Low Friction Ring Sizing

[belizesailor]

Im planning to replace some old mast organizer blocks with low friction rings. The line is 10mm, what ID rings should I use?

[SailRedemption]

I typically size them for the line that will be used. The rings are usually strong enough for the job in that case. If these are for halyard deck turning blocks you might want bigger for the wider bend radius. You'd be good with the 14mm, 17mm, or 20mm ID rings from Wichard or Antal. The larger ones may be too big and cumbersome, but I don't know what you're organizing.

Typically the rule is high load, fairly static line or low load, high speed/dynamic load. That's when it comes to chafe and wear on lines, especially non-dyneema lines.

[thinwater]

More information. Bend angle and rope type.


I suggest checking manufacture guidance. it is almost NEVER proper to use a ring less than 160% the line size, and more than that if the rope is polyester, if friction is important, or if the angle is greater than 90 degrees. Line friction increases rapidly when the bend is sharp.


(From Antal web page--they more or less invented them)




They only work with polyester covers if the deflection is slight our you can tolerate a lot of friction. I would NOT use LFRs at the mast base unless the line is all Dyneema. Otherwise, use a ball bearing block.



Smaller rings can be used only if the ring is being used as a thimble. Even as a fairlead, 150% is better.

[belizesailor]

Ah, so "low friction" is a relative term....maybe coined assuming a low friction line like dyneema?

In my case the lines are polyester covered (sta-set or similar), no plans to change them to dyneema. The bend is about 90d. These are cockpit led reefing and outhaul lines. They currently go to blocks at mast base then up to enter boom. Given that they are not "running" lines like sheets the friction should not be as big of an issue.

I like the simplicity of the LFRs, but maybe Im better off to stick with blocks?

[thinwater]

Originally Posted by belizesailor

Ah, so "low friction" is a relative term....maybe coined assuming a low friction line like dyneema?

In my case the lines are polyester covered (sta-set or similar), no plans to change them to dyneema. The bend is about 90d. These are cockpit led reefing and outhaul lines. They currently go to blocks at mast base then up to enter boom. Given that they are not "running" lines like sheets the friction should not be as big of an issue.

I like the simplicity of the LFRs, but maybe Im better off to stick with blocks?

With polyester you will likely see 20% tension loss through the ring, depending on the line. I mostly reserve LFRs for Dyneema. Yes, they are nearly always used with Dyneema for this reason.


Amsteel Blue Bobstay. Not adjusted under load.

[belizesailor]

Ok. Will stick w blocks in this case.

However, on my Hobie 33, I could see getting really carried away w LFRs & dyneema!

[deluxe68]

Originally Posted by thinwater

More information. Bend angle and rope type.


I suggest checking manufacture guidance. it is almost NEVER proper to use a ring less than 160% the line size, and more than that if the rope is polyester, if friction is important, or if the angle is greater than 90 degrees. Line friction increases rapidly when the bend is sharp.


(From Antal web page--they more or less invented them)




They only work with polyester covers if the deflection is slight our you can tolerate a lot of friction. I would NOT use LFRs at the mast base unless the line is all Dyneema. Otherwise, use a ball bearing block.



Smaller rings can be used only if the ring is being used as a thimble. Even as a fairlead, 150% is better.

What is the downside to using them at the mast base with polyester lines? Is it just 20% more friction or line degradation?

[psk125]

Originally Posted by deluxe68

What is the downside to using them at the mast base with polyester lines? Is it just 20% more friction or line degradation?

Both. Plus, don't forget that the additional friction works both ways - it will make it slower and more difficult to lower sails as well as to hoist them.

[deluxe68]

Originally Posted by psk125

Both. Plus, don't forget that the additional friction works both ways - it will make it slower and more difficult to lower sails as well as to hoist them.

I could not imagine a scenario where lowering the sails would be hindered by a slight increase in friction. When lowering the sails, typically there is not much tension on the line after the process is started. I have tried searching on the internet for specifics regarding dyneema vs polyester use in low friction rings and found nothing other than opinions in this forum.

[deluxe68]

I asked Barton Marine about using their rings at the mast base with polyester lines and here was their response today.

I can’t comment on what reasons you may have been told concerning rope types, but our high load eyes are successfully used for many boat applications instead of blocks with rope of both polyester and polypropylene outers, as well as for dyneema. We have never had a complaint to date as to their suitability.

It might have been that the rope your were discussing using was of a limited braid strand - say 3 strand, as opposed to more typically used ropes of 12 or 16 strand, and was felt may have been a cause of concern.

But I personally use our high load eyes for many racing applications and have never experienced any issue of wear or loss of desired function.

Kind regards

Simon

Business Development, Sales & Marketing Manager

[thinwater]

Originally Posted by deluxe68

I could not imagine a scenario where lowering the sails would be hindered by a slight increase in friction. When lowering the sails, typically there is not much tension on the line after the process is started. I have tried searching on the internet for specifics regarding dyneema vs polyester use in low friction rings and found nothing other than opinions in this forum.

Practical Sailor April 2018. Review, including friction comparison.


I've used them with both. They are a compromise solution with both pluses and minuses. I would lean towards ball bearing blocks for halyards, since sails are hard to raise anyway. No, it wouldn't matter on the drop.


These ropes are polyester:




These ropes are HMPE:

Tip: if you want low friction from a LFR, you have to go bigger than you think. The hole must be at least 2x the size of the rope for polyester if the line is adjusted under load and the angle is severe; much or the friction actually comes from inside the rope. Also, the newer the rope the better,

[deluxe68]

One thing I did just find that applies to all ropes, the diameter of the bend is recommended to be from 5-8 times that of the line. That part makes sense, my 12mm polyester Sta-Set has about the same load rating as 5mm dyneema.

[Dockhead]

Thinwater is giving good advice.


I love low friction eyes and am using by now dozens of them on my boat.


But one should recognize their limitations. I would never use them for halyards -- you want ball bearing blocks for that for minimum friction and highest precision in tensioning.



I do use them for jib sheet leads, but there is a certain amount of judder under really high loads. I might strip the cover of the dyneema sheets next year, so that dyneema and not the polyester cover bears on the rings.


They are called "low friction" but compared to ball bearing blocks, the friction is quite high, especially with polyester rope or polyester-covered rope.

[deluxe68]

Originally Posted by thinwater

Practical Sailor April 2018. Review, including friction comparison.


I've used them with both. They are a compromise solution with both pluses and minuses. I would lean towards ball bearing blocks for halyards, since sails are hard to raise anyway. No, it wouldn't matter on the drop.


These ropes are polyester:




These ropes are HMPE:

Tip: if you want low friction from a LFR, you have to go bigger than you think. The hole must be at least 2x the size of the rope for polyester if the line is adjusted under load and the angle is severe; much or the friction actually comes from inside the rope. Also, the newer the rope the better,

We are fairly lazy retired cruisers, not in a hurry to get anywhere. So we tend to set and forget. Not much fine tuning for the main halyard.

The current mast base blocks are 30 years old, the biggest problem is that the attachment points are very small. The hard shackle on a Harken 75 ESP block will not fit. So we are limited to soft attachments in the 5000 lb working load range.

[Dockhead]

Originally Posted by deluxe68

We are fairly lazy retired cruisers, not in a hurry to get anywhere. So we tend to set and forget. Not much fine tuning for the main halyard.

The current mast base blocks are 30 years old, the biggest problem is that the attachment points are very small. The hard shackle on a Harken 75 ESP block will not fit. So we are limited to soft attachments in the 5000 lb working load range.

You could attach ball bearing blocks using dyneema strops.