"Pilots, Man Your Planes!"   
                                         WWII U.S. Naval Aviation Collector's Guide                                                                              
Life jacket Shark Chaser   
Captain Chris Magee (of VMF-214 fame) poses in front of his F7F Tigercat, as squadron CO of VMF-911, spring of 1945.


                                                            By Dustin Clingenpeel

In March 1942 Dr. Henry Field, whom recently returned from a public relations mission from Trinidad, and Dr. Harold J. Coolidge, of the OSS, began to discuss the psychological factor of military personnel in regards to sharks.  Dr. Field became interested in this topic after viewing shark activity while flying over the Caribbean and hearing firsthand concern from aviators . Together they drafted a memorandum to President Roosevelt on the feasibility to development a shark deterrent. After much deliberation between military leaders it was concluded that development of a shark repellent would greatly benefit morale and decrease anxiety among survivors. The Bureau of Aeronautics issued a directive In June 1942 to initiate research on a shark deterrent. In July 1942 the BuAer contracted personnel with the Committee on Medical Research of the Office of Scientific Research & Development and Marine Studios Inc. for preliminary testing. After receiving reports of shark attacks on shipwreck victims the Bureau of Ships wanted to develop a unit for use by all naval forces operating in forward areas and in April 1943 took over the project assigning the Naval Research Laboratory the task working in cooperation with the OSRD. On September 1, 1943 the NRL assumed full responsibility of the investigation.

   Testing began in July 1942 conducted at Woods Hole Oceanographic Institute, Massachusetts. Live dog sharks were collected from the institute docks and placed in laboratory tanks. From July-September a series of controlled elimination experiments were conducted using 150 possible repellents in the form fish poisons, irritants, stenches, poisonous gases, ink and a variety of other chemicals. For these tests groups of 3-5 dog sharks were observed and individually given a score card. Strikes were then recorded on treated and untreated bait with each test about one to two hours in duration. The overall results were inconclusive. Irritants and stenches showed no results. Ink clouds only inhibited sight. Sharks would eat the poisoned meat only to die later making it unsuitable as a repellent for protecting humans. Maleic acid, copper sulfate, and decomposing shark meat were the only three materials found to have some effect. Still the results were discouraging and the project was almost abandoned at this point.

   Senior investigator and professional shark catcher Stewart Springer introduced the idea to use decomposing shark meat based off his knowledge of fishermen lore. It was recognized by fishermen that rotting shark flesh rendered the immediate area un-fishable and drove sharks away. Woods Hole investigators, as a last resort, concentrated efforts on decomposing shark meat. The Lab tests found that decomposing shark meat exudes chemical called ammonium acetate and when dissolved in water leaves acetic acid. Acetic acid was found to be the repelling agent. Since copper sulfate and acetic acid proved to be the most effective as a repellent it was decided to combine both the copper ion and acetate ion into one compound creating what was called copper acetate for maximum effect. Initial tank tests were promising, field tests were now in order.


   The first field tests were conducted in the gulf of Guayaquil near Ecuador, South America from December 6 1942- February 10 1943 by the OSRD. Four agents were evaluated. Maleic acid, copper sulfate, copper acetate, and  extract from decomposing shark meat. A series of fishing tests were conducted using three lines at various depths with one control, recording strikes on each line throughout the day. In progress report no.5 submitted to the committee of OSRD dated 28 February 1943 William Burden writes: “The tests for copper acetate were 100% satisfactory”. All others were found to be unfavorable in this report. Further studies were concentrated on the repellent quality of copper acetate.

   Additional field tests were conducted off the coast of Florida, Florida Keys and in the Gulf of Mexico from May 1943- January 1944 by the NRL with cooperation from the OSRD. Copper acetate was tested under a variety of conditions and depths. The tests included various fishing techniques, chumming, and even using trash to manipulate shark behavior. Cakes were secured to life jackets for simulation purposes placed on the surface and up to 12’ deep. Many shark species were encountered during these evaluations giving overall mixed results. Under low shark activity copper acetate was found to be effective up to 80%. With increased shark activity or frenzy feeding effectiveness dropped to under 50%. The two methods used to test copper acetate were in the form of cakes for both surface and depth and sprays for surface tests.

    Copper acetate is a colorless solution and to better see the dispersion for test purposes from the surface dye was added first incorporated in tests conducted off Mayport, Florida in June 1943. Supported by tests off Biloxi, Mississippi in August 1943 it was concluded that dark dye posses’ repellent qualities affecting visual senses of sharks on the surface. It was realized at this time that dark dye stuff could be used as a camouflage or concealment much like an octopus or squid. Another important factor was on the psychological aspect that with a dark dye the user can see the weapon in action. The NRL consulted the Calco Chemical Division of the American Cynamid Co. to develop a water soluble dye compatible with copper acetate. After a series of lab tests Calco presented a dark dyestuff of the nigrosine type. When dissolved in water nigrosine would color the water black or a very dark blue. In NRL report no. P-2230 25 February 1944 entitled “First Partial Report on the use of Chemical Materials as shark Repellents” it concluded that the Calco dyestuff provides an effective visual stimulus against sharks.

  For maximum effect the NRL concluded that a compound of copper acetate and Calco dyestuff should be prepared. The properties of both substances could affect multiple senses increasing the repellent effectiveness. The final mixture included 80% nigrosine dyestuff and 20% copper acetate. A series of three tests were scheduled off Mayport, Florida on May 27th and June 3rd 1944. For these tests an experimental packet for individual use was developed in the form of a chemical cake contained in a waterproof container. These final fishing tests on the shark repellent proved the mixture to be effective. Based off the results an interim specification was drafted until further data from service tests could be gathered.

