Running rigging measurements

[Tatheelrod22]

I was blessed to have come through the gulf coast’s hurricane Sally recently relatively unscathed. I do however have some running rigging that needs to be replaced. My boat is a gaff rigged schooner I bought a little over a year ago.
It’s interesting to me that the 3 ply line came through fine, but most of the smaller braided line has unraveled and is toast.
Here is my question. Is there a fool proof way other than a tape measure to determine the line diameter? I currently live 4 hours from the boat. Where she is berthed there aren’t dependable chandlers to get the needed replacement line. I’d like to order a bulk spool to have delivered and take it down with me but I don’t know whether to order 3/8 or 1/2 inch? They are so darn close in size I don’t know why both are available but suspect there is a good reason that for now escapes me?
Does anyone have some suggestions on how I can determine what to order? I’ll attach a pic with a tape measure but nor sure that will really help.

[dfelsent]

Looks like 3/8 to me. Counting tick marks on the rule. But it so depends on the age and tension when you took the pic.
1/2” line has lots more strength than 3/8” line. 5000 vs 10000 lbs says sta-set specs
and is easier on the hand. But may not run well through smaller blocks.
It has to do with the cross sectional area of the fibers in the line. So the square of the diameter. 3x diameter gives 10x strength.
Maybe buy a few feet of each and compare with your photo and your memory.
Or be really patient ( hard for me to do sometimes) and bring the samples to the boat and re-rig next trip.

[dfelsent]

Btw is the rigging the halyards? Peak and throat? And with the usual 2:1 for the throat and more blocks on the gaff?
And how big are the blocks? If they can handle 1/2” your hands will be happier and your trim in puffs will be better than with 3/8 because of less stretch.
But your wallet lighter.

[grantmc]

Perhaps a metric size?

[Tatheelrod22]

Very good points on the size and the advantages to half-inch if the blocks will handle them. What a difference 12 hours can make as a posted this before bed last night thinking I would order the line before my next trip down and now it looks like I will have to decide tomorrow morning if I need to go down and get out of the marina and go to my hurricane hole for the fourth time in the last two months! tropical storm ZETA begs watching for anyone between the Florida Panhandle and the Texas coast at this point. I am now getting so good at this I think for amusement I should start timing myself sort of like a NASCAR pit stop!
Maybe start a stopwatch when I cast off from the dock and let it run until I dinghy back to shore and start drinking!

[dfelsent]

Best of luck!

[Spot]

9" of snow on the boat cover does not seem so bad now that folks are up to 'Zeta' on named storms along the coast. I hope all fare well.

Tat, will there be time to cut off some sample pieces or messenger the old ones to allow you to bring thoses home for measuring and refitting?