Hi, Brion,
Yes, the tension should be set to 15% of 1/4 316 steel - probably around 1100 lbs.
Not 100% sure about the pin size, but I doubt it's 1/2". The backstay pin doesn't look 1/2" either.
Here is an old rigging invoice. Is it possible to figure out the pin size from it? I was thinking that 3/8 indicated the pin size, but maybe it's the thread?
258046 COTTER-1/8X1 2.000 1.500 3.00
113670 Marine Eye 1/4" 2.000 15.730 31.46
12SE1412RH !!! EXT STUD 1/4-SWAGE 1/2-20 RH 1.000 21.840 21.84
113664 Marine Eye 7/32" 6.000 13.600 81.60
114043 Swage Stud 7/32" x 3/8"RH 5.000 16.240 81.20
ARC-TS001212 3/8"x3/8" Turnbuckle w/o Stud 7.000 43.350 303.45
114050 Swage Stud 1/4" X 3/8"RH 1.000 17.850 17.85
000188955 1/4" 1x19 Wire Type 316 78.000 2.650 206.70
000156112 7/32" 1x19 Wire Type 316 144.000 1.960 282.24
There is the second item on the list that has 1/2 in it, but it's most likely the thread on the forestay , right?
Realistically, I don't think it's possible to replace this entire SS bow section in the village of Taravao, Tahiti - that's where the boat is - or the solution may be worse than the problem. At least some of the stain visible in the picture is not corrosion, and is from the old rigging. If the stem fitting could hold until 2016 when the mast can be unstepped, and I can take off all chainplates and this bow section and bring them to a metal shop, it would be ideal...
Do you think a temporary solution exists?
Many thanks!
Gleb