Several decades later, Lee Fierro, who plays Mrs. Kintner, walked into a seafood restaurant and noticed that the menu had an "Alex Kintner Sandwich". She commented that she had played his mother so many years ago. The owner of the restaurant ran out to meet her - none other than Jeffrey Voorhees, who had played her son. They hadn't seen each other since the original movie shoot.
The mechanical shark spent most of the movie broken-down, and was unavailable for certain shots. This led Steven Spielberg to use the camera as the "shark", and film from the shark's point of view. Many think this added to the "chilling/haunting" quality in the final release saying that it would have made it too "cheesy" had they shown the shark as much as originally planned.
An accident during filming caused the Orca to begin sinking. Steven Spielberg began screaming over a bullhorn for the nearby safety boats to rescue the actors. John R. Carter, already up to his knees in water on the sinking Orca, held his Nagra (tape recorder) up over his head and screamed, "F**k the actors, save the sound department!" During the accident, the film camera was submerged, so its film, still submerged in sea water, was flown to a New York film lab where technicians were able to save the film. The accident is described starting at 01:30:07 in "The Making of Jaws" on the 30th Anniversary edition DVD.
Roy Scheider stated in an interview that in the scene where Lee Fierro (Mrs. Kintner) smacks him in the face, she was actually hitting him. Apparently, the actress could not fake a slap and so the multiple takes were some of the "most painful" of his (Scheider's) acting career.
Though respected as an actor, Robert Shaw's trouble with alcohol was a frequent source of tension during filming. In later interviews, Roy Scheider described his co-star as "a perfect gentleman whenever he was sober. All he needed was one drink and then he turned into a competitive son-of-a-bitch." According to Carl Gottlieb's book "The Jaws Log," Shaw was having a drink between takes, at which point he announced "I wish I could quit drinking." Much to the surprise and horror of the crew, Richard Dreyfuss simply grabbed Shaw's glass and tossed it into the ocean. When it came time to shoot the infamous USS Indianapolis Scene, Shaw attempted to do the monologue while intoxicated as it called for the men to be drinking late at night. Nothing in the take could be used. A remorseful Shaw called Steven Spielberg late that night and asked if he could have another try. The next day of shooting, Shaw's electrifying performance was done in one take.
During pre-production, director Steven Spielberg, accompanied by friends Martin Scorsese, George Lucas and John Milius, visited the effects shop where "Bruce" the shark was being constructed. Lucas stuck his head in the shark's mouth to see how it worked and, as a joke, Milius and Spielberg sneaked to the controls and made the jaw clamp shut on Lucas' head. Unfortunately, and rather prophetically, considering the later technical difficulties the production would suffer, the shark malfunctioned, and Lucas got stuck in the mouth of the shark. When Spielberg and Milius were finally able to free him, the three men ran out of the workshop, afraid they'd done major damage to the creature.
Composer John Williams conducted the orchestra during the 1976 Academy Awards, so when it was announced that he won the Oscar for Best Score, he had to run up to the podium to accept his Oscar and then run back to continue conducting the orchestra.
Martha's Vineyard, Massachusetts, was used as Amity Island primarily because even 12 miles out to sea, the sandy bottom was only 30 feet down, allowing the mechanical shark to function. Residents were paid $64 to scream and run across the beach as extras.
According to Steven Spielberg in the DVD 'making of' documentary, his original idea for introducing Quint was to have him in the local movie theater watching Moby Dick (1956) starring Gregory Peck. Quint was to be sitting at the back of the theater and laughing so loudly at the absurd special effects of the whale that he drove the other viewers to exit the theater, leaving Quint by himself. Spielberg says that the only thing that stopped him from doing that scene was Gregory Peck. Peck held part of the rights to that movie and when Spielberg approached him for permission, Peck turned him down. Not because he thought it was a bad idea to use the film that way, but because Peck didn't like his performance in Moby Dick (1956) and didn't want the film seen again.
Preview audiences screamed when the head of a shark victim appears in the hole in the bottom of the boat. Director Steven Spielberg re-shot the scene in editor Verna Fields swimming pool because he wanted them to "scream louder".
Three mechanical "Bruces" were made, each with specialized functions. One shark was open on the right side, one was open on the left side, and the third was fully skinned. Each shark cost approximately $250,000.
In a biography, Steven Spielberg revealed how Robert Duvall helped to encourage him into making the movie. In return, Spielberg offered the role of Brody to Duvall but he turned it down, fearing that it may make him too famous as a result.
