12' Cargo Trailer Design

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12' Cargo Trailer Design

Postby grassgd » Tue Nov 24, 2015 10:32 pm

Basic design calls for full size fold down Murphy bed with dining table that folds down from bottom of bed when in upright stowed position along with spacious kitchen and bath area. I have created a number of layouts and played with various trailer widths ranging from 7' to 8.5' wide. I currently think a 7.5' width would be the minimum with 8' wide likely being the sweet spot to provide passage and avoid feeling too closed in. There are many mechanical issues with each of the designs which I have given alot of thought to, but the layouts shown are my two best options to date. The front bath design leaves the rear area open to all living space with rear door leading out to a fold down platform (cargo rear ramp) as a patio (not shown in layouts), Tub size is 36' x 24". This layout also provides an area in the front v-nose between the tub and the side entry door for all mechanical equipment.

137653

The rear bath design provides better space in the kitchen area and larger bath/shower (4' x 24" tub shown in the attached layout). The rear bath door swings to close off the bath area with access to the rear door/patio ramp but can be closed off to provide a bath area of about 8' x 4' total area with is really nice and big. Mechanical equipment would have to be located in the kitchen/v-nose cabinets.

137652

My designs are not in sketchup (haven't learned to use yet); I currently use MS Visio and do 3d in Chief Architech. The attached PFD file includes the basic layouts and 3d shots from Chief Architech program.

I am currently leaning toward the front bath layout at the moment, but keep mulling over the various designs searching for the best of the best while trying to stay with a small 12' body + v-nose.
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Re: 12' Cargo Trailer Design

Postby aggie79 » Fri Nov 27, 2015 4:26 pm

Thank you for posting your designs. I've been semi-planning to do a cargo trailer conversion myself and will refer to your layouts when I get a little more serious about building (and have the money to do so).

Please keep in mind that when you go to widths greater than 7' the wheels are inset into the trailer "box". This could affect equipment layout and circulation.

Take care,
Tom
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Re: 12' Cargo Trailer Design

Postby grassgd » Sun Nov 29, 2015 1:07 am

You're correct about widths greater than 7' requiring wheel well inserts in the floor unless you opt for a deck over design which also provides a trailer with greater ground clearance. My current thinking is to use a deck over trailer to enable better access to forest roads and unimproved areas. Many conventional trailers are so low even going up some driveways may cause dragging much less going off the improved roads. A deck over will require more steps to access the trailer and much higher hitch height though. Of course a 7' wide trailer would be better for towing but I am concerned with the lack of space for two people moving around when inside. Looking at pictures of other designs with 7' width gives me the impression that greater width than 7' may be a blessing in the long run.
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Re: 12' Cargo Trailer Design

Postby Padilen » Sun Nov 29, 2015 10:26 am

For years many travel trailers only had a narrow "hallway". We always had 5 or more in a 19'. As kids we'd sit at the table while adults did what needed to be done. You could design for less dual occupancy area's. But if you hate the idea now your build will never be just right.
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Re: 12' Cargo Trailer Design

Postby lrrowe » Sun Nov 29, 2015 12:01 pm

grassgd wrote:You're correct about widths greater than 7' requiring wheel well inserts in the floor unless you opt for a deck over design which also provides a trailer with greater ground clearance. My current thinking is to use a deck over trailer to enable better access to forest roads and unimproved areas. Many conventional trailers are so low even going up some driveways may cause dragging much less going off the improved roads. A deck over will require more steps to access the trailer and much higher hitch height though. Of course a 7' wide trailer would be better for towing but I am concerned with the lack of space for two people moving around when inside. Looking at pictures of other designs with 7' width gives me the impression that greater width than 7' may be a blessing in the long run.



The one piece of advice on this I can offer is to say that I wish I wish I had not ordered my CT with 6 extra inches of ground clearance because the step height is an issue and because the extra height creates more of a sail for me to pull. I too was concerned about forest roads, but to date, I do not see the extra ground clearance as that much of an advantage.

