"TrailTop" modular trailer topper building components

jscherb

Expedition Leader
So far, I've made the molds for four TrailTop parts - 8' straight rails, a 90-degree 3.5" radius corner, a 12" radius 90-degree curve and a 36" radius 90-degree curve. I'll be molding the first set of those parts next week... I'd mold them this week except that I'm traveling all week.

Here are some camper shapes that can be made with those parts:



I've received input that some additional angle/curve parts that could allow different camper shapes might be a good idea, so I've drawn a few concepts for your comment. So what if I took the 12"-radius 90-degree curve and made versions of it that weren't 90 degrees?

In this next drawing, I've shown several camper shapes that would be possible with a 12"-radius 60-degree curve and a 12" radius 30-degree curve. I've shown them used in three different ways here:



Another idea using the 60-degree and 30-degree parts... a "Teardrop" shape could be made that has a hatch with only straight pieces of wood, rather than curving plywood. The one short curve in the hatch would be done with a TrailTop fiberglass part, so the DIY builder wouldn't have to worry about making curved ribs for a hatch, this hatch would use straight pieces of wood, and a 12"-radius roof curve piece that I showed yesterday. There would be a few ribs to strengthen the assembly that would have a curved section that cole easily be traced off the TrailTop part before cutting to shape.



In the last drawing, I've gone a step further and done a two-angle roof, using a pair of 37-degree 12" radius curves and a 16-degree 12" radius curve. I've also shown a rear view with a large entry door, this idea could be used on all of the shapes in the drawings above except the teardrop shape.



I've drawn all of these new pieces with a 12" radius for two reasons:

1. The 12" radius roof curve piece I showed yesterday could be trimmed from 90 degrees down to 60 and 30 in order to provide curved roof sections to go with these additional pieces, so that mold/part gets reused for all of these angles. (I'll do 3-d views showing how the roof would be assembled once I get feedback on these new angle ideas).

2. These new parts can be very quickly derived from the 12" radius 90-degree curve mold I've made already.

Do any of these angle/curve ideas appeal to anyone or are we good with the set of four parts and the camper shapes shown in the first drawing in this post? Are there other angles/curves that you would find useful to implement a camper design you've got in mind?

All of the concepts above are shown as camper caps on a Jeep-tub trailer, but as I've said before, the Jeep-tub trailer base isn't required.
 

Bhos

Adventurer
This is just amazing! I love the teardrop design and the 60/30, just not the prices companies want for them! This is a great way to get into one w/o that cost, plus the chance to do some DIY'ing. Thank you for posting and keep 'em coming.
 

jwiereng

Active member
I would be satisfied with your offerings even without the 16 and 37 degrees. Keeping to only a few SKUs should help you with inventory management.
 

jscherb

Expedition Leader
I would be satisfied with your offerings even without the 16 and 37 degrees. Keeping to only a few SKUs should help you with inventory management.
Thanks - I was thinking it would be the 60 and 30 degree parts OR the 37/16 parts, not both. Should I take your comment as a vote for 60/30?
 

M35A2

Tinkerer
Great variations - each has its own appeal. I wonder which roof configuration would provide the least aerodynamic drag on the highway behind a hardtop'd Jeep - with no roof racks on the Jeep or the trailer.
 

bonomonster

Adventurer
I like them all, but if I had to pick one route I'd go with the 60/30 parts. Maybe throw in a 15°, although it may be over kill.

What would a 30/30/30 look like?

Sent from my SCH-I535 using Tapatalk
 

jscherb

Expedition Leader
I like them all, but if I had to pick one route I'd go with the 60/30 parts. Maybe throw in a 15°, although it may be over kill.
The way the math works, the angles have to total to 90, because you're going from vertical in the front to horizontal at the roof. So to use a 15, you'd have to also use another 15 and a 60 or another 15 and two 30's. The latter one isn't too different from the 37/37/16 example I showed (someone privately requested those angles BTW). As for the former, none of the combinations of 15/15/60 that I can think of look very good to me.

What would a 30/30/30 look like?
The reason I did the 60/30 instead of something like a 30/30/30 is because depending on where you put the 60 and where you put the 30, you can end up with different camper shapes, even a "teardrop" shape that's easier to build because it doesn't require a curved hatch. With 30/30/30, you basically get one shape.
 

jscherb

Expedition Leader
Great variations - each has its own appeal. I wonder which roof configuration would provide the least aerodynamic drag on the highway behind a hardtop'd Jeep - with no roof racks on the Jeep or the trailer.
I suspect it would be one of the teardrop shapes, I believe those have less wind resistance than the "breadbox shapes".
 

Canadian Camper

New member
Re: angles for the trail top

I suspect it would be one of the teardrop shapes, I believe those have less wind resistance than the "breadbox shapes".
I like the 60 30 angles as they make for room on the roof for a boat or canoe or luggage rack. I am very interested in this thread. How thick is the plywood you plan to use for the sides and top
 

jscherb

Expedition Leader
I like the 60 30 angles as they make for room on the roof for a boat or canoe or luggage rack. I am very interested in this thread. How thick is the plywood you plan to use for the sides and top
The TrailTop parts are designed to accept 1/4"-thick panels.
 

jscherb

Expedition Leader
One design requirement on my list is the ability for a TrailTop to support a roof-top tent. The TrailTop side rail parts, both straight and curved, will help TrailTop-based campers support substantial loads on top because the curved section of all of the parts maximizes the strength of the fiberglass structure.