When composer John Williams originally played the score for Steven Spielberg, Spielberg laughed and said, "That's funny, John, really. But what did you really have in mind for the theme of Jaws (1975)?" Spielberg later stated that without Williams's score, the movie would only have been half as successful.
Although Steven Spielberg wanted Charlton Heston to play Brody, the main reason Spielberg decided against casting him was because of Heston's "saving the day" role in his previous movies, Airport 1975 (1974) and Earthquake (1974). Spielberg reasoned that if Heston would have been cast, it signifies to the audience that the shark has virtually no chance against the hero.
The line "that's some bad hat, Harry", at 16:35, is the slogan for Bad Hat Harry Production Company. Their ad page features a cartoon rendition of Martin and Harry sitting by the beach, with a shark fin in the water in the background.
With the schedule expanding from 52 to 155 days, Steven Spielberg had to juggle Universal's impossible deadlines, an unfinished script, chaotic conditions off Martha's Vineyard and a belligerent Robert Shaw. On the last day of shooting, Spielberg wore his most expensive clothes to deter a dunking from the mutinous crew. As soon as the shot was captured, he jumped in a speedboat and sped shoreward yelling, "I shall not return."
Quint's boathouse set was built in Martha's Vineyard on an abandoned lot. The city council made the production crew sign an agreement to demolish it after filming and replace everything exactly as it had been - right down to the litter.
Steven Spielberg was not the original director of Jaws. The first person was fired after a meeting with producers and studio execs. In the meeting he said that his opening shot would have the camera come out of the water to show the town, then the whale (instead of the shark) would come out of the water. The producers said that they were not making 'Moby Dick' and would not work with someone who did not know the difference between a whale and a shark.
In the actual Jersey Beach shark attacks of 1916 (which Hooper mentions in the film), the sequence of attacks is similar to that of the film: a swimmer in the surf; a dog; a boy; and the leg of a man in a tidal slough.
There is a much-repeated story that a lot of the pain on Susan Backlinie's face (Chrissie Watkins, the first victim) is real, since as well as moving her about in the water, the frame she was strapped into was breaking her ribs. In a radio interview, she denied being injured.
Charlton Heston was so annoyed with being rejected for the role of Brody that he later made disparaging comments about Steven Spielberg and vowed never to work with him. He later turned down Spielberg's offer of the role of General Stilwell in 1941 (1979).
Steven Spielberg observed at the first testing screening that the first surprise appearance of the shark got the biggest scream from the audience. But after he re shot the scene at Ben Gardner's boat, the surprise appearance of Ben Gardner's head got the biggest scream, while the appearance of the shark received half the reaction it used to. Spielberg said it taught him a lesson that a movie can have only one major scare moment, because afterward the audience will be on guard against the film.
A scene filmed, but not included in the final release, was during the second beach attack. Brody's son, swimming in the "shallow area" is frozen in terror as the shark approaches him; the man saves his life by pushing the boy out of the way at the last minute and putting himself in the path of the shark. There is a shot of the bloody, dying man's upper body being dragged briefly along in the shark's jaws before being pulled underwater. Steven Spielberg shot the scene, but decided it was far too gruesome and didn't include it. The DVD release shows the scene being shot, blood and all, during the The Making of Steven Spielberg's 'Jaws' (1995) documentary, but it is not included in the "Deleted Footage" or "Outtakes" sections of the DVD.
There were two 300-pound weights attached to Susan Backlinie that were being tugged by two groups of crewmen on shore. One group would pull right, and the other would pull left. It took three days to film that sequence.
Quint's tale of the USS Indianapolis was conceived by playwright Howard Sackler, lengthened by screenwriter John Milius and rewritten by Robert Shaw following a disagreement between screenwriters Peter Benchley and Carl Gottlieb. Shaw presented his text, and Benchley and Gottlieb agreed that this was exactly what was needed.
Robert Shaw ad-libbed the "Here lies the grave of Mary Lee" line after Steven Spielberg prompted him to give Brody's wife (on the dock) a hard time. Asked later where he quoted it from, as it would require getting a license and release from the author to be used in the film, Shaw said that was unlikely, as it was off an old grave marker in Ireland.
