This is a question borne purely of aesthetics. My wife doesn't want anything blocking the view out of the deck.
I'd like to install string lights above the deck. The deck has the house on two sides and nothing on the other two. It measures ~21'x16'.
My thought was to install a pole on the far corner from the house and run rope wire from the house to that pole (pink line in picture). Then, I'd run the string-lights-on-guide-wire from the house to the wire (black zig-zag lines).
My only experience with rope wire is an old laundry line. I know it can be strong, but I'm not sure if it can withstand this sort of stress. The string lights can't weight more than 20lbs, but I'm worried that the stress of a nearly 20' run, combined with the pulling towards the house is going to be too much.
Can anyone walk me through how to figure this out?
Update: Here's a thought for overcoming the pulling force on the end of a long pole…
Best Answer
Funny, I'm facing this exact project with the same spousal parameters at home. Your issue isn't with wire or rope strength. That's not a concern, though 1/16" steel cable is what I'll probably use to keep the diameter small.
You're only talking a few tens of lbs. of tension. Try it yourself by running out an appropriate length of twine and pulling until you have the sag you're after. A gently-sagging string of lights actually tends to look better--more relaxed--so you might consider not pulling it laser tight.
Your concern is with the post. You'll need it quite tall--probably 8' or higher depending on the aesthetic you want. And it will need to be rigid. Multiple cables pulling the same direction will want to tilt or flex the post, so it needs to be robust and have a very solid footing or mounting.
If you accomplish that, the rest is cake. No physics or trigonometry necessary. (I'm not sure why some folks insist on a pile of math when some good ol' intuition does just fine.) Select a rope or wire that won't rot away in a few months and be happy.