Animating a convincing swim cycle is all about rhythm, flow, and believable body mechanics in a weightless environment. In this tutorial, Supervising Animator and longtime Animation Mentor mentor Jason Martinsen walks through how to create smooth, natural swimming motion for characters in Maya, building on the same core body mechanics principles taught in Animation Mentor’s Character Animation program.
Meet Jason Martinsen
Jason Martinsen has been a professional animator since 2006 and is currently a supervising animator at Sunrise Productions. He previously worked at Framestore, Reel FX, Sony Imageworks, and Blue Sky Studios on film productions like Storks and Ferdinand. Other projects include Scoob!, Back to the Outback, Rumble and Monkey King.
You can learn more about Jason and his work here.
Studying Swimming Motion
Jason starts by grounding the exercise in reference, just as he does for walks, runs, and jumps in his other body mechanics demos. He encourages animators to:
- Study live-action footage of different swim styles such as freestyle, breaststroke, or underwater gliding.
- Look for the main cycle rhythm, where the body leads, and how the arms, legs, and head offset one another over time.
- Pay attention to how buoyancy changes the feel of weight, with slower acceleration and smoother deceleration than on land.
Rather than copying reference exactly, Jason recommends using it as a base to understand timing and arcs, then stylizing for clarity and character.
Blocking the Swim Cycle
Jason blocks the swim much like a walk or run cycle, using a repeatable time range with matched first and last frames so the action can loop cleanly. Core keys include:
- A streamlined “reach” pose with arms extended and body aligned.
- A “pull” pose where the arms sweep back and the torso compresses slightly.
- A “kick” or leg pose that supports the thrust of the stroke.
He emphasizes:
- Working in stepped keys at first to focus on clear silhouettes and strong, readable poses.
- Using the character’s center of mass to define a smooth path through the water, similar to tracking the hips in walk or jump cycles.
- Making sure the body does not stay rigid from head to toe; instead, the spine should flow in a gentle wave that follows the stroke rhythm.
Adding Timing, Arcs, and Offsets
Once the main poses are in, Jason moves to breakdowns and splines to add life to the cycle. He focuses on:
- Offsetting arms and legs so they do not all hit extremes on the same frame, which helps avoid robotic motion.
- Building soft ease-in and ease-out on the center of mass so each stroke feels like it pushes through water, not air.
- Checking arcs in the graph editor and, when helpful, attaching helper objects to wrists or hips to visualize smooth paths through 3D space.
Jason also stresses checking the animation from multiple camera angles, not just the main shot, to be sure the swim reads clearly and maintains appealing lines of action.
Refining Body Mechanics in Water
To sell the idea of swimming rather than flying, Jason notes several key details:
- The head and chest often lag slightly behind the main thrust of the arms and legs, then catch up, creating subtle overlap.
- Kicks should feel like they are pushing against resistance, so extreme poses are slightly delayed compared to the torso motion.
- The spine should never feel locked; even in a strong stroke, there is a continuous, flowing bend that runs through shoulders, torso, and hips.
He draws parallels to other body mechanics exercises at Animation Mentor, such as walk cycles and jumps, showing how the same principles of timing, spacing, and overlap apply, just with different gravity and resistance.
Polish and Presentation
In the final polish passes, Jason:
- Cleans foot and hand paths to keep them from jittering or drifting unintentionally.
- Adjusts spacing on fast versus slow parts of the stroke to keep the motion alive and textured.
- Encourages using a thoughtful camera choice, just as in other body mechanics demos, so the audience can best appreciate the flow of the swim.
He also points students toward Animation Mentor’s Body Mechanics and advanced courses for deeper dives into physicality, cycles, and performance, including walks, runs, and other locomotion exercises that build on the same skill set used in this swimming tutorial.
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