Deep Diving Into WWII Naval Warfare Aboard Sub Hunter GREYHOUND

by TREVOR HOGG

Not only does Tom Hanks portray Commander Ernest Krause in Greyhound, but he also wrote the screenplay based on The Good Shepherd by English novelist C.S. Forester. (Image courtesy of Apple)

Seafaring adventures inspired the imagination of English novelist C.S. Forester who wrote the Napoleonic War-era Horatio Hornblower series and World War II-era The Good Shepherd, which Tom Hanks turned into a screenplay and retitled Greyhound in reference to the code name of the destroyer USS Keeling. The Oscar-winning actor stars as Commander Ernest Krause who is given his first wartime command escorting 37 allied ships across the North Atlantic while being hunted by German U-boats.

In order to guide the production, director Aaron Schneider (Get Low) put together an extensive website with details and photographs of all of the ships that were suppose to be in the story. Trouble arose when the visual effects methodology proved to be problematic once post-production commenced. In order to fix the issue, executive producer Aaron Ryder (Arrival) turned to the visual effects team responsible for Transcendence.

“Aaron called me and asked, ‘Can you help me out with this?’” recalls VFX Producer Mike Chambers (Tenet, Dunkirk). “We talked about supervisors and he said, ‘What do you think about Nathan McGuinness?’ I answered, ‘I like Nathan. We both know how we did on Transcendence. Let’s go.’ Over the course of this show, Nathan and I were absolutely partners joined at the hip to make the effects look great and fight whatever battles that had to be fought.”

The practical effects had to be digitally replaced in post-production lasting from October 2018 to February 2019. “The interiors and a lot of the exterior immediate deck [of the Greyhound] were shot on an actual Fletcher-class destroyer [USS Kidd in Baton Rouge] but it was landlocked,” states Chambers. “There was no motion or background to speak of. The bridge was built on a gimbal to try to help with the motion, but a lot of the practical stuff didn’t work as well as it needed to. That’s why we had to work over all of those shots.”

There were over 1,300 visual effects shots, with the water and exteriors being entirely CG. “Nothing was just an A/B composite,” Chambers remarks. “A lot of the shot count was treating shots where we had existing foreground material, like the dialogue scenes. There are not as many huge, full-on-CG, wide, epic shots, but a good number of them. Every day we kept dealing with whatever the issues were, and trying to get everybody on track and moving forward. It was certainly a scramble towards the end.

“Early on I was screaming to get more editorial turnovers than what I was getting, but eventually got what we needed,” adds Chambers. “Fortunately, we did have a semi-rough cut of the movie. We definitely knew which sequences were going to need more focus, resources and time. As things got fine-tuned, what we would think of as simple shots came late [in post-production], so that became more of a thing.” Originally, there were going to be multiple visual effects vendors.

“However,” explains Chambers, “due to circumstance, schedule availability, and knowing that we needed a certain level of quality and believability [the decision was made to go with a single vendor]. Fortunately, Nathan and I have a long-term relationship with DNEG and knew what they are capable of. When we learned that their visual effects supervisor was going to be Pete Bebb, I said, ‘Sign me up.’ I had a great deal of confidence in DNEG, and they went above and beyond.”

“[We visited the HMS Belfast in London because] I wanted to look at an actual World War II destroyer to see what’s involved in the build of it, because we were going to get incredibly close to the Greyhound. The ship build took the duration of the show.”
—Pete Bebb, Visual Effects Supervisor, DNEG

“The interiors and a lot of the exterior immediate deck [of the Greyhound] were shot on an actual Fletcher-class destroyer [USS Kidd in Baton Rouge] but it was landlocked. There was no motion or background to speak of. The bridge was built on a gimbal to try to help with the motion, but a lot of the practical stuff didn’t work as well as it needed
to. That’s why we had to work over all of those shots [in post-production].”
—Mike Chambers, VFX Producer

DNEG visited the HMS Belfast in London to get a sense of how the Fletcher-class destroyers were actually built and applied that knowledge to the CG versions. The sky was mapped out for the entire duration of the film’s journey across the Atlantic and determined the light source for each shot. (Images courtesy of DNEG. Final image courtesy of Apple)

It was critical to create the impression that the bow of the Greyhound was crashing through the water with the help of atmospherics such as ocean spray. The weathering of crossing the Atlantic Ocean was something lacking in the practical shooting on the USS Kidd and was added to the CG version of the Greyhound. (Images courtesy of DNEG)

A detailed chart was produced that categorized the difficulty and state of development of each shot for DNEG facilities in London, Vancouver and Mumbai. “I picked out shots within these categories at certain points of the film to fast-track so we knew what we were aiming for,” explains DNEG VFX Supervisor Pete Bebb. “What you can’t do is change your mind with this huge machine behind you. Nathan, Mike, Aaron and Tom could see it and sign off from the look development point of view.”

