Dyneema reefing lines - what exactly to buy?

[prv]

Ariam's single-line reefing system is due an overhaul this winter. As part of that I want to replace the old 10mm polyester braid-on-braid with something a bit more high-tech. I would like to have thin, slippery, unobtrusive line for the part that lies against the sail when not reefed, and perhaps for most of the part inside the boom in order to reduce friction, but something big enough to grip at the cockpit end as I generally haul in the reef by hand before final tensioning on a winch. Plus of course I'd like to use the same clutches and winch as now.

Originally I was thinking of a thin dyneema line, spliced somehow onto a conventional polyester tail. However, this is asking a lot of the splice, which will be under load when the sail is reefed. So then I found out that you can buy line with a dyneema core and polyester cover, where the cover is designed to be removed for part of the length for exactly this sort of reason. So that's option two, provided that it's available in the right combination of sizes (as thin as possible for the required strength at one end, around 10mm at the other). Option three, I realised, was to stitch a length of dyneema onto the core of a polyester rope and pull it through so that the dyneema replaces the core - essentially making a rope like in option two. And I guess there's also (provided it doesn't slip in the clutches) a kind of option 3.5 where what I pull through is a complete core/cover rope, ending up with two covers for additional bulk.

I would also, if possible and I know it's a bit silly, like to colour the three reefs green, yellow, red in increasing order of scariness . Some high-tech ropes seem to be available only in quite limited colours.

Given that my sailing was in bermudan rig before dyneema was known outside top-flight racing, then in square rig, then in gaff rig, and only now back to bermudan - I know little about dyneema and have never knowingly even held a piece of it. I'm also using "dyneema" as a collective term for all applicable high-tech fibres.

Advice from experienced workers with dyneema would be very welcome.

What diameter do I need for enough strength on the sail ends of the lines? 34-foot boat and I do want a respectable safety margin so I don't worry about the line snapping in high winds.

Do my plans two and / or three make sense?

What actual product names do I need to look for?

Cheers,

Pete

 

[GrahamM376]

When using single line reefing particularly 3rd reef, I think you will find that you would be pulling the small diameter rope out of the boom so would end up with that on the winch, not the thicker "handling" end. Also, you would be pulling a splice around a 180 degree sheeve - assuming back to back blocks in the boom. Why not just go for 8mm dyneema, available in lots of colours? http://www.jimmygreen.co.uk/item/37442/50m-short-reel-deal-liros-dynamic-plus-cruising-dyneema-

 

[lpdsn]

Beware that line with the braid removed can get twisted and knotted very easily. Not what you really want with single line reefing.

Maybe go for fully braided dyneema say 6mm or 8mm and put in a bit of extra core where the clutch is going to be when reefed.

Strength won't be your issue - a lot of chandelry websites will have have the breaking strain/SWL anyway so you can double check.

I find posters on this forum get hung up on the thickness of lines. I don't know where the idea that you can't haul in a 6 or 8mm line comes from - maybe I just raced too much got used to not having oversized lines.

Splicing one line to another can be done properly. Look around raceboats in the marina with a German mainsail system and you'll find that many have a continuous mainsheet (allows you to trim in on one winch whilst easing on another so you can trim through every wave). Bet you can't find the splice.

 

[William_H]

I am a real doubter about single line reefing and prefer 2 line reefing. Never the less don't forget that unless you have a decent sized pulley at the clew ie if you use the sail eyelet as a turning point you will get quite a bit of chafe at this point. Chafe needs bulk to resist or wear out. So I suggest that at least at the clew point with reef in you need additional cover over a thin dyneema. Do check this point often for chafe. Bare in mind also when purchasing the dyneema that they often have a plyester cover for UV protection and chafe protection so make sure you know what you are getting.
Really hwever I think you should stick with 10mm polyester you have although thinner dyneema might roll through the sytem easier. good luck olewill

 

[William_H]

I am a real doubter about single line reefing and prefer 2 line reefing. Never the less don't forget that unless you have a decent sized pulley at the clew ie if you use the sail eyelet as a turning point you will get quite a bit of chafe at this point. Chafe needs bulk to resist or wear out. So I suggest that at least at the clew point with reef in you need additional cover over a thin dyneema. Do check this point often for chafe. Bare in mind also when purchasing the dyneema that they often have a plyester cover for UV protection and chafe protection so make sure you know what you are getting.
Really hwever I think you should stick with 10mm polyester you have although thinner dyneema might roll through the sytem easier. good luck olewill

 

[han34]

I have 8mm dynema and it works well. A good place to visit is Aladdins Cave rigging shop at Swanick, not the Chandlers (Force 4) the rigging shop behind. They have a very good rope selection and will advise. Normally cheaper than most places and can splice anythinng you need.

