Jib Hank Installation

[Simon Sexton]

Hey Y'all,

Good afternoon! As I was doing some repairs on the original sails that came with the AMF Sunbird I'm restoring, I noticed the jib came on a furler that was:
1.) Not functional anymore
2.) Even if it was, then it was a piece of garbage anyway
So. I removed it and decided to get some hanks soon and install them. They're this type, because my budget is very limited:

Aaaaand that's a really big picture, but. Oh well. Anyway, I've got a pretty good idea on the layout and measurements and everything, but I don't know how to properly attach them to the luff. Any help would be awesome!

God Bless,
S.S.

 

[dlochner]

With a screwdriver.

The the screw out slide the hank on, poke a hole for the screw to go through and then tighten it down.

 

[Simon Sexton]

With a screwdriver.

The the screw out slide the hank on, poke a hole for the screw to go through and then tighten it down.

....tha's it?! I thought for sure it would be a little more complicated!

 

[LakeShark]

Umm and make sure you still have the grommets for the screws to go through. If the jib has been reconfigured with a wire luff you may have to add the grommets.

 

[JRT]

Ya I think you need to add grommets too.

 

[dlochner]

I don't think you will need grommets and it doesn't appear to have enough room for a grommet. The compression of the screw should hold the hank in place. If the screw hole is going to only be in the sail cloth and not the luff tape, then reinforcing the sail with some sail repair tape at each hank would be a good idea.

 

[LakeShark]

I have had a lot of small boats and every one with hanks (even the twist on kind) had small grommets in the luff. The AMF Sunbird I owned came with standard brass piston hanks and grommets in the head sail.



This just looks like an accident waiting to happen. But as they say your boat your choice

 

[Scott T-Bird]

I agree with "your boat, your choice" ... but that bottom photo from LakeShark looks pretty secure to me for a small sail. The flat surface of the hank where the screw secures it seems like a pretty secure clamp over the sail material (and mitigates the stress around the hole). It would seem to me that a grommet would introduce a little slop that doesn't need to be there and might even allow the hank to fail from fatigue if the screw diameter doesn't match the inside diameter of the grommet exactly. I guess I'm in agreement with Dave.
Picture size of the hank is perfect!

 

[dlochner]

@Simon Sexton let me explain my thinking about the no grommets (and put off cutting the grass).

Think about the forces on the sail luff, there is a vertical force from the halyard and a horizontal force from the sail. The bolt rope and the luff tape carry the load. The bolt rope is typically a low stretch line, like braided dacron attached to a piece of very heavy dacron. The rope is in the middle and the tape forms 2 flaps which encase the forward end of the sail cloth. There are usually several rows of stitching to secure it to the sailcloth. That tape distributes the horizontal load on the sail.

Consider 3 ways to attach the sail to the boat, a luff foil, piston hanks, and the hanks you have.

The luff foil allows the horizontal loads to be transmitted to the forestay along the whole length of the sail by capturing the bolt rope.

A piston hank transmits the load from the sail through the hank to the forestay. The weak point is the attachment to the sail. A grommet is necessary for several reasons, to locate the hank, reduce chafe and wear at the attachment point and to distribute the load over a larger diameter hole in the sail cloth. Sailcloth is relatively flexible, if the hank relies on the cloth alone to transmit the load, the hole in the cloth will elongate causing the stresses to point load on the small diameter hank. This will weaken the sailcloth and tear the sail. A grommet spreads the load across a larger diameter hole thus reducing the point loading and the metal reduces chafe.

Think of your hanks as a segmented foil. The hank is constructed so that the load of the sail is transmitted directly from the bolt rope to the forestay, just like a foil. On a smaller sail you can get away with the small plastic hanks because the loads are relatively small. The screw is there to provide clamping pressure to keep the hank in place and reduce chafe from any movement. Some of the forces may be distributed by the clamping pressure, but most of the forces will be dealt by the hank at the bolt rope.

Make sense?

 

[jssailem]

@Simon Sexton You can clear up some of our conjecture about what to do if you take a photo of the sail luff and post it.
What @dlochner is saying is the way many small (less than 28ft) craft have their fore sails constructed.

 

[Simon Sexton]

@Simon Sexton let me explain my thinking about the no grommets (and put off cutting the grass).

Think about the forces on the sail luff, there is a vertical force from the halyard and a horizontal force from the sail. The bolt rope and the luff tape carry the load. The bolt rope is typically a low stretch line, like braided dacron attached to a piece of very heavy dacron. The rope is in the middle and the tape forms 2 flaps which encase the forward end of the sail cloth. There are usually several rows of stitching to secure it to the sailcloth. That tape distributes the horizontal load on the sail.

