trailer enclosure opinions wanted

[dfink]

I currently have an 18' aluma 8218 aluminum trailer. With the recent changes to my car it is no longer exactly water tight. I thought of trading in the open trailer for an enclosed but the idea of all the extra weight just isn't very appealing. So I am thinking of making a canas enclosure to cover the car while hauling.
My idea basically is to make a frame by bending 1/2 electrical conduit and placing one "rib" every 2 feet to make up a center section. The center ribs would be perpendicular to the trailer bed.
For the front I though the ribs could go parallel to the trailer and be bent to form an aerodymanic angle. The front section would be hinged to open or would be rigid with zippered openings to access the front tie down.
My though was to have the rear section hinged and supported by gas shocks to allow the car to exit. I was only going to make the enclosure 5' tall so most of the wind should be blocked by the toe vehicle.
To connect the fabric to the ribs I would make pockets the go the entire width of the enclosure then slide the conduit into the pockets. To secure to the bottom I thought that canopy welting rails could attach to the bottom of the ribs then the canvas with a welting bead sewn in the bottom would slide on the welting rails. Kind of a canopy mount in reverse.
I have been looking at fabric and think sunbrella marine fabric would work well. I think about 30 yards. If bought on ebay the fabric would be maybe $300.00 and $100 to $150 for other supplies. I am pretty sure that a max budget of $600 would easily get the job done.
Has anyone used a canvas cover. I see them on semi trucks all the time and they appear to work well. I would think a tight custom fitted cover would help protect the car and at perhaps a couple hundred pounds would not impact towing and could possibly make it better.
Thoughs ideas would be appreciated.
Yes it would be a C.R.A.P. cover

[kerthunk]

Not sure if this helps or not, but if you are looking to build a frame for the canvas, you should check out the Kee Klamp products. They make an aluminum version called Kee Lite. They have all kinds of fittings and mounting options that should make the job quite easy.

http://www.simplifiedbuilding.com/products/2-kee-lite.html

[dfink]

Well the work has begun on the enclosure. I decided to use 1/2 EMT conduit and build a frame as shown below. For the cover I am using Surlast marine polyester fabric. This stuff is really tough. You can't even get a pin in it for sewing. If you do this make sure your machine is up to the task. The frame has an opening where a zip open door will be placed to get the car door open. The entire front and the entire rear will zip open for accessing storage and for driving the car on and off the trailer. There will be zipper access at each of the wheels for placing the tie down straps I use to hold the car. I have also added a few additional braces since the pictures. ie the front center tubes. The rear cross brace will be removable with spring loaded pins for easy removal.
The frame comes apart in four pieces so it can be stored easier. It may never be taken apart but I thought it would be a nice feature. The entire structure when complete will be maybe 150 lbs. Want a tent just unbolt the hold down clamps and two people lift and walk it off the trailer and set it on the ground. Instant tent and you can still use the trailer with no top if desired.

Any a couple of pictures of the frame.

[barney911rs]

Keep us posted, it will be interesteing to see how well it holds up to the buffeting wind as you go dow the road.

[175K911]

Hope it works for you. I tried this 20 years ago to haul my SCCA Sport Renault around. After my first 1,000 mile tow in pelting rain the canvas started shredding, and ended up making the trailer unstable at speed. But I didn't make a sloped nose like you're doing. Though I might still encourage you to cover the front with aluminum or something stronger than canvas.

[JohnJL]

I like the idea. With the massive Lemans wing on the back now I can't tow the car back-end-forward that properly balances the weight on the trailer.

As suggested above you might cover the forward surface with 2mm aluminum sheet.

[dfink]

I will try to keep this up to date with progress and how it performs. The canvas is not like a cotton tent or tarp canvas. It is extremely strong. Strange thing is it cuts pretty easily with scissors but you can't rip, poke or tear or scrape the stuff. For a test today I took a piece and put it on the bed of the aluminum trailer and did the twist. The fabric got a little dirty but I think it was harder on the the trailer than on the fabric. I took it to the sink and rinsed it off could tell I just trampled it to death. Water just beads up and runs off. Not sure how it will handle a driving rain. Didn't feel like getting the power washer out.
The suggestions of an aluminum front are probably good ones but I think I will at least give this a try if it doesn't work I have enough material I can redo the front if needed. The fabric is naturally kind of stiff. I think if I can get it taunt enough the air will flow up and over and not put a horrible amount of pressure on the front. Since I am not an engineer the only way to find out is to build it and see.

[CBRacerX]

Get the fabric as tight as you can and good luck!

[stevemfr]

Your frame looks real nice. Why don't you talk to truck tarp people, though? Sunbrella, while nice looking, may be too prone to getting dirty and possibly too light. Trucks usually use a rubberized canvas with the weave enclosed so that the outside surface is smooth and easier to keep clean. The material is also usually quite heavy to keep fluttering at speed down. I just did a quick google, but here's an address:
http://www.merlottarp.com/

Trucks with tarp enclosures are much more common on this side of the pond - as are trailers. This is a 'down the road' project for my open trailer too. Here are some pics of small trailer tarp systems:







The frames are designed to be easily removable and often rely on the tarp to hold everything together. The vertical pieces are just dropped into holder-tubes and the horizontal pieces are hung in 'pockets' (like joist-hangers) - just in case you ever decide to build a more industrial trailer sometime. I'm just assuming this is all relatively uncommon in the States as I've only seen it over here, BTW. I hope I'm not passing on redundant information.