But then again, you may be planning to go further off road then I do.
Bob

First Post on Purchase of Trailer: http://www.tnttt.com/viewtopic.php?f=42&t=60722
Hot water infloor and radiator heating project:[url]http://www.tnttt.com/posting.php?mode=reply&f=54&t=62327[/

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Re: 12' Cargo Trailer Design

Postby aggie79 » Sun Nov 29, 2015 4:38 pm

Bob brings up a good point to consider. The "sail" or frontal area really affects towing. Increasing width and/or height makes it harder to tow unless your toe vehicle is in the "3/4 ton" truck range or greater. My F-150 manual has a maximum trailer frontal area of 70'. (I have the max towing package with integrated brake controller and 3.55 rear drive ratio.). For this reason I'm considering a 7' width and a longer length - say 18' or 20' - to get the area needed for all of the internal requirements/desires and still keep things within the 70 square foot frontal area.
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Re: 12' Cargo Trailer Design

Postby grassgd » Mon Nov 30, 2015 3:39 am

Bob and Tom: Good point concerning frontal area and maximum tow vehicle specification. Although I'm aware of the greater towing resistance with the wider trailer, I had forgot vehicles do have a max towed trailer frontal area specified. Not sure if all vehicles have this specified but I will have to check it out for my vehicle.

I know the wider trailers also have poorer visibility. I have towed boats that are 8' wide and 6x12 cargo trailers. With the narrower trailer, it is nice being able to see past the trailer with normal side mirrors (ie big pick up have those extended side mirrors which I don't have) but with that said, it's not a deal killer for me.

I may try to do a mock up if I can get my hands on some large pieces of cardboard to see how the 7' to 8.5' wide layouts feel.

As far as ground clearance, I am concerned with the extra steps to get into the trailer and you are correct it puts the trailer higher up above the to vehicle which means more drag too. I'll have to give this one some careful consideration before proceeding.
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Re: 12' Cargo Trailer Design

Postby lrrowe » Mon Nov 30, 2015 8:38 pm

grassgd wrote:Bob and Tom: Good point concerning frontal area and maximum tow vehicle specification. Although I'm aware of the greater towing resistance with the wider trailer, I had forgot vehicles do have a max towed trailer frontal area specified. Not sure if all vehicles have this specified but I will have to check it out for my vehicle.

I know the wider trailers also have poorer visibility. I have towed boats that are 8' wide and 6x12 cargo trailers. With the narrower trailer, it is nice being able to see past the trailer with normal side mirrors (ie big pick up have those extended side mirrors which I don't have) but with that said, it's not a deal killer for me.

I may try to do a mock up if I can get my hands on some large pieces of cardboard to see how the 7' to 8.5' wide layouts feel.

As far as ground clearance, I am concerned with the extra steps to get into the trailer and you are correct it puts the trailer higher up above the to vehicle which means more drag too. I'll have to give this one some careful consideration before proceeding.


And as you decide which step method to use, please share that. I have not figured out a low cost solution yet. I mainly use a kitchen type step stool now and dislike it immensely. I would like the RV fold up type but the cost and how low they hang stop me from really considering them. I do have some DIY ideas however that I ought to dust off and share them for others to review and critique.
Bob

First Post on Purchase of Trailer: http://www.tnttt.com/viewtopic.php?f=42&t=60722
Hot water infloor and radiator heating project:[url]http://www.tnttt.com/posting.php?mode=reply&f=54&t=62327[/

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Re: 12' Cargo Trailer Design

Postby grassgd » Tue Dec 01, 2015 2:43 am

Bob,

I really have not given that very much thought yet. I assume you need at least two steps since I believe you said you have a 6" higher than standard height.

Truck campers have a height problems too. There are a number of manufactures that offer various steps geared for truck slide in campers, seem to run $200 and up though. Have a look at these links:

http://www.rv.net/cforum/index.cfm/fuse ... 031400.cfm

https://www.etrailer.com/Enclosed-Trail ... /AS24.html


This site appears to be typical steps for travel trailers where you can get 2 or 3 steps:

http://www.expressdistributing.com/cart ... l_step.htm

You may have already seen these. For a DIY there is a concept for a ladder on small boats that may be adapted to a trailer. See this link:

http://tinboats.net/forum/viewtopic.php?f=3&t=3127

You may already have much better ideas than this.

