Stus-List Re: 30 MK I Forestay Length

[Randy Stafford via CnC-List]

Hi Garry,

Today I measured my forestay using a tape measure hoisted on a genoa halyard.  
Its length was 40’ 1.5” with the turnbuckle more than halfway extended (photo 
at 
https://drive.google.com/file/d/1sxleLIDl3c1WqF-PZ0XumIcFVJU8toRb/view?usp=sharing).
  That’s from the masthead attachment point to the clevis pin holding the 
toggle to the chainplate.  That’s as accurate as I can get without going up the 
mast, or removing the forestay and measuring it stretched out on the ground.

Cheers,
Randy

> On Jan 22, 2022, at 11:21 AM, Garry Cross  wrote:
> 
> 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  > 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 > > 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 
>> mailto: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 1/2” jaw to jaw turnbuckle & toggle.  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 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

Stus-List Re: 30 MK I Forestay Length

[Garry Cross via CnC-List]

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 
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  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 1/2” jaw to jaw turnbuckle & toggle.  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 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

Stus-List Re: 30 MK I Forestay Length

[Randy Stafford via CnC-List]

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  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 
> mailto: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 1/2” jaw to jaw turnbuckle & toggle.  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 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

Stus-List Re: 30 MK I Forestay Length

[Garry Cross via CnC-List]

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 1/2” jaw to jaw turnbuckle & toggle.  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 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

Stus-List Re: 30 MK I Forestay Length

[jhnelson24 via CnC-List]

Looks same as mine. Not sure of overall length thoSent from my Galaxy
 Original message From: Randy Stafford via CnC-List 
 Date: 2022-01-19  20:50  (GMT-04:00) To: Stus-List 
 Cc: Randy Stafford  
Subject: Stus-List 30 MK I Forestay Length 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 1/2” jaw to jaw turnbuckle & toggle.  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 StaffordSV GrenadineC 30 MK I #79Ken Caryl, 
COThanks 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 - StuThanks 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