That main sheet attachment point...

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vizwhiz
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That main sheet attachment point...

Post by vizwhiz » Sat Apr 16, 2011 1:53 pm

I was in the cockpit a bunch working on the boat over the last couple weekends. I couldn't help but realize how many times I'd sat on, slid across, bumped, kicked, kneeled on, stepped on, or nearly hurt myself on that silly strap eye that is the bottom attachment point of the main sheet. It is located on the boat's centerline, below where the mainsheet attaches to the boom, on the flat surface of the cockpit seating that runs across the front of the companionway...perfect for catching the front lip of your topsider and tripping you into the cockpit as you leave the companionway, or for you to slide your bum across as you move from one side to the other...ouch!

I searched and most of the discussions I found related to main sheets were for X's and M's, which don't apply to my S boat...but I also saw many discussions of travelers and such which got me thinking...

(1) can this strap eye be replaced with a folding pad eye, or maybe even a small stainless pop-up cleat (for strength) so that it can go flat (or at least flatter) to the surface??

(2) would it be worthwhile to mount two others, one port, one starboard, to use as a traveler of sorts? I have a spring-clip on the lower main sheet block already, so can easily unsnap, move, re-attach...

Anyone else done this on an S or D boat??
Thanks, as always...

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Re: That main sheet attachment point...

Post by Catigale » Sun Apr 17, 2011 5:13 am

I'm not quite sure I get the full picture but it would seem a cinch to replace it with a folding padeye from Wichard for example. There is some force on the main sheet (perhaps about 500 pounds?) so it would need about 10 sq inches of backing plate or washers IMHO.

vizwhiz
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Re: That main sheet attachment point...

Post by vizwhiz » Sun Apr 17, 2011 9:10 am

Thanks Cat - I didn't have a good pic, but this should be enough to help show what I mean...
Image

I could put an extra one on either side as traveler "points"...

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Judy B
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Re: That main sheet attachment point...

Post by Judy B » Sat Apr 23, 2011 11:38 am

vizwhiz wrote:...<<snipped>>

I searched and most of the discussions I found related to main sheets were for X's and M's, which don't apply to my S boat...but I also saw many discussions of travelers and such which got me thinking...

(1) can this strap eye be replaced with a folding pad eye, or maybe even a small stainless pop-up cleat (for strength) so that it can go flat (or at least flatter) to the surface??

(2) would it be worthwhile to mount two others, one port, one starboard, to use as a traveler of sorts? I have a spring-clip on the lower main sheet block already, so can easily unsnap, move, re-attach...

Anyone else done this on an S or D boat??
Thanks, as always...
Hello Vizwhiz,

I'm not super familiar with the rigging on the 26S, but here are my thoughts after a little reflection. I'm working from memory of the 26S and pictures rather than actual measurements, so please cut me a little slack when it comes to the engineering calculations.... 8)

given the size of the mainsail, and my estimate of where the mainsheet attaches on the boom (looks like about 7' from the mast in the pictures I've got), I calculate the static load on the mainsheet at about 825 pounds (using Harken's loading formulas) and 500 pounds using Lewmar's guidelines for a 25 foot boat (and reducing the load by 20% to reflect the fact that the Mac26S carries only about 80% of themainsail area of most 26-27 foot cruisers). Those are static loads, and dynamic loads might be 8-10 times larger, so if you use a folding padeye, you should use hardware with a breaking strength of 4-5,000 pounds.

Option 1: Replace the eye strap with a folding padeye.
A folding padeye with a breaking strength of 5000 pounds, won't be hard to find, because that's about the required breaking strength for a padeye that would be used as an anchor point for a safety tether. It will, however, be a lot more expensive than an eyestrap is.

Option 2: Replace the eyestrap with a piece of line forming a bridle.
From the point of view of a rigger and sailmaker, a single attachment point would be preferable to a short bridle. There would be a performance cost associated with using a piece of line spanning the companionway as a bridle. It would adversly affect mainsail shape when pointing. With a short bridle, you'll be pulling the leech of the mainsail tighter than before, and tighter than you want, when you're sailing close hauled. That will reduce twist in the mainsail, which in turn will cause you to be overpowered more easily in the gusts. If you want to use a bridle, you'd want to design the mainsail with more "twist" in it than for a single attachment point.

Option 3: Add a cabintop traveller.
The poptop would get in the way of a cabintop traveller, and you would probablly need to re-engineer how the mainsheet attaches to the boom due to increased loads mid-boom.
Image



Option 4: Add a mid-cockpit arch, a la Hunter.
This would be VERY slick, and work beautifully :) , but be expensive :evil:

Image


Image





Option 5:
Switch to end-boom sheeting. Get a much longer boom and put a traveller on the transom somehow. This would work very well from a rigging and sail-shape perspective, but you might not like having the long mainsheet getting in your way in the cockpit. (My 27 footer is rigged this way and I'm very happy with it that way. I care alot about getting sail shape right, and don't mind having a lot of mainsheet in the cockpit when we're running downwind.)