 

[vyv_cox]

My single line reefing for two points is all in 8 mm Dyneema. I bought offcut lengths on Ebay which worked out quite cheaply, various colours. No problems at all in hauling them in and they work fine with winches and clutches.

 

[Storyline]

What are the advantages of dyneema over braid on braid ? Have 10mm at the moment (iirc) and it seems plenty strong enough and the tiny amount of stretch does not seem to be issue.

Edit: don't know if it is relevant but we have conventional slab reefing done at the mast and pulled in on boom mounted winches and the tack is held to the gooseneck by cringles.

 

[prv]

What are the advantages of dyneema over braid on braid ?

You can have it thinner for the same strength and thus have less friction through all the blocks and sheaves. Plus if you reduce it to just the thin off-white core for the bits that are against the sail when not reefed, you have less weight and visual clutter hanging off the leech.

Edit: don't know if it is relevant but we have conventional slab reefing done at the mast and pulled in on boom mounted winches and the tack is held to the gooseneck by cringles.

Edit: It is somewhat relevant, because compared to that system a single-line setup led to the cockpit has many more sheaves and blocks and so more scope for friction. Whereas your clew pendants simply come in at one end of the boom and out at the other, mine go in at the clew, round a sheave on a moving slider on a track inside the boom, back to the clew end where they go round a block shackled to the inside of the end cap, then back again down the whole length of the boom before emerging at the gooseneck. Then they go round turning blocks at the foot of the mast, then a deck organiser, and then through a clutch in the cockpit. If you can cut out a little friction at each of these points then it makes a big difference overall.

I know this sounds insanely complicated, and it wouldn't be my first choice if starting from scratch. But it's what the boat was designed to use, and for various reasons switching to something else wouldn't really be satisfactory.

Pete

 

[prv]

When using single line reefing particularly 3rd reef, I think you will find that you would be pulling the small diameter rope out of the boom so would end up with that on the winch, not the thicker "handling" end.

The third reef uses two lines, because the depth of the reef is greater than the length of the boom. I still need to work out the various lengths, but by eye I think there's enough through the boom and back along the deck to balance the part on the sail. Certainly will be on the second and third reef, because of course there are three lengths inside the boom. If on the third reef the cover ends up protruding a little from the clew end of the boom then that's not the end of the world.

Also, you would be pulling a splice around a 180 degree sheeve

Already decided not to use a splice, because I would worry about it drawing.

Beware that line with the braid removed can get twisted and knotted very easily. Not what you really want with single line reefing.

Really? Does that apply to dyneema as well? The dinghy-racing guys I shared a house with when I first moved to Southampton used to strip the cover off most of their lines - it's probably where I first got the idea.

Strength won't be your issue - a lot of chandelry websites will have have the breaking strain/SWL anyway so you can double check.

Yep, I'd want to check the breaking strain - but unfortunately I don't know what strength I need! I wonder if Selden or someone publishes a formula?

I don't know where the idea that you can't haul in a 6 or 8mm line comes from - maybe I just raced too much got used to not having oversized lines.

Most racers I see wear gloves

I am a real doubter about single line reefing and prefer 2 line reefing.

I do too really, but Ariam has a windscreen with small slots underneath for the lines to pass through to the winches. So the number of lines is essentially fixed and there isn't room for separate tack and clew pendants.

if you use the sail eyelet as a turning point you will get quite a bit of chafe at this point.

I haven't noticed any chafe on the current lines, and they've been there a very long time - possibly since 1998 - with heavy charter use. And isn't dyneema supposed to be more chafe-resistant than polyester (not allowing for size)?

Really hwever I think you should stick with 10mm polyester you have although thinner dyneema might roll through the sytem easier.

