Atomic's 1968 Tradewind Twin Renovation

[Atomic_13]

Thanks, Ron, David and Dan.

With the galley nearing completion, my focus is shifting towards other components of the trailer’s interior. I plan to tackle the curb side clothes closet opposite the pantry next since it sets the location for the bathroom vanity and the curb side couch (that will transform into a bunk bed). More on that later…

Also, I sourced a reasonably priced freshwater tank. If you are in the market for one, make note that the prices of tanks at horse trailer conversion companies are much cheaper than RV specific sites. My trailer has two 26 gallon grey tanks (52 gallons total) between the floor and axles and a 36 gallon black tank below the rear floor. So in total I could generate 88 gallons of waste water before needing to empty the tanks. As a result, I decided on a 59 gallon freshwater tank (48” wide, 12” tall, and 24” deep, https://jazzsales.com/product/water-tank-12x48x25-59g/ ) Shipped to my door it cost $250.

So let me get to the point… What location would be best for 490 pounds of water to reside inside the trailer? While I wouldn’t want to travel any distance with this volume/weight of water (due to it dropping my TV’s fuel economy), I suspect it’s nice to have some for road side stops. Although, a gallon of water in the fridge may suffice for breaks. Additionally, we plan to boondock quite a bit which will require some travel will a full fresh tank.

At present, most of the interior weight of the trailer is on the street side (e.g. toilet, shower, pantry/food, overhead storage bin above galley, lower galley and associated kitchen items, cooktop, sink, fridge/perishable food, and finally the heater). Perhaps I should have been more attentive to this during the design phase. How big of a deal is this given the frame i welded is pretty stout (11 gauge 2x6 rectangular tubing)?

I’m considering two options. Option A would place the fresh tank under the curb side dinette seat to provide some weight to balance the currently heavier street side. In this approach, I’d place the battery bank at the front center of the trailer. Option B would flip this with the water tank at the front center of the trailer and the battery bank under the curb side dinette seat.

My primary reservation with option B is lack of subfloor support for the freshwater tank at the front center since this the location of my spare tire below the subfloor (i.e, it lacks frame support to accommodate the tire under the trailer). If I decide to place the freshwater tank at the front center, I’ll need to weld an above floor support frame that spans across the two frame rails. The curb side dinette seat area has several supported areas not requiring this (here’s a photo).



Additionally, if the tank is installed under the curb side dinette seat, I am able to move the water tank further aft in the trailer which will reduce the tongue weight by 100 pounds when traveling with a full tank. I’m currently sitting at a tongue weight of ~400 pounds (without the front interior or batteries installed). I still need to weigh the trailer so I can target a tongue weight of 10-15% of the overall trailer weight. I’m guessing it will end up being 5500-6500 pounds dry, so a tongue weight of 600-900 pounds would be ideal. I’m estimating that the addition of batteries and the front dinette will increase the tongue weight by 200 additional pounds (so 600 before fresh water).

Using some fancy math (thanks to my son who is in engineering school), we were able to estimate the impact of the freshwater on tongue weight at various locations in the trailer. If I place the tank at the center front it adds 343# to the tongue and 156# to axles. If I position the tank under the curb side dinette seat, the center mass of the tank is pretty much at the half way point between the coupler/hitch ball and front axle, so it would reduce the tongue weight by just under 100# (~250 to the tongue and axle, each). So in summary, with the water tanks full, option A would end up with an estimated tongue weight up to ~850 pounds and option B may be up to ~950 pounds (on the heavy side). My F250’s payload is 2200#s. Without water, the tongue weight for options A and B are similar (with perhaps A being slightly heavier since the batteries are at the front most area of the trailer).

