Designing a Rafting Mooring Buoy for the Puerto Rican Cays

team boats #2Sponsoring organization: Departamento de Recursos Naturales y Ambientales

Team members: Hussain Muhammad Abdullah Bin Riaz Khan (Electrical and Computer Engineering ’16), Kelsey Ouellette (Environmental Engineering ’16), Kaitlin Poss (Electrical and Computer Engineering ’16), Sarah Sisson (Biomedical Engineering ’16)

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Executive Summary: The Departamento de Recursos Naturales y Ambientales (DRNA) of Puerto Rico has been striving to alleviate damage of sensitive marine ecosystems, such as coral reefs and seagrass, caused by boat anchors. In 1990, the DRNA began a project to install mooring buoys around Puerto Rico in areas with high boat traffic and a large concentration of coral reefs or seagrass. There are currently over 320 DRNA mooring buoys around Puerto Rico for public use. Mooring buoys are used as alternative boat-securing devices in place of anchors. However, Bouchard et al (2013) documented that these mooring buoys were being misused. Boaters are using mooring buoys, but they tie to other boats while using them. This behavior is prevalent in Puerto Rico and is known as rafting. These boats are also dropping their anchors while attached to moorings, putting excessive stress on mooring buoys and defeating their purpose. The goal of our project was to design a rafting mooring buoy system so that boaters would be able to raft while using mooring buoys without damaging marine ecosystems. We achieved this goal by addressing a series of objectives. First, we gathered information about the knowledge of boaters and DRNA staff using a survey and conducting informal interviews. We then created sketches of rafting moorings, and surveyed boaters again to ask their opinions and concerns with the designs. Results of the second survey were used in a value analysis to determine the best design for implementation in Puerto Rico. We concluded our project by creating a strategic plan for the DRNA, outlining the installation and promotion of our design.

We first determined what boaters already knew about benthic communities and mooring buoys. To do this, we created a survey with questions about mooring buoys, anchors, marine ecosystems, and how all three relate among each other. This survey was distributed online via Facebook and the list of subscribers of La Regata, a local nautical newspaper. We also handed out surveys in-person to boaters in San Juan and Culebra Island. We created survey questions to assess what boaters already knew about marine ecosystems and their attitudes towards current mooring buoys.

Using results from the first survey as guidelines, we created four different designs of a rafting mooring buoy. Due to lack of permits, no new permanent anchors could be installed, so we had to assume that any rafting moorings installed in the future would have to be constructed using the existing moorings. Knowing this constraint, we created designs so that the new system could be constructed with moorings already in place. When drafting the rafting mooring design, we considered our background research and our knowledge of engineering feasibility, as well as boaters’ knowledge, opinions, and concerns about existing mooring buoys. We first created two dimensional (2D) sketches of the designs.

We then showed surface components of the 2D designs to boaters by distributing a second survey to the La Regata newspaper subscribers and emails obtained from the first survey, asking boaters to give feedback on our designs. Results from this survey aided in the selection of our final design recommendations. We conducted a value analysis to select the most suitable design for the needs of the DRNA and boaters. In this analysis, each design was ranked on five different categories that included: estimated cost, ease-of-use, ease of installation, maintenance, and strength. When our final design was selected, we created the individual parts of the rafting mooring buoy in SolidWorks 2014. In SolidWorks, we assembled a three dimensional (3D) model of the final 2D rafting mooring buoy design using these individual parts.

team boats #1We used results from both surveys to create a strategic plan for the DRNA to implement and promote usage of the rafting moorings. Informal interviews with the DRNA staff gave us insight on estimated costs and available materials, so we knew what designs would be most appropriate considering the resources available to the DRNA. Theses interviews also gave us an idea on maintenance and installation for a regular mooring buoy. We also calculated the overall strength of each design using basic engineering fundamentals of static systems, and we were able to determine ease-of-use through results from our second survey. Using results from both surveys and a DRNA database pinpointing the locations of existing mooring buoys, we formulated suggestions for the DRNA. These suggestions included specific locations to install the new rafting mooring buoys, and what boater concerns to address before installation begins. We then created a promotion plan that suggested what information regarding the rafting mooring should be promoted, along with recommended methods of disseminating information the DRNA can use to reach the maximum number of boaters.

We received a total of 97 responses to our initial survey. We received 74 survey responses from the subscribers of the La Regata newspaper, 22 responses from in-person surveys, and one response from the social media website, Facebook. From these results, we concluded that most boaters do feel that they know about the importance of the marine ecosystems such as coral reefs and seagrass. However, data from this survey also showed that boaters continue to drop anchor even when using the mooring buoys. Through the survey and informal interviews with the boaters, we learned that they do not trust the DRNA mooring buoys. Boaters drop their anchors because they want the extra security; they fear the mooring could fail or they do not want the wind to move their boats. This suggests that boaters need to know more information about how much weight the mooring buoys can sustain. Another conclusion we made from our first survey is that boaters do not know about all of the mooring buoys located throughout Puerto Rico. The survey also showed us that when boats raft together, it usually involves anywhere from two to ten other boats. This makes the total number of boats that are rafting together, on average, range from three to eleven boats. This information was important so we knew how many attachment lines to have when creating the rafting mooring design.

