I think it depends more on compatibility of the end connectors (such as the clevis pin diameter) with your existing rig, than the actual rated strength. As I was planning the re-rigging of my M15, I got a chance to see the standing rigging on six different M15s at the cruiser challenge. The majority of M15s had 3/16" clevis pins and stay adjusters, which are generally rated to a SWL (safe working load) of 400 lbs, whereas a few had larger 1/4" hardware rated to 1000 lbs SWL. The actual breaking strength is much higher than the SWL- even the breaking strength of the 400 lb SWL hardware likely exceeds the weight of the entire fully loaded vessel. 1/8" 1x19 316 stainless wire has a breaking strength of around 1700lbs. So the 400 lb SWL hardware is widely used on M15s, and doesn't fail in service- it seems adequately strong. The main issue I saw is that those smaller clevis pins wear quicker, especially on the 1/4" chainplate holes, and may eventually fail from wear or stress cracking with lots of use. Some of the 3/16" pins I saw (especially on my vessel) had lost noticeable diameter at the contact points over the years due to wear, and were wearing a groove wherever they passed through 1/4" holes. In a very high situation with the mast in the water or a collision with a tree, the weak link is likely to be the 400 lb hardware as the 1/8" wire itself is much stronger. With the 1000 lb hardware I think the rig is less likely to break in such a situation, but if it does it's more likely to cause damage to the hull to deck joint during the failure. I think with the 1000lb hardware, the aft chainplate mounting bolts are likely the weak link and might crack or get ripped through the deck. I decided to go with all 1000 lb (1/4" pin) hardware on my re-rig, not because the extra strength is needed, but to get a larger surface area and lower wear surface on the clevis pins, and a better fit in the chainplates without a point load. Tyler
On Sep 4, 2015, at 7:30 PM, George Iemmolo <griemmolo2@gmail.com> wrote:
Wrinkle Boat Mates
I am in the processing of researching a Harken Furler #434 Lo Load 500 lbs, @ $316 vs #435 Hi Load 950 lbs @ $365. Max wire size 1/8 inch on both
Q 1. Is the Lo Load sufficient on a M15?
Q 2. Is the extra $49 for a Hi Load worth it?
George "We Can Not Control the Wind But We Can Adjust Our Sails"