The other issue I’m keeping in mind is the size of the tank and the kinetic energy produced from water sloshing/shifting in the tank if it’s partially filled while towing. I wouldn’t want to exacerbate trailer stability / sway. While I understand it’s best to travel with either an empty or full tank, I’ll likely have to travel with a partially filled tank on occasion. Would it be preferable for the long (48”) side of the tank to be positioned in line with the direction of trailer travel rather than perpendicular? This makes me wonder why tank manufacturers don’t install internal walls (with holes at the bottom) to baffle water movement in transit. Perhaps, I’m overthinking this… I have a tendency to do so.

[chrisetmike]

I am amazed by your cabinets! Very unique!

[Slats]

Originally Posted by Atomic_13

Perhaps, I’m overthinking this… .

Well, Brian, even though my tendency to overthink stuff falls far short of yours in depth and scope, I am all too familiar with the Committee in the Head. Mine usually convenes at around 3 a.m. and rarely adjourns much before sunrise. I've sometimes found a trip downstairs for a warm milk helps when the committee gets out of hand.

[ALUMINUMINUM]

“I’m overthinking this… I have a tendency to do so.”


Overthinking is the way to go... I have a well worn “contemplation bucket”.. Sometimes I shelve an idea long enough not to remember it, then an inspiration occurs. “Think Time” pays off.

It's unlikely that Airstream thought it out as much as you. You have a remarkable effort to rebuild an Airstream “Better than New”. Better than 1968 standards, and better than 2019 standards.

Not knowing all the architectural and furnishing elements, Either way seems viable. If the battery/converter/inverter/solar controller is along the curbside, it may be more convenient to access than under the front bed. I would mount the watertank athwartship below the front window. My watertank is up-front under bed, It never needs access, It rests in a PVC showerpan liner flashed up the walls to contain any catastrophic leak. Water pumps from there to bath and beyond to kitchen on curbside.



Would the sloshing weight be more manageable by the TV at the tongue or the trailer wheels? The battery and its ancillaries on the curbside would always be the same unvariable weight. The watertank up-front would vary in weight, but always be centered.

The electrical system will require more frequent visitation, so should take the most conveniently accessed area. My electrical “Del Centro” is very convenient at the entry door. Every switch and meter is right there, where I don't have to enter the trailer to adjust, engage, or monitor its electrical systems. There's room for three group 31s under the converter, with outside access thru the former refrigerator door.


You'll think it thru suitably

[TouringDan]

I like to think stuff out in as much detail as possible, so that when I make a decision, I am happy with it and sure of it. The last thing I want to do is learn of something that I never considered which would have affected my decision. Unfortunately there have been times when this has happened. Now I work hard to make sure that doesn’t happen again. I am not sure when you are thinking things through enough or over thinking things. Whether you are thinking things through enough or too much I am confident you will make the right decision.

Dan

[dbj216]

You're going to have quite a "honey wagon" with nearly 90 gallons of dirty water. Interesting you found a source of molded tanks without the "RV" price. They do mold tanks with baffles to reduce sloshing, but they would be more expensive.

So from your comments, I thing the tank in the front of the trailer would be very fine. It will add tongue weight when full, but you can adjust the amount of water weight depending on the travel arrangements. Your TV won't mind the extra tongue weight one bit except for fuel usage. I think the fresh water fill used to be in the front of these trailers also, which will simplify installation a bit. Same with the water pump as Aluminuminum's Globetrotter photos shows.

Actually my son's 69 Globetrotter has a front above floor fresh water tank, and a spare tire "cavity" under it between the frame rails. It rests on the subfloor with no additional support. It is the stock 12x12 square tank. I forget the length or volume. My 75 Overlander also has a spare tire cavity under the front of the trailer, but fresh water is below the subfloor just ahead of the front axle. Maybe Airstream frame design was the same independent of the spare tire cavity option.

Your new fresh water tank loading will be pretty evenly distributed over its bottom surface. Let's see, a cubic foot of water is about 60 pounds. The subfloor loading ought to handle 60 pounds per square foot. My son's Globetrotter subfloor has handled this max water weight load load per square foot for 49 years. Heck, if my big Aunt Bee came to the trailer for lunch, the floor loading would be much more than that with every step she took, like 300 pounds per square foot. Maybe just an extra layer of 1/2" ply under the tank would suffice to increase load capacity so you will sleep at night.