Option 6
Doh! I can't believe I didn't think of this right at the beginning. :? I must need another cup of coffee! :wink: Put a traveller on the bridgedeck!!! 8) 8) 8) . It'll cost you a couple of hundred $, get that butt-pokey eyestrap out of the way, AND improve your sail shape so you can point higher!!! 8) 8) I love it!!!. When you're relaxing in the cockpit, slide the traveller car out of your way. Slick.

From a performance and cost/benefit perspective Option #6, a traveller on the bridgedeck is the clear winner.

Option #1 (a folding padeye) is cheap and performance-neutral.

Option #5 (Hunter-style arch) is a **very** elegantly engineered solution but over-the-top cost-wise. If money were no object, I'd go with #5 -- it's elegant: there are no performance compromises and it makes the cockpit more comfy and usable.

I vote for either #1 or #6 8)

If I can be of any further assistance, please contact me.

Judy B
Last edited by Judy B on Sat Apr 23, 2011 1:06 pm, edited 1 time in total.

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Judy B
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Re: That main sheet attachment point...

Post by Judy B » Sat Apr 23, 2011 11:57 am

Judy B wrote:
vizwhiz wrote:...<<snipped>>

I searched and most of the discussions I found related to main sheets were for X's and M's, which don't apply to my S boat...but I also saw many discussions of travelers and such which got me thinking...

(1) can this strap eye be replaced with a folding pad eye, or maybe even a small stainless pop-up cleat (for strength) so that it can go flat (or at least flatter) to the surface??

(2) would it be worthwhile to mount two others, one port, one starboard, to use as a traveler of sorts? I have a spring-clip on the lower main sheet block already, so can easily unsnap, move, re-attach...

Anyone else done this on an S or D boat??
Thanks, as always...
Hello Vizwhiz,

I'm not super familiar with the rigging on the 26S, but here are my thoughts after a little reflection. I'm working from memory of the 26S and pictures rather than actual measurements, so please cut me a little slack when it comes to the engineering calculations.... 8)

given the size of the mainsail, and my estimate of where the mainsheet attaches on the boom (looks like about 7' from the mast in the pictures I've got), I calculate the static load on the mainsheet at about 825 pounds (using Harken's loading formulas) and 500 pounds using Lewmar's guidelines for a 25 foot boat (and reducing the load by 20% to reflect the fact that the Mac26S carries only about 80% of themainsail area of most 26-27 foot cruisers). Those are static loads, and dynamic loads might be 8-10 times larger, so if you use a folding padeye, you should use hardware with a breaking strength of 4-5,000 pounds.

Option 1: Replace the eye strap with a folding padeye.
A folding padeye with a breaking strength of 5000 pounds, won't be hard to find, because that's about the required breaking strength for a padeye that would be used as an anchor point for a safety tether. It will, however, be a lot more expensive than an eyestrap is.

Option 2: Replace the eyestrap with a piece of line forming a bridle.
From the point of view of a rigger and sailmaker, a single attachment point would be preferable to a short bridle. There would be a performance cost associated with using a piece of line spanning the companionway as a bridle. It would adversly affect mainsail shape when pointing. With a short bridle, you'll be pulling the leech of the mainsail tighter than before, and tighter than you want, when you're sailing close hauled. That will reduce twist in the mainsail, which in turn will cause you to be overpowered more easily in the gusts. If you want to use a bridle, you'd want to design the mainsail with more "twist" in it than for a single attachment point.

Option 3: Add a cabintop traveller.
The poptop would get in the way of a cabintop traveller, and you would probablly need to re-engineer how the mainsheet attaches to the boom due to increased loads mid-boom.

Option 4: Add a mid-cockpit arch, a la Hunter.
This would be VERY slick, and work beautifully :) , but be expensive :evil:

Option 5:
Switch to end-boom sheeting. Get a much longer boom and put a traveller on the transom somehow. This would work very well from a rigging and sail-shape perspective, but you might not like having the long mainsheet getting in your way in the cockpit. (My 27 footer is rigged this way and I'm very happy with it that way. I care alot about getting sail shape right, and don't mind having a lot of mainsheet in the cockpit when we're running downwind.)

Option 6
Doh! I can't believe I didn't think of this right at the beginning. :? I must need another cup of coffee! :wink: Put a traveller on the bridgedeck!!! 8) 8) 8) . It'll cost you a couple of hundred $, get that butt-pokey eyestrap out of the way, AND improve your sail shape so you can point higher!!! 8) 8) I love it!!!. When you're relaxing in the cockpit, slide the traveller car out of your way. Slick.

Option #6, a traveller on the bridgedeck is the OBVIOUS WINNER, from a performance and cost/benefit perspective

Option #1 (a folding padeye) is cheap and performance-neutral.

