Dux all in a row

Dynex Dux was the first mainstream heat set Dyneema to arrive in the yachting world, and  had a huge effect on rope selection on racing boats.  Using heat and tension, it gave us higher strengths and lower stretch in a smaller package, and quickly stole ground from not just regular Dyneema, but has replaced Vectran and Zylon as well.

These days, there are quite a few varieties available in heat set prestretched rope. Stopping by this week is the most recent version, and likely the strongest,  from New England Ropes.  I thought it might be interesting to compare the available options, so below are some notes.

On the left is Gleistein’s Dyne One HS.  This is by far the easiest heat set product to work with, as it has a pretty wide angle, and is soft compared to Dux.  It’s also the roundest option, and tends not to flatten out over sheaves.  The downside is the high angle between braids should theoretically make it stretchier.  The other drawback is that it doesn’t seem to be much stronger than regular Dyneema, at least in the small sizes.  Last summer when doing some break testing I found that the 4mm Dyna One HS broke at ~3800lbs, where as plain old New England STS75 breaks well over 4000lbs.  The 9mm shown is supposed to be approx 18000lbs, which is again in line with regular Dyneema.

Second from left is Maffioli Ultra 75, actually the core from 11mm double braid. This is probably the least stretched product, and rated at 17000lbs it’s the weakest as well. It’s kind of an odd duck(x) here as it’s not targeted or made like the others, and I believe it’s just a quick prestretch to take out some of the constructional stretch.

Middle line, in dark gray, is Marlow’s D12 Max 78 product. Rated at ~23000lbs, this is much stronger than the first 2.  It has quite a long angle, partly from construction and partly from stretching.  This is the only SK78 product here, but they also offer an SK90 heatset, for max (ha) tensile.  Marlow has the widest range of fiber choices, and more importantly sizes, going all the way down to 3mm which is unique for a heat set dyneema.  The downside to Marlow is the stretching process makes for a rope that isn’t very round,  as it’s flattened out over whatever bobbin they use to stretch the product.  The Dyneema is a bit fuzzy when new, due to the fibers that fail during prestretching.  This is the choice of high tech dinghy and small cats, as the range of sizes makes for lots of options.

At the far right (I’m skipping the second right for the moment) is a piece of Dynex Dux in 7mm, as I was out of the 9.  The original, and still very good, it has a rated break of ~26000lbs, and is quite round and very stiff with less popped strands than the Marlow. The amount of prestretch is very high, which makes it a good choice for running rigging where stretch is key, as well as some standing rigging and slings.  I really like this material for backstays as it’s so light and strong you can be quite aggressive in downsizing.  Most people call any prestretch Dux, but that can be troublesome as some of the other heatset products aren’t exactly interchangeable as far as strength and stretch.

Second from the right is the newest arrival, an as-yet-unnamed product from New England Ropes.  Pretty excited about it, as it seems to have taken all the best attributes from the other brands and improved on them.  The construction is very similar to Dynex Dux, but lacks the flyaway/popped strands. The roundness of the rope is closest to Gleisteins product, and the smoothness is better than any of them.  NER hasn’t released final break numbers, but the initial tests had it all comparing very favorably with Dynex Dux, which is really saying something.  This particular spool is destined for the VO70 Il Mostro, replacing the Gleistein rope is arrived with.  I’ve got more spools arriving soon and am going to have more info soon!

Big Boat check stay upgrade

There are tons of great old IOR boats out there that can benefit from more recent technology.  The old wire check stays and blocks in the picture above were heavy and a bear to use.  We were able to match working loads with much lighter gear and still keep the traditional look favored by the owner. 

The Harken runner block shown (4″ stainless runner) isn’t in the Harken catalog anymore, but is still available on a special order basis, which is great as they’re excellent blocks with a traditional appearance. These weight less than a third of what the old mammoth blocks weighed, and still deliver much less friction.  We replaced the wire-to-rope (yuck!) tails with simple New England STS 75 covered with a Marlow MGP cover.

Always nice to get kind feedback, and one of the funniest of the season Iv’e gotten was from this boat: “I know I’ll get whacked in the head by the checks at least once, so I’d much rather have it be the new runners than the old runners!”

T10 Backstay: Cascade

Here are a few pics of the T10 fiber backstay with cascades

Above is the tackle, composed of Antal thimbles for the first few high load and low speed cascades, then Harken ball bearing blocks for the faster cascade and control.  Total power  is 32:1.  The control lines ease much more quickly, and the trimming is easier.  Total weight for the backstay is less than 2 lbs.

Here is the transom attachment.  The first cascade goes to port, everything else to starboard to keep the standing stay centered. Important with shackles-especially as part of a boats standing rigging-are plastic ties to hold the shackle pin closed.  Alternatively, the shackle could be drilled to remove the threads, and a clevis pin and cotter used.  

Here is a photo of the flicker on the masthead before taping. On this boat there was a windex mounted on centerline near the aft end of the crane, so I reused that hole with a 1/4″ machine screw and nut.  The windex was moved slightly off center and retapped.  If theres no hardware at the top of the mast, drilled and tapped 10-24 machine screws are sufficient. Very important: use washers as large as the batten under the screw heads, and use plenty of loctite on the fasteners: there is a lot of load on the aft screw, and the screws will see thousands of cycles in a season, so if they’re not really secure it will loosen and break.

Long view of the flicker installed on the mast.

T10 Cascading Backstay

Updating the popular T10 fiber backstay,  we now offer a cascading purchase to replace the “pinch” style with 2 legs and a lashing.  When the fiber backstay rule was legalized in 2007, the hope was that cascades would be legal, but according to the measurer only 2 leg deflection systems were ok.  A couple years have gone by and now the cascading system has been ok’d and is on several boats.  Our system is incredibly light, works great with the flicker and pins right into place, needing only your boats original control line and blocks.

The standing backstay weighs .6lbs (vs over 3 for the wire standing portion) and total weight including cascades/less control lines is 1.2lbs (vs over 9 for a typical wire system with link plates, toggles etc).  Pretty nice weight savings, but just as important is how effective this makes the backstay flickers.  Dyneema cover where the flicker and battens hit the stay makes the sail cross easily in tacks, and the light weight means the flicker can lift the stay out of the way with little pressure.

Total power is 32:1, for plenty of adjustment of mast bend and forestay tension. The standing stay is heat set SK78, and the legs are prestretched SK75.  The SK78 is the lowest creep grade Dyneema available, and the heat setting improves the strength, stretch and makes the stay fit perfectly the first time out. Hardware is all captive spliced for safety, and uses Antal thimbles and your choice of Karver or Harken for the final cascade. Shackles for the transom chainplates.

Cost for the system is $445, and with the flicker is $580, send me any questions you may have at kristian@chicagoyachtrigging.com