Funny, I have been staring at this pic on my desktop. Here is an old gaffer I photographed at Antigua Classic Yacht Regatta couple of years ago. Shes using a bowsprit traveler and flying jib. See a.ttached
Based on some quick trig, the horizontal load
vector along the bowsprit is ~ 470 lb and the
vertical load vector along the mast is ~ 1,100
It follows, the line that pulls the bowsprit ring
traveler out must be loaded to 470 lb to equal a
1,200 lb load on the Dynex luff tape/jib stay.
This assumes zero friction. Friction between the
bowsprit and ring traveler will increase as the
vertical load vector increases, hence more force
is required to overcome the friction. Let’s
assume a 200 lb force is required to overcome the
friction between the ring and bowsprit, then a 670
lb horizontal load will be required to achieve a
1,200 lb load in the Dynex luff tape/jib stay. I
question if this degree of loading can be achieved
with a hi-field lever.
Rod, I’m a bit confused about “friction between the bowsprit and the ring traveler”. I thought that the ring is run out the sprit without any tension on its halyard/sail. Once it is out in position, its outhaul is cleated and then tension is applied to the halyard? I think this is the setup we saw on Kikorangi back in 1980 when we considered buying her.
A concern I’ve always had about putting a lot of tension in the jibstay is that the bowsprit exerts a lot of aft pressure on a relatively small area of the bits, assuming the usual fid arrangement. The fid pressing against the aft side of the bit’s notch tends to split the the lower corner of the notch (ash on Shaula). Any thoughts?
You may have had a flaw in your wood. Between Angelsea and Shanti I have never had a problem with the bits. And I set the rig up hard. Although the fid on Shanti looks a little squished right now.
If I end up going with the ring, I may not have to set the headstay up as tight as normal. This is something I will need to look into.
Holy cow Batman!
I just found out from Carlos (previous owner), that my rig is something like 20 years old! You have to admit, and so do I that over sized 316 and wire splices are a pretty secure way to go!!! It was just a year ago that I sailed Shanti down from Florida in one of the most miserable trips of my 40 years of sailing. A dead beat to weather in 25-40kts for 1400 miles.
But now I have to re-rig ASAP. I thought maybe another year max.
OK … I’m going to do it! Have to go and check all my measurements. I will be getting the rigging from Precourt in Canada. I plan on setting up a blog to document the whole process and subsequent use.
But now I have to paint my bulwarks so she looks good when we shoot the first photos of Shanti sailing with her new rig!
Also going to go with bowsprit traveler and continuous line furler.
Check back for more details and the address for the blog. I figure about 3-4 weeks before I start. Depends on how long it takes to get the gear shipped down from Canada. That could take years and cost thousands of lives.
Gary, Please be cognizant of the fact that Hampidjan has a requirement of at least a 5/1 Dia/dia ratio of line terminations for Dynex Dux. Dynex Dux is not like normal sk-75 (amsteel) and is very stiff. The small bending radii puts the inner UHWMPE strands in compression. Our research has confirmed that you need at least 5/1 to maintain line strength and fatique life over time. The reason we have developed our line of termination hardware is that no existing hardware met that requirement, including Precourt’s from Canada. Their line of hardware was designed for SK-75 or Kevlar type line that can tolerate a higher bending radius. Uninformed people will tell you that the breaking strength is so high it does not matter. If you change your line often then that is true, especially for trailerable boats which is what Precourt’s main experience is with. Trailerables have the advantage of having their rigging checked often and out of the sun a significant amount of time.
The reason I need to make this clear is that this is a new technology and with new technologies, misuse that leads to failures can generate alot of undeserved negative publicity. We have used Dynex Dux for over 6 years now and have spent a considerable amount of time and money on understanding it and want to make sure you are correctly informed when making your decisions. Since you made it a point to use our website for most of your information on Dux, and reference it in your posts, I feel that I need to make it clear that we do not endorse the use of any hardware that does not meet the requirements of Hampidjan. You have a boat in the tropics that experiences high UV exposure and that will definitely affect the long term durability of Dynex Dux, having hardware that does not meet the line requirements will only exacerbate the problem. Our research so far has shown some strength degradation due to UV (year 2 coming up) but the interesting thing is that physically, the line does not appear any different. So there are no physical indicators of line strength degradation over at least 2 years.
I am glad to hear that Precourt seems to be back in business from bankcruptcy (competition is always good) but they should give you some assurances of line life since their hardware presents the limiting and overriding design factor in a standing rigging system using Dynex Dux.
John Franta, Colligo Marine
Thank you for the well written post on the use of Dynex. It was most informative.
Why is it Dynex Dux does not employ a UV sacrificial cover? A braided polyester or something? If UV degradation is the limiting factor of the lifespan, this would seem to be a an easy method of prevetion.
Thanks John, That is some good information.
I know this is going to be an “experiment”. I’m willing to give it a go. The BIG question is going to be the UV. Are you guys doing any pull to distruction testing at timed intervals?
Wow, I just found this thread and find the whole thing really intriguing. Saving all that weight aloft has GOT to make a big difference in windward performance.