Bebb realized that the layout pipeline needed to be rewritten. “You could scrub through the entire period of time with all of the ships,” he says. “The cameras would go instantly into layout so they would be in the correct place in the ocean, the right type of Beaufort scale and the proper time of day. Then you could render them out and review it the next day. In regards to the color pipeline, I pushed for using an internal one so we balanced all of our neutral grade all the way through the entire film. We suggested CDLs on top of that and always gave it a half stop more so there was more latitude that Nathan could play with.”

Even though the water was fully CG, it was important for Visual Effects Supervisor Nathan McGuinness (Master and Commander: The Far Side of the World) to emulate the actual shooting conditions of being out in the ocean. “One of the hardest parts is the motion of the ocean as well as the camera placement,” McGuinness says. “Applying a real-world approach in the beginning was a better way to put everyone’s mindset to get to where we were going. I had a team from a small previs company called Day For Nite. I mapped out the journey so you could come up on a bird’s eye view with one camera and see where the convoy or the Greyhound was. Then I would drop the camera back down into where it was supposed to be in that part of the movie. I felt that was the only way to do it as accurately as possible because otherwise I wouldn’t have known where West and East was or the time of day.

“Along with the zigzagging and maneuvers that the convoys take, we had to also know that there was a destination point,” adds McGuinness. “It was a difficult process to share with other people. I brought in the previs artists to work side by side with me and my visual effects team. I was building the story and everybody who needed to be part of the filmmaking process was around us. The editors were dropping in the sequences.

[Producer] Gary Goetzman and Tom Hanks were looking at it, saying, ‘I don’t know if this makes sense. We have to do a bird’s eye.’ [Cinematographer] Shelly Johnson (Hidalgo) came in consistently with me and sat with the EXR files. I had the Avid running on one screen, and DaVinci Resolve running on another screen. We’re
looking at the cut and then the shots.”

Naval consultant Gordon Laco was brought onto the project to ensure authenticity. “I’d say, ‘This maneuver written in the script,” McGuiness notes. “Tell me more about it. Why has this maneuver been so traditional in maritime warfare since the 1600s?’ He would give me a good explanation. I would then start prevising the tactics. But then I would have to say to him, ‘This is a movie!’ Gordon also had a strong understanding of the sonar and the capabilities at the time.”

Balancing readability and believability of what the lighting conditions would be like in the North Atlantic was hard. “It was a difficult part of the process, especially when you’re telling the studio that you’re putting as much effort in a shot that at the end of the day you’d only see 5% of it,” remarks McGuinness. “But we had to because Tom was so passionate about what you don’t see. People smoking on the deck would be court martialed because that would be an immediate telltale for the U-boats. The ships had to cross with no lights. It was dark. We had to portray that. I did numerous 24-hour HDRs on beaches. I picked the lighting for the lighting teams.”

DNEG had 10 Canon 5D cameras each placed upon an individual tripod which took time-lapse HDRs every 30 seconds to produce a 60K sky. “We put that on the top of the office in London and a team was sent to Brighton Beach to do the same thing because we needed a clean horizon,” explains Bebb. “It gave us the exact time, clouds, and light which were then offered to Nathan. He picked specific ones and that gave us an HDR map per scene and time of day.”

“The shots from Brighton Beach provided us with weather all of the way down to the horizon line. It gave us this narrow band where the sky finishes and you get this band of light. We used that quite a lot to silhouette ships against it.”
—Pete Bebb, Visual Effects Supervisor, DNEG

“I spoke to some guys who explained to me that German torpedoes sounded like a 125cc engine on a motorbike, so they screamed. That helped me to visualize the turbulence
underneath.”
—Nathan McGuinness, Visual Effects Supervisor

Visual Effects Supervisor Nathan McGuinness did extensive research into what German U-boats were in operation during the time period of Greyhound, and he became fascinated as to what it would have been actually like to be onboard one. Shots featuring the U-boats were a late addition to the post-production schedule and had to be created from scratch. (Images courtesy of DNEG)

VFX Supervisor Nathan McGuinness did extensive research into what German U-boats were in operation during the time period of Greyhound, and he became fascinated as to what it would have been actually like to be onboard one. Shots featuring the U-boats were a late addition to the post-production schedule and had to be created from scratch. (Images courtesy of DNEG)

Journals were a critical part of the research. “I also researched the era,” states McGuinness. “My rooms were covered in every U-boat that potentially crossed. I almost felt that I had a stronger connection to the wolfpack [eight to 20 U-boats would join together to attack convoys at night] than to Tom Hanks because I would have loved to be inside one of them. The taunting that those U-boats gave these convoys were horrific, but their life was horrific too.”

