Advice Please on Canvass Sides

[JMPC]

Hi All,

I built an off-road camper trailer last year, for pics see earlier thread I posted on this forum...

http://www.expeditionportal.com/forum/showthread.php?t=35494


I am now building another one, with some improvements.

However, I am currently stuck on a major decision, which is what to make the walls and roof out of.

I could make them as before, aluminium for exterior, polystyrene insulation and PVC or GRP for inside walls.

However, I have recently thought about making the exterior walls out of a marine grade canvass like Sunbrella, or Topgun. These are the type of waterproof yet breathable canvases that you´ll find on the back of leisure boats. I live near a marina, so have quizzed lots of boat owners who live aboard to ask whether or not the canvasses are truly weather proof in all conditions and everyone has said 'yes, completely water proof, never had any problems at all. I live in the UK so winters are long with lots of rain.

I have spoken to couple of firms who can make me a complete canvass set up, complete with integral windows, fly screens, blinds. The canvass would then be dropped over a steel frame and secured down at the bottom of the walls with lockable clips.

Advantages of this are...

Very light, approx. 60kg for all the roof, walls and windows.

Windows will open up completely ( like the front of a tent) so giving a great 'outdoors feeling' on warm days and nights even when inside. And I can have the windows any size I want.

Manufacture is obviously much easier because I am just dropping a complete canvass over a metal frame, and the whole unit is ready.

I could still line the interior walls with GRP or PVC, and probably still have insulation between the exterior canvass and the interior walls. Or I could just go rough and ready and not bother with any kind of lining, just go for a tent style feel inside.

Between the metal frame and the exterior canvass I would place a lightweight mesh cover, (think chicken wire) effectively making it impossible for anyone to break in.

What are peoples thoughts on this?

Would you still be worried about the windows being a week area, and prone to people breaking in?

What dis-advantages do you percieve?

Any thoughts most welcome

All the best
JMPC

[ntsqd]

If the "tent" can move against the frame at all it will abrade any coating and the metal itself. Probably won't do the metal much harm, but it won't do the coating any good. Bare metal exposed to condensation held in place by the "tent" (~capillary action) would be the result.

Solve that and I think it's a novel solution. Not sure that if I were going to go to the trouble of building a trailer that I wouldn't want hard sides, but it's not mine.

[Tucson T4R]

On my KK trailer I have enough canvas to set up an entire MASH unit. :sombrero:

My experience has been that good canvas is fully weather proof but the down side is when it gets windy. As long as you have a solid frame to mount the canvas to it will stand up to the winds but it can get pretty noisy inside with high winds and all the canvas banging around.

If winds are not a big problem where you live it may be a great design for you. If you get abused frequently with high winds then I would go for a hard sided design.

[JMPC]

If the "tent" can move against the frame at all it will abrade any coating and the metal itself. Probably won't do the metal much harm, but it won't do the coating any good. Bare metal exposed to condensation held in place by the "tent" (~capillary action) would be the result.

Solve that and I think it's a novel solution. Not sure that if I were going to go to the trouble of building a trailer that I wouldn't want hard sides, but it's not mine.

Yup, good point, the capillary action is a possible problem. I have spoken about this with the canvass manufacture who assures me it won't happen becasue of the type of coating on the canvass on its exterior. Not quite sure how this works but the evidence is there in that the boat canvases dont suffer form this.

Thanks for the feedback

[JMPC]

On my KK trailer I have enough canvas to set up an entire MASH unit. :sombrero:

My experience has been that good canvas is fully weather proof but the down side is when it gets windy. As long as you have a solid frame to mount the canvas to it will stand up to the winds but it can get pretty noisy inside with high winds and all the canvas banging around.

If winds are not a big problem where you live it may be a great design for you. If you get abused frequently with high winds then I would go for a hard sided design.

Thanks Brad,

good to hear your experiance concerning 'weatherproofness' bears out my research and what I am being told, so that certainly reassures me.

It is a good point you make about the wind noise, (romantic for about 5 minutes and then nothing but stressfull) I intend to have lots of points where the canvass will attached firmly to the metal frame, approx. every 50cm in every direction, so that should keep things tight. It is also another point in favour of lining it with interior walls and insulation just to offer a barrier against unwanted noise.

Thanks
JMPC

[ntsqd]

Does the material also have that coating on the inside surface? I'm not thinking that it could wick moisture in from the outside, but rather that the moisture exhaled from breathing inside the trailer could condense on the surface and drain towards where the canvas is pulled tight against the frame.

