I need help validating my clothesline design. It'll be on our deck for convenience (I don't want to lug a heavy basket of wet laundry down to the backyard). I want it to be collapsible so we can hide it if we ever have guests again. And, if we have to sell the house to someone who doesn't appreciate clotheslines, we'll just unscrew the hinges and take the whole thing down with minimal damage to the railings.
The idea is, the clothesline posts will be attached to the top of the deck railings with hinges. When in use, the bottom ends of the posts will simply sit on the deck railings. When we need to hide them, we'll simply fold them back so they hang upside down behind the railings.
My questions are specifically about the stability of this design. I'm only expecting less than 15 lbs of load, consisting of 2 king-size sheets and up to 2 bath towels, so maybe I'm overthinking this, but better safe than sorry. By which I mean, better to ask now and look like the beginner that I am, than spend 5 hours putting it together and have it sag or bend or fall apart 😬
In my mind, these are the Bad Things™ that can happen:
The hinges may be pulled out by heavy wet laundry pulling on the top of the posts. I read that screws can withstand shear forces of 600 lbs so I don't think this is likely.
The hinge itself may pull itself out of shape, or even come apart, from bearing the weight of the posts when the posts are stowed. That would actually be dangerous, since the posts can then fall on someone under the deck. And obviously hinges are not meant to be used like this - not as part of a set, and bearing forces that pull them apart. But then I think the posts will only weigh 40 lbs or less, and in any case, I think I can work around this by simply nailing some blocks of wood to the railings under the posts when they're stowed, to bear the weight of the posts instead of the hinges.
The posts may lean inward when there's laundry on the lines, since they're just sitting on the railings with no fasteners. Is this a risk with the center post being a 4x4 (so there's a decent amount of surface for it to sit on)? I can also add shims underneath to counter any leaning.
So, what do you think? Are there other glaring design flaws I'm not thinking of?
Thanks all in advance!
EDIT Aug 2, 2020: Some people have suggested some intriguing ideas, including a prop in the middle of the line and a telescoping post. I am interested in all those ideas, but could you please include some details on the materials and hardware I need to implement them? I am a DIY beginner, and this project is apparently far more demanding, engineering-wise, than I'd estimated. Who knew hanging 13 lbs of sheets to dry would be this complicated?
Also, the 13 lbs estimate is from Googling the weights of the sheets and towels, cotton absorbency and washer spin cycle water extraction rates. I am aware that wet laundry weighs more than dry laundry.