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Author Topic: Double ended mainsheet  (Read 1110 times)
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TonyP
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« on: October 31, 2011, 06:32:43 AM »

I am new to owning, and this is my first major question.
We (a share boat) are looking into extending the end of he mainsheet that normally finishes at the end of the boom to the floor of the cockpit or more likely through 2 fixings, one in each side of the cockpit walls with a double block with cam cleats set in the centre of the cockpit with rope/cord with the free end easily controlled from the wheel with the original end passed threw a new triple clutch on the starboard side to be jammed when required or free to pull on or winch. This setup is for solo sailing.
My main question is strength in the cockpit. Would the cockpit walls, maybe with some large aluminium angle strengthening behind (inside the port lazarette and inside the stern stateroom.
Any thoughts from out there

cheers
Tony
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Ken Juul
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« Reply #1 on: October 31, 2011, 07:29:35 AM »

Tony,
I really can't picture what you are asking.  A diagram or sketch would help. 

Many of us single hand with the current system by using an auto pilot or wheel friction to hold the wheel while adjusting the mainsheet.
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Ken & Vicki Juul
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Stu Jackson
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« Reply #2 on: October 31, 2011, 12:21:16 PM »

Welcome, Tony.

It appears that you're looking for end boom mainsheeting.  If it was my boat I wouldn't for a lot of reasons.

---  The strength required to move the mainsheet comes from the multiple tackles involved.  I recommend checking Harken's website for the design you would need to accomplish that.

---  The force on the boom would change, requiring a very careful structural analysis of how many bails you would need to do that, again see Harken.

---  Many of us have faced this issue when singlehanding.  As Ken said, we use the AP or the wheel brake when needing to adjust the mainsheet.  See Jim Hardesty's Single Handing topic:  http://c34.org/bbs/index.php/topic,5445.0.html    See reply #15 on page 2.  Also see reply #16 from John Langford about his mainsheet.

---  The boat is new to you.  Many folks have all sorts of "great ideas" when they buy new boats.  I recommend living with it for a while before you make any major changes.

---  I haven't heard of anyone doing it in the 25 years these boats have been around.  Even those of us who race haven't done it.

---  In addition to the AP use, we find it incredibly easier to use the traveler than the mainsheet when it's time to dump air.  The mainsheet takes a looong time to reset, where the traveler, especially if upgraded to the newer 6:1 Garhauer system on older boats, makes resetting the boom relatively effortless compared to readjusting the mainsheet.

---  You'd be making a modification that could affect resale value.

If you're just trying to move the mainsheet end back to the wheel, see the discussions above, it just doesn't seem necessary.

« Last Edit: October 31, 2011, 12:59:52 PM by Stu Jackson » Logged

Stu Jackson, C34 IA Secretary, #224 1986, "Aquavite"  San Francisco Bay, SR/FK, M25, Rocna 10 (22#) (NZ model)

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Lance Jones
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« Reply #3 on: October 31, 2011, 03:57:29 PM »

I agree with Stu. The last time I had an arrangement like that was on a Catalina 22. It is perfectly safe (AND EASY) to single hand the 34 with its current set-up. the other configuration can lend itself to cockpit clutter.
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Lance Jones
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Barry White
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« Reply #4 on: October 31, 2011, 06:40:13 PM »

Two years ago after a season with our 1986 C-34 TM, I configured a double ended mainsheet system on Endorfin by adding two Anderson 28 self tailing winches to the comings just aft of the primary winches. The helmsman can easily control the mainsheet on either tack, (as well as the jib) when single handing. When the wind is up, and variable as it often is in the narrows of Halifax Harbour, letting it out in a sudden gust is nearly instantaneous not requiring a timely response by others who are likely in "relaxed mode". Not a cheap solution, but one of the best investments we've made on the boat, (combined with some new Garhauer blocks for the re-routing of the single continueous sheet. Very Happy Cheers, Barry
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Ken Juul
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« Reply #5 on: November 01, 2011, 07:27:14 AM »

Barry,
Can you post some pictures or a diagram of you set up.  Inquiring minds want to know!!
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Ken & Vicki Juul
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Barry White
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« Reply #6 on: November 01, 2011, 03:28:41 PM »

Glad to oblige; I'll see what I have and will prepare a sketch if necessary for clarity. (all to follow).
Cheers,

Barry
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TonyP
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« Reply #7 on: November 01, 2011, 06:29:47 PM »

Spent over an hour trying to insert a scan of my drawing but to no avail.
Imagine fitting a small eye plate (what you would attach your lifeline to) to the lower walls towards the rear of the cockpit just in front of the wheel. You have a double block with cam cleats centred on small diameter rope or cable with a shackle at either end which clips onto the eye plates. Also a double block attached to the end of the boom. Now (assuming there is enough length in your mainsheet) release the mainsheet from the boom and feed through the new blocks leaving the bitter end at the wheel with enough length to release the boom. Meanwhile the original working end of the mainsheet is still on the starboard cabin roof  but through a clutch to lock it off whilst using the new working end.
The mainsheet still passes through all the original blocks so I would think less forces would be on the new fittings in the cockpit though understand there would be some.
cheers
Tony
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Stu Jackson
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« Reply #8 on: November 02, 2011, 01:50:33 PM »