Lee Marvin was Spielberg's first choice for the role of Quint, despite his reservations about using big-name actors. Marvin thanked him but replied that he'd rather go fishing. Spielberg then wanted Sterling Hayden for the role of Quint. Hayden, however, was in trouble with the Internal Revenue Service for unpaid tax. All Hayden's income from acting was subject to a levy by the IRS, so there was an attempt to circumvent that: Hayden was also a writer, so one idea was to pay him union scale for his acting, and buy a story from him (his literary income wasn't subject to levy) for a large sum. It was concluded that the IRS would see through this scheme, so Robert Shaw was cast by Spielberg instead on the recommendation of the film's producers, Zanuck and Brown.
According to the boat handlers who worked on the film, Quint's boat, "Orca", was a studio fabrication based upon a boat purchased locally. After the special effects team finished with it, it was so top-heavy as to be unseaworthy. Ballast would correct that, but the only large quantity of lead that could be located locally was owned by a local dentist who was going to use it to shield his X-Ray room. So that was rented from him at an exorbitant fee. The fake Orca, designed to sink, was actually more seaworthy than the real thing.
The last known surviving mechanical shark of 'Bruce' is suspended atop two metal poles in the middle of an auto wrecking yard, at U Pick Parts in Sun Valley, CA, in the San Fernando Valley. The lot is owned by Nathan Adlen.
When the shark attacks Hooper's cage, there's live footage of a real Great White with a rope hanging from its mouth. This shark's mouth is clearly much smaller than the shark's mouth when it attacks the boat moments later. These scenes were filmed by noted shark photographers Ron Taylor and Valerie Taylor with the help of shark expert Rodney Fox specifically for the movie. Because the Great White sharks they filmed would be smaller than the mechanical shark in the movie, they constructed a smaller version of Hooper's shark cage. Inside the cage they alternately used a small mannequin or a little person. One of the sharks they attracted got caught in the cage's cables and tore it apart trying to escape. The footage was so good that they changed the script to reflect the destroyed cage and Hooper escaping by hiding on the ocean floor. However, the small person used in the scene refused to go back in the miniature cage, which was damaged in the incident.
The gray and cloudy sky in water scenes is artificial. It is an image on a giant wall placed in the Universal studios. In front of the wall is a huge artificial lake, the "Falls Lake", which - together with the wall - was a backdrop for more than 20 movies already, including Jaws (1975).
The first shark killed on the docks, which is supposed to be the "man-eater" in the movie, is actually a real shark killed in Florida because there wasn't a big enough one in Martha's Vineyard. According to Carl Gottlieb's "The Jaws Log", by the time it had been shipped to the set and prepared for filming, it was starting to decompose quite badly and the smell was appalling. As it was hung from its tail, its internal organs broke loose and piled up in the back of its throat, adding to the discomfort of those forced to work in close proximity to it.
After the surprise success of the film, Hollywood insiders ascribed the film's effectiveness mostly to veteran editor Verna Fields rather than the little-known, 28-year-old Steven Spielberg. Although he undoubtedly learned much from Fields, Spielberg wished to prove his worth in following films and never worked with Fields again. It should be said that from Jaws (1975) until Fields death, Spielberg only made three films: Close Encounters of the Third Kind (1977), 1941 (1979) and Raiders of the Lost Ark (1981).
This was the first movie to reach the coveted $100 million mark in "theatrical rentals", which is about 45% of the "box office gross". It was the highest-grossing of all-time in the U.S. until Star Wars: Episode IV - A New Hope (1977).
The "forward tracking, zoom out" shot used when Brody realizes Alex Kintner has been eaten has been called "the Jaws shot" by some video teachers who instruct students on using this move. However, this shot is merely a reverse of the "forward zoom and reverse tracking" shot invented by Irmin Roberts for the disorienting height shots in Vertigo (1958). A similar shot appears to have been used for the dream sequences in Truffaut's Fahrenheit 451 (1966), in which Montag runs down an apparently endless corridor, passing doors on both sides but seems to never get closer to the end.
The lighthouse in the film near the beach is an actual lighthouse on Martha's Vineyard where the filming took place. Because of the billboard in the scene, the lighthouse had to be "moved" with special effects in post-production.
The scene where the head pops out from under the boat was not originally scripted. Director Steven Spielberg says he "got greedy" after he saw the preview audience's reaction to the scene where the shark jumps out behind Brody's head and wanted "one more scare."
One oft-repeated falsehood about the movie was that the color red is never used in any clothes or any backgrounds as Steven Spielberg wanted it to be only seen as blood. However, a simple viewing of the film shows plenty of red throughout: hats and clothing, American flags, Coca-Cola items, upholstery, sign lettering, coolers, can and jar labels, et al, as well as much of the hull of the Orca itself.
