Cal Poly Students Design & Build Adaptive Paddleboard from Urethane Foam

Cal Poly San Luis Obispo requires a Senior Capstone Project that is the culmination of a student’s undergrad education.  Each year groups of 3 to 4 students pick a “real world” project sponsored by industry or the community and devote three quarters to the design, build and testing of their project.  One such group took on a “Paddle Board for all Persons” project for the Central California Adaptive Sports Center (CCASC) based at Shaver Lake, California with Professor Sarah Harding as their Advisor.  

For their project the four mechanical engineering students, Alexander Holthaus, Garrett Holmes, Garett Jones and Sean Yuch, not only built a highly adaptable outrigger pontoon system for a standard paddleboard, they also created a collapsible ramp that can be used from a beach or dock.  Volunteer Composites Consultant George Leone fills us in on this senior student project, designed using Precision Board urethane tooling foam from Coastal Enterprises.

In George’s own words…

Stand-up Paddleboarding (SUP) is a popular watersport activity, but current SUP technology is limited for persons with various disabilities.  While there are currently adaptive paddleboards on the market, they are often limited to only certain types of disabilities, feature parts that are fixed onto the board, and are priced beyond what most adaptive sports nonprofits can afford.

The student’s challenge was to design a system that could attach to any commercial stand-up paddleboard and make it extremely stable so that people with a variety of disabilities could safely use it. The system also needed to be assembled with a minimum of tools, disassembled quickly, and be easily portable.  Finally, it needed to be made of commonly available materials since the design needed to be “open source” to allow more wheelchair users to enjoy stand-up paddleboarding.


A primary design focus of the project is to make it usable by a large number of people with different disabilities and levels of mobility.   Another factor was that the system had to support a person or persons with a combined weight of over 350 pounds since an instructor often needed to be onboard with the participant.  Further, the harness system needed to accommodate a wide variety of wheel chairs so that participants could use their own chair.

The result was an adaptive SUP system that can be adjusted and modified for each user. Instead of drilling holes into the board and bolting a chair (limiting its usage and buoyancy), the students created a Velcro strap system that can connect any wheelchair to an aluminum support frame attached to a standard commercial SUP.  They also created two adjustable outrigger pontoons that connect to the SUP for stability and buoyancy.  Finally, the students also created a collapsible ramp so a wheelchair user can roll onto the SUP in their own wheelchair and be secured down with the help of another person.


Coastal Enterprises’ Precision Board High Density Urethane PBLT-6 density foam was chosen for its consistent density and flexibility for both hand and machine shaping.   The added benefit of the foam’s versatility with all resin systems during the manufacturing process was also a plus. Finally, the availability of educational on-line videos covering everything from basic shaping to gluing pieces together was definitely important to the team!

The foam needed to be light and strong not only as a final product, but also because it had to be moved many times during the build process.  Its high ‘Rapidly Renewable Resource’ content of 23.9{afbea94bd31582343c3017644f03ec8d7d8fa2386ecb82c250661e06c0c6e111} was also a factor in the Team’s decision to use Precision Board foam, and it resonated well with project sponsor Randy Coffman, Executive Director of CCASC.


After the design phase was complete, the students moved to the construction phase.  Since they knew nothing about fiberglassing, they enlisted my help (Ed note: George Leone is the recently retired Student Projects Lab Supervisor and long-time surfboard maker).  I welcomed the students and talked them through the foam shaping and fiberglassing elements of their project.

The components of the paddleboard were built in two of the shops in the Engineering College. The Mustang’ 60 shop in the Bonderson Projects Center and the Hangar Student Projects shop. A real airplane hangar. There used to be an airport on campus and a hangar big enough for a DC-3 (15,000 sq. ft.) was built in 1947.

The Team used an older ShopBot CNC router to shape the foam sheets to fit together internally, while leaving a “rough shape” on the exterior to save machine time. Since time on the university’s ShopBot is in high demand, the Team opted to do the final shaping by hand.

After they bonded the layers of foam into a single piece for each pontoon, they left the top open so they could glass the hollowed out interior using polyester resin, thus saving weight and strengthening the pontoons.  Once they bonded the top foam “cap” on each pontoon, the exterior was hand-shaped to the final contours, using “cereal-box edge” templates and bending long strips of metal to blend the larger curves.  Finally, the exterior was glassed with polyester resin.

In the testing phase they measured the buoyancy to find the height where the outrigger pontoons sat in the water. They marked the height and punched holes through the pontoons above that line,  inserted .25″ (6mm) wall 2.5″ (65mm) aluminum tubing,  then bonded the tubing to the pontoon with micro-balloons and epoxy, wrapped carbon tow around the tubing and over the top of the pontoons to reinforce the general area.

These pontoons slide on a pair of 10 ft. (3m) 2″ (50 mm) diameter aluminum tubes that bisect the SUP through the aluminum support frame. This allows the pontoons to be moved to a wider or narrower stance depending on the weight and skill level of the user.