[JMPC]

Does the material also have that coating on the inside surface? I'm not thinking that it could wick moisture in from the outside, but rather that the moisture exhaled from breathing inside the trailer could condense on the surface and drain towards where the canvas is pulled tight against the frame.


I´m not sure if coating is on both sides? I guess though if condensation is going to be a problem it will happen with or without the coating?

I am concerned about condensation, wich is one of the reasons I may line the interior with walls. If not, I´ll make sure that there is plently of cross venitaltion high up in the roof to try and eliminate the worst of it.

[etbadger]

The pop-top sides on our van are a plasticized canvas of some sort. We do get a significant amount of condensation in colder temperatures and humid climates. Some of this is alleviated by using chemical air-dryers (calcium choloride crystals) used for damp closets and camper storage (or snow melt).

Additionally we have all our heat and cooking done with sealed diesel appliances which vent outside.

-e

[Lynn]

You mentioned the inside mesh to provide security. Someone passing by with a knife might be tempted to cut the canvas to see what they could grab. Yes, the mesh will then stop them, but the canvas is still cut.

Hard walls should deter most of the less-determined criminals, not to mention the random opportunistic idiot with a pocket knife.

Just a thought.

[JMPC]

You mentioned the inside mesh to provide security. Someone passing by with a knife might be tempted to cut the canvas to see what they could grab. Yes, the mesh will then stop them, but the canvas is still cut.

Hard walls should deter most of the less-determined criminals, not to mention the random opportunistic idiot with a pocket knife.

Just a thought.

Yes, you are quite right and this is my biggest concern too. As you say, it is perhaps inviting breakin attempts or just mindless vandalism. A way of detering breakins could be to advertise on the side that there is protective metal mesh'. Not sure exactly how this could be done effectivly, but sure there is a way.

Don´t know if vandalism could be guarded against? This is tricky

Thanks for your reply, ultimatly, given a choice, which would you prefer, the benefits of canvass (lighter weight and able to create a much more open environment when camping) or hard walls?

All the best
JMPC

[JMPC]

The pop-top sides on our van are a plasticized canvas of some sort. We do get a significant amount of condensation in colder temperatures and humid climates. Some of this is alleviated by using chemical air-dryers (calcium choloride crystals) used for damp closets and camper storage (or snow melt).

Additionally we have all our heat and cooking done with sealed diesel appliances which vent outside.

-e

I am guessing these are bags of crystals that you place strategically aroung the inside?

Are you using a 'webasto' diesel applicance?

I suppose even though the combustion takes place outside, cooking itself, like boiling water, must create lots of condensation. Here what do people do, leave windows and doors open, or rely on extracter fans?

[compactcamping]

Personally I'm a big fan of the "softsided" approach as a way to notably reduce weight and potentially have a smaller in transit profile.

The challenge is waterproof and breathable. There are a number of fabrics that do a good job of balancing the two. A double wall design does help in dealing with condensation.

Here is a frame I've been playing with for a fabric wall camper.

http://www.mikenchell.com/forums/album_pic.php?pic_id=62540

[JMPC]

Personally I'm a big fan of the "softsided" approach as a way to notably reduce weight and potentially have a smaller in transit profile.

The challenge is waterproof and breathable. There are a number of fabrics that do a good job of balancing the two. A double wall design does help in dealing with condensation.

Here is a frame I've been playing with for a fabric wall camper.

http://www.mikenchell.com/forums/album_pic.php?pic_id=62540

Hi, thanks for the photo, and feedback. Yes double walled design might be a must to avoide the worst of the condensation.

I am aware of 3 big brands for the canvass, Sunbrella, Topgun and Harbourtime. Are you ware of any others?
Great to see someonelse sees the merit in this idea. Are you intending to have windows? Waht are you going to use for the interior wall, something solid, or another breathable lightwight fabric that wicks away the mousture, like the inside of a tent?

All the best
JMPC

[compactcamping]

There are lots of fabrics to choose from. I find it most cost effective to figure out the criteria it needs to meet and see what is readily available from my local supplier. My fabric source carrys Tri Vantage and Glen Raven fabrics. Topgun and Harbor-Time are both Tri Vantage products, Sunbrella is from Glen Raven.

Sunforger and Weather-Mate are cotton marine canvas I like. HydroKing is a poly/cotton blend canvas that looks promising.

