Dyneema Loops/Blocks as an Alternative to a Jib Car

[Dockhead]

Here are the snaps of my outboard twings:






This is v2.0.

V1.0 had a ring holding both jib sheets and shackled to my staysail sheet to use as the inboard twing.

I found out from experience that the inboard twing is not needed except hard on the wind, so simplified the rig like this. The other advantage is that I can now use the staysail together with the blade. When I need to twing inboard, I go forward, disconnect the shackle from the staysail and reattach it to the ring. Using one of Seaworthy Lass' special soft shackles, this is a cinch.

[poiu]

Originally Posted by Dockhead

Here are the snaps of my outboard twings:

Attachment 102772

Attachment 102773


This is v2.0.

V1.0 had a ring holding both jib sheets and shackled to my staysail sheet to use as the inboard twing.

I found out from experience that the inboard twing is not needed except hard on the wind, so simplified the rig like this. The other advantage is that I can now use the staysail together with the blade. When I need to twing inboard, I go forward, disconnect the shackle from the staysail and reattach it to the ring. Using one of Seaworthy Lass' special soft shackles, this is a cinch.

That's a neat arrangement. I have a regular track and the forces are pretty huge on the sheave. Two people can't push the sheet down a tiny bit even to unload it (hundreds of kg load). Did you work out the load? If so, how? Are the pad eyes bolted through?

[Dockhead]

Originally Posted by poiu

That's a neat arrangement. I have a regular track and the forces are pretty huge on the sheave. Two people can't push the sheet down a tiny bit even to unload it (hundreds of kg load). Did you work out the load? If so, how? Are the pad eyes bolted through?

Same for me, but the loads on these are less for some reason. For one thing, there is multiple purchase, so the load is spread between two pad eyes. For another, the blade jib -- contrary to what I expected -- has rather lower sheet loads than the yankee.

Went through 24 hours of a Force 9 and surprisingly the pad eyes didn't rip out. Bent the bails of one of them, though.

These pad eyes are probably temporary until I get the location worked out exactly. Then I will have Lallow's in Cowes do through bolted ones, a PITA due to dismantling of the cabinets required to get under the rail.


I reported above about the amazingly lightness of the action of these twings compared to the regular cars. The regular cars (beefy Lewmar Type 3) have really big loads on them, and are hard to adjust. To move them forward, you have to slack the sheet. These are smooth as butter; I can almost do it without a winch.

[poiu]

Originally Posted by Dockhead

Same for me, but the loads on these are less for some reason. For one thing, there is multiple purchase, so the load is spread between two pad eyes. For another, the blade jib -- contrary to what I expected -- has rather lower sheet loads than the yankee.

Went through 24 hours of a Force 9 and surprisingly the pad eyes didn't rip out. Bent the bails of one of them, though.

These pad eyes are probably temporary until I get the location worked out exactly. Then I will have Lallow's in Cowes do through bolted ones, a PITA due to dismantling of the cabinets required to get under the rail.


I reported above about the amazingly lightness of the action of these twings compared to the regular cars. The regular cars (beefy Lewmar Type 3) have really big loads on them, and are hard to adjust. To move them forward, you have to slack the sheet. These are smooth as butter; I can almost do it without a winch.

The bending of the pad eyes are a good measure of the load. As the yield point for most stainless steel is around a half to two thirds of its UTS.The load testing you have done can support your final design.

Interesting about the reduced loads. I find adjusting the cars a pain because of the need to sheet out almost all the way first. I have leads and a block system to supposedly adjust mine from the cockpit, but the loads are so high I can't do it by hand and dangerous even when slackened off. I was going to lengthen the car leads and run them through a turning block to a winch to try to adjust them more easily, but maybe there is another way.

[Dockhead]

Originally Posted by poiu

The bending of the pad eyes are a good measure of the load. As the yield point for most stainless steel is around a half to two thirds of its UTS.The load testing you have done can support your final design.

Interesting about the reduced loads. I find adjusting the cars a pain because of the need to sheet out almost all the way first. I have leads and a block system to supposedly adjust mine from the cockpit, but the loads are so high I can't do it by hand and dangerous even when slackened off. I was going to lengthen the car leads and run them through a turning block to a winch to try to adjust them more easily, but maybe there is another way.

My regular jib car leads are very well rigged, with triple purchase control lines going to a clutch and turning block so intended to be used with a winch. But even with the winch, you have to slack the sheets -- you'd break something, the loads are such huge. And your boat is a good bit bigger than mine.

[monte]

Originally Posted by Dockhead

Here are the snaps of my outboard twings:









This is v2.0.



V1.0 had a ring holding both jib sheets and shackled to my staysail sheet to use as the inboard twing.



