Pool Chair

Designers: Luke Li, Andy Pettit, Xinli Zhang

Client Coordinator: Jean Bridges, Lenox Baker Hospital, Duke University Medical Center, Durham NC

Supervising Professors: Kevin Caves and Richard Goldberg


Lenox Baker Hospital offers Aquatic Physical Therapy (APT) conducted by physical therapists.  Physical therapists utilize the buoyancy, viscosity, and hydrostatic pressure of the water to help support the body by diminishing the effects of gravity. The water also helps reduce stress on joints and muscles, while improving circulation due to the compressive forces of the water. The patients at Lenox Baker undergo APT to help relieve or recover from arthritis, chronic pain, balance impairments, obesity, and profound weakness.

For patients who need assistance in entering the pool, physical therapists transfer them to a water wheelchair, and then roll them down a narrow ramp into the water.  The ramp includes a narrow, 180 degree turn that is difficult to maneuver.  They have a commercial PVC wheelchair that can be used for patients that weigh in excess of 250 lbs, but it is difficult to maneuver for heavy patients.  This is due to the force of the patient’s weight on the rotating front casters, making them resistant to rotation.  In addition, the pool wheelchairs are subjected to water and chlorine exposure for around 6 hours a day, leading to the constant need for repair and replacement of the tires and axles. To address all of these concerns, we developed a pool wheelchair that is easy to maneuver up and down the narrow ramp into the pool (figure 1).  It is durable and can accommodate patients who weigh up to 400 lbs.


The Physical Therapists at Lenox Baker found that the Pool Chair is safe, effective, and easy to use.  One PT commented that “The firmness of the seat is perfect. If we need any extra padding for the seat we’ll just use towels.”  And a patient stated that “the central bar you have is great. It’s nice because it reminds you there are bars beneath the seat. I also like the removable arm because it gives you more flexibility in transferring into the chair… I had no problems getting into or out of the chair.”  Finally, a PT stated that “Can we just have you make a few more?”


Our design was based on a three-wheel frame made out of furniture-grade PVC.  Preliminary research and testing showed that this would provide a much smaller turning radius than a conventional four-wheel design, making it easier to navigate the ramp at Lenox Baker.  The device contains four main components: frame, front caster, rear wheels, and seat.

The frame of our water wheelchair is constructed out of furniture grade PVC (1.5” Diameter).  Our design uses a base in the shape of a pentagon to incorporate our three-wheel design and provide the support necessary for a 400 lb client.  Our decision to include only three wheels required us to provide additional vertical supports. These supports, which connect the pentagon base and seat, provide our wheelchair with necessary vertical support and allow the seat to be at a comfortable height.  A removable armrest was also constructed to facilitate side transfers. This modification also allows wider patients to sit comfortably in the chair.  The PVC pipes and fittings were connected using Oatey’s Clear Advanced Cement. The product has been approved for use in extended water exposure situations (plumbing).

The front wheel is a stainless steel swivel caster, which is threaded into a 6” piece (1.5” Diameter) of solid PVC. This is connected to our frame using Oatey’s Clear Advanced Cement.  The rear wheels consist of commercial wheelchair wheels. These have solid tires, and are attached using a quick release axle and four washers. This allows the wheel to be easily and rapidly assembled and disassembled. PVC caps have been designed which cover the axle and limit water exposure.

We created a seat made of cross-hatched nylon straps and heavy-duty canvas. The nylon straps are rated for 1,000 lbs and are sewn to the canvas.  Upholstery thread approved for outdoor (water exposure) use was used to sew the straps. Nylon straps and canvas were used due to the additional safety measures a nylon seat would provide. The final cover was attached to the PVC frame using anchor rope (approved for extended water exposure) and heavy upholstery grommets.

The total cost of the Pool Chair is $517.

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