I'm still very early in sorting out this idea. Yes windows, thinking exterior flaps than can act as awnings. Interior wall a lightweight cotton canvas, very breathable and moisture wicking. Exterior wall, waterproof coated fabric, with some form of an overlaping panel design that allows for adjustable ventilation between the walls.

[JMPC]

There are lots of fabrics to choose from. I find it most cost effective to figure out the criteria it needs to meet and see what is readily available from my local supplier. My fabric source carrys Tri Vantage and Glen Raven fabrics. Topgun and Harbor-Time are both Tri Vantage products, Sunbrella is from Glen Raven.

Sunforger and Weather-Mate are cotton marine canvas I like. HydroKing is a poly/cotton blend canvas that looks promising.

I'm still very early in sorting out this idea. Yes windows, thinking exterior flaps than can act as awnings. Interior wall a lightweight cotton canvas, very breathable and moisture wicking. Exterior wall, waterproof coated fabric, with some form of an overlaping panel design that allows for adjustable ventilation between the walls.

Thanks Scott,

Interesting stuff. Like the idea of exterior flaps working as awnings, that hadn´t occured to me, but great idea.

All the best
JMPC

[Tucson T4R]

My KK trailer has the window flap design and it does work very well by allowing you have the windows open while it's raining. The flaps have corner grommets so you can stake them out at and angle to protect the window from the rain but still have great ventilation.

BTW, my window flaps are zippered on the sides and just Velcro at the bottom edge when closed if you want to consider that option.

[JMPC]

My KK trailer has the window flap design and it does work very well by allowing you have the windows open while it's raining. The flaps have corner grommets so you can stake them out at and angle to protect the window from the rain but still have great ventilation.

BTW, my window flaps are zippered on the sides and just Velcro at the bottom edge when closed if you want to consider that option.

Thanks Tuscan

Again, I hadn't thought about having windows open while raining, but obvious of course!


Have you any pictures?

All the best
JMPC

[Lynn]

Thanks for your reply, ultimatly, given a choice, which would you prefer, the benefits of canvass (lighter weight and able to create a much more open environment when camping) or hard walls?


Since you asked, I, personally, would rather have a hard-sided walls (better insulation, security) with largish windows set in really large opening panels.

Like what Bimobile does,

http://www.bimobil.com/english/modelleexpedition_benz/diashow/ansichten/G_3.jpg

or what Rob Gray did with Wot I.
http://www.robgray.com/graynomad/wothahellizat/15721.jpg

I would strive to use the lightest construction possible, but it would certainly weigh more than a canvas approach.

I want to be comfortable in either very hot or very cold environments, and I don't believe it would be very difficult to get sufficient insulation with soft sides.

[Tucson T4R]

Thanks Tuscan

Again, I hadn't thought about having windows open while raining, but obvious of course!


Have you any pictures?

All the best
JMPC

This one shows the large end screened panel:

http://i103.photobucket.com/albums/m125/bgarland40/07%20Gila%20Camp/07GilaCamp19.jpg

The canvas windows roll up when you just want the screen in good weather:

http://i103.photobucket.com/albums/m125/bgarland40/07%20Richmond%20Basin/DSC02422.jpg

Larger view with all the canvas sides on:

http://i103.photobucket.com/albums/m125/bgarland40/07%20Richmond%20Basin/RichmondBasin07086.jpg

Side window rolled up:

http://i103.photobucket.com/albums/m125/bgarland40/07%20Richmond%20Basin/RichmondBasin07047-1.jpg

Hope that helps.

[JMPC]

This one shows the large end screened panel:


The canvas windows roll up when you just want the screen in good weather:



Larger view with all the canvas sides on:



Side window rolled up:



Hope that helps.

Thanks Brad

AAAHHHH I´ve finally twigged - KK = Kimberly Kamper!

Very nice set up I see. Is that a ZODI I spy? You guys have all gear, Very nice!

Thanks for the pics, certainly give some good ideas

All the best
JMPC

[JMPC]

Since you asked, I, personally, would rather have a hard-sided walls (better insulation, security) with largish windows set in really large opening panels.

Like what Bimobile does,

http://www.bimobil.com/english/modelleexpedition_benz/diashow/ansichten/G_3.jpg

or what Rob Gray did with Wot I.
http://www.robgray.com/graynomad/wothahellizat/15721.jpg

I would strive to use the lightest construction possible, but it would certainly weigh more than a canvas approach.