On June 8, 2019, the Adaptive Paddleboard was tested in Morro Bay, CA and passed with flying colors.  Ten days later, on June 18,  2019, a 26 year-old woman who has spastic quadriplegia (a severe from of cerebral palsy) set out on Shaver Lake to experience a watersport that she never dreamed possible.  Here’s some photos from the CCASC Facebook Page of that day.

George Leone ran the Cal Poly Projects Shop from 2001 to 2017.  This shop includes facilities for machining, student welding, woodworking, sheet metal work, advanced composites and design space for senior projects, as well as nine engineering clubs that compete at a national level.  After retiring in July of 2017, he signed up as a volunteer again working with student teams and Senior Projects at least 1 day a week.

The College of Engineering at Cal Poly San Luis Obispo is an internationally-recognized, premier undergraduate engineering college. Its mission is to provide an excellent Learn by Doing education and to graduate in-demand, Day One-ready professionals. The College vision is to transform students into world class, innovative and collaborative engineers to meet the challenges of the 21st century.

State-of-the-art facilities and laboratories form the core of Engineering’s project-centered curriculum. Ranging from the Aircraft Design Lab to the Rotor Dynamics Laboratory, these facilities offer advanced technological systems that allow students to link theory with practice. College buildings also promote interdisciplinary project activities, including the Advanced Technology Laboratories, Bonderson Projects Center, and Engineering IV. With 19,000 square feet of space for individual and team-based projects, the Bonderson Center offers enriched opportunities for multidisciplinary projects and collaboration with industry. Engineering IV, a 104,000-square-foot building includes modern classrooms and laboratories for aerospace, mechanical, civil, environmental, industrial and manufacturing engineering programs.

At Coastal Enterprises, we like to look at the composites industry as a fully collaborative effort. Every fresh new development by an individual is really a contribution to a collective knowledge base. Like any scientific pursuit, the most potent advancements are made when information is shared freely between likeminded groups of people. For this reason, we feel obliged to do everything we can to enlighten and empower the future community of composites professionals.  That’s why we support school programs with donations of Precision Board HDU.  Click HERE to find out more about the program or give us a call with your questions at 800-845-0745.

Using Precision Board Foam to Create Architectural Scale Models

The following Precision Board guest blog is from Hans Wendel, a teacher, and Tomasz Jan Groza, a student, both with the UCLA Architecture and Urban Design program (A.UD).  They describe a recent architectural project using PBLT-20 Precision Board urethane foam to create scale models.

Here’s a more specific description of the project from the A.UD Instagram account:

“The stacked section—mute, repetitive, indeterminate—has been the foil against which many architectural projects have positioned themselves. As the primary object of study, the M.Arch. first-year studio, Section and Elevation, is concerned with the capacity of the section to move beyond seriality to develop complex spatial propositions. In an effort to challenge and interrogate the limitations of the stack the studio proposes to nest together a parking garage and a gym.”⁠



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The stacked section—mute, repetitive, indeterminate—has been the foil against which many architectural projects have positioned themselves. As the primary object of study, the M.Arch. first-year studio, Section and Elevation, is concerned with the capacity of the section to move beyond seriality to develop complex spatial propositions. In an effort to challenge and interrogate the limitations of the stack the studio proposes to nest together a parking garage and a gym. ⁠ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⁠ “This project began as a project about the articulation of the individual parking spot. In my reading of the parking and gym, I see both as highly individualized spaces with certain ergonomics that call for a 1:1 relationship. If the prompt suggests an exploration of the opportunistic mingling of gym and parking, then​125 Gyms removes the notion of mingling and forces the two programs to confront each other head-on, taking the two smallest units of parking and gym and interlocking them with one another.”⁠ #uclaAUD⁠ Work by: Sana Jahani⁠ Section led by: Katy Barkan, Spring 2019⁠ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⁠ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⁠ #uclaarchitecture #archimodel #studentwork #archinect #archilevelup #architecturestudio #architectureschool #archiboom #critday #allofarchi #uclaarts

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From Hans Wendel:

In the course of the studio project students produced 1’=1/8″ scale models. One of these models, work of Tomasz Jan Groza, was realized mainly with 20pcf 1.5″ HDU foam. The model proposes a stacked system of jogged vaults to house the entwined gym and parking programs within gently undulating interior spaces.

CNC Cutting in progress. Milling precision foam is quick and precise. With a 3/16” ball nose bit and moderate feed rate, even the most delicate 3D features can be carved in one pass.


Milling marks can be sanded off easily with medium grit sandpaper.


One layer of the vault system after sanding.

One layer of the system assembled. Some of the most delicate features tend to break off during finishing.


Although it was possible to carve small delicate details in precision foam, handling can easily damage them. To reinforce the model 1 / 8” MDF inserts were used to make up the forest of arcaded arches holding up the vaults. They were tension fitted and spot-superglued.

Stacked assembly up-side-down and right-side-up. Partial fragments of the model in various stages can be seen in the background.

Pieces in various stages of finishing.  Bulk of the model was milled out of 1.5” thick foam sheets and stacked, but some of the most delicate vertical features required a different method. Offcuts from the CNC’s sheets were used to produce foam strips about 1 / 8” thick which could be cut by hand and laser.

