Fiberglass shell v bonded sandwich construction

[Brian B-P]

Originally Posted by Cathy P.

I could not find a stated GVWR on the Prolite ...

I didn't see a GVWR (gross vehicle weight rating), either. While this is an unfortunate omission from the specifications, I don't think it's important, and I don't think the GVWR matters to most owners of lightweight trailers. The situation is the same for the Scamp 13': no GVWR on the Scamp web site.

The Prolite Mini 13 specs do include the gross axle weight rating (GAWR): 2000 pounds. The GVWR is likely the same, and is unlikely to be more than 2200 pounds, or less than 2000 pounds.

More importantly, the GVWR doesn't provide much information about the equipped weight of the trailer. It does set an upper limit, but a low GVWR might just mean there is very little allowance for cargo - that would be one thing to watch for. A high GVWR might be interpreted as the manufacturer allowing for a lot of option weight, but it also might be allowing for a lot of cargo, or just an almost arbitrary choice reflecting axle capacity and frame dimensions. I would not conclude that a high GVWR means the trailer is going to be heavy compared to the base dry weight.

The GAWR doesn't mean much, either. An axle rating much higher than the trailer empty weight might mean an allowance for lots more trailer weight, but it might also just the be cheapest or most readily available axle.

For an example, Bigfoot sets the GVWR of their tandem-axle trailers equal to the total of the two GAWRs, plus another 500 lb of tongue weight... giving them a 7500 lb GVWR for a trailer with an empty weight 3000 lb lower. The axles, in turn, are just the most common capacity available over one ton (3500 pounds each). That doesn't mean that their trailers go down the road weighing 7500 pounds, even though a collector of rocks might do that.

In this case, the Prolite Mini 13 and Scamp 13' have similar axle ratings: 2000 lb for Prolite and 2200 lb for Scamp... each likely equal to the maximum rating for the series of axle used, neither optimized to the trailer.

Scamp 13' specs
Bigfoot specs

[cpaharley2008]

I believe Airstream has several videos on it's construction method.

[honda03842]

Our Motorhomes were glued and vacuum bagged, some 32 feet long.

[Francesca Knowles]

Vacuum-bonding and getting away from the use of plywood in the process is becoming a lot more common in stick-built Rv's than it was just five years ago.

Here's one such process, used for Everlite trailers and perhaps others.

Here's another, used by Rockwood in at least some of their units.

And the materials themselves are changing fast- here's a cutaway of the walls on a supposedly "high-end" toyhauler that appears to use no wood at all!



Guess the only way to find out about the Prolite specifically is to ask them, which is what I'd advise the O.P. to do if it's a matter of concern...

Francesca

[carlkeigley]

Originally Posted by Francesca Knowles

Do you see that in the article Cathy posted a link for, Jim?

The only language I see there about the walls seems to me to refer to wood/metal studs-???

Here's the quote:
This is something that really frustrates me generally in the RV world...tons of info about color swatches, floor plans etc, but virtually NOTHING about the nitty gritties of construction.

And while we're on the subject, in my opinion molded fiberglass trailer manufacturers are no better than everybody else in that department...

Francesca

I agree. That's why I took the bare bone pictures when I visited the Snoozy plant. When I pick it up, then I'll show the "pretty" pictures. Curtain colors, bedding swatches, food coloring in mealtime, etc. lol.

My dad always said the sign of a good carpenter was the ability to "cover up" his mistakes. But I prefer knowing the actual "craftsmanship" that goes into a product.

[carlkeigley]

Sorry, couldn't resist.....................lol.

[David Tilston]

Carl, What are we looking at there?

[carlkeigley]

That is the wall, ceiling, and floor of the Lil Snoozy Trailer.

Particularly, this is the bedroom window cutout.

It's one of the pics in my album.

[Mike Magee]

In addition to the factors already mentioned, figure that a molded, rounded 'egg' trailer will get 25% to 50% better fuel economy.