Tony sent this to me to post:


* Mainsheet led aft sketch.jpg (81.59 KB, 612x839 - viewed 59 times.)
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Stu Jackson, C34 IA Secretary, #224 1986, "Aquavite"  San Francisco Bay, SR/FK, M25, Rocna 10 (22#) (NZ model)

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TonyP
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« Reply #9 on: November 04, 2011, 09:13:41 AM »

Tell me if I am wrong...
Even in an uncontrolled jibe all tackles take an equal strain so should be even tension on all fittings
cheers
Tony
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Stu Jackson
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« Reply #10 on: November 04, 2011, 09:41:35 AM »

In many discussions of mid-boom vs. end boom sheeting, the talk revolves around the different strains because of the moment arms between the gooseneck and the connections mid or end boom.  That's why I suggested going to the Harken website for loads on different systems.

Your case is, well, unique, now that we can see the concept from your diagram.  What you are doing is adding essentially a control bail at the aft end of the boom.  My initial feeling, without engineering analysis, is that the mid-boom sheeting loads haven't changed much and adding the bail would reduce the load on the existing bails and make the added load at the end boom bail much less than if it was just an added single end boom point of connection replacing the existing bails.

Seems like it would work.  Still have questions about the need for the concept based on earlier posts., but Barry did something similar, so why not?

Your boat, your choice.   Very Happy Very Happy Very Happy
« Last Edit: November 04, 2011, 09:48:36 AM by Stu Jackson » Logged

Stu Jackson, C34 IA Secretary, #224 1986, "Aquavite"  San Francisco Bay, SR/FK, M25, Rocna 10 (22#) (NZ model)

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Ken Juul
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« Reply #11 on: November 04, 2011, 12:46:28 PM »

The boat has such a user friendly cockpit, I personally wouldn't want to make any mods that make it less accommodating.

Perhaps another way to get the mainsheet back to the helm would be to add another winch to the stbd coaming. Route the mainsheet down the cabin top to the new winch.  Add a roller/guide to the cabin top just aft of the existing winch (roller is better for friction) to route the sheet back to the new winch.  

When single handing, you have the mainsheet at the helm.  When more are aboard, use the cabin top winch to keep the cockpit clear.


* Mainsheet routing 1.jpg (74.19 KB, 940x705 - viewed 15 times.)

* new winch location.jpg (57.66 KB, 1110x705 - viewed 8 times.)

* Mainsheet routing 2.jpg (80.12 KB, 1043x710 - viewed 7 times.)
« Last Edit: November 04, 2011, 12:47:36 PM by Ken Juul » Logged

Ken & Vicki Juul
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scotty
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« Reply #12 on: November 04, 2011, 04:47:42 PM »

I agree, Ken.  KISS. (keep it simple, SMART GUY).  By the way, put winches on both sides and you can lead the jib sheets aft for easier single handing.  Add wenches to both sides and you aren't single handing!!
« Last Edit: November 04, 2011, 04:49:49 PM by scotty » Logged

Scotty
Stu Jackson
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« Reply #13 on: November 04, 2011, 08:48:20 PM »

Yes, Scotty, "It's Good To Be King!"   Cool

In the "Single Handing" topic I referenced above (http://c34.org/bbs/index.php/topic,5445.0.html)  we discussed the concept of staying in front of the wheel when you're alone, or even with a few guests or family.

Some people like to be behind the wheel all the time.  I like it better where the center of balance of the boat is: as close to the companionway opening as possible.  I find it is a lot less "bouncy."  I spend time beind the wheel when running downwind, w-o-w.  Otherwise...

Enjoy, YB, YC.   Very Happy

PS - When you install that end boom bail, I strongly suggest that you consider putting a sleeve around the thru-bolt.  It will enlarge the hole you need to drill, but give you more surface area for the material to penetrate the boom and avoid having the bolt enlarge the hole from pressure.  I'll find and post a photo of what i did with all my boom bails as soon as I can find the flix.

« Last Edit: November 04, 2011, 08:51:37 PM by Stu Jackson » Logged

Stu Jackson, C34 IA Secretary, #224 1986, "Aquavite"  San Francisco Bay, SR/FK, M25, Rocna 10 (22#) (NZ model)

"There is no problem so great that it can't be solved."
Stu Jackson
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Boat Name / Hull Number: Aquavite #224 1986 SR/FK, M25, NZ Rocna 10 (22#)
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« Reply #14 on: November 04, 2011, 09:40:16 PM »

Photos


* Blocks10013s.JPG (20.59 KB, 576x432 - viewed 178 times.)

* Blocks10015.JPG (117.4 KB, 640x480 - viewed 184 times.)

* Blocks10017.JPG (34.29 KB, 480x640 - viewed 9 times.)
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Stu Jackson, C34 IA Secretary, #224 1986, "Aquavite"  San Francisco Bay, SR/FK, M25, Rocna 10 (22#) (NZ model)

"There is no problem so great that it can't be solved."
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