   The Bureau of Ships issued interim specification R51S48 (INT), Shark Chaser (Life Jacket) on 15 June 1944. The Packet designed for individual use consisted of a 5 ½ oz. cake of repellent in a cotton bag protected by a blue outer envelope made from a vinyl-copolymer-coated fabric. The unit measures 8 ½” x 4 ½” x ¾” with cotton tie tapes to attach to inflatable life preservers and a lanyard with safety pin for use with kapok type life vests. The unit functions in the same manner as the dye markers but the chemical bag can be returned and secured by a snap fastener on the outer envelope.  The chemical cake is composed of 76% dyestuff, 19% copper acetate, and 5% soluble wax binder. Specification R51S48 Shark Chaser (Life Jacket) was standardized on October 1st 1945. Until this time the shark chaser was considered experimental.

The USAAF issued specification no. 40828 Packet, Shark Deterrent on 25 July 1944.The packet differs slightly from the navy’s version in that it does not have tie tapes and is not reusable. The overall unit is constructed from the same material and chemical mixture.


   On 23 September 1944 the NRL released the final report on the use of chemical materials as shark repellents. Based on the evidence the USAAF were the first to procure the shark deterrent in large quantities. Contract 33038-AC-6701 was awarded in December 1944 under specification 40828 for 85,000 packets to American Products Co. of Cincinnati OH. Deliveries were being made to general supply depots in February 1945. Official nomenclature: Packet, Shark Deterrent, Class 13, Stock no. 8300-623748. It should be noted that the original stock number issued upon contract was 8300-623738 and later changed at an unknown date and reason. Additional supplemental reading includes ADTIC Informational Bulletin no.4 titled “Sharks” dated July 1944.

In June 1944 the BuAer procured 2500 packets for field testing. The experimental packets were the same as used in the tests from May & June. These packets had no lanyard with safety pin and the chemical cake was contained in a paper bag protected by a waterproof envelope labeled Life Jacket Shark Chaser. In January 1945 the Aviation Supply Office initiated contract N288s-28906 under BuShips specification R51S48 (INT) for 160,000 packets to Zinc Howard Corp. of Passaic NJ. Deliveries to major supply points were expected by March 1945. Official nomenclature: Shark Chaser (Life Jacket) Stock no. R37-S-75.

 BuAer Technical Note 87-45 dated September 17, 1945 states:

Until further data has been accumulated from service areas to confirm the experimental results of the Shark Chaser, BuAer considers that the primary shark defense should continue to be the conventional technique outlined in “Shark Sense” and other publications”. It also goes on to say: “activities using the Shark Chaser are requested to furnish the Bureau of Aeronautics with any data available from actual survival experience”.

The project investigators understood that a 100% effective deterrent was not realistic based off existing knowledge. The objective was to find the most effective repellent as quickly as possible.   It was agreed that 67% effectiveness was satisfactory. The primary focus was orientated to morale and if the repellent actually worked that was a bonus. Shark deterrent was considered a medical project until it was found that it was possible to repel sharks. Calculations were determined by the following formula:  number on control minus number on repellent {divided by} number on control X 100 = % effectiveness. Ultimately the tests conducted in the labs and in the field were inconsistent. Further studies or amendments would rely on actual service use in the combat theatres. Design changes were made in the post war era designated under specification MIL-S-2785. In future generations the tapes were changed to nylon, first yellow then red and renamed Shark Repellent Compound, Packet. Shark repellent was still utilized into the 1980’s by US military forces.

   Survival reports and other era literature mention the use of chlorine capsules or tablets for use against sharks within naval aviation. These documents date from 1942-1944. It is not isolated to one unit so it cannot be easily dismissed and suggests common usage amongst the fleet. In tests conducted at Woods Hole in 1942 the results showed that chlorine had no effect. It is not clear where the idea of using chlorine as a repellent originated. No documentation has surfaced to suggest this as an official recommendation. The information contained in these documents mentioning the use of chlorine tablets (stored in a vial and carried in a pocket) come from the combat theaters. From here, we can only speculate why they used chlorine tablets. Was it based on folklore of the sea, or the reasoning that it is an effective irritant against humans so why not sharks? Was it used as a psychological factor for morale purposes? The truth is, it was probably some of each, but mostly the latter.

Above:  Test sample of 2500, as listed in the Air Sea Rescue Service supply catalog.

Below:  Photo from Navy TN 87-45.
Above:  Navy contract shark chaser.

Below:  Comparison to AAF shark chaser.

Above:  Enlargement of the early production  shark chaser from a Navy survival equipment display. This example appears to have no cord, only the safety pin.

Below:  Enlargement from our opening photo of Chris Magee. Note early production shark chaser and how the safety pin has been secured around the crotch strap of the life vest.

Bottom:  Captain Magee and his squadron members relax while awaiting transportation to the flight line. Three pilots have the chaser tied to their vests.

Their ride arrives, but it looks like some will be hoofing it.
Above:  Another VMF-911 pilot, Captain Wallace B. Thompson, USMCR. Following a combat tour flying Corsairs from Bougainville with VMF-211 in early 1944, he went on to join the newly formed squadron that started training with Corsairs, but was re-outfitted with twin engine Grumman F7F Tigercats.

Below:  LT (j.g.) Mel Cozzens (with headset and flight cap) flew with VF-29 off of U.S.S. Cabot from 11/44 - 4/45, scoring 6.5 victories. He is seen in this undated photo with the members of his division, one of whom wears a shark chaser packet.