As Hooper examines the remains of Chrissie Watkins, he says that the tissue damage "indicates the non-frenzied feeding of a large squalus." "Squalus" is simply Latin for "shark" (though "Squalus" is also the genus name for dogfish sharks). Hooper uses the Latin for the oceanic whitetip shark ("Longimanus") and what's probably supposed to be the longfin mako shark ("Isurus glaucus").
On the DVD documentary, Steven Spielberg states that his original idea for introducing the shark was going to be a scene that took place at the dock at night: The harbor master would be watching TV, and through the window behind him the audience would see a row of boats rising and falling as the shark swam underneath them. Spielberg believed that the swell of the boats would help indicate the huge size of the shark; however, the logistics involved (for example, getting all the boats to go up and down at the correct intervals) proved too difficult to coordinate properly. Additionally, the constantly malfunctioning shark would not allow the scene to be filmed. Much to Spielberg's disappointment, the scene had to be shelved.
Despite reports to the contrary, "Bruce" was actually tested in water before it arrived on Martha's Vineyard and worked perfectly. However, the tests were done in the non-salt water tank at Universal Studios. Once it was placed in actual ocean water, the salt played havoc with the shark's controls.
As most of the seaside resorts in 1975 experienced a downturn in visitors, some of the establishments would resort to innovative ways to lure in customers. One recorded example was a seafood restaurant in Cape Cod which proudly displayed the sign "Eat Fish - Get Even".
Producers Richard D. Zanuck and David Brown optioned the film rights to the novel for $175,000 in a deal which also included a first-draft screenplay from author Peter Benchley. This draft, extremely faithful to the novel, would later be rejected by Steven Spielberg. The subsequent two drafts from Benchley would also be rejected.
Fabien Cousteau - grandson of Jacques-Yves Cousteau - invented a Great White Shark-shaped submarine to study the sharks in a natural setting. He discovered that, contrary to the killing-machine nature shown in Jaws, Great Whites are actually very cautious fish. They also communicate with each other via their fins and body language.
This was Jonathan Filley's only appearance on film. He was discovered through local auditions. Although never appearing after that, he became a successful production assistant and would eventually reunite with Steven Spielberg 30 years later on War of the Worlds (2005) as the head production assistant.
Howard Sackler was asked to contribute to the screenplay because of his experience as a scuba diver. Sackler's only proviso was that he not receive screen credit as he felt that he didn't work long enough on the film.
Pre-production had been cut short in the hopes of taking advantage of the unseasonably good weather in Martha's Vineyard. However, when the production landed at the Vineyard, the weather took a turn for the worse. Consequently, shooting had to begin without a finalized script, meaning Steven Spielberg and Carl Gottlieb had to work on the screenplay after they'd finished filming for the day.
Steven Spielberg cast Roy Scheider based on his performance in The French Connection (1971). The studio was wary of having him but eventually agreed to the casting decision when Scheider signed a three-picture deal. The sequel, Jaws 2 (1978), would be Scheider's last film under the deal, the other one was Sorcerer (1977).
After filming was completed Steven Spielberg said "My next picture will be on dry land. There won't even be a bathroom scene". He was predominantly true to his word. His next film would be Close Encounters of the Third Kind (1977) which took place on land, but there were nevertheless a couple of bathroom scenes.
The "oceanographic institution on the mainland" that Matt Hooper comes from refers to the real-life Woods Hole Oceanographic Institution in Woods Hole, Massachusetts. Bob Ballard who rediscovered the RMS Titanic worked from Woods Hole.
Despite the film's mammoth box-office returns, Robert Shaw didn't earn a penny out of it. He was facing heat from the IRS for tax evasion, and due to working in countries as diverse as the US, Canada and Ireland, he had to forgo his salary to make amends.
The film was simultaneously shown in 490 theaters on its opening weekend, the first time for Hollywood, setting the standard for subsequent films. The film was originally booked in about 1000 theaters, but MCA executive Lew Wasserman wanted that cut back, saying he wanted lines at the box office.
Following the release of the film, a sort of hysteria overtook some members of the public, resulting in numerous incidents across the country. In one, a beach in Southern California was cleared by lifeguards due to sharks in the water, which turned out to be dolphins; and in a sadder incident in Florida, an immature pygmy sperm whale that beached itself was beaten to death by bystanders who mistook it for a shark.