You could make an "upstairs" for the kids:
..
 

jscherb

Expedition Leader
Project update: A week ago I finished the molds for the main TrailTop framing parts, and I had planned to mold the first sets of test parts this coming week. I've been traveling the past week, and unforseen circumstances will delay my return home for at least a week, so unfortunately it'll be a little bit before I can mold the parts. In the meantime, I've been working on design for a "finish free" method of assembling a TrailTop.

So far most of the concept drawings I've shown have used plywood side panels. These would get bonded or bolted to the TrailTop framing pieces, and sealed/finished appropriately.

For a "Finish Free" assembly, plywood would be used as an inner layer, with a fiberglass outer skin. Here's one way it could be done...

Home Depot sells 4x8 sheets of 1/8" "FRP" fiberglass-reinforced wall panels intended for use in wet environments like bathrooms. They also sell 4x8 sheets of 1/8" plywood. The drawing below shows how these could be used to skin a TrailTop. The fiberglass panel is bonded to the plywood using contact cement applied evenly with a roller; once they're bonded they form a 1/4"-thick fiberglass-skinned panel. The edges of these panels are sealed with a rubber u-channel molding, and the panel assembly is bolted to the TrailTop framework with 1/8" neoprene/edpm soft rubber weatherstrip.



Probably it would be best to apply the u-channel to the panel with a bead of seam-sealer inside the u-channel to form an impenetrable weather seal. Instead of bolting/using 1/8" weatherstrip, the panels could also be bonded to the TrailTop framework, and the bonding adhesive (two-part urethane is a good choice) would also form the weather seal between the panel and the framework.

A rough concept drawing of a Finish-free TrailTop teardrop on a Harbor Freight frame. I've drawn the rubber u-channel moldings in black so it's clear where they'd be used, but I believe white is available as well.

 
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cwm

Observer
One concern about the FRP panels at Home Depot is are they going to be UV stable? Their normal use is inside for bathroom walls as mentioned.

Living in the Colorado mountains where the high altitude sun can damage a lot of materials many materials will not stand up to the sun and outside conditions.

There is a company in Arvada, Colorado, Denver area, that sells products for the RV industry. They sell siding and roofing materials designed for RVs.

Go to their web site www.themetalcompany.com and click on the Fiberglass Products listing. See the "Smooth Fiberglass Siding" and "Pebble Roof-Flex Siding". But if you are not in Colorado the cost of shipping might be a factor.

There might be similar suppliers in other parts of the country.
 

jscherb

Expedition Leader
One concern about the FRP panels at Home Depot is are they going to be UV stable? Their normal use is inside for bathroom walls as mentioned.

Living in the Colorado mountains where the high altitude sun can damage a lot of materials many materials will not stand up to the sun and outside conditions.

There is a company in Arvada, Colorado, Denver area, that sells products for the RV industry. They sell siding and roofing materials designed for RVs.

Go to their web site www.themetalcompany.com and click on the Fiberglass Products listing. See the "Smooth Fiberglass Siding" and "Pebble Roof-Flex Siding". But if you are not in Colorado the cost of shipping might be a factor.

There might be similar suppliers in other parts of the country.
The Home Depot/Lowes FRP panels are do not have UV-protection additives, which may be a problem depending on the environment and usage of the trailer, although in my research I've found many people report success with it.

Non-UV-protected fiberglass will "chalk" over time and eventually can even lose structural integrity under long exposure in very harsh environments. Depending on the type and formulation of the resin, it may yellow in the process or it may not. The definition of "over time" depends on how the fiberglass item is used and the environmental conditions it's exposed to.

An non-UV-fiberglass-wrapped camper that's kept outside in the weather all year will probably go some years before it gets to the point that some remedial action is needed. In South Florida, for example, due to the intensity of the sun, the time could be much shorter; in overcast upstate NY it could be a lot longer.

If it's garage-kept and only outside for some weeks of the year during camping trips, it should last a good long time.

Stored outside, it can be protected with a breathable car cover that filters light but lets moisture out; that will significantly reduce UV effects on the fiberglass.

To some degree, a quality marine wax with UV additives will delay the onset of UV damage, although wax doesn't really provide very good UV protection and needs to be reapplied regularly to have any meaningful effect.

Fiberglass is easily painted with most paints; automotive paints work particularly well. A strategy for a budget-minded build could be to leave the fiberglass bare for the first year or two (or more, depending on the environmental conditions and usage) and paint it later as finances permit. Some people may find it easier to get a high-quality finish on fiberglass than on wood, so an FRP skin would be a good option if the plan is to paint the shell.

Based on the Home Depot/Lowes pricing, which for most people wouldn't require shipping costs added on vs. the pricing plus shipping of the typical UV-protected skin products (Filon is one brand name), the non-UV stuff is about $1.00 per square foot when bought in a 4x8 sheet locally, and the UV stuff can be about 6x more ($200 or more shipped for a 4' length or 102"-wide Filon from http://www.factoryrvsurplus.com/products.php?product_id=2122, for example), so depending on the environment, usage and budget requirements of the builder, either the Home Depot/Lowes FRP or the RV-industry Filon (or equivalent) might be the right choice.

Another alternative would be to use something such as aluminum sheet, in the same manner as I've drawn for the FRP sheet.
 
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