Option #5 (Hunter-style arch) is a **very** elegantly engineered solution but over-the-top cost-wise. If money were no object, I'd go with #5 -- it's elegant: there are no performance compromises and it makes the cockpit more comfy and usable.

I vote for either #1 or #6 8)

If I can be of any further assistance, please contact me.

Judy B

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Newell
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Re: That main sheet attachment point...

Post by Newell » Sat Apr 23, 2011 4:55 pm

Most of the Classics D or S and the M series option to have a traveler where you have the eyestrap, so for getting around in the cockpit when not sailing, they have it worse than you do, so when you are inventing a solution, we will be watching for the breakthrough design. Good luck.

Judy I don't follow your reference to having alot of mainsheet in the cockpit when running downwind (is running downwind a redundant term?). Seems it is just the opposite in my mind. The main is out on the side and the sheeting is extended, sometimes fully.


Option 5:
Switch to end-boom sheeting. Get a much longer boom and put a traveller on the transom somehow. This would work very well from a rigging and sail-shape perspective, but you might not like having the long mainsheet getting in your way in the cockpit. (My 27 footer is rigged this way and I'm very happy with it that way. I care alot about getting sail shape right, and don't mind having a lot of mainsheet in the cockpit when we're running downwind.)

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Re: That main sheet attachment point...

Post by Judy B » Sat Apr 23, 2011 5:31 pm

Hi,

You're quite correct with what you said, Newell, but I'm describing something different. The mainsheet will be in the air between the end of the boom and the mainsheet block. If you're not careful, the mainsheet knocks off people's hats and sunglasses when you jibe.

It's hanging from the boom end, which is outboard when running, across the cockpit to the mainsheet block. There's a big bight of mainsheet that sweeps across the cockpit when you jibe.

Is that a more clear way to describe it?

Fair winds,
Judy B

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Re: That main sheet attachment point...

Post by Newell » Sat Apr 23, 2011 7:06 pm

Judy,

Since I have never been on a sailboat where the mainsheet is behind me or aft, I couldn't picture what you were saying, I now understand entirely. The further to the outboard end of the boom the mainsheet is attached, the longer the sheet needs to be, so when sheeted-in more sheet lies in the cockpit. So either way, boom out, boom in, more purchase on the boom, but with some tradeoffs in sheet management.

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Re: That main sheet attachment point...

Post by vizwhiz » Sat Apr 23, 2011 7:17 pm

Thanks for the ideas...
I've seen a few that had the traveller there, and while a workable solution for having a traveller it once again puts something in the cockpit.

Performance isn't my #1 concern - we're going to be daysailing and overnighting as "water campers"...watching sunsets, listening to the waves and seagulls, fishing, and just general goofing off. Of course I'd like the boat to perform pretty well, and being able to get good performance out of the boat will be needed when working my way against the tides and such, but I have old sails and am not worrying about tuning for performance at this point (no jib cars, etc.).

So the hassle of having a "bump" sticking up in the walkway is what I'm looking at more than the performance aspect.

I think the ultimate would be to find a traveller that was recessed, and you only had a little "track" or rail along the seat, that would be the best of both worlds...but would also require a lot of internal work to install. Not worth it at this point, and in this boat. So I was just trying to find a solution that allowed me to make that bump disappear, and the ideas of travellers was just gravy.

I'll keep thinking about it... :idea: :idea:

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Re: That main sheet attachment point...

Post by Rick Westlake » Sat Apr 23, 2011 7:30 pm

Vizwhiz, I use a double-mainsheet rig on my 26X, and it works very well. There's no reason you couldn't do the same on a 26S, or any sailboat.

Here is a pointer to my rig: http://www.macgregorsailors.com/modt/in ... ?view=1186

You might have to install padeyes on the cockpit coaming, if you don't have genoa tracks on the coamings already. I'm not familiar with the 26S so I don't know. I got the double-mainsheet idea from a book on cruising, and I've been so satisfied with it that I'm likely to put it on my next boat instead of using its traveler. (I'm getting a bad case of four-foot-itis, looking over a Bristol 29.9 at a marina south of Annapolis.)

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Re: That main sheet attachment point...

Post by vizwhiz » Sun Apr 24, 2011 9:52 pm

Thanks Rick... Certainly looks like it would work on my boat. I'm going to keep thinking about it - I have to sail this sucker still...my whole thought may change some once I use it a bunch (although I doubt it). This whole thing came up because of how many times I looked at the strap-eye with that ugly look while working in the cockpit... :x
(God only knows what will happen if the Admiral hurts herself on it!) :o

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Re: That main sheet attachment point...

Post by tomchitecture » Mon May 16, 2011 11:58 am

I have a 26s. My favorite feature about the Hunters is the combination of main sheet support and bimini. Brilliant! I didn't even think about trying to do that with mine. Now you have my wheels turning. I might be the guy who is silly enough to make the conversion.

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