Jerry
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Re: 12' Cargo Trailer Design

Postby lrrowe » Tue Dec 01, 2015 7:36 am

Thanks grassgd,

Yes, I have seen the RV ones before. I considered even $99 one too much. My idea has to do with a permanet one which lays on the floor while in transit and then just snaps into place when you arrive at the camp site. I had not seen the boat one, but I do have a pontoon boat and have seen many which fit them. I really do not see them fitting my needs.
Bob

First Post on Purchase of Trailer: http://www.tnttt.com/viewtopic.php?f=42&t=60722
Hot water infloor and radiator heating project:[url]http://www.tnttt.com/posting.php?mode=reply&f=54&t=62327[/

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Re: 12' Cargo Trailer Design

Postby grassgd » Tue Dec 01, 2015 9:40 pm

Bob,

Not sure if this is what you are looking for but take a look at the steps this guy built for a truck camper that folds and flips up on to a rear platform deck behind his camper:

http://www.truckcampermagazine.com/camp ... est-part-1

Jerry
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Re: 12' Cargo Trailer Design

Postby lrrowe » Tue Dec 01, 2015 10:08 pm

That guy has put together some nice looking steps. I am not that talented and so forth. But my installed concept sort of follows this example.
Image

See if you can visualize my description. If I add two of the 1 1/2" trailer receivers under the CT door and fabricate a non-adjustable set of steps that I could store just inside the door. Then when at the campsite, slide the mounting bars into the receivers. I believe I can design a simple design and have a fabrication shop weld it together for me.
Bob

First Post on Purchase of Trailer: http://www.tnttt.com/viewtopic.php?f=42&t=60722
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Re: 12' Cargo Trailer Design

Postby grassgd » Wed Dec 02, 2015 12:17 am

Bob,

That should work just fine. Assuming you fab it from steel to keep cost down, it might be on the heavy side. Aluminum much lighter but would be more expensive. Only other consideration would be the bulk/size of the steps you need to store inside for travel unless you have a receiver on the front or rear of the trailer to carry it.

Jerry
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Re: 12' Cargo Trailer Design

Postby Al Swope » Mon Dec 07, 2015 10:29 pm

grassgd wrote:
As far as ground clearance, I am concerned with the extra steps to get into the trailer and you are correct it puts the trailer higher up above the to vehicle which means more drag too. I'll have to give this one some careful consideration before proceeding.


My 2 cents....I have only built one CT, so I can,t help much with design but for offroad capability, you don't need much height. I started with P205/R15 tires. I towed it on state forest road extensively. If your stock vehicle can travel the road so can the stock CT. I tow wth a stock 2013 Tundra. If the truck does not drag, neither does the CT. I also use my rock crawler Jeep Wrangler on 36" tires. I upgraded the trailer to P265/75R15 tires and new (larger) fenders. I have towed the CT over seriously rough terrain with off camber, rut, and hills with the jeep. No clearance issues at all but the CT is very tippy. I have had it on one wheel a few times. I worry more about that than dragging.
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Re: 12' Cargo Trailer Design

Postby lrrowe » Tue Dec 08, 2015 8:00 am

Al Swope wrote:
grassgd wrote:
As far as ground clearance, I am concerned with the extra steps to get into the trailer and you are correct it puts the trailer higher up above the to vehicle which means more drag too. I'll have to give this one some careful consideration before proceeding.


My 2 cents....I have only built one CT, so I can,t help much with design but for offroad capability, you don't need much height. I started with P205/R15 tires. I towed it on state forest road extensively. If your stock vehicle can travel the road so can the stock CT. I tow wth a stock 2013 Tundra. If the truck does not drag, neither does the CT. I also use my rock crawler Jeep Wrangler on 36" tires. I upgraded the trailer to P265/75R15 tires and new (larger) fenders. I have towed the CT over seriously rough terrain with off camber, rut, and hills with the jeep. No clearance issues at all but the CT is very tippy. I have had it on one wheel a few times. I worry more about that than dragging.



As mentioned earlier, I wish I had not gone with the added height on the trailer ground elevation. But now that I have it, maybe I will look to mount some storage boxes under there, or maybe add a larger water tank there. I for sure should have the room.
Bob

First Post on Purchase of Trailer: http://www.tnttt.com/viewtopic.php?f=42&t=60722
Hot water infloor and radiator heating project:[url]http://www.tnttt.com/posting.php?mode=reply&f=54&t=62327[/

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