I want to be comfortable in either very hot or very cold environments, and I don't believe it would be very difficult to get sufficient insulation with soft sides.

Thanks again Lynn

great pics. I have seen the WOT 1 before, fantastic! (What On Earth Is That?, I think is the acranym, correct me if I´m wrong?)

I do agree with you, ultimatly one can´t expect insualtion to work as well with soft sides. And of course security, or perceived security is certainly not as good.

Thanks for the opinion

All the best
JMPC

[Lynn]

Sorry, but I just can't seem to stay away from this one. Possibly because I'm airing and evaluating my own thoughts on the idea :)

Anyway, I was thinking, how much weight are you going to save with double soft walls, insulation, and chicken wire versus a fiberglas/styrofoam sandwich w hard walls? I'm guessing not much. The heaviest part of either approach is the framing, and that might actually have to be heavier with canvas. Especially if you could build the sandwich walls as SIP (Structural Insulated Panels) and only reinforce where necessary.

That's my theory, and what I'm planning, so I'm hoping someone who has done the engineering analysis will chime in here and save me the trouble. :)

[Lynn]

Oh, and if you are building this as a trailer, I think you should pull it with a Velorex:

http://www.3goose.com/velorex/DSCF2463-01.jpg

http://www.tamabi.ac.jp/IDD/shiro/facility/bmw/bmw-skin/velorex-2.gif

[dsw4x4]

Here is what my research of pop up slide in found. Here in Colorado the manufacturers use Aqualon or and equivilant. Rockwalon (rockford supply own name) also know as a spa material (hottub covers) sandwiched with 1/8 or 1/4 foam (think a big roll of packing foam is what they use) in between two layers, most between two layers of aqualon. Some use aqualon on the outside and a breathable fabric on the inside. I am guessing to eliminate encapsulating moister in with the foam. Aqualon or an equivilant will not breath no matter what, the plus is it will not leak no matter what! I use either single wall aqualon on our vans or double wall if the owner wants it built for four seasons. Currently my van (1st prototype) uses a pack cloth "breathable/ waterproof" material, yes it sweats and it leaks if you are constantly touching the inside on a rainy day. Sunbrella type fabrics will still leak and sweat (climb under a boat on a rainy day) after time. The big draw back is they take a long time to dry out. So if it rains on vacation chances are your fabric will be wet the whole time until you get a breeze sunny warm day. These fabrics also seem to not have very good abrasion resistance. If you pinch it closing your top and drive down a wash board road that area is now going to leak.
My advice would be use a water proof non breathable material for any surface that can hold water. If you really want breathable and not by opening a window than use breathable fabric for the walls and if you can design the wall so that it slightly tilts out ward and give it a overhang if possible. This keeps the rain off of it and allows it to drain outwards instead of absorbing it into the fabric.
Don't take this info to the bank! I just know how hard it is to find out any info on this stuff and how many choices there are out there. The only people that seem to know anything are the sales man and of course their material will rock your world stand up to a hurricane keep you dry and last 40 years!!! Riiiiight.
Good luck and hope this helps.
Derek

[JMPC]

Sorry, but I just can't seem to stay away from this one. Possibly because I'm airing and evaluating my own thoughts on the idea :)

Anyway, I was thinking, how much weight are you going to save with double soft walls, insulation, and chicken wire versus a fiberglas/styrofoam sandwich w hard walls? I'm guessing not much. The heaviest part of either approach is the framing, and that might actually have to be heavier with canvas. Especially if you could build the sandwich walls as SIP (Structural Insulated Panels) and only reinforce where necessary.

That's my theory, and what I'm planning, so I'm hoping someone who has done the engineering analysis will chime in here and save me the trouble. :)

Weight saving I guess will work out at about 200kg, after everything is taken into consideration, angle to knit walls and roof together, windows, etc.

For me, one of the main reasons for going for a canvass is ease of manufacture, just drop it over the top`and cost. It also allows me to have as many windows as I like, and of any size.

Complete 'off the shelf' window units with integral blinds and flyscreens run into appox. £500 or $700 per window, and that's not even getting the window size i want. So here, for what I wish to acheive, I´m looking at a bill of a £2000 or $3000 just for these alone. I have made windows myself before, and they worked out OK, but these are perhaps the most difficult component to make onself as margin for error is small.