Some scenes that have been declared "missing" from the video were not in the original theatrical release. When the movie was first televised, the network needed fillers after editing it for TV, so they used extra footage from the film's production.
The mechanical shark used in the film was nicknamed "Bruce" by its handlers, and the "full body" version tours around museums, while "Bruce II" resides at the Universal Theme Parks and "bites at" tourists on the tour ride.
Steven Spielberg always considered Jurassic Park (1993) a sequel to Jaws (1975), but on land. People saw differences though, where the latter focused on character development as much as on its creature, while the former only used the dinosaurs to sell the film, and not the characters.
In the inquest scene where Hooper confirms the shark attacks as he analyzes the remains of the first victim Chrissie Watkins, he names two likely suspects by their scientific names but never clarifies them. Longimanus refers to the Oceanic Whitetip Shark (Carcharhinus Longimanus), well-known for following ships in the expectation of a sinking. Issurus Paucus is the rare Longfin Mako. The latter is an unusual choice since there are no record of attacks of humans compared to its plentiful cousin the aggressive Shortin Mako (Issurus Oxyrhincus).
Peter Benchley's novel was first discovered in galley form at early 1973 by then Cosmopolitan Magazine editor and producer David Brown's wife Helen Gurley Brown who was to be excerpting part of the novel to be published in an upcoming issue. Brown saw it by accident, having read it then a few days brought it to the attention of his partner Richard D. Zanuck, subsequently obtaining the rights to the book at the end of the year.
In the socialist Hungary, the movie was only released in 1985. It became the second biggest grossing film that year: 1.5 million tickets were sold (Hungary's population was around 10 million at that time!) The biggest hit that year was Bomber (1982) starring Bud Spencer.
Just before Hooper goes down in the shark cage, he tries to spit on his scuba mask and says "I've got no spit." This line is meant to imply that he has been under extreme duress, since high levels of stress are known to cause inadequate saliva production and dry mouth.
Steven Spielberg originally wanted Joe Spinell and Frank Pesce to be the two guys on the dock fishing for the shark at night (Pesce as the guy who falls in the water and Spinell shouting to him). Unfortunately, Pesce couldn't make it to Martha's Vineyard.
Although he goes uncredited, the baseball announcer we hear over the radio during one of the beach scenes is sports announcer, Charlie Jones. He was mostly known for football. All of the players he announces here are fictional.
Quint's boat, named the "Orca", was also the name of a knock-film film named Orca (1977) that was released in 1977, largely to capitalize on the "shark craze" that came after the success of Jaws (1975) in 1975.
The original U.K. video release of the 25th Anniversary version was wrongly labeled as a P.G. rating, when it should have been a 12 rating, due to Roy Scheider saying the "F" word in the documentary. The mislabeled videos have been withdrawn.
The trivia items below may give away important plot points.
When Roy Scheider was trapped in the sinking Orca, it took 75 takes to get the shot right. Scheider did not trust the special effects team to rescue him in case of an emergency so he hid axes and hatchets around the cabin just in case.
After the shark blows up, the groaning sound effects during the shot of the carcass sinking are the same ones the truck makes as it crashes off a cliff in Steven Spielberg's first film, Duel (1971). The sound effect is from the original Creature from the Black Lagoon (1954).
Peter Benchley was not happy with Steven Spielberg's ending where the shark is killed when a compressed air tank explodes in its mouth, claiming it was unrealistic. Spielberg defended himself by saying he will have held his audiences' attention for two hours and they would believe anything in the end no matter how unrealistic or unbelievable the ending really was.
In the original script, Quint was killed off by drowning. The rope from the harpoon that he fires at the shark wraps around his foot and he is pulled under by the shark, calling for Brody to give him the knife. (This was also the way the character was killed off in the book and, according to an interview with Steven Spielberg about this scene, it is similar to the way Ahab dies in "Moby Dick".) However, it was decided that Quint should be eaten as this would be the most tragic for the character based on his experiences on the USS Indianapolis, so the script was changed to what is in the movie.
In the original novel, Hooper has an affair with Brody's wife, and is killed by the shark in the cage at the end. However, because the relationship between Brody's wife and Hooper was considered by many to be irrelevant to the plot, and arbitrarily included in the novel just to "sex it up", it was omitted from the film script, and Hooper was allowed to survive.
