Why Design My Own?
There are a goodly number of teardrops on the market today being manufactured by small- and large-scale operations. Prices range from around $5k to $30k and more. (See the Orvis model here as an extreme example.)Each manufacturer brings their own sensibilities to their products, and I have to admit that several available trailers caught my eye. In the end, though, none fit my requirements just right, and I decided to "roll my own."
The primary consideration was that the available teardrops are generally limited to a 4' height. I sleep in a chair, not on a flat bed, for two primary reasons: 1) My back hates being on a horizontal surface; I can take no more than a few minutes in a traditional bed, and 2) sleep apnea is an issue with which I am intimately acquainted.
Sometime around 1994 I had to fly to Fort Worth, TX, to a manufacturing operation of the company for which I worked. I was stuck in the window seat on a 2-5-2 aircraft, and spent the flight from ATL to DFW forced to lean left but constrained by the next passenger. Upon my arrival there I was in serious pain, as I had several years prior pinched a nerve in my lower back.
The conference room at our plant had, in addition to the customary tables and chairs, a sofa and a matching chair. I found that, if I sat in that chair, all back pain subsided. I convinced the plant manager to have his people move the chair to my hotel room for the duration of my stay.
I hadn't slept so well in many years. Not only did the chair alleviate my back pain, sleeping upright addressed the apnea as well. I haven't slept in a bed since.
I have determined that an Ikea Poäng chair with foot stool will suit me well. It will fit into my design, it is lightweight, and should I decide to check into a hotel/motel for the night, I am not going to be constrained in my choices by whether or not they have an appropriate chair for my slumber - I can simply bring my own chair inside!
Teardrop Design Considerations
Sleeping comfort
As you might infer from above, the first consideration is that the cabin be large enough to accommodate sleeping in a chair. That drives the interior height dimension. Further, should my wife decide to join me on an adventure, it needs to be wide enough for the chair and a second person sleeping "normally."Galley
Another consideration is an adequate but not overdone galley. I'd like to have running water in a sink, but I am content with using a Coleman cooler for refrigeration. A stove is a requirement, and I initially decided to do a built-in propane stove. I also wished to have a grille, whether gas-powered or charcoal-based. However, I went to Cabela's one day and was looking at their camping gear. There I found a portable propane-powered portable grille that can fold and stow. It also provides for a stove top burner with an optional part. This is a perfect solution for me - both functions in one unit, not requiring an onboard propane tank with associated hose, not requiring the additional space of two units, easily replaceable should the need arise, and foldable/stowable. Some teardrops go so far as to provide microwave ovens, hot water and other appurtenances, but I find those both unnecessary and resource- and space-intensive.Stowage
The teardrop should be capable of carrying all the requisites for life on the road or in the campground - a table, chairs, and even a screen room - as well as a spare tire and the tools necessary to change it out.Dual-voltage electrical system
Most RVs have an onboard dual-voltage (12v - 120v) system. Some even include 240v (well, those are the behemoths built on bus platforms) and generators. I want to have onboard battery capacity to get me through a couple of nights if need be, while being ready to plug into "shore power" - the 120v feed available in most RV campgrounds. (I find it interesting that not only is this a nautical term, but the general components of boat and RV electrical systems show a high degree of overlap.) No generator is desired.The idea is that most of the time the systems in the trailer can run on 12v from battery. My laptop computer can run from an available 12v power supply. I have no requirement for a radio, DVD or TV system. Lights, fans and ventilation can easily operate on 12v. However, some components (such as the Coffee Maker - an absolute, non-negotiable requirement) require 120v.
The hookup to my car provides for charging the battery while underway. I have found an available converter/charger that takes an incoming 120v feed (from shore power while in an established facility), converts it to 12v and charges the battery. Any 12v outlets/appliances run from the battery, while 120v devices run directly from the shore power feed. When no shore power is available, the inverter section will take 12v DC from the battery and invert it to 120v AC.
