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macbeth · 13-11-2012, 15:44

Next Spring, I'll be installing a new forestay and assembling a new Furler. The new furler can take 7/32", 8/32" (1/4") or 9/32" diameter wire.

Are there any disadvantages to using the largest size, i.e. 9/32" ? (other than weight, which I'm not that concerned about).

The previous wire was 8/32" (1/4'), but I don't know whether it was 304 or 316 stainless steel. I've been recommended to move up to 9/32" and use 316 grade ss wire.

barnakiel · 13-11-2012, 17:39

If the new terminals that go with the thicker wire have the same pins then you are fine. But if the pins are larger diameter then you may be forced to drill bigger holes in the plate(s).

If strength is an issue you can use dyform to get an extra edge.

b.

SkiprJohn · 13-11-2012, 17:41

Will the larger wire require chainplate and tang holes being bored out to accomodate larger clevis pins? If so, don't do it. If you can maintain the same turnbuckles, tangs and clevis pins then 9/32 would be ok. 9/32 requires the use of 1/2 turnbuckles and clevis.
Weight aloft is always a consideration but the difference in wire weight will not be much.
kind regards,

Stumble · 13-11-2012, 19:23

Unless you have a justification for moving up in size I can't see why you would. Even the smallest size is pretty large for a 30' boat.

**Jim Cate** · 13-11-2012, 19:28

Quote:

Originally Posted by Stumble

Unless you have a justification for moving up in size I can't see why you would. Even the smallest size is pretty large for a 30' boat.

For rigs with furling headsails, a common failure mode is fatigue cracking of the wire where it exits the upper terminal. The extra strength of the 9/32 wire would give a slightly better margin against this happening.

So, if the other hardware is compatible, I'd go 9/32 myself. The differences in weight and cost are insignificant IMO.

Cheers,

Jim

Ziggy · 13-11-2012, 19:32

Actually, 1/2" turnbuckles and pins are often used with 1/4" wire, so you may be fine with 9/32". Incidentally, for 316 stainless 1x19 wire, the breaking strength of 1/4" is 6900lbs and for 9/32" it is 9250 lbs.

Cruiser2B · 13-11-2012, 19:56

I just rerigged my Alberg and upsized to 9/32, from 1/4 and all of the pins were still 1/2 clevis and 1/2 turnbuckles. I used sta-locs. No drilling required

I did this because I believe the original design of the boat was factored for 304 stainless which is quite a bite stronger than 316. The upsized 9/32 316 1x19 wire was only about 1000lbs stronger than the orginal 304 1/4 wire. Since i did not want to put weaker parts back on my boat I upsized. And it looks good too!

GaryMayo · 13-11-2012, 20:15

Someone posted a ratio of displacement to cable breaking strength. Does anyone here know that formula? Ment to jot it down, and did not.

Ziggy · 14-11-2012, 04:56

Quote:

Originally Posted by GaryMayo

Someone posted a ratio of displacement to cable breaking strength. Does anyone here know that formula? Ment to jot it down, and did not.

I think such formula is way too simplistic. You need to calculate the actual loads on standing rigging.

macbeth · 14-11-2012, 17:22

Thanks so far. All current clevis pins are 1/2", so going to 9/32" would not be a problem. And I can get a Sta Lok stud for the upper end of the turnbuckle in either 1/4" or 9/32" fitting in a turnbuckle that has a toggle pin diameter at the bottom end that is 0.5"

I was more thinking about having a bigger bulk of wire in the inner plastic lining/tubing with the 9/32" - less room for the wire to "slop" about in as the furler twists. For example, is it going to be harder to pull in or reef the genoa with 9/32" wire as opposed to 8/32" wire ? Will it be more necessary to ensure the forestay is tight with 9/32" ? etc.

Can you tell the difference between 304 and 316 visually ? If I knew the old 8/32" (1/4') was 316, I'd probably stay with it.

More opinions welcome.

Ziggy · 14-11-2012, 18:48

Quote:

Originally Posted by macbeth

Can you tell the difference between 304 and 316 visually ? If I knew the old 8/32" (1/4') was 316, I'd probably stay with it.

The breaking strength of 1/4" 304 wire is 8,200 lbs. For 9/32" 316 it is 9,250 lbs. So you'll be safe replacing your 1/4" forestay with 316 9/32" regardless. If the manufacture says the new furler can take 9/32", I expect it will fit and furl without any problems.