'73 Tradewind replacing fresh water tank, from up top

[alistheman]

Hello everybody! I'm replacing plywood floor, and i got to the fresh water tank. since i am doing it from the top i cut top angle iron floor support to be welded in when done. I pulled tank out, thank god it was empty, and removed 1 inch plywood and underbelly pan came up with it. My questions are, how many gallons is this thing , it's huge! Roughly 48" x 56" x 6" thats alot of heavy water. How is the black tank only 15 gallons or so, what happens to the shower water when black tank is full? Thats like the old saying of putting 10 pounds of poop in a 5 pound bag? Since there is no grey water tank where does it go? My 1 inch plywood is shot, can I use 3/4 inch like floor? Called every lumber place locally and they said no, so that means if I find it, it's gonna cost me. Thinking about thin polished aluminum diamond plate for underbelly. I know im spitting out questions like a machine gun, lol!

[Belegedhel]

Hi: The answers are as follows:

I have seen the capacity of the FW tank quoted from 35 to 45 gallons. Regardless, as you have observed, it is way larger than the black water tank. Back in '73, apparently campgrounds weren't too concerned about grey water just running out on the dirt. Your grey plumbing goes back to the dump valve, but there is no valve to keep the grey water from just running out on the ground (or straight down the stinky slinky, if you are hooked up). There was a cap you could put over the end of the trailer's rectum, and the idea was that you put the cap on, open the valve to the black tank, and you would then be able to back-fill some grey water into your black tank. This is highly NOT-recommended, as you can easily end up with black water in your shower pan, and contaminating your grey water system.

I was able to find 1" marine grade plywood at my local specialty hardwood store (this is the kind of place that wood workers go for fine hardwoods, not dimensional lumber). I think it was over $100 for a 4x8 sheet. Before I found it, I considered taking two sheets of 1/2" plywood, and gluing them together to get the full 1 inch. Didn't end up having to go that route though--but it would have been a lot cheaper! Anyway, as you note, the tank is going to heavy as heck when full of water, and I figure if the guys who designed the trailer in the first place concluded that 1" play was needed, despite its expense and weight, then I can't recommend less.

Another thing to consider as long as you have it all torn apart, is installing a clean-out port in your FW tank. I used a hole cutting device on a rotary cutting tool to cut about a 6" hole in the top of my tank, and installed a marine deck port in there. This way, I can open up the cap, and run a wet-vac in there to suck up residual water, get in there with a pressure washer, etc.. I haven't had any leak issues so far. I posted some pictures in another thread--you might find them if you search for "clean out port," or some permutation of that.

Good Luck!

[Belegedhel]

Here is the thread I was referring to. Clean-out port installation starts at post #11.

http://www.airforums.com/forums/f443...ons-93918.html

[Belegedhel]

Take a good hard look at the condition of your stairs, since you have that area mostly exposed. If you need to do anything to repair the stairs, or the outriggers that they slide in, now would be the time to do it.

[Inland RV Center, In]

Originally Posted by alistheman

Hello everybody! I'm replacing plywood floor, and i got to the fresh water tank. since i am doing it from the top i cut top angle iron floor support to be welded in when done. I pulled tank out, thank god it was empty, and removed 1 inch plywood and underbelly pan came up with it. My questions are, how many gallons is this thing , it's huge! Roughly 48" x 56" x 6" thats alot of heavy water. How is the black tank only 15 gallons or so, what happens to the shower water when black tank is full? Thats like the old saying of putting 10 pounds of poop in a 5 pound bag? Since there is no grey water tank where does it go? My 1 inch plywood is shot, can I use 3/4 inch like floor? Called every lumber place locally and they said no, so that means if I find it, it's gonna cost me. Thinking about thin polished aluminum diamond plate for underbelly. I know im spitting out questions like a machine gun, lol!

The formula for determining how many gallons is, length times width times thickness in inches, divided by 231.

That will tell you how many gallons.

Remember to subtract a little from those dimensions, because of the thickness of the tank.

Basically, your water tank was listed as being 50 gallons.

Andy

[alistheman]

I was thinking of putting some kind of opening up top to really clean it out. I have to admit I'm a little apprehensive in doing that. I like that clean out port, but instead of silicone what about the 2 gasket idea, one under and one on top to sandwich the plastic? Before i do that I have to check it for leaks. I purchased 3/4 plywood, same as i have for the floor, 80 dollars for 2 sheets. I will use that along with my epoxy paint, and i am going to put a 1/4 " piece of low density styrafoam on top of plywood under tank, seems logical to keep tank off of wood. I needle scaled the angles holding up plywood and painted them with a special rust inhibitor paint, the same paint I used on my 50 chevy frame after i had it sandblasted. Will cover that paint with black rustolium. OK, so the grey water just runs out onto ground. The only water that goes into black tank is when toilet is flushed. I am contiplating if that is more funny or nasty, lol.

[Belegedhel]

Well, its funny to some, nasty to others, and problematic for those who want to camp places without full hookups.

One option is to get one of those wheeled external tanks commonly referred to as a "Blue Boy" to catch the grey water as it is produced. This requires you to haul the blue boy to a dump station every so often, which can be a pain. The other option is to install grey water tanks in your trailer. I used two tanks purchased from Vintage Trailer Supply. They fit inside my frame rails in the bays immediately behind the axle. Took some modifications to the bellypan, and installation of a suspension system, but I am looking forward to being able to boondock and use the sink.

good luck!