Designing Inflatable Pontoons as Boat Stabilizers for Dock Safety (Embry-Riddle Aeronautical University)

Grace McSween, Skyler Singleton, Katelyn Wentworth, Katie McBrayer, Gus Galarnyk

Abstract

Rowers with physical disabilities, also known as adaptive rowers, often use pontoons to stabilize their boats on the water; however, the installation of the pontoon when leaving the dock creates instability on the water. Additional problems have been recognized with the stability of the boat on the dock when getting into and out of the boat. The problem of this project is to research and design a device to increase stability at the dock while adaptive rowers are entering and exiting the boat and attaching the pontoon in the water. This project addresses how the docking process can be made more efficient and safe through boat stabilization using inflatable pontoons. The design process followed the d.school Human Centered Design “Bootcamp Bootleg” process. The design of an inflatable pontoon was chosen because of its ability to address both stability at the dock as well as on the water. The premise of the system was its ability to partially deflate at the dock providing resistance with its resting surface to decrease boat movement, and inflate on the water providing stability. This device helps adaptive rowers’ autonomy at the dock by eliminating the need for assistive personnel to keep their boats steady.

Background

Adaptive Rowing is a form of rowing that provides an opportunity for athletes with physical disabilities to compete. The sport is very versatile, so many athletes with a physical impairment choose rowing as their exercise (1).   Traditionally, there are three different classes of adapted rowing, Arms and Shoulders, Trunk and Arms, and Leg, Trunk and Arms (Table 1).

 

Table 1. Adapted Rowing Categories (5), (6)

Adapted Rowing

Sport Class

Description

Arms and Shoulders (AS)

Rowers with inability to use a sliding seat and a limited trunk function

Trunk and Arms (TA)

Rowers who have use of trunk but inability to use a sliding seat

Leg, Trunk and Arms (LTA)

Rowers with a permanent disability meeting a set minimum, but have functional use of legs, trunk, and arms

 

The client for this project is long-time rower who has amputated legs classifying as a TA. She currently owns two different styles of pontoons, favoring one style over the other because it has a shorter rigger attachment that is less cumbersome to maneuver when detaching the pontoon.

Figure 1. WinTech single with fixed seat and pontoons attached

WinTechSingle.jpg

 

Rowers also are limited by their need for help getting the boat to the water and preparing to row (3). They need people to help carry boats, oars, and stabilizing the boat while they get in and ready to row. With pontoons attached, the boats can not come in next to the dock, so rowers are required to balance themselves while leaning over and out of the boat to attach and detach the pontoons.

Problem Statement & Research Questions

This project researches the question of how the docking process can be made more efficient and safe for adaptive rowers through boat stabilization. It further explores how well inflatable pontoons stabilize the boat at the dock in addition to on the water by researching the parameters under which the pontoon must function. These parameters include buoyancy on the water to adequately support the boat, and minimal drag so as not to inhibit and reduce the speed of the boat on the water. The target audience is LTA, TA, and AS adaptive rowers. The dependent design variables considered include buoyant force, time it takes to remove or attach the pontoon, and the size of any force assisting members into or out of the boat. The independent design variables utilized were material, size, weight, and shape of the pontoon.

Design Methodology

The project applied the principles Human Centered Design adapted from the d.school “Bootcamp Bootleg” (3). The bootcamp bootleg is an overview of design processes developed by the Hasso Plattner Institute of Design at Stanford. It outlines the stages of design that include empathy, problem definition from the users perspective, ideation, prototyping, and testing (Table 2).

Table 2. Stages of design

Stage

Description

Empathize

Observe, engage, and experience with the users

Define

Create a problem statement and point of view

Ideate

Generate radical design alternatives

Prototype

Create preliminary design

Test

Refine prototypes and solutions

During the empathize stage, group members conducted interviews and observed members of the adaptive rowing club at the local rowing association. The group went to practices of the local adaptive rowing association and took notes on the processes involved in getting the boats onto the water. They also learned about the sport and how to row. One group member is on the ERAU Rowing Team and provided insight into the sweeping and sculling methods of rowing.

Figure 1. Descriptions of sculling and sweeping boats (7)rowing_shells.jpg

The group’s client primarily uses a sculling double. Another group member got into the double with the client’s assistive rower and experienced what the client experiences when she enters and exits the boat, attaches the pontoon, and rows. Once the group had a better understanding of the sport of rowing, the group interviewed the rowers to hear their perspective of the sport.

During the definition and ideation stages, the group discussed design alternatives, exploring all aspects of the rowing process, focusing on the general safety and stability of the boat. Facts and observations were written down onto sticky notes and placed in groups to better visualize how the observations related to common problems. This helped to highlight themes and commonalities between notes to identify where the group could best help the client. The group finally decided to focus on the safety and stability of the boat specifically at the dock and while attaching the pontoons.

To generate design ideas, the group brainstormed concepts to match the functions of the device (Table 3). A function is the task that a device completes. Following the brainstorming, the team generated design alternatives to further evaluate. Once design alternative involved clamps connecting the rigger to the dock, another was a set of inflatable bumpers that supported the boat at the dock, and the last was an inflatable pontoon that supported the boat on the water and at the dock.

Table 3. Design alternatives

Functions

Concepts

Hold Next to Dock

Bungee Cord

Pontoon

Rope/String

Stop Rock/Roll

Fins/Wing

Pontoons

Inflatable bumpers

Distribute Weight

Pontoons

Pontoons

Draft Attachment

Secure Rower

Seat Design

Seat Belt

Seat Belt

Ease Access

Guiding Arm

Ramp

Handles

 

Prior to prototyping, the group also calculated buoyancy specified by the shape of the inflatable pontoon.   The pontoon with a cylindrical body and cone end caps holds 31.474 pounds, comparable to the WinTech pontoons that support approximately 32.059 lbs.

