Custom camper top design feedback


  • This is an off-topic post not relating to Angus boats specifically, but to stitch-and-glue construction. If this violates the forum rules, please feel free to delete!

    I'm designing a stitch-and-glue camper top for a Toyota Prius (with design inspiration from the CLC Teardrop Camper). I'm posting because I can't decide whether or not to go with 4mm or 6mm for the hull panels.

    My current plan is to use 4mm for the “hull” with fiberglass on both sides, and then 6mm (or possibly thicker for the “underside” that mounts to the roof. On the interior, there will be a handful of shallow ribs perpendicular to the chines (1.5–2" deep to avoid undermining the interior space).

    This is my first S&G-designed craft, so I'm just looking for a sanity check. Does 4mm with both sides glassed seem reasonable?

     


  • Hey Jay. I love the concept - a camper small car!   It would be perfect if your car had a sunroof so you could have both a "living room" and bedroom all accessible without going outside.  Overall, I think 4 mm plywood glassed on both sides should be sufficient.  Most of our boats, for example, are made with a similar layup, and they are not going to fall apart while car-topping down the highway.  Obviously, from a structural design standpoint it needs to have the overall rigidity to withstand these forces.  


  • Looks good, and I can definitely see the design cues from that iconic teardrop camper!

    wrt the thicknesses - I think they should work fine. In essence, the compound curves will add lots of strength into the shape, so you should be able to go to thinner sheets.

    My one concern for you is the overall design limits for the roof rack for the vehicle - I don't know the Prius limits, but many vehicles top out at 75kg. With such a bulbous shape, I'd be cautious on dynamic loads from wind if travelling at speed.

    I'd suggest a desktop exercise to work out expected weight of the wood & fibreglass to check you can hit sensible weights.

    But overall, I love the idea!


  • @Colin Angus thank for the feedback! On your sunrofo point, I will be able to enter the top “bedroom” directly from inside the vehicle because I'll be removing the trunk hatch.

    @John P that's a fair concern! For what it's worth, the topper will be bolted directly through the aluminum channels across and along the roof, as well as along the sides of the trunk frame. The current design for the shell is sitting at around 12m², / 130ft², of surface area, which is about 32kg / 70lb of 4mm Okoume. The final design will weigh more, of course—attachment points need to be reinforced, fiberglass and epoxy will add weight—but I would wager at this point that it will weight less than 75 kg / 165 lb.

    I'll also be removing the trunk hatch and the rear seats; that won't reduce the weight on the roof, but it does reduce the overall weight of the vehicle.

    In terms of upright stability, the Prius has a fairly low center of gravity due to its hybrid battery and low profile, so hopefully it doesn't turn into a Reliant Robin on sharp turns.

     

  • @Jay Bonthius Sounds good, Jay! The cornering would not be such a concern for me - a low CoG to start with and your added weigh relative to that isn't so great in the grand scheme of things. Based on how you intend to mount it, the loads will probably be fine. While the design is fairly aerodynamic in shape, it does still present a fairly sizeable additional frontal area into the direction of travel - I presume you don't plan to floor it on the German autobahns!

    Will be interested to see how you progress this through build & hear how it handles in practice. I do think it is a great concept, and can only wonder why I haven't seen someone try it out before now!

    For now, I will have to make do with my soon-to-be delivered Crua Aer rooftop tent...


  • That all sounds pretty sound to me.  Bolting through the frames in the roof should be pretty robust.  What I've done in the past for extra large "roof objects" is simply strapped them to the car through the door openings, so the straps run right through the interior. That's a bomb proof way of doing it, but not as clean as bolting.  As John metnioned, the overall shape of the structure will create a very rigid and strong object.  Love that you'll have a means to go upstairs without going outside.  So what do you plan on doing for windows?  Would be nice to have a couple of windows for ventilation and to enjoy the view.


  • @John P, right, I can't imagine it'll handle particularly great at high speeds. But then again, it's a Prius, and it wasn't meant to go high speeds ;-) Anyway, thanks for the feedback!

    @Colin Angus, I haven't quite decided on windows yet, but I think adding a roof vent might be a good idea in the future. For now, I'm going forward with no windows or vents, and experiment down the line with other options.

    I'm pleased to report that the design is complete and the parts are ready to be CNC cut. I went with 4mm for the top of the “hull”, and 6mm for the flat bits / mounting points. Since 4mm Okoume BS1088 is in short supply, I went with 4mm and 6mm Meranti BS1088 (Hydrotek) plywood instead. Compared to Okoume, Meranti is supposedly slightly stronger and heavier, and has similar flexibility. The cradle panels are cut out of 12mm birch.

    The model was designed using Rhino / Grasshopper, a program that I was unfamiliar with until a few months ago. It allows one to design models programmatically, rather than entirely by hand. For example, the puzzle joints are generated automatically by a Grasshopper script that I wrote.

    I'm so excited to break ground in the next few weeks. Will post updates here when I've got them!

     

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