Price can be a factor, however. If the 'bonded sandwich' trailer is far less costly to start with, as was mine (under $10,000 new), you might choose to buy it if you can't or won't spend the money for a comparable new molded FG unit. That's what I did... but I went into the transaction with the mindset that my trailer is basically a throwaway. It probably depreciated 30-40% in the first year, and if it develops leaks I don't catch quickly it could become essentially worthless in a very short length of time.

[GPJ]

For eveyone that is interested...There is a good video of a Prolite factory tour on youtube. It shows virtually every step of the construction in varying amounts of detail (yes, wall is a glued sandwich construction - no vac bagging). The video is located here:

Campkin's RV presents the Prolite Factory Tour 2012 - YouTube

There are a couple of interesting points applicable to molded trailers too - eg. the guide talks about not sealing the bottom of the walls so as to allow spilled water to escape. Trapped water seems to be a problem with many molded units. Condensation or spills rot out the floor as the moisture cannot escape (although a couple of brands have small drain holes drilled to help in this regard).

There are also good videos of some other RV factories - in particular, several showing the Lance facility.

Enjoy....

[Donna D.]

Originally Posted by GPJ

There are a couple of interesting points applicable to molded trailers too - eg. the guide talks about not sealing the bottom of the walls so as to allow spilled water to escape. Trapped water seems to be a problem with many molded units. Condensation or spills rot out the floor as the moisture cannot escape (although a couple of brands have small drain holes drilled to help in this regard).

Rather than NOT sealing the floor to the sides, I truly believe maintenance/prevention and attention is a far better solution. If you pay attention to the needs of the trailer, you should never have floor rot problems.

[GPJ]

Donna - I agree completely. But sadly, not everyone is so diligent or knowledgeable in regards maintenance and prevention - it is interesting to see how manufacturers deal with the possibility of poor maintenance - essentially trying to protect us from ourselves...and reduce warranty claims of course .

[David Tilston]

Originally Posted by GPJ

Donna - I agree completely. But sadly, not everyone is so diligent or knowledgeable in regards maintenance and prevention - it is interesting to see how manufacturers deal with the possibility of poor maintenance - essentially trying to protect us from ourselves...and reduce warranty claims of course .

There was that Bigfoot Silver Cloud that had the whole interior destroyed because it sat wet for years.

[Night Sailor]

Originally Posted by carlkeigley

That is the wall, ceiling, and floor of the Lil Snoozy Trailer.

Particularly, this is the bedroom window cutout.

It's one of the pics in my album.

Nice path for water to get in.

On boats this sort of thing is frightening. The core material is typically removed at the edges and filled with thickened epoxy to prevent any water migration into the laminate. Once inside, cyclical freezing causes de-lamination.

[Cathy P.]

Originally Posted by Donna D.

Rather than NOT sealing the floor to the sides, I truly believe maintenance/prevention and attention is a far better solution. If you pay attention to the needs of the trailer, you should never have floor rot problems.

Even in the entry level trailers, if you do proper maintenance (a little more often), you can get your money's worth out of the trailer. Sadly, we have seen so many used models of everything from pop-ups to giant motorhomes that were not properly cared for and I keep thinking what a shame that it is. Imagine being able to afford something so nice, and some were so nice, and just running it until it was crappy and then moving on probably often repossessed. I would always try to see a used unit of anything I was going to buy new if possible because you can tell if a unit is just showing wear and tear or neglect versus a sloppy job/crappy materials coming from the factory. It seems pretty easy to sell a fiberglass egg if you decide you don't like it or need cash which is a biggy in the RV market today.

[Perry J]

David, there is a simple answer to you question.

How many 30 year old non moulded fiberglass travel trailers do you see in use today?

I just bought a 1982 13' Scamp that hasn't moved in the seven years I've been trying to buy it.
It's been sitting in 110 degree High Desert sun in the summer and rained on in the winter.
It has no leaks.
Other than the Ensolite seam tape needing to be replaced, cosmetic, and a slight smell from being closed up for so long the interior is in great shape.