Rather than having one 12v battery, my research indicates that one is better off with a pair of 6v golf cart batteries in series (thereby creating a 12v supply.) Car batteries employ plates that are essentially lead-coated sponges. By multiplying the surface area with a "sponge" form factor, they achieve a greater cranking amperage. But these batteries do not hold charge for long or have long lives, since they are designed to deliver maximum amps over a short period of time and do not presume "deep discharge." Marine "deep discharge" batteries improve upon this by making the lead coating on the sponge thicker, extending the life span of the battery.
Golf cart batteries, on the other hand, employ solid lead plates. While they are not designed to deliver high instantaneous current, they deliver much longer discharge times and overall battery life. This is perfect for my requirements. Golf cart batteries are typically 6v, so a pair of them in series will deliver the 12v required.
I've been looking at solar charging system as well. Simply put, you mount a solar panel on your roof, feed the output into a charge controller, and connect to the battery. These systems are not inexpensive. Further, one has to assure that the solar system, the car charger, and shore power do not conflict. Maybe, but not likely initially.
Light Weight, Durability
As I will be towing the trailer with my car, weight is a critical concern. Obviously, the heavier the trailer, the lower the gas mileage. I've been spoiled by owning a car that can achieve 36+ MPG highway. To paraphrase a well-known actor/association president, those MPG will be pried "from my cold, dead hands." Well, I know I'll give some up, but no more than necessary.I live in New England, very near the shoreline. Corrosion is a concern, though I probably won't be towing the trailer through a lot of snow and salted slush. The typical teardrop is built upon either a custom-welded steel frame, or a bolt-together steel frame, such as this one from Northern Tool and Equipment. Steel corrodes. Further, when building a trailer on a platform of this type, the underside of the plywood floor must be properly waterproofed (and maintained.)
Aluminum trailers avoid the corrosion issue, and are light-weight.
Construction
Typical teardrop construction is based on the same sheet of plywood that drives the overall dimensions. A sheet of plywood is bolted to the steel frame. Two plywood slab sides are cut to profile, mounted to the platform and connected by 1x2 stringers or similar members. The inside and outside of the curves are covered with 1/8" or 1/4" plywood. The trailer is most often covered with painted or mill finish aluminum. Some finer examples leave the exterior in wood, stained and varnished (or covered with resin), some trimmed with hardwoods.The issues with that typical platform include the lack of insulation, flimsy construction (in my opinion) and a general sense of lacking longevity.
Further, such examples require the builder to have the trailer inspected by state authorities and a VIN assigned so the trailer can be registered.
I determined that I would build my trailer on top of an all-aluminum utility trailer from an established source. The advantages are that the base trailer will be complete, including a VIN and DOT-approved lighting, that it will be lightweight and it will be resistant to corrosion, indicating expected reliability and longevity. By selecting the heavy-duty axle version of the trailer, I can be confident of towing the trailer over dirt roads in the Western US without fear of it breaking down.
The base trailer I selected has a bed that is 63" wide by 10' long. Both of those dimensions exceed the typical 4'x8' sheet of plywood. The choice drives the selection of Baltic Birch plywood as a prime construction material, as it is available in 5'x5' sizes.
For the side walls I decided upon a sandwich construction, comprised of 3/4" x 1-1/2" structural members between layers of Baltic Birch plywood, filled with semi-rigid foam sheets, clad in aluminum. This construction establishes a rigid, lightweight system (assuming all the layers are glued together.)
For the roof/front I decided upon a similar construction. This drives the requirement for curved ribs matching the overall profile. To create the curved sandwich construction I opted to create laminated ribs with solid cross-members infilled with rigid foam insulation and covered by Baltic Birch plywood.
The construction of the galley components will primarily be 3/4" birch plywood, giving the overall structure additional rigidity. The hatch will be built from the laminated ribs and self-manufactured bead-board, exposed on the inside, to highlight the overall construction techniques and craftsmanship.
By selecting sandwich construction for both the sides and the top I hope to keep weight minimized. Creating the laminated ribs for the curved sections becomes a technical challenge that I welcome.
The next post will begin to detail the construction methods selected and follow the construction process.
