I've been in touch with a couple of friends who have Leopard 38's with hard tops to get pictures and design ideas. One had a tubular aluminum frame, and plastic panels were laid on top to create the bimini. The other was a molded fiberglass top that only utilized metal for a few struts at the front of top to hold it above the cabin roof (it may actually be one of the $15K tops built in Florida). They are both nice tops and served their purpose, but the decision on which direction to go was an easy one there. I'm no welder, so the more I can do out of fiberglass the better. I guess I'm no expert at fiberglass either, but at least I've done small fiberglass projects with some success.
The next part of the design was how I wanted the top to cover the cockpit. The soft top comes straight forward from the arch and then curves down as it gets to the helm, and I don't particularly like that. All of the winches, except for the dinghy/traveler one, are also out in the weather, and it would be nice to have access to them from a dry location while sailing in rainy weather. So it made sense to try to create a 3-D model of the cockpit and see how various top configurations might look.
|The top with an example 230 watt solar panel|
I downloaded a program called SketchUp and began working on creating a model of our cockpit. I wasn't looking for a detailed replica of our cockpit, just a rough approximation except for a few critical areas like the dimension and curve of the arch and cabin top as well as the location of the two sheet winches. It took me a while to
I tried a variety of different ideas. Should I embed the solar panels into the top thereby reducing the amount of materials I may need and allowing for better cooling of the panels? Do I want to integrate a water collection system into the top? How far can I extend the top and brace it while allowing sufficient clearance for the winch handles? Can I integrate wiring chases into the design for the solar and cockpit lighting? Can I integrate storage into the top?
|The side profile of the top...I think it looks decent.|
So far, I've decided that the best approach I can take is one of relative simplicity. I'm adapting simple designs that I know have worked for other people, adjusting only to simplify the build and as needed to fit the boat. I've had a difficult time finding solid engineering data so I'm leaning on the existing working designs as well as the advice of a couple of aerospace engineers I've met here at the marina (yep, I did in fact ask a couple of rocket scientists). The pictures you see in this post are what I have come up with.
|An underside view of the top. A couple minor drawing glitches.|
The plan is that most of the top will consist of a foam cored fiberglass panel. I'll use either 3/4" or 1" foam that will then have two layers of 12 oz biaxial cloth glassed on each side. I may add a third layer to the bottom side for added rigidity as a deck surface. The best information I have indicates the panel alone should be more than enough to support the weight of people and gear.
|The handhold edge, bolt rope and rear tab detail.|
U shaped channels will be created that run from front to back on the underside of the top to provide for wire chases as well as add a little additional rigidity across the length of the structure. At the front and around the window cutout at the helm seat, a foam doubler may be added for additional rigidity in those areas, Around the edges I'll create a rounded surface to act as a hand hold and to provide a bolt rope slot for attaching fabric dodgers. The rear tab for mounting the top to the arch will be solid fiberglass around all mounting locations. In all locations where there will be penetrations, holes will be over-drilled and filled to seal the core.
So, what do you think? I know some of you out there have some experience with fiberglass...so what have I missed? I think I'm going cross-eyed staring at this drawing on the computer screen.