On longer runs, say over 20', there is a lot of mechanical ( geometric ? ) purchase pulling on the jackline mid way. I use low stretch webbing, the stuff sailmakers use for tacks and reinforcing corners. Even on a 28' run firmly tightened down I can easily lift the midpoint 2'. I suspect on a 40' run with extreme low stretch webbing pre-tensioned to 500 lbs a 250 lb shock load at the mid span would transfer a few tons of force into the cleats.
After you set up the jacklines have a couple of people go mid span and give it the hardest yank they can. I would be interested in the results. Here is an article on webbing and stretch: http://www.balancecommunity.com/knowledge/slackline-webbing/ Michael Brown Windburn C&C 30-1 Date: Thu, 12 Mar 2015 22:29:39 -0700 From: Jim Watts <paradigmat...@gmail.com> To: Rick Brass <rickbr...@earthlink.net>, 1 CnC List <cnc-list@cnc-list.com> Subject: Re: Stus-List How to run jacklines on an LF38. Message-ID: <ca+jz0fe51csomuff2xuutmo4tsysk4id09pmh11q5fsvngm...@mail.gmail.com> Content-Type: text/plain; charset="utf-8" Nylon is not the best choice for jacklines, you want something that doesn't stretch and lose half its strength when wet. One taut centerline jackline, if you can rig it, the idea is to stay on the boat, not be cushioned in your ride behind it. Jim Watts Paradigm Shift C&C 35 Mk III Victoria, BC On 12 March 2015 at 19:10, Rick Brass via CnC-List <cnc-list@cnc-list.com> wrote: > For starters you need 40? or 45? flat nylon jacklines. It is best if you > can find or make a set with Dynema line or steel wire inside the flat > nylon. > > > > On my 38 the jacklines get rigged with the eyes attached to the two 10? > cleats in the bow of the boat, then led on the deck inside of the shrouds, > aft to the cockpit where they are secured to a pair of padeyes in the > cockpit. The padeyes were left behind when I upgraded my traveler. > > > > My tethers are double ended, so crew on deck can pass inside the shrouds > when going forward or ?Hook on, hook off? to go around the outside of the > shrouds. I?ve also been known to use the padeyes on the side of the mast > for the reaching strut as a place to hook on when standing at the mast to > reef or crank on the outhaul. > > > Rick Brass > > *Imzadi *C&C 38 mk 2 > > *la Belle Aurore *C&C 25 mk1 > > Washington, NC > > > *From:* CnC-List [mailto:cnc-list-boun...@cnc-list.com] *On Behalf Of *Daniel > Sheer via CnC-List > *Sent:* Thursday, March 12, 2015 4:00 PM > *To:* Cnc-list CNC Boat Owners > *Subject:* Stus-List How to run jacklines on an LF38. > > > > I need 'em for the NE voyage. The mast is 16+ ft back from the bow. Theres > a good, sturdy eye near the bow. I can run them to the cabintop handrails > at the cockpit, but that seems strange. Suggestions, please.
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