That's exactly what I'm looking to achieve. Currently it's really sticky, shaking out a reef involves the boom being dragged way up into the air as the clew pendants fail to pull through, then hauled back down on the kicker. Then I usually need to reach up to the end of the boom to overhaul them and avoid deforming the leech. It's far from satisfactory and although newer polyester would be a bit more flexible I would rather have something lighter and thinner which will slide through really easily.

Pete

 

[reeac]

My only experience with Dyneema was using it as a line to raise a steel centre plate on our dayboat. When left on a mooring for a week with just light tension on this line the outer covering was worn away completely where it pressed against the plate casing. I replaced it with 7x19 stainless steel.

 

[prv]

I have 8mm dynema and it works well. A good place to visit is Aladdins Cave rigging shop at Swanick

Thanks (and to Vyv as well) - maybe I should just keep it simple and go for 8mm dyneema throughout. My clutches are Spinlock XA, and I think these cover 6mm to 12mm, though it's a little hard to find online as everything is talking about the replacement XAS instead.

I do still like the idea of just a skinny white core running up the sail though

Pete

 

[srah1953]

Hi Pete
Seeing as you always very helpfully reply to queries I put out, I thought I'd see what I can add.

The main question, I think, is – if you used thinner lines for the whole length of the reefing line, would there be too much slip in the clutch. Even if I knew what type of clutches you use, I wouldn't have the expertise to comment. (There is also the question to what extent there might be slip on the halyard side.) What I might suggest is that you replace the first reef with 8mm dyneema for the whole length of the reef and take it out on the water and see whether it is acceptable. I have Spinlock 0814 clutches which means in theory that they will take rope diameters from 8-14mm, although I believe that, with sufficient pressure, there would be greater slip with smaller diameters. I also understand for these you can replace the inner workings so that the mechanism will only accept smaller ropes.

There are two kinds of splices (that I know of) where you join 2 ropes- one where the two covers are just joined and there is a disconnect between the cores and a full end to end splice where the core is joined to the core and cover to cover. This latter can get bulky, whereas the former will lose a lot of the strength. The latter retains full strength. The former is used for control lines, eg, continuous furler line. The only place I've seen how to make the full splice is in the Splicing Handbook. (I don't know what they use for a continuous mainsheet).
In a dyneema cored rope, if you are going to take the cover off for part of the rope, the dyneema core must be one that is coated (for UV protection).
There is a Dutch site – premium ropes.com - which has lots of explanatory videos incl how to take off the cover. Indeed if you know the lengths involved, I'm sure they'll make up one for you.
Cheers
Philip

 

[charles_reed]

2 single-line and 2 conventional jiffy reefs with rams-horn.
Probably a larger main than yours 32m2.
All now 8mm dyneema/spectra. See no benefit of a polyester tail - but single line not feasible with greater than 2nd reef, purely due to the amount of string involved in the cockpit. Single line dyneema used for the last 12 years - polyester tail for 4th reef replacement of 10mm by 8mm dyneema start last season. 6mm probably adequate strengthwise but difficult to handle. You need low-friction blocks for single-line, I use Harken Carbo-blocks.
No slip at all in clutches - 2 Rutgerson 12-8mm.dia rope. Better for hold, but smaller size range are Lewmar multi-ring - used with dyneema on all halyards (including two spinnaker).
Also use 8mm dyneema on mainsheet, no problem to handle despite arthritis in both hands.

 

[estarzinger]

I want to replace the old 10mm polyester braid-on-braid

So, that old line would have had around 2,300kgs of breaking strength. Bog standard 5mm dyneema (bare/single braid/no cover) will have that breaking strength. So, I would say strength wise that you are good with 6mm.

I would like to have thin, slippery, unobtrusive line for the part that lies against the sail when not reefed, and perhaps for most of the part inside the boom in order to reduce friction, but something big enough to grip at the cockpit end as I generally haul in the reef by hand before final tensioning on a winch. Plus of course I'd like to use the same clutches and winch as now.