Ridged hard walls that come perfabricated with a sandwich contruction, GRP exterior and interior with a styromoam middle, are certainly a good option, and you´re quite right they do need less framing, as they self support. It may still be the option I go for, but the cost here is about £80 or $130 per sqaure metre. So this quickly gets pricy too.

They do have other benefits too, however, that are worth considering, one of the main ones being that colour range is very good, so no need for any kind of spray painting. So that's another point in their favour.

The deliberation contunues! Thanks again for your thoughts, much appreciated.

All the best
JMPC

[JMPC]

Oh, and if you are building this as a trailer, I think you should pull it with a Velorex:

http://www.3goose.com/velorex/DSCF2463-01.jpg

http://www.tamabi.ac.jp/IDD/shiro/facility/bmw/bmw-skin/velorex-2.gif

Lynn

This is my tow vehicle! How did you know? Although mine is in poor condition and needs much work, unlike the fine examples shown here:)

All the best
JMPC

[JMPC]

Here is what my research of pop up slide in found. Here in Colorado the manufacturers use Aqualon or and equivilant. Rockwalon (rockford supply own name) also know as a spa material (hottub covers) sandwiched with 1/8 or 1/4 foam (think a big roll of packing foam is what they use) in between two layers, most between two layers of aqualon. Some use aqualon on the outside and a breathable fabric on the inside. I am guessing to eliminate encapsulating moister in with the foam. Aqualon or an equivilant will not breath no matter what, the plus is it will not leak no matter what! I use either single wall aqualon on our vans or double wall if the owner wants it built for four seasons. Currently my van (1st prototype) uses a pack cloth "breathable/ waterproof" material, yes it sweats and it leaks if you are constantly touching the inside on a rainy day. Sunbrella type fabrics will still leak and sweat (climb under a boat on a rainy day) after time. The big draw back is they take a long time to dry out. So if it rains on vacation chances are your fabric will be wet the whole time until you get a breeze sunny warm day. These fabrics also seem to not have very good abrasion resistance. If you pinch it closing your top and drive down a wash board road that area is now going to leak.
My advice would be use a water proof non breathable material for any surface that can hold water. If you really want breathable and not by opening a window than use breathable fabric for the walls and if you can design the wall so that it slightly tilts out ward and give it a overhang if possible. This keeps the rain off of it and allows it to drain outwards instead of absorbing it into the fabric.
Don't take this info to the bank! I just know how hard it is to find out any info on this stuff and how many choices there are out there. The only people that seem to know anything are the sales man and of course their material will rock your world stand up to a hurricane keep you dry and last 40 years!!! Riiiiight.
Good luck and hope this helps.
Derek

Derek,

Valuable insight, clearly from experience, thanks. As they they say ' the devil's in the detail' and your points about breathability, abrasion resistance, fabric drying times, are very uselfull. The sort of things that one only finds out after the money and hard work is put in.

Thanks for the input,

All the best
JMPC

[JMPC]

I'm a bit confused...couple of questions -
these are fixed, non folding walls? Permanent fabric walls in effect?
what sort of windows are you building & how do you mount them in fabric?
the roof also might be fabric?

England...fabric walls, damp = interior mold I'd think. Even waterproof fabrics have enough texture to retain enough dirt, dust & crud to feed mold - and you can't clean them really well - certainly not as well as a hard surface. Mold for me would be a real deal killer...


That's a lot of weight savings for sure...but I wonder if you made hard walls only as strong as fabric walls what would they weigh? You don't have to jump from fabric to a strong rigid composite - there is a middle ground. Maybe even just uninsulated ply walls - given that you want lots of windows - unless they are $$$ double paned the heat will blow right through them (or the cold in the other direction...) so insulation in the walls won't help much...That approach might be cheaper, more comfortable, easier to build & certainly longer lasting. Good ply with epoxy coatings & paint is extremely weather durable. It would just need a good heater...Peter

Hi Peter,

I´ve was very interested in your recent build project and seeing the level of craftsmanship involved ( well ,well above my level) i take your opinion very seriously.

You suggest a good compromise, and of course in comparison to most other options ply is very inexpensive. And, since starting this thread, I have also managed to source re-fabricated RV windows for approx a 1/4 of the price of the standard ones available. So all that's working out well.

In answer to your questions, if I went for canvass walls and roof, the windows would also be of fabric, or clear pvc.

What you say about mould is relevant, and well thought through, becasue an offroad trailer will encounter much dirtier conditions than a boat, where the majoiry of this type of cavass is used.

