Submitted on August 19, 2004 by John Reid

Question: Trying to select headboard shackle and new halyard for the Mainsail
on our Tartan 42 - used for long-distance ocean cruising. Do you have any
calculation for the forces on the head shackle?

Our current cast aluminum shackle is reated at 2000# but I notice that others are available in stainless etc with ratings to 4500#?

We also have a storm trysail of about 120 sq ft (roughly 1/3 of the Main). Knowing
that a 60 knot wind will generate 4 times as much force as a 30 knot wind, it
would appear that a "safe" shackle for the trysail should be approx = 4/3 or 1.33
times as strong as the Main Shackle?

Finally, on halyard material, I have alwsys thought that the "give" in a Dacron
halyard (1/2") would absorb the gusts, and be preferable to the rigidity of say
Spectra?

I would appreciate North input on these items.

Keep up the good work!

Regards,

John A Reid
s/v Caretta

Answer: Dear John,

There are several options of main halyard shackles that would work well for your
boat and be stronger than your present shackle.

One is a stainless Wichard #1495 rated at 4200lbs safe work load. The other is a Tylaska H8 aluminium main halyard shackle rated at 4000lbs safe work load. I
prefer the Tylaska as it is a light weight clean design with a captive pin so you
won't drop it overboard in rough conditions. Both shackles are a nice upgrade in strength over your present shackle.

As far as halyard materials go, we recomend something that is a bit less stretchy than your present 1/2" Dacron. Having a halyard that doesn't give as much as the Dacron halyard, will help you to hold your sail shape better and require fewer adjustments as the wind increase. Yale makes a product called Aratech that is a combination of Technora and Spectra. It is a nice cruising material and is less stretchy than Dacron, has greater break strength than Dacron of the same diameter and is reasonably priced. Provided your rope clutches can handle a smaller
diameter, you could use 3/8" Aratech instead of the 1/2" Dacron and have a better performing halyard that is easier to handle due to the smaller diameter.

I hope we have answered your question and please don't hesitate to contact us directly if we can help you out with any rigging needs.

Regards,
Chuck Brown
Southern Service


Phone: (401) 683 6966
E-mail: cbrown@aramidrigging.com

www.aramidrigging.com
www.sparcraft-hardware.com
www.southernspars.com

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