Chain Plate Sizing

[Brion Toss]

Hi again,
Oh dear, the original specs. What is the date on the plans? Even in older versions of Skene's, 5/16" takes a 5/8" pin, unless the wire is a 7x construction; any details available on construction? If the wire is described as 1x19, then either the recommended chainplate has too small a hole, or the wire is oversized for the load. I can tell you from experience that even the justly revered house of S&S was capable of making mistakes.
Please consider at least coming down a size for the backstay; either 9/32" or 1/4" take a 1/2" pin, and the lower will bear significantly less load than the jibstay does, so there is no sense in making both the same size.
Fair leads,
Brion Toss

[Storm]

Originally Posted by Brion Toss

Hi again,
Oh dear, the original specs. What is the date on the plans? Even in older versions of Skene's, 5/16" takes a 5/8" pin, unless the wire is a 7x construction; any details available on construction? If the wire is described as 1x19, then either the recommended chainplate has too small a hole, or the wire is oversized for the load. I can tell you from experience that even the justly revered house of S&S was capable of making mistakes.
Please consider at least coming down a size for the backstay; either 9/32" or 1/4" take a 1/2" pin, and the lower will bear significantly less load than the jibstay does, so there is no sense in making both the same size.
Fair leads,
Brion Toss

Hi Brion,
Thanks for your input. The S&S drawing is dated 1968 (S&S 34 design #1959). The drawing calls out for the forestay and backstay to be 5/16 inch BSF wire with a breaking strength of 9,640 lbs. The fore and aft lowers are called out 1/4 inch BSF wire with a breaking strength of 5,000 lbs. The drawings do not say if 1x19 or 7x, and I am curious as to what the "BSF" means. I plan to use 316 ss 1x19 wire.

[Brion Toss]

Hi again,
I do not yet know what BSF means for wire (for threads, it means British Standard Fine), but I do know that the wire in use today is significantly stronger than what S&S listed. See here: http://www.sailingservices.com/stand...d_1x19wire.htm. And here: http://www.riggingonly.com/wire.htm#WIRE. 9/32" for your uppers. Smaller for the lowers and backstay.
Fair leads,
Brion Toss