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06-06-2007, 08:27
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#1
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Registered User
Join Date: Nov 2005
Location: Bradenton FL
Boat: Med Yachts 62 Trawler
Posts: 1,180
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Main Halyard - Snap Shackle??
Current attachment has me tying a bowline - works but is sometimes a pain. I always remove the halyard when docked so as to avoid slapping the mast and annoying my neighbors.
I was thinking that a high-strength snap shackle would work, but how do I calculate what strength I will need? Main sail is 468 square feet, fully-battened big boy....
Would a heavy (7,000lb) Nicro snap shackle be suitable or am I just asking for trouble?
__________________
Mark
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06-06-2007, 09:38
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#2
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Registered User
Join Date: Jul 2004
Location: Stuart, FL & Bahamas Cruising
Boat: Lagoon 37
Posts: 880
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my halyard has a spliced eye connected to a shackle and secured with a split ring. No chance of coming loose. I would be scared of anything else some how releasing
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06-06-2007, 09:51
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#3
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Registered User
Join Date: Dec 2006
Location: Seattle
Boat: Cal 40 (sold). Still have a Hobie 20
Posts: 2,974
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Product made for the job.
Fisheries Supply
and you can use lock wire to secure the shackle pin if you're that worried about it. I never have.
John
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06-06-2007, 10:28
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#4
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Senior Cruiser
Join Date: Apr 2006
Location: California
Boat: 1980 Endeavour 43 (Ketch)
Posts: 2,457
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Splicing is always better for a number of reasons. I used a metal eye insert in my splice and just a regular shackle.
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06-06-2007, 10:34
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#5
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Registered User
Join Date: Apr 2004
Location: Toronto
Boat: CS36Merlin, "La Belle Aurore"
Posts: 7,557
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I would not use a snap shackle. Use a double thread shackle. If you don't replace the halyard you'll have to use a bowline on the shackle as you won't be able to splice old double braid.
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Rick I
Toronto in summer, Bahamas in winter.
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06-06-2007, 10:36
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#6
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Registered User
Join Date: Jul 2005
Posts: 318
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Quote:
Originally Posted by cal40john
Product made for the job.
Fisheries Supply
and you can use lock wire to secure the shackle pin if you're that worried about it. I never have.
John
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Go with this or the appropiate locking D-shackle. It is what I have used and it has not let me down.
__________________
It's kind of like tearing up $100 bills while standing in a cold shower.
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06-06-2007, 10:53
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#7
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Moderator Emeritus
Join Date: Aug 2005
Location: Carlsbad, CA
Boat: 1976 Sabre 28-2
Posts: 7,505
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Why don't you stick with the Bowline. 1. It doesn't have a potential lethal weapon hanging on the end of a swinging pendulum if it should ever get loose. 2. You can end for end or cut off a little of the line to shift wear points greatly extending safe working life of the halyard. 3. The proper threaded halyard shackles take longer to attach than it takes to tie a bowline. In short, there's no advantage and a lot of downsides, like safety and cost, to going with a shackle.
We've more than 10,000 miles using bowlines, instead of shackles, without a hitch. No conks on the noggin, halyards lasted for the entire cruise, and you can tie them off anywhere.
Don't let the phu-phu people talk you into an expensive, unsafe modification to a safe, efficient arrangement.
Aloha
Peter O.
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06-06-2007, 12:21
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#8
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Registered User
Join Date: Mar 2003
Location: Philippines in the winters
Boat: It’s in French Polynesia now
Posts: 11,372
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This IS the correct shackle to use for main halyards...................._/)
http://www.fisheriessupply.com/onlin...ct/A03/Ntk/All
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06-06-2007, 16:50
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#9
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Registered User
Join Date: Nov 2005
Location: Tasmania
Boat: VandeStadt IOR 40' - Insatiable
Posts: 2,317
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If you get hold of a Harken catalogue, it will help you out a lot. It has a section on sail loads, with simple formula for calculating loads. Once you calculate the loads, you can then size not only your shackles, but also your rope (halyards and sheets) and your associated blocks and cars, jammers, etc. Remember, the system is only as good as it's weakest link... there is no point in having 90% of your gear correctly spec'ed if 10% of it is under-spec'ed.
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06-06-2007, 18:01
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#10
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Registered User
Join Date: Nov 2005
Location: Tasmania
Boat: VandeStadt IOR 40' - Insatiable
Posts: 2,317
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For what it is worth, breaking strength for standard double braid rope is typically around
3/8" = 3,750 lb
7/16" = 5,500 lb
1/2" = 7,000 lb
9/16" = 10,000 lb
Bear in mind that the load on your main halyard is not just wind load, but should also take into account pre-load from halyard tension generated by halyard winch and cunningham.
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07-06-2007, 09:42
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#11
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Registered User
Join Date: Nov 2005
Location: Bradenton FL
Boat: Med Yachts 62 Trawler
Posts: 1,180
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Many thanks for all the replies
__________________
Mark
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