Tyler Thanks for the feedback, I believe from your comments that the Lo Load 500 lb will work on the M15 and give way first in the event of stress. George George "We Can Not Control the Wind But We Can Adjust Our Sails" On Sat, Sep 5, 2015 at 11:38 AM, Tyler Backman <casioqv@usermail.com> wrote:
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"