Suggestions much appreceiated - looks like I am leaning away from canvass.

Al the best
JMPC

[UK4X4]

personally I would not go the fabric route for anything seeing road use, even a steel trailer after 1 gravel road shows grit blasting along the front edge, I think you'd wear through pretty dam quick using a fabric.

I will be recovering my RTT with some marine polycanvas- no there's no coating as such its in the weave and probably silicone on the fibers themselves, but was concidering a laminated PVC type roof for the top and all the sides in the breathable material.

The boat poly canvas is extremly tough for its thickness.

Lightweight - UK weather, I'd stick with 3mm ply with a fiberglass top coat and re-inforced joints and webs, foam the inside if required.

I think my next trailer will be a pop top fold out type design as the babe is now a child and the dog refuses to move out of the RTT

Now if you look at old aircraft they used fabric over wood frame and then varnished it.........

maybe a neat solution would be to use a modern fabric and a resin top coat, I bet you could built a beautiful curved and ridgid structure and very light weight.

mmmmm I like that idea

[ntsqd]

snip.....

Now if you look at old aircraft they used fabric over wood frame and then varnished it.........

maybe a neat solution would be to use a modern fabric and a resin top coat, I bet you could built a beautiful curved and ridgid structure and very light weight.

mmmmm I like that idea
Just exactly what I was about to suggest. Light frame, stretch the fabric over it tightly, apply resin of choice.

[JMPC]

personally I would not go the fabric route for anything seeing road use, even a steel trailer after 1 gravel road shows grit blasting along the front edge, I think you'd wear through pretty dam quick using a fabric.

I will be recovering my RTT with some marine polycanvas- no there's no coating as such its in the weave and probably silicone on the fibers themselves, but was concidering a laminated PVC type roof for the top and all the sides in the breathable material.

The boat poly canvas is extremly tough for its thickness.

Lightweight - UK weather, I'd stick with 3mm ply with a fiberglass top coat and re-inforced joints and webs, foam the inside if required.

I think my next trailer will be a pop top fold out type design as the babe is now a child and the dog refuses to move out of the RTT

Now if you look at old aircraft they used fabric over wood frame and then varnished it.........

maybe a neat solution would be to use a modern fabric and a resin top coat, I bet you could built a beautiful curved and ridgid structure and very light weight.

mmmmm I like that idea

Thanks UK4x4.

Before investigating canvasses I was considering PVC, which is 100% waterproof, but not breathable. In the end I decided against it not only becasue it doesn't breath but because it tends to give off quite a strong 'plasticy' smell that is difficult to get rid of.

Varnishing a canvass would make it clean easier, and this would then perhaps take care of the mould & damp problem that Peter referred to in his post above, but then I gusee it would no longer be breathable?

As i write this I suppose I should take the view, that consdiering the conditions the trailer will encounter, I will need a 100% waterproof fabric if I were to go down the fabric route. Therefore, I think I would decided to go for a 600g 'lorry curtain' style PVC, and get around the condensation/insulation/unwanted smell issues by having a proper lined interior.

However, this is all getting quite complicated, and untested, it may just be easier to go for hard walls again, as these seams to be less compromising.

The abilty to acheive nice lines, using a rigid frame with fabric is tempting, but perhaps this is the only advantage left, and this could also be acheived working in ply with galss matt ovet the top to finish corners off etc?

All the best
JMPC

[UK4X4]

3mm ply will curve in a single plane really well and two planes with persussion!

you can also laminate thinner panels together if available

http://www.dixdesign.com/didi5.jpg

plywood wood frame with plywood sheath

[JMPC]

3mm ply will curve in a single plane really well and two planes with persussion!

you can also laminate thinner panels together if available

http://www.dixdesign.com/didi5.jpg

plywood wood frame with plywood sheath

That's usefull to know, I wasn´t sure how curves like the ones on boat hulls were acheived, I had always thought that the wood needed a lot of 'treating' and setting to get it that way.

But I guess you´re saying that with 3mm ply it can be curved and fastened into place 'dry'?.

All the best
JMPC

[UK4X4]

1 plane dry, for small radia you could steam, bathe in hot water first, or notch the rear with a skill saw

see StompXJ trailer build for some lovely woodwork and curvey ply.

His construction is heavy duty, but the curves apply

http://expeditionportal.com/forum/showthread.php?t=18142