My First Soft Shackle

[Dockhead]

Originally Posted by Seaworthy Lass

This is a new sheeting technique and little info is available. Attachment points need to be preplanned because, as Evans has pointd out, welding is a complex thing if the alu is insulated (and headlining needs to be removed before insulation can be). At the welding phase of construction it is dead easy to weld on lots of pad eyes (we will have about 40 scattered around the new boat) or tracks. Attachment points are useful for a host of things.

Rather than relying on the designer or builder to get is absolutely right, providing future flexibility is sensible.

I may be missing something very basic, but regarding the position of the low friction ring system, I can't see how one would completely cover a full range of clew movement for all headsails or their reefing alternatives or wind angles and amounts. Otherwise why would it matter where you put it?

For example, where would you put the attachment for the low friction ring to suit both these clews for all situations?

We know how clever you are with exactly this kind of task. Just draw it.

You'll see, I think, that one pad-eye midway (horizontal-wise) between the two clew positions would more or less work for both sails. This system is relatively insensitive to the location of the padeye. For the overlapping sail, the ring would have a forward-pulling vector which wouldn't actually interfere with the effectiveness of it, other than requiring more force because of the oblique angle.

My experiments (performed at the cost of ripped-out chunks of rail) show that the optimum position is somewhere forward of the clew position, horizontal-wise. Aft of the clew position dilutes the mechanical advantage and starts to require much more horizontal motion to produce the same change in sheeting angle.

[Seaworthy Lass]

Originally Posted by Dockhead

We know how clever you are with exactly this kind of task. Just draw it.

You'll see, I think, that one pad-eye midway (horizontal-wise) between the two clew positions would more or less work for both sails. This system is relatively insensitive to the location of the padeye. For the overlapping sail, the ring would have a forward-pulling vector which wouldn't actually interfere with the effectiveness of it, other than requiring more force because of the oblique angle.

My experiments (performed at the cost of ripped-out chunks of rail) show that the optimum position is somewhere forward of the clew position, horizontal-wise. Aft of the clew position dilutes the mechanical advantage and starts to require much more horizontal motion to produce the same change in sheeting angle.

"More or less work" does not seem like "optimal". Why limit yourself to one point rather than the selection of lots of points optimally suited for a host of sails, when this can be accomplished easily at the build phase?

If one point was perfectly adequate, why would you want one pad eye per sail, as you stated earlier?

I am feeling a bit thick here, but I just don't get it .

Anyway, I will eventually report back how it works out and if one point is adequate for all sails and all situations . I think we just need to have a play with this. Regardless, the track won't go to waste. Attachment points are useful for lots of things.

SWL

[Matt Johnson]

The fore and aft adjustment is handled by allowing the ring to raise or lower. If you allow the ring to raise, it is like having the line go to a block aft. If you pull the ring into the deck, it pulls the clew down just like moving a car forward.

Matt

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[Seaworthy Lass]

Originally Posted by funjohnson

The fore and aft adjustment is handled by allowing the ring to raise or lower. If you allow the ring to raise, it is like having the line go to a block aft. If you pull the ring into the deck, it pulls the clew down just like moving a car forward.

Matt

Hi Matt,
Yes, by adjusting the height of the low friction ring when it is positioned near the stretched out clew of a sail, then a large range of movement is possible (equivalent to moving a car fore and aft on a track), but with only one fixed position I can't see how it can absolutely optimally suit a large range of sails sizes, say from a storm jib to a gennaker.

SWL

[Matt Johnson]

Originally Posted by Seaworthy Lass

Hi Matt,
Yes, by adjusting the height of the low friction ring when it is positioned near the stretched out clew of a sail, then a large range of movement is possible, but with only one fixed position I can't see how it can absolutely optimally suit a large range of sails sizes, say from a storm jib to a gennaker.

SWL

Oh, I see what you're asking. Between a storm jib and gennaker, this would not be optimal.... A typical genoa track wouldn't be long enough for this either. Usually, you would have a snatch block for both the gennaker and storm jib on a padeye. The floating ring would be used the other 99% of the time with your headsail.

