Offroad trailer build - need insights

[Skiedra]

Hey, everyone,

New teardrop fan here. Would appreciate tips & insights on my first planned build.

Needs:
a) a functional, easily towable off-road teardrop (will mainly stay on regular roads). Thus, I'm reluctant to buy a regular travel trailer / towable.
b) climbable and usable top/roof
c) does not become a pain when using for 500 - 4000 km (300 - 2500 miles) trips 2-4 times a year.
d) Able to deploy a small tent on top.
e) Able to carry 5 bikes on top or on the back.
f) Aimed to be used 4-5 people at one time (trailer + tent on top)


Aiming at

My approach would be:

a) Use the following trailer 2m wide x 3 m length (6,5 x ~10 feet). Total weight 750 kg (1650 lbs), max weight 1500 kgs (3300 lbs)

b) Add a decent wooden structure (fir wood ~2 inch x 1.5 inch for framing. Height around 170 cm (5.5 feet, ground to roof) as less air resistance when towing. Very much willing to keep it all box-shaped.

c) Add birch plywood (1/2 inch)
d) Add stainless steel on top as a solid roof
e) Add roof rack & ladder.
f) I would reserve the front part of the trailer for the cargo box & the kitchen/galley. Both as a side slide-out.
g) Get a side tent for those rainy days.

 

[working on it]

* Nice blueprint and concept; I found a similar blueprint on a YouTuber's channel, and I was comparing it to my homebuilt, awhile back. I never completed my comparison (and plans to implement some features as changes), but I saved the drawing in my files:

* But, why are you planning to build such a heavy inner structure, when you could use plywood (or a composite) as a stressed-skin monocoque box, instead? On my simple 4' x 8' (1219.2 mm x 2438.4 mm) trailer, I used 3/4" plywood for walls/floor/roof, Loctite PL Premium polyurethane adhesive, and gusseted steel angle and corner braces (bolted, not screwed) to join it together. There's an inner bulkhead wall at the mid-rear, which prevents any twist, and the 3/4" plywood roof is laid (bolted and glued) on top of the walls and bulkhead, so there's plenty of strength added, and it'll support all the weight you'll want up there (I've walked on mine, and also confirmed its' strength by using the Sagulator The Sagulator – WoodBin). There are no inner roof supports, as I'm not going to put a rooftop tent on mine, and the steel bracing seems quite sufficient for my needs, but to be safe, you could always put spars under your roof.

* One thing I've noticed about both design blueprints, is the apparent large mass/weight? behind the axle, which my little trailer also has (though not as outwardly visible, as the loading inside caused the weight problem); I solved my weight-bias problem by transferring as much load as I could forward, to the heavy tongue box, and subsequent front racks. If you plan on carrying bikes along, then might I suggest making a load rack for them above your front boxes, where they'll be more easily accessible than on the roof, and provide better weight balance for towing. And you wouldn't have to remove them, if you needed to erect the rooftop tent, only.

 

[Skiedra]

Top-quality reply, working on it. Thank you!

Well, I do have some woodworking skills and almost 0% metalworking skills. Thus, a sturdy wooden frame an elephant could sleep on seemed like a decent solution. That would also allow me to put the necessary wiring and isolation materials between the studs...

 

[Tony Latham]

I agree with WorkingOnIt’s comment on your heavy inner structure. I would suggest you use sandwich construction.

Take a peek at the walls in my build log.

T


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[Socal Tom]

Have you read the generic Ben Roy plans? That is what I have, if I ever finish I plan on adding a roof rack supported by the side walls 3/4 ply.
If that isn’t enough strength, an external “cage” tied into the frame could be added with less weight than what you have proposed.


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[Skiedra]

Thanks, tony.latham and Socal Tom for pointing in the right direction.

 

[campbellinaz]

After starting my build and building a frame from 1x3 poplar Kreg screwed together and using 1/4 ply inside and 1/2” ply outside, 1”x 2 1/2” (actual) for the roof framing, I wish I had built a box with 3/4” ply and then sub-framed on the inside for insulation, wiring and sheer. Would be a far easier, less time consuming and cheaper approach. Oh yeah, and lighter! I’d love to know how many pounds of Kreg screws I’ve used. Lol


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[campbellinaz]

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[campbellinaz]

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[KTM_Guy]

That trailer you posted has a weight of 1600#? And a gross weight of 3500#? Your will be over the gross weight if you don't build ultra light weight. Weight will sneak up on you very quickly. Ask me how I know. What is your tow vehicle and what is the towing capacity? Stainless is very heavy, why not aluminum for the roof?

My off-road teardrop was 1800# loaded when I had it weighed after a trip so less water and food. Realistic weight will be around 2200#.

Todd

 

[Modstock]

People tend to go a bit overboard with "off-road" . Which really isn't needed.
My standard teardrop does just fine with slightly bigger tires 5.30/12".
I never take it on a actual 4wd trail , it gets parked at camp and then I go jeeping.
Usually when I am on a rougher dirt road with miles to go I'll air the tires down to 25 psi to smooth out the ride along with the jeep tires.


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[Tony Latham]

People tend to go a bit overboard with "off-road" . Which really isn't needed.
My standard teardrop does just fine with slightly bigger tires 5.30/12".
I never take it on a actual 4wd trail , it gets parked at camp and then I go jeeping.
Usually when I am on a rougher dirt road with miles to go I'll air the tires down to 25 psi to smooth out the ride along with the jeep tires.


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I agree.