I would imagine the average age of all the trailes in this group is somewhere between 20 and thirty years old.

How about a survey to find out.

John

[Francesca Knowles]

Originally Posted by GPJ

There are a couple of interesting points applicable to molded trailers too - eg. the guide talks about not sealing the bottom of the walls so as to allow spilled water to escape. Trapped water seems to be a problem with many molded units. Condensation or spills rot out the floor as the moisture cannot escape (although a couple of brands have small drain holes drilled to help in this regard).

.

Thanks for the very informative video!

Per your remarks above:

This is a very important point, and one that certainly affects molded units too. Especially with the non-breathable shells we all have, trapped interior moisture can be as big a problem as any that may penetrate from the outside. Condensation alone can wreak havoc with interior wood- this not to mention spills/leaks as noted above.

How many rotted out floors have we read about at this forum? Here's one presently ongoing: http://www.fiberglassrv.com/forums/f...ent-56851.html, and if one needs to read about more, take your pick of these.

It's also worth noting that a much-discussed and approved of innovation on Escape trailers is the installation of drainholes in the so-called "pontoons" at each side of the trailer, purportedly for exactly the purpose described above and in the video.

Francesca

[GPJ]

Originally Posted by Francesca Knowles

Thanks for the very informative video!

Per your remarks above:

This is a very important point, and one that certainly affects molded units too. Especially with the non-breathable shells we all have, trapped interior moisture can be as big a problem as any that may penetrate from the outside. Condensation alone can wreak havoc with interior wood- this not to mention spills/leaks as noted above.

How many rotted out floors have we read about at this forum? Here's one presently ongoing: http://www.fiberglassrv.com/forums/f...ent-56851.html, and if one needs to read about more, take your pick of these.

It's also worth noting that a much-discussed and approved of innovation on Escape trailers is the installation of drainholes in the so-called "pontoons" at each side of the trailer, purportedly for exactly the purpose described above and in the video.

Francesca

Good point Francesca - the pontoons themselves seem to be a Trillium innovation from years earlier - I can't see any reason for them other than catching excess moisture in the trailer. From what I can tell, some Trilliums seem to have drain holes, but others (maybe most?) do not. Some owners seem to drill drain holes if they were not there before. How about yours?

To your point about rotted floors, etc. and Donna's point about proper maintenance, how many times have we heard stories of owners (thinking they are doing the right thing) tightly sealing or covering their unit for the winter (without leaving an opening for moisture to escape) and returning in the spring to find everything from mold and mildew to rot and other more serious damage.

The great thing about this forum is folks like yourself giving practical advice about things that are not in the manual.

[carlkeigley]

The dreaded manual. lol.
How many manuals have I encountered that really don't pertain to a product I purchase? Continuing to use an outdated manual even for new and improved products? It's good to keep a book or list of things we learn to be handy when needed. Lot's of information on this forum.

[Francesca Knowles]

Originally Posted by GPJ

Good point Francesca - the pontoons themselves seem to be a Trillium innovation from years earlier - I can't see any reason for them other than catching excess moisture in the trailer. From what I can tell, some Trilliums seem to have drain holes, but others (maybe most?) do not. Some owners seem to drill drain holes if they were not there before. How about yours?

My take on the "pontoons" in the original design is that they're a design feature unrelated to drainage- early Trilliums (or at least mine) didn't have drain holes. In mine at least the entire inside floor is fiberglassed anyway with the same material the rest of the trailer is made of. Except for up front under the bench and a small patch of visible board by the sink there's no place for water to penetrate to/past the marine plywood subfloor.

In Escape's case, it's my understanding that the wood floor is laid without the topping of sheet fiberglass sealed against the walls, so holes in the pontoons are to allow for the drainage of any condensation/leaks that might creep down that seam. Good idea!

Side note:
I did cut drainholes in four low places in the trailer, but those are for the purpose of draining washwater out- at least once a year I actually take a hose to the inside...

Francesca