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The Cutting Edge, Part I: Twisting Dodger Design
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Photo 1. By equipping the aft struts with hinges, the aft frame can be folded forward without removing any pins or screws and without taking anything apart. |
Photo 2. The forward mounting frame is supported by two vertical struts, and additional two struts between the forward and aft frames. |
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Photo 3. Leaving the windshield in place, the dodger top can be folded down, allowing free access down the companionway or to the side decks. |
Photo 4. A finished drop-top dodger. Among the advantages of this design are that it eliminates the need for rollup section in the windshield, and it's easier to store in the winter because the top and the windshield can be folded flat and stored separately. |
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Photo 5. The drop-top design enables the user to remove the top and leave the windshield in place. |
Photo 6. Building a dodger with a removable top and a stationary windshield requires one vital piece of additional hardware; a hinge. The hinge is composed of two hard-plastic plugs inserted into the ends of the adjoining tubes. He plugs are connected by a flat linking piece of plastic, which allows the two pieces of tubing to lay against each other when the strut is folded. |
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Most two-frame dodgers use the aft frame as the frame, with the forward frame attached to it with a jaw slide. While reversing this orientation can be helpful (e.g., to keep frame mounts away from winches) the geometry is unstable and the dodger wants to fall forward. (See Figure 1.)
However, you can stabilize the forward mounting frame by supporting it with two struts. Add two more struts between the forward and aft frames, and you have a superior dodger, but it won't fold down quickly. If, however, the aft struts (located between the frames) were equipped with hinges, you could then fold the aft frame forward against the other, without removing any pins or screws and without taking anything apart. The top would be out of the way, allowing free access down the companionway or around to the side decks.
While this arrangement alone will likely please many customers, adding a few more details will make the design more desirable yet. First, you can make a frame sleeve/pocket for the forward frame that will keep the windshield tight, even when the top is down. This addition not only gives the structure a clean look, it provides the operator with good visibility. Second, if you use a flap and zippers to make the dodger top removable and keep the wings sewn to the top (as on a traditional dodger), they can be removed as one unit. What is left on the frame is a tensioned windshield with great visibility, as well as splash pro' section for the companionway, for gear stored on the cabin house, and for the people in the cockpit not to mention continued protection from the wind. It's clean and attractive and offers a new look.
There are a number of other advantages to this design:
Those mysterious folding struts
While creating a prototype of this particular design, I looked briefly at other design styles that were made with stainless flat stock. However, I decided it would be best to use existing hardware and tubing for this design; I didn't want to complicate the installation process and I figured fabricators would be more apt to accept the design if it incorporated traditional materials. This meant devising a way to mount a hinge inside a piece of tubing. I considered using off the shelf brass hinges (e.g., for cabinetry), but they are expensive and galvanic corrosion was a concern. I finally settled on black Delrin, a hard plastic with built-in UV inhibitors that's available through various industrial supply catalogues. The hinge is composed of two plastic plugs, which are inserted into the ends of the adjoining tubes The plugs are connected by a flat linking piece of plastic, which is similar in style to a bicycle chain link. The link allows the two pieces of tubing to lay flat against each other when the strut is folded; it won't twist from side to side, and it locks into position when extended.
No matter what kind of dodger you're building, be it a West Coast or traditional style, the design is almost always compromised by the boat owner's belief that he or she must fold the structure down periodically, despite the fact that only a minority of owners ever do so regularly.
To stabilize these hinges, I have devised an outer stainless steel sleeve, which slides over the joint to keep the frame from accidentally folding. This 5inch sleeve locks in place using pressure halls, which are positioned inside the strut tubing on either end of the sleeve. By covering the roughly 1 1/2-inch plastic joint, which isn't as strong as the stainless steel, the sleeve gives the strut full strength. What's more, the applications for this piece of hardware are limited only to your imagination; use them to create such items as bimini frames that need to fold for storage, leg-less supports for cockpit or interior dinette tables or folding boarding ladders or swim platforms.
I'm working with a distributor, and we hope to make the hinge available to fabricators by late this summer. (If you have any questions about the hinge and its availability, call me at 888-767-7705.) Aside from the cost of this hinge, drop top dodgers feature virtually the same materials and require about the same amount of labor so they need not cost too much more than other designs. On the other hand, since they provide more features than traditional dodgers and lengthen the life span of window vinyl, a higher price is warranted. How much higher depends on whether you sell them as an upscale specialty item or as a standard design.
Note: In the next edition, LeMole explains, in detail, how to build a drop-top dodger, starting with design considerations and frame construction and continuing on through pattering and construction details.
An award-winning marine fabricator, John LeMole is owner of Gemini Marine Canvas, Rockland, Maine.
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