Figure 1 - sundeck and ladder

Transcription

1 The Problem: The problem that has been presented to the group is the case of an elderly woman who wishes to spend time with her family on their boat. The client in this case is Vivian Alford, a 92 year old woman who no longer has the strength or agility to climb aboard via conventional methods including dock to boat entry or ladder entry. Vivian's mobility, like most of the elderly, is limited due to her age and conditions such as arthritis. While she still has the ability to climb and descend stairs she relies heavily on the handrail for stability, and needs to travel at a slower pace; placing both feet on one stair and always leading with the same foot. Figure 1 - sundeck and ladder The family boat is a Glastron gx185, an 18 ft long bowrider. The traditional method of entry for this boat and most others of its type would be to step onto the rear sundeck from the dock when it has already been launched in the water. For entry to the boat while it is on the trailer, the manufacturer has provided a small ladder on the rear of the boat. Both the rear sundeck and the ladder may be seen in Figure 1. Due to the difficult nature of climbing a ladder or stepping onto a rocking surface, Vivian cannot currently enter the boat safely. The potential for her to slip or lose her balance and fall is too great. Our goal was to find a way for her to bypass these hazards, by creating an easily portable and deployable mechanism to fulfill the physical needs of the client. As the project was progressing, it became clear that Vivian was not the only potential customer for such a device. People have commented on online forums and in person at our project demonstration day, that increasing mobility problems related to age prevented them from enjoying their personal watercraft. This project has the potential to not only assist our client, but other families in similar situations, and those with young children. Solution: The solution for our client s problem was a portable, collapsible stair unit that is open and closed utilizing a slider mechanism. This unit is deployed from preferably a parking lot and connects to the swim deck of the client s boat while it is still on the trailer. The frame holding the moving parts of the stair unit is made of a 6063 ParFrame extruded aluminum. The high strength and lightweight characteristics of the material made it ideal to hold our dynamic load. The slots of the extruded aluminum could hold a variety of hardware specifically made for the ParFrame as well, simplifying manufacturing and eliminating difficult aluminum welding.

2 The design also took advantage of the inside slots to hold a piece of bar stock machined to the dimensions of the slot on the inside of both sides of the frame. This bar stock is connected to the moving parts of the stair. Through links, pivot points, and the sliding bar stock the stair system can be opened and closed through two people by pulling or pushing on two handles. This moving stair system allows for the stair unit to be easily storable because the stairs fold flat into the frame, the handrails collapse parallel to the frame, and the upper platform folds under to create a small dimension rectangle. The handles are connected through a milled slot of the ParFrame connected to the sliding bar stock. The handles provide a mechanical stop for the stairs to stop at the correct angle to be parallel with the ground. Being a mechanical stop, the handles also act as a load point. To alleviate the load from the two handles, the slider bar was cut to a length that distributes the load on the bolts that connect the feet of the unit. Holding the client while scaling the unit is a series of ½ thick polycarbonate steps connected to a steel frame. Although heavy, the polycarbonate gives little to no deflection giving our elderly client a complete feeling of safety. Lines of grip tape were added to keep the client from slipping if the step were to be wet. A pair of handrails was added at the request of our client with a specific height that she was comfortable with. These handrails were reinforced so that in an emergency situation, the handrail would keep her from falling and seriously injuring herself. A pivoting platform made of a ParFrame frame with PARTICLE BOARD connects the series of stairs to the swim platform providing a secure, sturdy base for the unit to lean against. This platform is locked with bolts at the correct angle for the height of our client s boat. The reason for it to pivot flat was because of portability and storage. Rubber stops are attached to the bottom and sides to deter damage to the boat when it is propped and provide a slip resistant surface. After a brief procedure of setting herself down into the boat, the stair unit successfully takes our client or any other persons from the parking lot into the boat. After casting the boat into the water the client can enjoy a great day of boating with her family. Design Features: Many unique design features are present on the stair unit to increase performance and safety. One such feature is the unique use of extruded aluminum stock as a frame rail. This not only provides a great strength to weight ratio but also provided strong convenient channels for parts to be secured to and also move in. The most unique design feature on the stair unit is the simultaneous motion of all five stairs. This is possible by having two pieces of stainless steel bar slide back and forth through the extruded aluminum's channels. These stainless steel pieces are connected by five cross-members ensuring equal motion between the pieces. Each individual cross-member is connected via two aluminum vertical supports to the stair frame. As the stainless steel bars and cross-members move in unison, this will in turn make the stair rotate either open or closed depending on the direction the stainless bars are moved. Figure 2 below shows the individual pieces and their location.