Using our design value analysis, we gave each design a score based on our assessment of its cost, strength, ease of use, maintenance, ease of installation, and visibility. We obtained this information through background research, informal interviews with DRNA staff, and results from the second survey to boaters. The results from this survey containing the 2D designs showed that the boaters have a slight preference for a design that uses a rope (throughline) to join the buoys together. Our alternative design uses a metal rod in place of the rope, and boaters indicated that they believe a metal rod would corrode in the ocean and cause its overall strength to weaken.

Based on this value analysis, we chose the Rope design to be most suitable for the Puerto Rican cays. This design received a score of 22 on our value analysis, which was the highest score out of all of the designs. It received a score of 9 for strength, 3 for installation, 3 for maintenance, 3 for cost, and 4 for ease-of-use.

Having completed the value analysis and settled on a final design, we proceeded to create the different parts of the rafting mooring design in SolidWorks. We then assembled all of the parts together to create a visual of the rafting mooring design to be implemented. The image below shows the final 3D design of the rafting mooring to be implemented, seen in Figure 1.


Our strategic plan consisted of two parts. First, we created an installation plan outlining steps the DRNA should take to install our system. This portion of the plan included figures of specific locations, with labeled pairs of mooring buoys that could be constructed into rafting moorings. Feedback from our second survey was also incorporated into the installation plan by including suggestions boaters made about how to make the rafting moorings more visible and user-friendly.

The second part of our strategic plan used results from both surveys and information gathered from informal interviews to develop a promotion plan for the DRNA to use when persuading boaters to accept our rafting moorings. This plan included specific ways for the DRNA to communicate with boaters and included information that would be most effective at encouraging boaters to use our system. For example, our first survey was filled out by 73 boaters through the La Regata subscriber list. Although this is a small percentage of their 6,422 subscribers, we learned from the editor of the newspaper that 743 people opened the email containing the survey link. Because the email was seen by a large amount of people, we believe that emailing the La Regata subscribers would be a great way to promote our rafting mooring buoys. Additionally, we received a 95.7% success rate in achieving survey responses when we surveyed boaters in person. Because of this, we suggest that when the rafting mooring buoys are installed, the DRNA rangers could promote the new rafting mooring buoys systems in person, although this may be time consuming.

Although we produced a complete design for a rafting mooring buoy and carried out functional analyses in excel, there are still many steps to take in order to install this system. First, we recommend that the DRNA should obtain more feedback from boaters about the rafting mooring design. Based on informal interviews with numerous boaters, as well as responses to open-ended survey questions, we learned that the boaters trust the mooring buoys located in the United States Virgin Islands more than the mooring buoys in Puerto Rico. Through our background research on current mooring buoys around the world, we learned that residents of the United States Virgin Islands were very involved in the mooring buoy design process. If the DRNA involves the Puerto Rican boaters more with the implementation of rafting mooring buoys, then it is possible that they will trust and use them.

Because we created our design in SolidWorks, we recommend that a professional mechanical engineer performs simulations on the rafting mooring design. This would be much more accurate than the calculations we completed. These simulations can more accurately measure the rafting mooring design’s strength.

Another recommendation for the DRNA is to conduct field testing on the rafting mooring design. This involves constructing the actual design and having boaters attach to the system while rafting. One possible field testing location that was mentioned was Boquerón. Results from the second survey showed that if boaters see a demonstration of the rafting mooring being used, then they would feel more comfortable using it. We realized that boaters are not aware that current mooring buoys are regularly maintained. We also found out that maintenance differs by region as some mooring sites are used more often than others. Therefore, we recommend that the DRNA’s current maintenance plan should be transparent and communicated to the public. In order to do this, we recommend creating an app for electronic devices that has the GPS locations all of the mooring buoys. With each mooring buoy, the DRNA can update the last time each mooring buoy was inspected. If repairs were completed, the app can specifically describe which parts were repaired or replaced. Along with this app, we recommend that the DRNA creates a map of all of the mooring buoys around Puerto Rico. This map can be downloaded online, or can be printed off as a brochure so boaters know of all of the locations of the mooring buoys. Then, perhaps, mooring buoys will be used more often.

Despite the fact that there are still many steps to take in this project, the rope design seems to be a great option for the Puerto Rican cays. It has the potential to be easy to use. It would also be relatively easy to install and maintain. Most importantly, the rope design is inexpensive yet still has a high overall strength.