I found out from experience that the inboard twing is not needed except hard on the wind, so simplified the rig like this. The other advantage is that I can now use the staysail together with the blade. When I need to twing inboard, I go forward, disconnect the shackle from the staysail and reattach it to the ring. Using one of Seaworthy Lass' special soft shackles, this is a cinch.

Very neat! Nice to see a plan come together. Are you going to replace the green line with dynema and splice further back as planned? It looks like one pad eye will be sufficient for both attachments. I'd guess there's a lot of load on that point as well.

[Matt Johnson]

Originally Posted by Dockhead

Here are the snaps of my outboard twings:

Attachment 102772

Attachment 102773


This is v2.0.

V1.0 had a ring holding both jib sheets and shackled to my staysail sheet to use as the inboard twing.

I found out from experience that the inboard twing is not needed except hard on the wind, so simplified the rig like this. The other advantage is that I can now use the staysail together with the blade. When I need to twing inboard, I go forward, disconnect the shackle from the staysail and reattach it to the ring. Using one of Seaworthy Lass' special soft shackles, this is a cinch.

Happy to see it has worked out for you. Any bagging of the lazy sheet's rings? A little bungee cord to the lifelines should work well to prevent that.

Matt

[transmitterdan]

Originally Posted by Dockhead

Here are the snaps of my outboard twings:

Attachment 102772

Attachment 102773


This is v2.0.

V1.0 had a ring holding both jib sheets and shackled to my staysail sheet to use as the inboard twing.

I found out from experience that the inboard twing is not needed except hard on the wind, so simplified the rig like this. The other advantage is that I can now use the staysail together with the blade. When I need to twing inboard, I go forward, disconnect the shackle from the staysail and reattach it to the ring. Using one of Seaworthy Lass' special soft shackles, this is a cinch.

Dockhead,

In this arrangement how do you route the sheet so it arrives fairly at the turning block? Are you running the sheet through the car on the jib track with it just positioned all the way aft?

[Schooner Chandlery]

I like this variation on the lizard line very much. Lizard lines are simply a small line hitched onto the sheet and then attached to the boat in a way to change the lead angle of the sheet (also can be used to bring the clew inboard like a barberhauler is used.) This is a nice system in use.

We *thought* we were going to set up a similar system with rings but then we decided to simply replace the clevis pins that hold turnbuckles to chainplates with SS bow shackles (making sure to use same strength as original pins) and then we lead the jib sheet to a snatch block clipped to the shackle. If we want to change angle, we can put the snatch block on a tether and we can bring it inboard with a different tether. I'll endeavor to find a pic of this in use--but same concept and uses the snatch blocks we already had, it only required the purchase of some good shackles to replace the pins with. We put bow shackles on several of our turnbuckles (schooner rig we have fore and main shrouds to work with) but find that we have a preference for leading to the forward main shroud and adjusting with the tether.

The only problem we've had is with fluky light winds we have to make sure and tie the block up in the air (line to the turnbuckle body usually) so it doesn't bang the deck as the wind drop and increase over and over.

[Dockhead]

Originally Posted by transmitterdan

Dockhead,

In this arrangement how do you route the sheet so it arrives fairly at the turning block? Are you running the sheet through the car on the jib track with it just positioned all the way aft?

I run it to the regular jib car, moved all the way forward.

This reduces the load on the twing, but I'm getting chafe on the shrouds. Trying to think of a solution for that.

[Dockhead]

Originally Posted by monte

Very neat! Nice to see a plan come together. Are you going to replace the green line with dynema and splice further back as planned? It looks like one pad eye will be sufficient for both attachments. I'd guess there's a lot of load on that point as well.

No, the spliced Dyneema is already there. The green line is the control lines, 10mm polyester double braid and very lightly loaded.

Yes, there will be a single much heavier pad eye with two loops on it, bolted through the rail once I am completely sure about the location (and have extra money for boatyard work).

[witzgall]

We have to take up the original tracks on Gossamer so we can do some deck work. This arrangement seems like a great way to improve sail handling and avoid putting tracks back (we will most likely destroy at least one of them in the removal process).


Dockhead - how do you manage the control line? Line clutch?


Chris

[Dockhead]

Originally Posted by witzgall

We have to take up the original tracks on Gossamer so we can do some deck work. This arrangement seems like a great way to improve sail handling and avoid putting tracks back (we will most likely destroy at least one of them in the removal process).


Dockhead - how do you manage the control line? Line clutch?


Chris

Yes - control lines led aft through stanchion blocks, rope clutch, turning blocks. With the triple purchase and low friction rings, incredibly light and smooth action. I am extremely happy with this system. Throw away your tracks.

Sent from my D6633 using Cruisers Sailing Forum mobile app

[mousenik]

This is a very interesting conversation. I know a picture is worth a 1000 words but a drawing is worth a whole chapter( at least for me). If anyones up to the task I'd love to see the plan and or elevation view of this system.

[ipsum]

witzgall, maybe it would help you. drop me PM if you need more images