3 Stainless bar runs in aluminum channel Vertical Support Cross member Figure 2 Portable Assist Unit Flat and Open Figure 3 Portable Assist Unit Flat and Open

4 Multiple design features were implemented to achieve a compact design for transport and storage, included in these features is the stair's ability to fold down mentioned above. Also aiding in the unit's compact design is the fact that the permanently attached handrails are able to fold down on top of the frame rail. This feature adds a great factor of safety as well as reduces the set up time of the unit without interfering with the motion of the stairs. Safety was of utmost importance in the design of the stair unit both while in use or in transport. One of these design features that greatly increased the safety of the unit is the pinned rigid links locking the upper platform in place at the correct angle of 145. These rigid links are located on the outside of each frame rail and are made out of 1/4 stainless steel for strength. Rigid links are also used to lock the handrails in their vertical position to prevent their collapse in the event the user loses balance. Fail safe designs were implemented where possible to eliminate a possible failure. The stair angle is locked in place by a physical stop. Grooves were milled into the sides of the frame where a cross-member bottoms out on locking the stair angle. For added strength of the fail safe the stainless steel connection bars inside the frame bottom out onto the bolts for the feet of the unit. Figure XX below highlights the design features that increase safety. Rigid links for handrail and upper platform Physical stop locations for stair locking Figure 2 Portable Assist Unit & Boat

5 Specifications: In order for our project to succeed as a project multiple specifications were met prior to design and made. Stair width, slope of stairs, riser height, handrail height, and tread depth were all based on OSHA standards. Set up time, tools required, stair friction, disassembly time, carrying load, and dimensions collapsed were chosen on a basis of portability and safety. Table 1: Specifications Number Part specification Units Acceptable value Actual value 1 Stair width in 22< width < Slope of Stairs Degree Degrees 45 degrees 3 Riser height in Friction of stairs µ Height of hand rail in Diameter of hand rail in 1.5 Round 1.5 Rectangle 7 Set up time Minutes < 5 minutes 1 minute 8 Tools required List Hand Tools Hand Tools 9 Manufacturing Cost USD $1000? 10 Disassembly time Minutes <5 Minutes 1 Minute 11 Carrying Load (dynamic) lbs Carrying Load (static) lbs Dimensions collapsed in > 80 in 72 in 14 Tread depth in The final design met or exceeded all ideal value specifications. The most important of value for us to obtain was the dynamic load. Safety was our number one concern by planning and achieving a high dynamic load rating we can insure the stability and strength of the stair system providing safety and a piece of mind for the customer. Set up time was another great specification for us to exceed the ability for the stair system to be set up in under 1 minute relieves the inconvenience of having to assemble a stair unit for Vivian to enter the boat. Operation: Ease of operation was one of the main specifications that we wanted to focus on at the beginning of the design process. When the family decides they want to go boating they simply lift the unit up, requiring two people, and place it on top of their large SUV and tie it down with bungee cords and the ratchet straps that are supplied with the unit. Upon arrival to the marina, while the boat is out of the water and still on the trailer, the family has to unload the unit. To do this they must unhook the bungee cords & ratchet straps and remove the unit from the top of the SUV, also requiring two people. This is the complete loading and unloading operation. The next step of the process is to mount the unit on the boat. To achieve this one of the helpers holds the unit at around a 45 angle while the other helper swings the upper platform so the rigid link attached to the side rails lines up with the hole of the upper platform. The helper then inserts the bolt into

6 the hole and hand tightens the bolt. Next the unit is placed onto the rear swim platform of the boat by both helpers lifting the unit up and setting the upper platform onto the swim deck. Now the unit is in place. The final step of setting up the unit is to raise the handrails. Each helper is in charge of one of the handrails. To raise the handrails the helper has to lift up the handrails until they are perpendicular to the side rails. Then each helper locks the handrails by turning the lever on the upper hinges clockwise. The final step in setting up the handrails is to attach the rigid link from the upper platform to the bottom section of the handrails by lining up the hole in the link with the bolt in the handrail, inserting the bolt into the hole and tightening. The next step in the operation of the stair unit is to detach the stairs from the swim platform. The first step is to unbolt the link that attaches from the handrail to the upper platform. The next step is to lower the handrails. To achieve this both helpers rotate the lever on the top hinges of the handrails counter clockwise and lower the handrails. One of the helpers then lifts the system while the other helper unbolts the top platform links by hand and swings the platform underneath the stair unit. Both helpers then lift the entire system and place it on top of the SUV. To secure the stair unit to the SUV each helper uses a ratchet strap to secure the unit down. Then the provided bungee cords are strapped on completing the operation. Conclusion We were able to design and build a portable assist unit that allows for much easier and safer entry into a boat, allowing those, who lack the necessary motor skills required for traditional boat entry methods, the opportunity to enter a boat. The device is easy to operate, portable, and safe - even for unintended loading situations. Our customer is very satisfied with our work and looks forward to enjoying her first boating season in over 10 years. Currently we are finalizing the design for preproduction on a much greater scale by simplifying parts, materials and subassemblies in order to decrease overall assembly and manufacturing time. We are hoping that this device will fit within a niche market of could-be boaters a market that lacks a device within reasonable cost, portability, and universality that ours will perfect by the end of the year.