Here are 2 pics of the same trailer:





They use various systems to stretch the tarp:



This is a little hard to see, but the use short ratcheting straps sewn into the tarp to stretch and secure it.



Cool stuff. Are you planning on doing the sewing yourself?

[dfink]

Well an update. We took the trailer for a test drive with no cover just to see how it reacted. The aluminum trailer has a tremendous amount of flex. The front being reinforced by the tounge does not flex much but the back lifted the attachment clips by nearly an inch.
Keep in mind I am a cheap SOB hense the reason for most of my insane projects. So I think I will have to work around the flex. If I try to make it too stiff I think it will tear itself apart.
To accomodate the rear flex I am going to try spring loaded clamps that pass through the trailer bed then clip over the bottom section of the frame. This way the trailer can flex and the attachment points will have some give. The entire tarp will be held to the trailer with 15 1" wide adjustable straps with quick release clips. My thought is as one side of the tarp goes up with flex the other side should come down. This may cause some wear to the fabric but shouldn't put a lot of stress on the framework. I think everything will need to have just a little give or it won't work well.
I reinforced the front section of the frame. I can now do a hand lift putting my full weight on the center of the front. 265 lbs and it holds just fine. If my calculations are correct that should be the entire load spread out over the front. I had it concentrated in two hand spots. I think the frame is now more than strong enough.
Next step is to start sewing the cover. I am still going to use the sunbrella fabric as that is what I have purchased. It appears to be super tough and is fairly stiff. I would never be able to sew the heavy rubberized tarp material.

[dfink]

Another update. The cover is coming along. Alot of work to make this. Way more time than I thought.

Anyhow starting to look like a trailer.

[dfink]

An update on the trailer enclosure. It is now pretty much complete and has been put into operation. It has made three trips one 150 mile round trip and two 100 mile round trips. I have not had it out in a rain storm yet. It has performed pretty mush as I had envisioned it. There is some puffing and indenting from travel and side winds but I have checked the stress points on the cover and so far it shows no signs of wear. The real test will come with a hard rain storm while towing. It gets alot of attention. At the last autocross I think I could have sold 10 of them if I had a way to make them reasonable. It is labor intensive. There is 450 feet of conduit, 33 yards of 60" wide material, 1600+ yards of thread, 25 yards of hook and loop, 30 feet of nylon strap and 20+ clamps There are 4 60" zippers and 2 72" zippers. The zippers are #10 size heavy duty. Anyhow some more pictures

The side view. It is about a 30* pitch on the front section.



The front view



To help take some stress off the fabric and keep it from indenting so much wihile towing I wove some rope around the ribs. The center section is bungie cords so they can be easily removed for front access.



This picture shows the rear cross braces from inside the trailer.



The rear braces are attached with spring clamps for easy installation and removal. I plan to make the braces convert to awning supports which will allow the rear access door to either roll up or become an awning.



This shows the side attachments. These help stablilze the sides against the wind.



The side attachments are made with hook and loop material for easy installation, removal and provides some adjustment.



The bottom is held in place with welting. A 1/4 inch rope is sewn into the bottom of the sides and is trapped by the bottom of the frame. The straps are to help pull the welting under the frame when installing the cover. The frame is held down with "J" bolts that are bolted to the trailer.

[CBRacerX]

Wow! You really pulled it off. Nice job.

[911st]

Very, very, impressive.

Just a thought, one could make a cover that uses the car for its support. Kind of like a tailored car cover that seals down to the trailer. Could have straps to take the slack out of it. Could even leave it rolled up like a jeep top if not needed.

[dfink]

Originally Posted by 911st

Very, very, impressive.

Just a thought, one could make a cover that uses the car for its support. Kind of like a tailored car cover that seals down to the trailer. Could have straps to take the slack out of it. Could even leave it rolled up like a jeep top if not needed.

Thought of that but is nearly impossible to get totally tight. Any movement eventually would casuse damage to the car. This is also nice as it fuctions as a tent at the events. No longer have to put up the easy-up.

I also make it tall enough that I can put my Harley Ultra Classic in there is I want to haul it someplace.

[JohnJL]

Massively impressive. Well done.

[911st]

Originally Posted by dfink

Thought of that but is nearly impossible to get totally tight. Any movement eventually would casuse damage to the car. This is also nice as it fuctions as a tent at the events. No longer have to put up the easy-up.

I also make it tall enough that I can put my Harley Ultra Classic in there is I want to haul it someplace.

Always great to be able to get out of the elements. Again, great project.

As to the car/trailer cover, was thinking 'cinch straps' would take the slack out. They could even have an rubber stretch element to them. With cinch straps on the sides and back, might even be able to make a more genaric product that would adapt to different cars. It is just an idea.

[911st]

Another thought, could add loops to the out side so fiberglass rods could be added at the track to turn it into a tent???

[stevemfr]

Nice!

[donporfi]

You can add some battens, like the ones used in sailboats sails and hangliders. With these the fabric will not flap. You can use aluminum tubing for these and sew batten pockets in your cover.