Consider 3 ways to attach the sail to the boat, a luff foil, piston hanks, and the hanks you have.

The luff foil allows the horizontal loads to be transmitted to the forestay along the whole length of the sail by capturing the bolt rope.

A piston hank transmits the load from the sail through the hank to the forestay. The weak point is the attachment to the sail. A grommet is necessary for several reasons, to locate the hank, reduce chafe and wear at the attachment point and to distribute the load over a larger diameter hole in the sail cloth. Sailcloth is relatively flexible, if the hank relies on the cloth alone to transmit the load, the hole in the cloth will elongate causing the stresses to point load on the small diameter hank. This will weaken the sailcloth and tear the sail. A grommet spreads the load across a larger diameter hole thus reducing the point loading and the metal reduces chafe.

Think of your hanks as a segmented foil. The hank is constructed so that the load of the sail is transmitted directly from the bolt rope to the forestay, just like a foil. On a smaller sail you can get away with the small plastic hanks because the loads are relatively small. The screw is there to provide clamping pressure to keep the hank in place and reduce chafe from any movement. Some of the forces may be distributed by the clamping pressure, but most of the forces will be dealt by the hank at the bolt rope.

Make sense?

Yes sir, that's what I figured; I'll get a picture of the luff when I get home from school and finish studies; it's finals week!

 

[DrJudyB]

Plastic screw-on hanks of that type are used for dinghy sails. They come in two sizes. They are frequently used for 1/8” diameter wire forestays. they are also,available for 3/16. they should be fine for a 16 ft Sunbird or lightweight dinghy or daysailer. I would not recommend their use on a sail for a keelboat.

They are not as reliable or strong as piston hanks, so I would not use them in winds over 15 mph. They also have an annoying tendency to twist off the forestay when you drop the jib.

Judy B
Sailmaker

 

[Simon Sexton]

Plastic screw-on hanks of that type are used for dinghy sails. They come in two sizes. They are frequently used for 1/8” diameter wire forestays. they are also,available for 3/16. they should be fine for a 16 ft Sunbird or lightweight dinghy or daysailer. I would not recommend their use on a sail for a keelboat.

They are not as reliable or strong as piston hanks, so I would not use them in winds over 15 mph. They also have an annoying tendency to twist off the forestay when you drop the jib.

Judy B
Sailmaker

Yes ma'am, I agree on the unsafeness of use of these hanks on a larger vessel! The Kirby Sonars I sail in Galveston have hank-on jibs, but they are the piston hanks. I would rather use piston hanks, but they're just so darned expensive!

 

[timlho]

Plastic screw-on hanks of that type are used for dinghy sails. They come in two sizes. They are frequently used for 1/8” diameter wire forestays. they are also,available for 3/16. they should be fine for a 16 ft Sunbird or lightweight dinghy or daysailer. I would not recommend their use on a sail for a keelboat.

They are not as reliable or strong as piston hanks, so I would not use them in winds over 15 mph. They also have an annoying tendency to twist off the forestay when you drop the jib.

Judy B
Sailmaker

 

[Johnb]

"so I would not use them in winds over 15 mph"

Huh?

What's that in knots, hon?

DrJudyB is one of the most knowledgeable and respected contributors to our forum. Recommend you reread your post and apologize forthwith.

 

[timlho]

DrJudyB is one of the most knowledgeable and respected contributors to our forum. Recommend you reread your post and apologize forthwith.

I read it just fine and found it to be a silly comment and who says MPH when discussing wind speed anywho?

If she had said these hanks didn't work well in Force 5 winds, I still would have disagreed, but we here in Annapolis are quite serious about two things, Monohulls and the proper usage of the lingo.

So sorry, not sorry.

 

[Joe]

I read it just fine and found it to be a silly comment and who says MPH when discussing wind speed anywho?

If she had said these hanks didn't work well in Force 5 winds, I still would have disagreed, but we here in Annapolis are quite serious about two things, Monohulls and the proper usage of the lingo.

So sorry, not sorry.

Dude..... give it a break. You sound ridiculous.

 

[Scott T-Bird]

I do miss Simon's posts, though. It would be good to hear from @Simon Sexton a bit more often!

 

[JRT]

so almost a 3 year old thread...

 

[Scott T-Bird]

This has to be a comedy act, no?