Multiple versions of ships had to be built for the purpose of continuity. “It wasn’t like one asset got you through the whole movie, because they’re under attack the whole time,” McGuinness says. “The asset library was massive. We started with absolutely nothing. We built various designs of U-boats, all based on my research.”

Bebb and his visual effects team visited the HMS Belfast in London. “I wanted to look at an actual World War II destroyer to see what’s involved in the build of it, because we were going
to get incredibly close to the Greyhound. The ship build took the duration of the show,” says Bebb. Sub assets were produced to reflect the various states of damage. Adds Bebb, “We’d know that the gun turret was destroyed so we would swap it out for a destroyed version, and that would happen automatically as part
of the layout system.”

Mathematics was key in making sure that ships interacted with the ocean properly. “You study the statistical drawing of the ships, find where the center of gravity is located, and take in account the dry and laden weights,” remarks Bebb. “You knew where the waterline was so you could put them down correctly for what they are. You can then calculate their tonnage and then calculate what that ship would do in a certain Beaufort scale of water.”

There are a couple of dramatic moments that occur like when the U-boat emerges right alongside the Greyhound resulting in a gun battle and a torpedo grazing off of the side of the destroyer. “Weirdly enough, that sort of stuff used to happen. U-boats would surface so close in proximity to these destroyers,” says Bebb. “The destroyer’s guns are five inches and couldn’t get down low enough to take them out. There was an interview with Tom Hanks where he asked if torpedoes could actually graze the side of a ship. The arming head at the front of the torpedo has to hit dead-on perpendicular to detonate.”

Sounds assisted with visualizing shots. “I spoke to some guys who explained to me that German torpedoes sounded like a 125cc engine on a motorbike, so they screamed,” notes McGuinness. “That helped me to visualize the turbulence underneath.”

DNEG researched what possible torpedoes would have been used by the U-boats at the time. “We tended to go with one that had a brass head,” explains Bebb, “so you could see it easier in the water, because most of them were grey so you couldn’t see them.” Natural elements also assisted with readability. “Most of the time, with the aerial shots of the convoy, it’s the actual wake and smoke stacks that you see as the ships blend in slightly,” continues Bebb. “The shots from Brighton Beach provided us with weather all of the way down to the horizon line. It gave us this narrow band where the sky finishes and you get this band of light. We used that quite a lot to silhouette ships against it.”

Most of the radar screens were replaced in order to reflect the story correctly. “400 to 500 foretold in bridge and radar shots,” reveals Bebb. “One of the visual effects supervisors at London, Ian Simpson, was an old analog engineer at BBC. He designed and built the radar screens to how they would have done it back in the day. We had numerous radar shots, so a lot of effort went  into making them look authentic.”

It was important to avoid having the trace fire look like lasers. “They used to load one in five rounds for tracers at night, so we animated it like that,” says McGuinness, who was driven by a certain mandate. “I wanted every shot to feel like it was at sea. The hard stuff was setting up the tone of the ocean. There were a couple of shots we did where I felt like we were looking at the bow and were plowing through. All of the visual effects ingredients are in that shot. It is a huge array of work. We stare at it and go, ‘It’s a water job!’ But at the same time, it was the assets of U-boats, fleets and convoys, as well as destruction, attacks, flares, night, skies and bird’s eye views. I don’t think there’s anything we’re missing, but it all contributes to the show as a whole. We drew from all of our past experiences and applied them to Greyhound.”

“It wasn’t like one asset got you through the whole movie, because they’re under attack the whole time. The asset library was massive. We started with absolutely
nothing. We built various designs of U-boats, all based on my research.”
—Nathan McGuinness, Visual Effects Supervisor

Even in the darkest corners of the frame a great attention was paid to detail. DNEG served as the sole vendor for Greyhound and had five categories of shots that went from simple, motion graphics, medium, full CG and very hard. (Images courtesy of DNEG. Final image courtesy of Apple)