Dyneema for furler line

[Project_Mayhem]

After lots of observations, experimenting, changing lines, etc, the spool on my furler still fills up and jams. I've come to the conclusion that it would be fine if I had a jib but the foresail is far past the mast. I removed the core on the last line I had and it helped a bit. The new line has a smaller overall diameter, a very solid feeling core and was recommended by a local rigger. The boat has Schaefer lead blocks on the stanchions and a spring mounted block on the bow pulpit. The line also passes through the center of a large plastic cleat in the cockpit.
I was thinking about switching the majority of the line to Dyneema to help reduce the bulk on the spool since I could potentially drop down to something as small as 1/8" while increasing strength. I'm aware that Dyneema does not feel good on the hands and it will take some experimenting/measuring to find a balance between spool bulk and comfort. My main concern, and the primary reason I am posting this, is chafe. The last line, which was 20 some years old, would shed dust at certain points along it's path. Would Dyneema be an acceptable line for this application?

 

[dlochner]

What size line were you using?

Letting the sail out too quickly will also cause the problem you are describing as will having too much line.

 

[Project_Mayhem]

I believe it's 1/4". It jams no matter how fast or slow it's let out. The only way to get the sail to unfurl completely is to release it suddenly in moderate winds and even then it jams but theres enough force to pull in the last bit of line. It's possible to make some improvements based on the amount of tension on the genoa line when rolling it up but it's very difficult to repeat this with the necessary precision every time and in every weather condition. I've tried virtually every tip everyone has mentioned. There's simply too much bulk on the spool.

This is a Hood furler that was torn down and serviced last year using one of @thinwater's blog posts as a guide. Green Grease was used. The furler itself spins freely with no noticeable friction

 

[dlochner]

The only way to get the sail to unfurl completely is to release it suddenly in moderate winds and even then it jams but theres enough force to pull in the last bit of line.

This causes the line to spool too quickly resulting in a loose wrap and overrides.

If there is too much sag in the forestay sail will resist unfurling and furling. Tension the backstay or increase the tension on the forestay to remove some of the sag.

Check the lead from the last block to the drum. The line should enter the drum at a right angle, i.e. if the line could continue it would go through the forestay, and mid way up the drum.

Also look for halyard wrap at the upper swivel. Spinnaker halyards can also interfere with furling and unfurling.

5/16" is pretty standard sized furling line.

 

[Project_Mayhem]

Even with careful, even loading of the drum by hand at the dock it's too much bulk. Is Dyneema appropriate for this application?

 

[jssailem]

Have you isolated the source of the friction? From your post it seems you think it is everywhere. That is not usually the case.

I know your boat is 25' and you think a smaller line may be better. I am not sure that to be the case. While Dyneema is strong and no stretch, it is also slippery. If the issue is overriding of line on the furler drum, then you may make it worse and the dyneema in a tight furl is likely to slip between the coiled line not ride on top and contribute more override risk.

I am sure you have put the system together and taken it apart... Most of the issues I have seen occur where there is not a fair lead.

• A block is at the wrong angle or height.
• There is rubbing leading to chafe.
• Check angles and height on the line and at the point you draw the line into the cockpit.

There is also the issue of the line on the furler drum.

• Does it coil properly or is there a glitch in the process?
• Does the drum get too full or unbalanced as you furl/unfurl the sail?
• Is the sail winding smoothly on the furler extrusions or is it bunching and causing the drum to be constricted or rub in it's case or on the bearings?
• Is the forestay tension adequate?

It is not easy and it is frustrating. There is always the idea of upgrade... I had a Profurler on my boat. I traded it up to the Harkin MKIV. They come is varying sizes for different boats. They are well designed (my opinion) and I am extremely happy with the resulting function.

Good luck

 

[dlochner]

Even with careful, even loading of the drum by hand at the dock it's too much bulk. Is Dyneema appropriate for this application?

I would not use dyneema because it is too slippery.

 

[AaronD]

Even with careful, even loading of the drum by hand at the dock it's too much bulk. Is Dyneema appropriate for this application?

We use a Dyneema line partially covered in Sta-Set - we've used it for a few years now, and it works fine for us. I find that 5/32" Dyneema fits nicely with 1/4" Sta-Set cover (replacing the original core - you can try Allen's Sta-Set to Amsteel splice, but I never got it to come out very smoothly).