 

Findings: Inflatable Pontoons

The designed approach is an inflatable pontoon that can be partially deflated at the dock to provide pressure and friction on the dock, thereby decreasing boat movement. When pushing off from the dock, the rower will then inflate the pontoon using a hand pump eliminating the need to reach out of the boat to handle the pontoons creating instability that has caused rowers to fall out of the boat. Through interaction with the boats and the rowers, the preliminary approach of a system of devices was found to be inconclusive and unnecessarily complicated, proving it more beneficial to create a device that solved both problems.

A prototype has been created using an existing product designed for stand-up paddleboards. The pontoon has a hose attached to the side closest to the boat. At the end of the hose is a double-action eight inch hand pump that inflates the pontoon. There is a release valve that will have a string attached that pulls the valve and deflates the pontoon.

The method of attachment from the pontoon to the rigger would be comprised of a lightweight and sturdy material such as PVC that could be sealed into the pontoon itself (Figure 7). The construction of the PVC would would be able to fit into the already existing pontoon attachment points on the boat that would only require one slot for the pin to go through rather than several. Several pin slots are used at the moment for the varying distances each boat places the rigger from the water. Our design prohibits the need for multiple pins due to its ability to inflate to the appropriate size and requires only one for the ability to remove it. The bottom piece of the PVC will have several ribs along its edges that will conform to the shape of the pontoon in order to minimize the amount of shifting on the dock and the water. The installation of the PVC will be done by sealing the PVC itself in fabric that will then also be sealed into the interior of the pontoon providing the best air tight seal to avoid water penetration (Figure 7). The final configuration is pictured in Figure 8.

 

Figure 2. Inflated prototypeInflated.JPG

 

Figure 3. Partially deflated prototypeDeflated.JPG

 

Figure 4. Hose connection on pontoonIMG_2453.JPG

 

Figure 5. Quick release valve and hole cut for hose connection

IMG_2451.JPG

Figure 6. Pump to tube attachment method

IMG_2454.JPG

Figure 7. Pontoon to rigger attachment methodPontoon-Rigger Attachment Method.jpeg

 

Figure 8. CAD renderings of pontoon and rigger configuration

Deflated Render V3.jpg

Bay Render V3 (save type).jpg

 

Design Evaluation

The current design proves the concept of an inflatable pontoon to provide stability on the dock and water. The current prototype provides a means for LTA, TA, and AS rowers to row on a single person boat thus removing the need for assistance adding and removing the pontoon.

Future designs can be adapted to have cones as the end caps and cylindrical main bodies. The pontoon would be 37 inches long with a three inch radius, providing enough buoyancy for boats with two people(4). It will also be equipped with a mini-diaphragm pump that will allow the user to inflate and partially deflate the pontoon at the flip of a switch, reducing the need for the manual inflation. Partially deflating it will allow the pontoon to provide added pressure on the dock, as well increase the surface area in contact with the dock,  making the boat even more secure.

The prototype cost a total of $36, excluding the stand-up paddleboard pontoons that were donated to the project. The retail price of the pontoons is $89.99.

Design Implications

There currently are pontoons that provide stability on the water, but this one is able to be deflated and provide, through friction and pressure, stability at the dock. That stability is important because it reduces the amount of help users need at the dock, facilitating users to achieve greater autonomy. This device also removes the need to lean over the edge of the boat to install and remove the pontoon when departing and approaching the dock.

Acknowledgments

This project would not have been possible without the kind help and support of many individuals and organizations: thank you to the Honors Programs at Embry Riddle for allowing us these opportunities, Engineering Fundamentals in the College of Engineering for their support and guidance. Thank you to the Halifax rowing association AROWS and VIPRS for allowing us to observe their practices and offer their insight into Adaptive Rowing. Our greatest gratitude is towards Dr. Pembridge, without whom this project would not be possible. Thank you for guiding us and helping us throughout our research. Thank you to Airhead SUPs for donating the SUP stability pontoons for use in our project.

References

(1)How Adaptive Rowing Is Growing In Popularity – Blog – Indoor Sport Services. (2010, April 25). Retrieved April 15, 2015, from http://indoorsportservices.co.uk/blog/post/how_adaptive_rowing_is_growing_in_popularity

(2)Lewis, K. (2011, January 1). USRowing. Retrieved April 12, 2015, from http://www.usrowing.org/DomesticRowing/AdaptiveRowing/AboutAdaptive.aspx

(3)World Rowing – The Official Site of World Rowing. (2014, January 1). Retrieved April 12, 2015, from http://www.worldrowing.com/para-rowing/

(3)Burnett, W. (2014). d. school Design Thinking Bootcamp. Stanford University. Stanford, CA

(4)WinTech Racing: Crew Racing Shells and Recreational Rowing Boats. (n.d.). Retrieved April 14, 2015, from http://www.wintechracing.com/index.php?target=/boats/recreational/explorer21.ph

(5)Smoljanovic, T. Complete Inclusion of Rowing Only 1000m Ahead. Retrieved April 13, 2015.

(6) Smoljanovic T, et al. Rib stress fracture in a male adaptive rower from the arms and shoulders sport class: case report. Croat Med J. 2011;52:644-7.

(7) Rowing 101. (n.d.). Retrieved April 16, 2015, from http://megunticookrowing.org/about/rowing-101

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