At this thickness 20pcf foam can bed around a two inch radius, and can be laser-cut with settings similar to 1/16” museum board. Thinning the strips with sandpaper allows the foam to bend around even tighter corners.

This fragment of the model is the ramping system for the vertical vehicular circulation in the building, It is made up of pieces of foam that were both 2D cut and 3D cut and glued together and to a wooden backer.

Views of the model interior at various stages of finishing and assembly.

Sanded and glued stacked vaults seen in the correct orientation.

Finished model of the building with a sectional fragment placed on a pedestal integrated into the model base.

Section views of the model

Views of the fragment showing mainly the facade


Close up of internal section view


The UCLA School of the Arts and Architecture (UCLA Arts) is dedicated to training exceptional artists, performers, architects and scholars who are enriched by a global view of the arts and prepared to serve as cultural leaders of the 21st century. Graduate degree programs are offered in the Departments of Architecture and Urban Design, Art, Design | Media Arts, Ethnomusicology, Music, and World Arts and Cultures. The School’s unique curriculum interweaves work in performance, studio and research studies, providing students with a solid creative, artistic and intellectual foundation. World-class faculty provides a depth of expertise and achievement that supports the most ambitious vision a student can bring to the campus.

Coastal Enterprises manufactures Precision Board, a versatile, cost-effective and eco-friendly urethane material used extensively in the tooling industry.  It is a closed-cell, rigid, dimensionally-stable substrate that is ideal for use in a number of different tooling applications.

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UCSD Human-Powered Submarine Mold-Making

A team of engineering students from the University of California – San Diego (UCSD) designed and fabricated a unique human-powered submarine as part of their classroom learning experience.  Instead of using a rotary propeller, they took a cue from marine life and designed a dolphin fin propeller.  The students created fiberglass female molds out of Precision Board HDU which were used to create a carbon fiber hull for their submarine.  In a series of videos, the human-powered submarine team show us how they went from design to fabrication and every step in-between.


Tobin Gutermuth a structural engineering student and president of UC San Diego’s Human Powered Submarine Team and documented their process from design to fabrication and showed how they used Precision Board HDU to create female molds that would eventually be used to make a carbon fiber hull.  Competing in the one-person non-propellor division, Vaquita features an up-down tail for propulsion, a unique six-bar linkage, and the team’s very first pneumatics systems. The heart of the submarine is its drivetrain, which translates rotational motion into oscillation. The pilot propels the submarine by pedaling the drivetrain, which uses an innovative six-bar linkage to swing the tail up and down.

According to an article on the UCSD website:

The students made several major design and material changes to their sub this year. For starters, they’ve switched from trying to emulate the side-to-side motion of a tuna tail, and instead are mimicking the up-and-down sinusoidal movement of dolphins. The races in Maryland only require contestants to speed in a straight line, whereas the race in England has an obstacle component that the sideways motion wouldn’t be ideal for.

“We came up with a linkage system in the submarine tail to optimize for a perfect sinusoidal force output,” Gutermuth said. “Linkage systems tend to jump, but this one was optimized using a genetic algorithm to optimize for a perfect sweeping motion.”

“We used several 1.5 inch sheets of Precision Board to build 7 blocks of foam,” he says. They then machined the blocks of foam with a Kuka Robot CNC at UCSD to build a plug in seven sections.


Tobin says, “we bonded the sections together and made a fiberglass female mold from the plug.”  He adds, “we made an awesome carbon fiber hull in two sections using the female mold!”

You can see videos of the entire process below, including their test run in the pool.

The UCSD crew first cut the sheets of Precision Board into smaller size pieces to be able to bond them together.

They then took the smaller pieces and bonded them together into larger blocks using Coastal Enterprises PB Bond 240.

Then the UCSD team used a CNC machine the bonded blocks and assemble them to form their plug.

Finally, they shared with us a compilation video of the build process for Vaquita, their human powered submarine, showing all the mold making processes.

After the submarine was built, it was time to test it out in the pool.

After the submarine was completely built and tested, it was time to compete.  You can find out how they did at the 2018 European International Submarine Races in our follow up post with a report from the UCSD HPV team themselves next week!

The Human Powered Submarine team at the University of California San Diego designs and builds a fast, safe, and reliable fiberglass submarine that competes at international submarine races, which take place in Bethesda, Maryland and Gossport, UK. Scuba-certified students control the submerged and flooded submarine with human powered propulsion. Students working on this project learn essential CAD, machining, and programming skills and gain a deeper understanding of the concepts that they learn in their classes.  The most recent submarine, completed in 2018, is “Vaquita,” named for an endangered species of dolphin. Competing in the one-person non-propellor division, Vaquita featured an up-down tail for propulsion, a unique six-bar linkage, and the team’s very first pneumatics systems.

Coastal Enterprises manufactures Precision Board HDU, a high-density urethane material used extensively in the tooling industry.  It is a closed-cell rigid material that does not rot, warp or crack.

Coastal has a long tradition of donating Precision Board HDU to schools around the country in support of the next generation of engineers, designers and artists working in composites.  If you are interested in finding out more about our Precision Board school donation program, check out our School Donation page and get in touch with us to see how we can help your program out.