We boondock 95% of the time. We find a camp spot and park. There really isn’t any practical reason to leave a two track and head off road in the western US. Generally it’s illegal.

Yes, there are some rough roads that need higher clearance.

T


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[working on it]

... I wish I had built a box with 3/4” ply and then sub-framed on the inside for insulation, wiring and sheer. Would be a far easier, less time consuming and cheaper approach. Oh yeah, and lighter! I’d love to know how many pounds of Kreg screws I’ve used. Lol

* I did build my box with 3/4" plywood, and sub-framed the doors windows, along the beltline inside (to support windows and shelves), and on both sides of the A/C cut-out in the rear bulkhead, with 1/2" x 3" wide red oak. No insulation (I would insulate it if I was to build again, but not a necessity here in N.Texas), and the wiring is semi-exposed (for simplicity and ease of repair).

* Lighter? not the way I doubled-up on PL adhesive, used 1/4"-20 stainless bolts everywhere (I bought lots of pounds in weight & hundreds of $$ in stainless carriage bolts alone), and always used more critical hardware than most anyone would do (hinges, where two would do, I used three; always doing the same for door locks and hatch hardware). And, I used 3/4" plywood for the galley shelf and inside overhead stereo shelf in the cabin, and 1" thick for the fold-down shelf on the inside bulkhead. Nothing is lightweight.

* But, if I had bought 1/2" ply, as I had set out to do, then maybe I would've/could've brought the build in at a more reasonable weight. When I realized that it wouldn't be towable by my smaller vehicles (with 1000 lb tow limits), then I went all-in, and built for durability and strength, instead. Towing with overbuilt pickups (one regularly towed 8000 lbs...capable of 12k, and the other 6000...capable to tow 10k, hauling drag-racing cars) made that decision not unreasonable. At least to me.

* Luckily, I made that decision before I extended my frame, and used rectangular tube steel, instead of C-channel, and used 3" square tubing to replace the 2" that had been bought for it. The single beam tongue was sistered to a central spine, that was extended to the rear, also, and the tongue is welded to three cross-members. The only weakness was trying to stay with a questionable-strength axle, which I intended to replace eventually, and did so a year later (reinforcing the frame at the same time).

* Though I probably will never off-road with it, I have brought it up to that capability-level over the years. I say go all the way towards your planned goal for your trailer...use no stop-gaps or substitutes for what you need, and you'll be happier for doing so.

... Build like a tank you wont regreate it 10 years later of off road travel....

 

[Skiedra]

Guys an gals - thanks for quality feedback.

1650 lbs total weight I mentioned is the legal limitation for a regular driving licence in my country. If over this limit, I'd need to get an upgraded "towing" licence. Thus, I'm thinking about going lightweight and staying under (for now). The axle itself can withstand 3300 lbs load.

@campbellinaz: great build & photos.

@KTM_Guy: my current tow vehicle is Nissan X-Trail, which also has 1650 lbs as unbraked towing capacity in specs.

I basically have 1000 lbs for the hull, the rest is trailer platform weight.

Thus, I'm thinking of swithcing to either stainless steel rectangular pipes or aluminum (which is pretty expensive to weld around here)
For the sides, I'd be looking at 1/2 outdoors grade plywood and an aluminum sheet on top.

 

[campbellinaz]

... I wish I had built a box with 3/4” ply and then sub-framed on the inside for insulation, wiring and sheer. Would be a far easier, less time consuming and cheaper approach. Oh yeah, and lighter! I’d love to know how many pounds of Kreg screws I’ve used. Lol

* I did build my box with 3/4" plywood, and sub-framed the doors windows, along the beltline inside (to support windows and shelves), and on both sides of the A/C cut-out in the rear bulkhead, with 1/2" x 3" wide red oak. No insulation (I would insulate it if I was to build again, but not a necessity here in N.Texas), and the wiring is semi-exposed (for simplicity and ease of repair).

* Lighter? not the way I doubled-up on PL adhesive, used 1/4"-20 stainless bolts everywhere (I bought lots of pounds in weight & hundreds of $$ in stainless carriage bolts alone), and always used more critical hardware than most anyone would do (hinges, where two would do, I used three; always doing the same for door locks and hatch hardware). And, I used 3/4" plywood for the galley shelf and inside overhead stereo shelf in the cabin, and 1" thick for the fold-down shelf on the inside bulkhead. Nothing is lightweight.

* But, if I had bought 1/2" ply, as I had set out to do, then maybe I would've/could've brought the build in at a more reasonable weight. When I realized that it wouldn't be towable by my smaller vehicles (with 1000 lb tow limits), then I went all-in, and built for durability and strength, instead. Towing with overbuilt pickups (one regularly towed 8000 lbs...capable of 12k, and the other 6000...capable to tow 10k, hauling drag-racing cars) made that decision not unreasonable. At least to me.

* Luckily, I made that decision before I extended my frame, and used rectangular tube steel, instead of C-channel, and used 3" square tubing to replace the 2" that had been bought for it. The single beam tongue was sistered to a central spine, that was extended to the rear, also, and the tongue is welded to three cross-members. The only weakness was trying to stay with a questionable-strength axle, which I intended to replace eventually, and did so a year later (reinforcing the frame at the same time).

* Though I probably will never off-road with it, I have brought it up to that capability-level over the years. I say go all the way towards your planned goal for your trailer...use no stop-gaps or substitutes for what you need, and you'll be happier for doing so.

... Build like a tank you wont regreate it 10 years later of off road travel....

Sounds like this trailer will survive the apocalypse!


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