I have not seen a sidewinder or saddlebag tank in an RV. Center mounted for good balance seems to be the preferred method.

David

[TouringDan]

I agree completely with David. Floor loading is not a concern, no matter what size the tank is.

My Tradewind tank sits right on the subfloor at the front under the front window.

Dan

[Joyflea]

Vision without execution is simple hallucination .

[KZGoodchild]

Glad I revisited your posts A 13. Just started interior build, using poplar for framing so far, but like your use of plywood. What kind do you like, looks like 3/4/ good one side birch or other is marine ? Also, we do like the Dickinson, but are worried about BTU for northern parts, and are also considering the "bigger" tiny stoves. Have you used the Dickinson yet, how well does it heat/take the chill out, or really send out the heat , and for how long/
Cheers for info, Mike

[Atomic_13]

Mike - there are lots of ways to construct cabinetry in airstreams. Poplar is a solid choice given its price and strength and it’s easy to work with. Since, I’ve been painting my face frames white, I’ve been using it for those and joining with pocket screws (to permit disassembly, if needed later).

Regarding plywood, when ever possible I’ve been using baltic birch for the interior walls, drawer boxes, and cabinets. I would highly recommend it. The layers of inner plies are 1.5 mm-thick solid birch veneer, cross-banded, void free, and laminated with exterior grade adhesive. Yes, it’s more expensive but the improvement you get in strength, dimensional stability, and superior screw holding is worth every extra dollar you spend. I found mine at Menards in Kansas City and it seems to be just fine. Woodcraft in our area (or I suspect any woodworking store in your area) sells finish grades if needed. I’ve been using a mixture of 1/4, 1/2 and 3/4 thick material, depending upon application and reserving 3/4 for load bearing walls (e.g. two walls that will hold an upper sleeping bunk). It’s heavy so only use the thickness you really need.

I really like the Dickinson P12000 heater for both its functionality and aesthetics. Its fan only draws 0.2 amps and the LP consumption is low (0.182 lbs/hr on LOW/4,000 BTU, 0.26 lbs/hr on HIGH/5,500 BTU). It’s rated to heat 1100 ft^3 (without any interior cabinetry, my trade wind is ~950 ft^3). I’ve been pleased so far with the limited experience I have had with the heater. I suspect the big difference is the time it takes to heat up the trailer. The forced air heaters would undoubtably bring the trailer up to preferred temperature much faster than the Dickinson. They also can heat storage tanks below the floor (which the Dickinson does not). It takes 30-90 minutes to get the temperature where I want, depending on how cold it is outside. Note, I also installed a bus fan near by to help circulate the heated air throughout the trailer. I really like that this heater isolates combustion to the outside using a double walled chimney (inner pipe for exhaust, outer pipe for fresh air in). This should somewhat minimize condensation on the inside to the trailer.

I also installed an Olympian Wave 6 catalytic heater in the bathroom to supplement the Dickinson. The Wave 6 provides an additional 3,200-6,000 BTU/hr and is rated to heat 230 ft^2 of space. It uses 0.25 lbs of LP/hr and draws no 12VDC. Note these do require a fresh air source and an upper vent to be cracked during use. Using both on their highest setting, I was able to warm the trailer into the upper 60’s when it was 15F outside. I’m optimistic this combination will work even better after I fill the living space with cabinetry, soft goods, and block the windows from the cold.

[Atomic_13]

As for the freshwater tank, I appreciate the sage advice and support from those responding. Sounds like option B (water tank up front, batteries/electronics under curb side dinette seat) is preferred. Aluminumum - excellent point regarding the frequency of access to the electronics. The use of a PVC liner as a safety net for leaks is a great idea.