Matt



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[Jim Cate]

SWL, I'm with you on this one! When it is trivially easy to add a wide range of positions, why the hell not do so? They may not be required at this time, but for a "forever" boat, who knows what experiments one might attempt in the future?

Jim

[cwyckham]

Originally Posted by Seaworthy Lass

Hi Matt,
Yes, by adjusting the height of the low friction ring when it is positioned near the stretched out clew of a sail, then a large range of movement is possible (equivalent to moving a car fore and aft on a track), but with only one fixed position I can't see how it can absolutely optimally suit a large range of sails sizes, say from a storm jib to a gennaker.

SWL

Like most things, I think the answer is somewhere in-between.

You seemed to be working on the assumption that you'd need one pad-eye per sail. In fact, you can use one for many sails (mine is just right at the front of my genoa track).

On the other hand, for the extreme like a storm jib, you might be better off further forward, and pad-eyes are easy to install now, so I agree that having a few isn't a bad thing. You just don't need one every meter or anything.

Personally, I value a fairly clean deck for walking on, but having lots of spots on the rail for attachments is also a very good thing. So it comes down to personal preference, just don't feel like you need 6 twinger attachments for 6 sails.

[Dockhead]

Originally Posted by Seaworthy Lass

"More or less work" does not seem like "optimal". Why limit yourself to one point rather than the selection of lots of points optimally suited for a host of sails, when this can be accomplished easily at the build phase?

If one point was perfectly adequate, why would you want one pad eye per sail, as you stated earlier?

I am feeling a bit thick here, but I just don't get it .

Anyway, I will eventually report back how it works out and if one point is adequate for all sails and all situations . I think we just need to have a play with this. Regardless, the track won't go to waste. Attachment points are useful for lots of things.

SWL

I was not suggesting only one anchor point! I was only suggesting a thought (or pen) experiment to demonstrate how insensitive this setup is to anchor point position.

One per sail is more than enough, and two or three would cover any conceivable future sail. Although as I wrote, more won't hurt anything. You don't need to futz with the anchor point fore and aft, once you've got it roughly in position. Because moving the ring up and down gives a huge range of adjustment.

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[Seaworthy Lass]

Originally Posted by Dockhead

I was not suggesting only one anchor point! I was only suggesting a thought (or pen) experiment to demonstrate how insensitive this setup is to anchor point position.

One per sail is more than enough, and two or three would cover any conceivable future sail. Although as I wrote, more won't hurt anything. You don't need to futz with the anchor point fore and aft, once you've got it roughly in position. Because moving the ring up and down gives a huge range of adjustment.

I have kept repeating one attachment per sail is needed, not multiple ones per sail (or at least maybe a couple between fully out and significantly reefed). We will not be using just one headsail, hence multiple points are needed.

As we have no idea what sails we will ultimately be mainly using (it will depend on cruising ground) it is really sensible to have lots of options. Rather than several pad eyes on the side deck to snub toes on, a track with lots of holes provides loads of redundancy and useful attachment points for all sorts of things.

Glad that is sorted! I just could not understand how everyone was saying just one point of attachment for the low friction ring system for all headsail options was perfectly adequate.

SWL

[Dockhead]

Originally Posted by Seaworthy Lass

. . .

Glad that is sorted! I just could not understand how everyone was saying just one point of attachment for the low friction ring system for all headsail options was perfectly adequate.

SWL

I don't think anyone actually said that. I think people just saw your track and thought you were planning to futz around with it fore and aft.

Concerning multiple headsails -- it's really beneficial. Because jibs don't really work upwind when roller reefed. A couple or even three jibs plus a Code Zero would be really great to have. I might even consider hanked-on jibs for the very great gain in upwind performance. If I had the budget for an adequate set of sails and was prepared to deal with reefing and setting hank-ons.

One thing about having multiple jibs -- you really extend the life of a headsail if instead of using it reefed in conditions beyond its natural wind range, you change down to a smaller one. It really stretches and wears a jib to use it roller reefed. So you get more than double the life out of a set of two different jibs, if they are sized so that you get to use both of them.