You have two primary choices choices to meet all that: (#1) 6mm bare dyneema all the way. It might/probably will slip at the clutches (depends on how good they are), but if it does you can fix it with a bit of internal and/or external sleeve just in the area the clutches engages. 8mm would be a bit easier to hold in the clutches but more expensive and less friction reduction. (#2) would be an 8mm double braid - dyneema cored Dacron covered - line, with the cover stripped off right up to the point where the clutches hold it (you want cover to start there). This would be a bit less slippery - good for the clutches, not so good for the covered parts running in the boom but still better than your current 10mm - and probably a bit less expensive than #1.

It is not clear to me, but it probably is to you, how much of each line could be stripped cover - eg how much is left in the boom/sail after the reef is pulled in? If the stripped section is only short and you have to pull a lot of covered section, then option #1 is probably better. But if you can strip off a lot of the cover and that reduces friction a lot then #2 would be the way to go.

I have used both options, and right now I am using #1 for my tack lines and #2 for the clew lines (because it holds better in the clutches)

Originally I was thinking of a thin dyneema line, spliced somehow onto a conventional polyester tail.

Yea, that is a possibility but I think the stripped cover double braid is all around better and easier.

I would also, if possible and I know it's a bit silly, like to colour the three reefs green, yellow, red in increasing order of scariness . Some high-tech ropes seem to be available only in quite limited colours.

I don't know anything at all about colors or brands available in the UK. The internet should tell you whats available. But I would think 3 colors would be no problem at all. If it is, you could easily use different models/brands (which have different colors available) for one of the lines - it does not all have to be the exact same stuff.

I know little about dyneema and have never knowingly even held a piece of it. I'm also using "dyneema" as a collective term for all applicable high-tech fibres.

Yea, dyneema is what you want - durable and slippery and UV resistant. Vectran would be the second 'high modulus' choice, but it is no where near as slippery or UV resistant.

Advice from experienced workers with dyneema would be very welcome.

What diameter do I need for enough strength on the sail ends of the lines? 34-foot boat and I do want a respectable safety margin so I don't worry about the line snapping in high winds.

Do my plans two and / or three make sense?

What actual product names do I need to look for?

Cheers,

Pete

.......

 

[lpdsn]

Really? Does that apply to dyneema as well? The dinghy-racing guys I shared a house with when I first moved to Southampton used to strip the cover off most of their lines - it's probably where I first got the idea.

Pretty common to strip the cover off spinny guys & sheets on much larger boats too. That's where I learnt about the knots. I've tried a few times to get the knots out of the core of a stripped dyneema spinny sheet and have had to give up each time.

 

[GrahamM376]

What diameter do I need for enough strength on the sail ends of the lines? 34-foot boat and I do want a respectable safety margin so I don't worry about the line snapping in high winds.
Pete

Pete, I don't think you need to worry, 8mm dyneema has breaking strain over 6 tons, I think your sail will be shredded long before that.
Graham.

 

[Simondjuk]

I wouldn't sweat about strength, 6mm dyneema will be as strong as your 10mm. 8mm much stronger.

I'd just go for straight 8mm poly covered dyneema. Be prepared for the possibility that you may need to put different cams in your clutches to prevent creep though.

Don't bother to whip the ends for a while, poly covered dyneema makes sheath for a bit even if well milked down at the start.

Finally, service the heck out of everything. I can pull in both my single line reefs and my two line third reef by hand and hoist all three of them back out from the cockpit by hand with a good pull. If I'm at the mast anyway, I pull them back through the boom there first for ease though. This is with 10 and 12mm reefing lines. Blocks on the sail help.

If your third reef has a luff line which comes back to the cockpit, put a shackle on it. That way you can easily rig it as a cunningham in light conditions and as a reef line in a blow. If you go from full main to reef three in one passage, then you just have to venture to the mast to shift it.

 

[langstonelayabout]

On my Jeanneau 25 I use 6mm Dyneema for the outhaul and the outhauls of reefs one and two. (no reef three). I'd use it for the downhaul too but my main has reef spectacles fitted.

The first season with this setup is coming to an end and I've experienced precisely zero problems with the setup. Expensive but slick, I'd do the same with the topping lift but that hums, much to the annoyance of everyone on board...

 

[vyv_cox]

I'd do the same with the topping lift but that hums, much to the annoyance of everyone on board...

You need to change its natural frequency a little, and/or add some damping. This can be done as simply as putting a clothes peg on it half a metre up, or maybe a slightly heavier mass about half height.