I looked into the load ratings for the 5/8 ACX plywood on the floor. The front most sheet spans 36” from the front hold down plate to the first 2x6 cross member on the frame. Since 36 inches is a pretty long span, I consulted the Engineered Wood Association reference tables for plywood that summarizes the load ratings at various spans. See: https://innovativepanel.com/wp-conte...Span-Table.pdf

For my plywood thickness (5/8”) and span (36” o.c.) it appears that its max rating is 50 pounds per square foot (PSF). The water tank weights 18 pounds itself, and 59 gallons of water weighs 490 pounds totaling to 508 pounds. The tank’s footprint is 8 ft^2 (2’x4’). So 508#/8ft^2 = 63.5 PSF which exceeds the load-span rating. It probably would be fine but, like Dave suggested, I’d sleep better if it were reinforced.

In this area, the frame rails of the trailer are 50” apart (the water tank is only 48" long). If I were to span an additional piece of plywood (flanked with steel angle on both long sides) across both the curb side and street side frame rails this should be more than adequate to support the tank weight. The steel angle would also serve as way to prevent the tank from moving fore/aft in transit. Self taping screws through the supplemental plywood and steel angle into the top of the frame rails would secure this into place. I believe wood blocks screwed through the plywood would be sufficient to prevent lateral movement.

[dbj216]

Very good Atomic 13. You have been sitting and thinking on your upside down drywall mud getting the fresh water tank design finalized. I think your approach will be very fine for the weight of the tank.

You will sleep very soundly indeed.

David

[ttbikes]

If you are not willing to overthink a project, then you should not own an Airstream.

[Atomic_13]

Agreed, Tim

[coloradoup]

Brian I think you can support this another way and not spend much needed dollars on plywood and angle iron. Just take some of that left over 2x2 metal you have at your dad's shop and weld in a chunk right down the middle of your spare tire area directly under the sub floor.

Next set up that fancy dado blade on your table saw and crank it up two and a quarter inches. Run you spare wheel and tire across it and dado out a slot for that 2x2. Pretty sure your dado doesn't go 2 inches wide so you will need to make a few passes at it. Now I know what you all are thinking but I figured that out too. Make sure you mount that wheel with the notch facing in when you go to use it. That way nobody thinks it looks stupid!

PS, don't forget your pump.

[Atomic_13]

Funny stuff, Mike. I'm a bit concerned about wheel balance with the 2" slot removed out of the spare.

[Slats]

Wheel weights on both sides of the notch?

[ttbikes]

By the way, I believe VTS has a fresh water tank with baffles. It is not that much more than the same size without baffles.

[Atomic_13]

I decided to place the 60 gallon freshwater tank at the front center of the trailer. It was installed using 2” 11 gauge (0.125”) steel angle that spans the main frame rails and a section of 1/2 Baltic birch plywood the same foot print of the tank. Prior to installing the tank, I sandwiched a strip of foam between the steel angle and the tank to prevent chaffing.





Following the tank installation, I finished the remaining plumbing between the freshwater tank and the galley. Vibration damping hoses, a particulate strainer, and an antifreeze siphon valve was inserted between the tank and water pump. I pre-ran a wire for a water pump switch by the galley sink and the shower area, which will activate the water pump using a 30 amp automotive relay. A low point drain exits through the subfloor through the spare tire area under the trailer. This also serves as a vent for the freshwater tank when filling. Lastly, I arranged a valve layout that permits filling the tank from either the front gravity fill neck or city water.




The only remaining plumbing items involves installing a city water inlet and finishing connecting the water lines and drains to the bathroom components and water heater.

I also made some changes to the galley.
Originally I whitewashed the galley drawer fronts. they ended up having a peach hue which frankly looked terrible against the white faceframe and walls.



I opted to paint the drawer fronts an olive drab green and ended up liking it. It’s a nice hint of subtle color and will match the green wool blankets we’ll use for bedding.





I’m moving on with the installation of the front dinette. More to follow.

[Slats]

You can’t go wrong with olive drab. It is, I think, an under appreciated hue.