so that range is displayed while the unit is releasing and rising to the surface.

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Click here for a comparison of the AR-60 vs. the AR-50 system.