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Old 08-22-2019, 05:32 PM   #1
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AS specs: "Net Carrying Capacity"?

For all the various AS trailer models, in the Specifications they list "Net Carrying Capacity." This number is the difference between the stated "Maximum Trailer Capacity" and the "Unit Base Weight (with LP & Batteries)."

The "Unit Base Weight" only lists the LP and Batteries, and doesn't mention an assumption of the weights of contents in the Fresh Water tank, Grey Water tank or Black Water tank. So, I assume those three tanks are not included in the assumptions for the "Unit Base Weight".

Obviously, if one assumes a standard of approximately 8.3 lbs per gallon, the total weight of full Fresh Water, Grey Water and Black Water tanks can really eat into the "Net Carrying Capacity".

For example, a Globetrotter 25' FB Twin has a "Net Carrying Capacity" of 1,226 lbs. With a full Fresh Water tank (39 gallon capacity) and (let's assume) 50% full Grey Water (37 gallon capacity) and 50% full Black Water (39 gallons capacity), the total weight of the contents of those three tanks would be 639 lbs.

Thus, the contents of those three tanks would consume about 52% of the "Net Carrying Capacity" of the trailer, leaving only 587 lbs for your cargo in the trailer.

Am I understanding those numbers correctly? Do I need to include the weight of the contents of those three tanks in calculating the "net" cargo weight available for other stuff?

Yes, I understand the importance of actually getting weights at a scale rather than relying on the numbers in the AS specifications.

Thank you.

Cheers,

Bryan
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Old 08-22-2019, 05:53 PM   #2
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Hi

Indeed, the assumption is that all water tanks are empty. If you fill everything (fresh, gray, black) you will indeed use up quite a bit of the "payload" available on the typical AS trailer. The good news is that filling all three tanks at once is pretty unusual. For many, a typical trip has all the tanks empty ....

Bob
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Old 08-22-2019, 06:14 PM   #3
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A whopping CCC...

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Old 08-22-2019, 06:21 PM   #4
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And in my example I didn't include an assumption of the water heater being full. That's an additional approximately 50 lbs (6 gallons) reduction in "net" available payload weight for cargo in the trailer.

Cheers,

Bryan
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Old 08-22-2019, 06:42 PM   #5
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Yes, I think the contents in the tanks count as weight. We travel with one half or more full and 2 empty or close to that. Have never seen a carry weight figure for ours. Have weighed twice and we carry 5700 lbs on the axles against a 6300 lb axle limit. Advantage of old, narrow body trailers I guess.
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Old 08-22-2019, 06:44 PM   #6
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Bill,

I assume the "half or more full" tank is the Fresh Water, and the empties are the Black and Gray. Correct?

Cheers,

Bryan
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Old 08-22-2019, 07:42 PM   #7
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Originally Posted by Bill M. View Post
Yes, I think the contents in the tanks count as weight. We travel with one half or more full and 2 empty or close to that. Have never seen a carry weight figure for ours. Have weighed twice and we carry 5700 lbs on the axles against a 6300 lb axle limit. Advantage of old, narrow body trailers I guess.
Hi

The yellow stickers with "cargo carrying capacity" on them are a creature of this century. Apparently there are regulations here and there that now require them. The sticker on ours specifically mentions the weight of a full load of water after it talks about the capacity of the trailer.

Bob
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Old 08-22-2019, 08:12 PM   #8
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I kinda forgot I am still living in the last century.
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Old 08-22-2019, 11:21 PM   #9
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Since, as has already been mentioned, the contents of the fresh/grey/black tanks do eat into the net carrying capacity it helps to have a strategy for managing the fluid levels.

If we're travelling between locations where hook ups are going to be available I'll only carry enough in the fresh water tank to get us between stops. Once the grey and black tanks get around 50-60% I'll dump. If we're boondocking I'll fill the fresh tank to 100% but that amount dwindles as the grey and black tanks get filled. We sometimes have to add fresh water but I'll also dump grey water with the blue boy so it all equals out.

Bottom line, I can't imagine a situation where all 3 tanks would have to be filled to capacity; 50% total at most would be a much more common scenario and that greatly mitigates any net payload concerns.
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Old 08-23-2019, 04:31 AM   #10
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Do I need to include the weight of the contents of those three tanks in calculating the "net" cargo weight available for other stuff?

No, only figure on the weight of water in the fresh water tank and the hot water heater. Usually that's figured for you on the weight sheet.


Face it, Airstreams are very limited in a lot of things, one being CCC. For the most part they are intended for light easy highway travel from hook up to hook up in mild weather. In that regard they excel.
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Old 08-23-2019, 06:42 AM   #11
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To have all tanks full would be an unusual situation. If you weren’t somewhere you culd dump, why would the water tank be full. If we were boondocking I would expect to start with the water tank full and the others empty. Until we dumped there would be just a transfer of water between the fresh and other two tanks.

We mostly go where we will have at least a water hookup, so We tow with the water tank about 1/4 full.

Al
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Old 08-23-2019, 08:11 AM   #12
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Well, since there are no people in the trailer when underway, how much NCC do you need? Linens, cookware, food, clothes are not all that heavy and, at any rate, storage is not generous in most units.

I guess if you have a gun safe or a bowling ball collection...
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Old 08-23-2019, 08:16 AM   #13
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It usually ends up weighing more than you expect.
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Old 08-23-2019, 08:28 AM   #14
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Hi

All tanks full and in motion = just filled the fresh water at a site with water but no sewer and headed to the dump station.

Running with a full fresh water tank = at least my Classic is more stable with a full load of water. It took a couple of months of towing to figure that out.

How much other stuff .... well, when we first loaded up the trailer, I started counting loads carried out. Based on that count and a rough guess of the weight, we easily put 400 pounds into the trailer then. It's only gone up from there ....

=====

Not mentioned so far and never noted in the specs: Weight distribution does matter. On a truck you have numbers on a per axle basis. They don't just relate to the axles themselves. If you put 100% of the rated load in the front (or back) of the trailer, that's not going to be a good thing. Ignoring tongue weight for a moment, the structure of the trailer isn't going to be very happy that way. Same thing left to right ....

Bob
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