Bronco Winch Handle
Summary:
Our product is a sailboat winch handle. A winch handle is used like a lever to reduce the amount of work needed to pull in lines on a boat. Winch handles are used in tandem with a winch to provide an increased mechanical advantage while handling lines. Our iteration of the common winch handle design aims to fix the awkward position of the locking mechanism and to build the winch handle with a more robust material such as titanium.
The Problem:
Our chosen design project is to develop a more efficient and effective winch handle meant to be used in professional sailing. The specific winch handle that we are improving upon is a specific model which uses a “One Touch” locking mechanism. The one touch design is patented by (Harken/Lewmar), and conceptually, it allows the handle to be unlocked from the winch by pushing a rectangular recessed button along the length of the winch handle. This design is quite effective, as it theoretically allows the handle to be disengaged from the winch by touching any part of the button. However, this design suffers from the large amount of force that is required to disengage the locking mechanism, especially near the button pivot, where the mechanical advantage is the least. Moreover, the location of the locking mechanism is awkward for the user to quickly and intuitively use, as it requires either extra hand movement or the use of both hands -sometimes impossible on a sailboat- to unlock. We plan to remedy this and make the locking mechanism more ergonomic by moving it to the underside of the winch handle as opposed to the top.
The Concept:
We want to move the button mechanism to the underside of the handle similar to the drawing we sketched. By pressing the button on the underside, it will push the inner beam up. The inner beam has a pin in the middle, so it has a seesaw effect. When we push the button, pushing the beam up, the other end of the beam pushes down on the pin which will lock and unlock the mechanism.
Preliminary Design Work:
Potential Design Change 1:
One of the designs we came up with before we landed on the conceptual design was to use a spring loaded lock mechanism. We used Harken’s Winch Handle Design as a reference and adjusted their mechanism by moving the knob for the lock closer to the handle, so it is more accessible. By moving the knob for the lock, we would have to make an inner rod/beam that hits the elastic lock pin into the pin when turned by the knob to lock and unlock the winch handle.
Potential Design Change 2:
For this design, we thought of using a sliding tab mechanism to lock and unlock the winch handle similar to the iPhone silent mode sliding tab.
Current Design:
Our current design, as mentioned in the concept section above, uses a similar spring button as the “One Touch” winch. For the internal mechanism, we designed a beam that rotates around the pin if the button is pushed which allows for the button to be placed on the underside of the handle. Additionally, we want to produce the winch handle with both titanium and carbon fiber so that it can also be lighter and more durable than the competition.
Final Design Work
The internal Mechanism works very similar to the Lewmar One Touch Design that we tore down in the beginning. The key difference was that we needed to engineer it to work upside down with our vision of having the button on the bottom of the handle. The challenge was connecting the button to the vertical pin while it moved the horizontal hold pins that hold the handle to the winch, in the same way. We overcame this challenge by re-engineering the vertical pin that actuates the horizontal pins. By examining the known geometry of the pin, we were able to -figure out that the solution was flipping the tapered flange on the pin upside down and offsetting higher in the handle than Lewmar’s design. With our redesign, the body of the handle has less windage than their design, so we made the vertical pin shorter, which ultimately made it easier to attach the button mechanism.
Our concept design for the new button was to make it smaller, but nearer to the end of the handle where the user grips it. During thanksgiving break, Dylan had the design concept evaluated by local sailors at his club. While they liked the idea of the button being on the bottom of the handle, rather than on top, they suggested that the button should be a similar length to the one on the Lewmar design. With this in mind, we went back to the drawing board, and modified our design to make the button longer. This actually worked to our advantage in the end, as by making the button longer, we were able to remove more internal levers and connecting components between the button and vertical pin.
The connection between the vertical pin and horizontal button is very simple. Once we were able to get the unlock vertical pin to work in the same manner, but upside down, it was just designing a horizontal extension bar to branch the gap between the button and pin. The bar is very similar to the design by Lewmar, and allows it to be attached to the button by slotting it onto the bin.
Internal Mechanism Video:
As you can see, the end of the part that attaches to the pin is shaped like a Y. the gap in between the two extrusions allows it to grab onto the pin and move it up and down. The opposite, tapered, end allows the button to contact and move the connecting pin up and down, which then moves the vertical unlocking pins up and down.
Our final Solidworks model shows how the mechanism works in real life, when you push the button in, the button's horizontal hold pins retract into the body, and when the button is released, the pins extend into the locked position.
One of the biggest inspirations for taking on this redesign was to make the end product better for the user. One of the biggest gripes Dylan had while using the product on his own sailboat was that the button takes more force to activate the further away from the unlock mechanism you get. One of the biggest changes made to the design was that we moved the rotator pin position of the button to be closer to the surface of the button which will make it more effective when a user grips the button to release the handle from the winch. Another advantage to having the button on the bottom is that instead of using the palm to activate the button to unlock the handle, you primarily use your fingers when it is on the bottom. Using your fingers to unlock the button is much more effective, intuitive, and ergonomic than using your palm.
Ultimately, we designed this product with the aim of it being produced for the high performance market. Our decision to use exotic materials for the purpose of making our winch handle much lighter and stronger than the competition, ultimately means that our product will be expensive to produce. In the sailing world, new products usually hit the higher end of the market first, and trickle down to more casual users as time goes on. Our goal with building the lightest, strongest, most ergonomic winch handle is to show the high performance market that our product is worth the investment, and let their praise signify to the more casual sailor that it is worth the investment for this tool.
The components that make up the winch handle are made out of the three materials commercially pure grade 2 textured titanium and carbon fiber thornel mat vma. We choose grade 2 titanium as it is lightweight and corrosion resistant which will be perfect for the harsh environments of high performance boat racing. We decided to use this material for components that form inner and outer components of the winch handle which will ensure its durability when exposed to corrosive salt water and blunt force, conditions common on a sailboat. The handle component is made out of carbon fiber to reduce the overall weight of the winch handle and maximize the amount of force near the connecting mechanism.
References:
Harken Winch Handle Drawings Reference:
User and maintenance manual winch ... - harkenindustrial.com. from https://www.harkenindustrial.com/gallery/05cb5217-4c76-4dc4-9fb8-6079826c0992.pdf
Materials References:
Titanium Grade 2. From https://corrosionmaterials.com/alloys/titanium-grade-2/