The original scene of Alex Kintner's death called for a doll of Alex to be floating among the bathers, then the shark would jump out of the water and grab the doll and raft in its mouth. But as was typical of the mechanical shark, it didn't function properly. It would either come out of the water too high, not high enough or totally miss the raft. Finally, the shark succeeded in grabbing the raft, and in doing so, rolled over on its side, much like a real shark would do. This is the take Spielberg decided to use. However, the producers were concerned that the image of the shark with Alex in its mouth was too disturbing and might jeopardize the film's PG rating. Therefore, Spielberg and editor Verna Fields trimmed the beginning of the shot so only the shark's fins are briefly seen as it flips over.
Though his affair with Brody's wife was left out of the film, Hooper's death was actually in the script. The plan was to have a dummy representing Hooper placed in a cage underwater, and Australian filmmakers Ron and Valerie Taylor, who were filming the underwater shark scenes in Australia, would entice an actual shark to attack the cage and tear the dummy apart. They could never provoke the shark properly. Ultimately, the shark did attack and destroy the cage, but there was one problem: the Hooper dummy wasn't inside at the time. As this was the best footage they had, Steven Spielberg decided to use it, and allow Hooper to escape the shark.
Before the shark was blown up at the end, an explosives expert with a blasting permit was needed. Richard S. Edwards had done extensive explosives work while in the Navy and then for Woods Hole Oceanographic Institution, and he agreed to place the dynamite for the final scene. Finding he couldn't get past the teeth of the shark mock-up, he was forced to crawl into the back of the device, but it was made of sharp fiberglass. After wrapping his knees with towels and putting on heavy gloves, he had to carry the dynamite in his mouth to place it in the head of the "shark," where his picture was taken and is now in the archives of Woods Hole Oceanographic Institution, along with the oral history that describes his contribution to this classic movie.
In the book, it is revealed that Mayor Larry Vaughan is being blackmailed by the Mafia to keep the beaches open. The Mob has invested in Amity real estate, and is hoping for a multi-million dollar sale.
Regarding the ending, author Peter Benchley thought Steven Spielberg's idea of shooting and blowing up the compressed air tank was horrible. Spielberg even considered having Chief Brody kill the shark only to look up and observe several other fins coming towards him.
Quint's name comes from the Latin word for "fifth". Quint is the fifth person killed by the shark (after Chrissie Watkins, Alex Kintner, Ben Gardner's disembodied head in boat, and Michael's sailing teacher).
The entire second half of Jaws (1975) takes place on the ocean, with just Roy Scheider, Robert Shaw and Richard Dreyfuss carrying it between the three of them. No other characters appear (bar the shark) and dry land is glimpsed near the end of the move. The reason was Spielberg didn't want land to be seen because he thought the audience would think that the characters could just run back to shore. He wanted to isolate the audience as much as the characters.
When the shark is destroying the cage after Hooper swims away, you can see the shark turn and twist upside down. This was actual footage shot by Ron Taylor. As seen and explained in a recent Jaws (1975) documentary, the Great White Shark the couple had been filming became entangled in the cage's suspension ropes. The cage broke loose and sank to the bottom, however the shark managed to escape and swim off (as can also be seen in the film). After the shark had cleared the area, Ron had to take a second cage to the bottom in order to rescue the first. Ron and Valerie Taylor eventually went on to develop the chain-mail shark-proof diving suit.
The story that Quint tells about his experiences aboard a sinking cruiser is a fictionalized version of the actual World War II Portland-class cruiser USS Indianapolis. Of the 1,196 crewman aboard only 316 survived while 300 died during the sinking and the other 579 dying from exposure, dehydration and mostly shark attacks. The majority of the dialogue in the film was largely written by Robert Shaw. The most major difference between Quint's account and the actual event was the date of the sinking (mentioned in the film as June 29, 1945), while the ship was actually sunk over a month later on July 30.
According to Carl Gottlieb's "The Jaws Log", Steven Spielberg was never happy with the moment when Ben Gardner's head appears in the hole in the bottom of his boat. Preview audiences jumped at this scene, but Spielberg wanted more than an ordinary shock moment. However, the studio was unwilling to budget a re-shoot. So Spielberg declared that he'd pay for it himself, assembling a crew in editor Verna Fields' back-yard swimming pool, which would serve as the underwater location. A gallon of milk gave the water enough of the look of Nantucket Sound. The boat bottom was placed in the pool and Richard Dreyfuss' stunt double went through the action. The studio eventually ate the cost of the re-shoot, and the scene was taken to a much higher level, just by changing the composition and timing of a few feet of footage.