Good to know. I should have looked it up. I had to get a new furler as my old one broke. It was a bad mistake by me unstepping the mast. So the mast was down. Got a new forestay as I had no idea the age of it. Sadly the new furler tack attachment point was almost a foot higher. As a result required the #2 Genoa to be cut. Mast was up when I realized this. Measured with a tape measure and the slider on the furler. Turns out I should have subtracted some. I would say if the length was any longer it would not be tight all the way up. .5 in shorter and I could then tension the luff to a more desirable tension. Since it is in the slot all the way up it looks fine. Just not perfect.
On Sat, Jan 22, 2022 at 11:45 AM Randy Stafford <randal.staff...@icloud.com> wrote: > Thanks Garry. > > J is defined as the horizontal length of the base of the foretriangle from > the landing point of the forestay on the deck to the front side of the > mast. For a 30 MK I that landing point is the chainplate at the top of the > bow stem. A horizontal line aft from that point meets the front of the > mast just below the partners. But I don’t think that invalidates the > geometric estimate of forestay length. > > In any case, I’ll be measuring it this weekend using a tape on a genoa > halyard from the bow, and I'll report back. I’ll have to compare the > halyard sheave height to the forestay attachment height and adjust the > measurement accordingly (I can’t go up the mast right now because the boat > is shrink-wrapped). > > This is all for the purpose of determining the luff length for a new sail > I’m ordering to go on a new furler I have yet to install - a Selden Furlex > 204S. Selden has calculators for the luff length, that take the forestay > length as an input. > > Cheers, > Randy > SV Grenadine > > On Jan 22, 2022, at 9:01 AM, Garry Cross <garr...@gmail.com> wrote: > > I doubt the geometric calculation you are using will work. A straight line > at right angles to the mast will likely cross the bow line below where the > forestay attaches. > If you have a halyard that turns near where the forestay attaches, you > likely will get a closer approximation than the geometry method. > > According to sailboatdata.com > Est. Forestay Len: 41.27 ft / 12.58 m > Seems your calculation agrees with that. > > > On Wed, Jan 19, 2022 at 7:51 PM Randy Stafford via CnC-List < > cnc-list@cnc-list.com> wrote: > >> Hello Listers, >> >> Does anybody know the forestay length of a 30 MK I as it came from the >> factory, with the rig properly tuned for 8” of mast rake? >> >> By geometry (square root of I squared plus J squared) I’d expect it to be >> in the neighborhood of 41’3”. I is 39’ for a 30 MK I, and J is 13.5’. >> >> According to the owner’s manual the forestay cable is 1/4” and the lower >> fitting is <quote>1/2” jaw to jaw turnbuckle & toggle</quote>. On mine, >> the cable is swaged into an eye fitting on the lower end, which is pinned >> to a turnbuckle screw that’s probably 1/2” jaw to jaw (if that’s what’s >> meant by the owner’s manual). The screw at the other end of the turnbuckle >> is identical, and is pinned to a toggle that’s pinned to the bow stem. >> Picture at >> https://drive.google.com/file/d/1ZT794BQaw0R8aWZCK9NqmVqRJ9K85VT9/view?usp=sharing >> . >> >> I’m wondering if this is the standard from-the-factory setup, and what >> the overall forestay length is from pin at masthead to pin at bow stem, >> when the rig is properly tuned. >> >> Thank You, >> Randy Stafford >> SV Grenadine >> C&C 30 MK I #79 >> Ken Caryl, CO >> Thanks to all of the subscribers that contributed to the list to help >> with the costs involved. If you want to show your support to the list - >> use PayPal to send contribution -- https://www.paypal.me/stumurray >> Thanks - Stu > > >
Thanks to all of the subscribers that contributed to the list to help with the costs involved. If you want to show your support to the list - use PayPal to send contribution -- https://www.paypal.me/stumurray Thanks - Stu