As you say, it saves space on the furling drum, and is very low stretch; which doesn't matter often on a furler, but does if you reef - if it's blowing enough to want to reef, you don't want the line to stretch and unroll the headsail in a gust.

As others have noted, this might not solve the root cause, but as for your original question - yes, Dyneema should work fine.

 

[AaronD]

I would not use dyneema because it is too slippery.

Partially covered (like a tapered halyard) works well.

 

[jssailem]

yes, Dyneema should work fine.

If it is covered with a non dyneema cover. i.e. Sta-Set.

The Dyneema can slide inside the cover as the cover stretches trying to constrict on the dyneema.

There are now some more expensive lines hybred that are tailored to this mixing of ideas. Just be sure that the line is not too stiff. Your furler line needs to be able to wrap around the drum and also run hockle free back to your cockpit control point.

 

[Don S/V ILLusion]

Even with careful, even loading of the drum by hand at the dock it's too much bulk. Is Dyneema appropriate for this application?

No. Wrong tool!
The problem it appears you have is common and using a line too small to handle properly isn’t a good solution. You are better served either removing the core on the line section on the drum or splicing in a smaller line only on that section while maintaining traditional line of sufficient diameter to comfortably handle.
Dyneema has its purpose but this isn’t it.

 

[Project_Mayhem]

Why is too slippery a bad thing when we're trying to reduce friction?

 

[dlochner]

Why is too slippery a bad thing when we're trying to reduce friction?

The problem you are having is not due to friction from the furling line. If friction on the line is causing issues, then it is probably the old worn Schaeffer lead blocks. But, that is probably not the reason the it takes so much force to pull the sail all of the way out.

When the line is spooled there needs to be some friction between the wraps to keep them from sliding around on the drum and developing over rides.

 

[Project_Mayhem]

Two known issues are the forestay is a bit loose and the lead block closest to the drum has a broken spring. I assume the loose fore/back stay causes the entry angle to change when the line is pulled? Does anyone know where to get a new spring? Online searches haven't come up with anything

 

[dlochner]

Two known issues are the forestay is a bit loose and the lead block closest to the drum has a broken spring. I assume the loose fore/back stay causes the entry angle to change when the line is pulled? Does anyone know where to get a new spring? Online searches haven't come up with anything

If you tighten the fore stay, most if not all of the problem will go away.

Schaeffer may sell you a spring, contact them.

 

[rgranger]

I'm aware that Dyneema does not feel good on the hands and it will take some experimenting/measuring to find a balance between spool bulk and comfort.

As I'm thinking about this... I don't see why it has to be one or the other. If you are retrieving your furler line from the cockpit (as most people do), then all of the line from the last fairlead to the spool can be dyneema... and your hands will never touch it. That line needs to be strong but it does not need to be thick. You could butt-splice two lines together and make the end nearer the cockpit a bit thicker and easier on the hands and keep the end of the line nearer the furler thin.

 

[dLj]

Two known issues are the forestay is a bit loose and the lead block closest to the drum has a broken spring. I assume the loose fore/back stay causes the entry angle to change when the line is pulled? Does anyone know where to get a new spring? Online searches haven't come up with anything

Mcmaster has a wide range of springs - this list is just the stainless options, they also have bronze springs.

dj

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

 

[Tally Ho]

My furling line was very old and crusty. And my furler would jam like @Project_Mayhem is describing.

I replaced the furling line (same size), and the fresh line loaded on the drum much smoother and tighter, and no jamming.

So, if you havent replaced the furling line, do that first.

Greg

 

[SycloneDriver]

Thinking outside the box, would adding a foam luff to the head sail reduce the total number of wraps on the furler?

A couple pictures would be helpful.

 

[All U Get]

I’ve used a hollow chaff cover (sometimes called ice cover)on dyneema 12 strand for different purposes and it’s worked well. I made the cover splice with a very small fid and sewed a whipping lockstich where the cover entered the dyneema. Then I repeatedly milked the lines so the cover was as tight as I could get it. I also sewed the very end of the line and covered it with whipping to keep it from unraveling and then melted the butt (probably overkill but it worked). I believe you can find it from WM or other suppliers.