I wonder what the effect will be to the gentle rolling I experience going to weather. I once had to motor a mastless 40 footer up the California coast and I can tell you that without the weight aloft the boat would snap back from a wave induced roll.
I do have a financial question though. This five plus years useful life of the synthetic line doesn’t compare well with stainless wire. I easily got 15 years out of my first set of rigging and even then it was showing no outward sign of fatigue.
I’m cheap as well as poor so I’ll have to leave the experimentation
of these things to those more well off. But don’t read me wrong…I really like the idea of reducing weight aloft and will be following along this thead with good wishes.
The most cost is for the first re-rig, since you have to buy terminators. They can then be reused. The line itself is a little cheaper size for size. I am seriously considering going over size because of the UV factor (I’m in the Caribbean). Instead of 7mm and 9mm, I may go 9mm and 11mm. That would make it a little more expensive than replacing wire.
My present rig is 5/16 with wire splices. It is 20 years old. But it now needs replacing and would be very expensive to have the splicing done again. Here in the tropics they say swagged rigging is only safe for 3 years. Of course stalocks would be have a lot longer life. But then I would have to buy those which is equivalent cost to the synthetic terminals.
We have and can put together rigging systems that use covered Dynex Dux, Hampidjan sells a very durable version of it. However, it is difficult to cover (and maintain the cover) the line as it goes around the terminator and this happens to be the high stress area, also why you need a minimum 5/1 radius there. After long term exposure this is the most probable area of line separation.
UHMWPE line as Dynex Dux presents the best synthetic for UV resistance. A study by the University of Aukland found that SK-75 gets some initial UV damage and then becomes relatively Opaque to UV, so the damage slows considerable. We have a boat in Mexico (where it rains about 3 days a year) that we are pull testing line from the shrouds every year to develop a characteristic on. This month is year 2 and, now that we have 2 data points we will be posting the results on our site. Our goal here is to come up with a replacement schedule for Dux. In addition, we have several customers in different areas of the world, that have agreed to trade in their shrouds so that we can pull test them and maintain our database.
Subjectively we are saying 3-5 years and probably more than 5. I have had people tell me 8-10 years but they have no data. It remains to be seen, but I would feel save now changing it out every 5 years, know more in a couple of weeks. As you noted, Gary, the line can be changed using the same hardware, bringing costs down considerably over time.
Most wire rigging and terminal companies give 8 years as a maximum replacement interval. We all know many people that have used their wire rigging for much longer than that, I suspect Dynex Dux will be the same, varying conditions do exist. Manufacturers have to spec to worst case with a safety factor.
To date we have rigged several monohulls including a 60 foot schooner near Annapolis with Dux. Currently working on a Westsail 32, Dolphin 46 Cat, Ranger 33, some beach cat (5mm Dux) and small sport boat systems as well. We have just developed a process to splice shrouds or stays to any lengths to within 5/16"(8mm), using a locking brummel splice, enabling the use of “normal” short travel turnbuckles for those choosing to use turnbuckles. In addition we have Terminator mounted cleats to eliminate the need for tying off lashings for those desiring a mechanical lock.
As noted before, we have spent a good deal of time and money on understanding this line for standing rigging use and are willingly sharing this information. We would appreciate an opportunity to bid on any re-rigging opportunities that are out there. We give discounts on complete boat builds. Talk with some of the rigging experts out there for reccomendations, Brion Toss on the West Coast (Port Townsend), Brian Duff on the East Coast (Annapolis) are just a few.
Thanks and let me know if you have any other questions.
John Franta, Colligo Marine
So, to be clear, the Dynex Dux is available with a sacrificial cover? It would seem easy to rig some sort of cover over the terminals.
I would be very interested to get the contact info for the person rigging their Westsail 32. It would be fun to do a write up for the Westsail Owner’s Association’s quarterly newsletter about the process. I’ve sent you a private message for this.
Thanks for the info,
Shaula’s ash bits were ‘as new’ for 20 yrs, so I don’t think they had a flaw. Using Rod’s vector numbers and your 1200 lbs of jibstay tension, it looks like there would be a lot of pressure on the bottom of the bit’s notch. Assuming that the back side of the notch is 1"X2.5", that’s 2.5 sq. in., times two, or 5 sq. in., bearing 470 lbs. 470 divided by 5 is about 94 psi–a lot of pressure on the bottom of the notch, and this is before a gust of wind hits, and doubles the pressure!?
Does anyone have any thoughts on this? Has everyone looked carefully at their bits to check out the bit’s health? I suspect that most of us don’t tension our jibstay all that tight, so maybe most of us don’t have a problem? Since most of us have furling gear on the jibstay, there’s no way to measure the stay’s tension, is there? Jack, on Spicer, skipped the fid, and through-bolted the bits and sprit. He made his bits out of Australian Spotted Gum. I wonder what the most split-resistant wood would be? A matter of interlocking grain?
The 1200lb number comes from what I think I can achieve as far as tension on a flying jib. So this would not be on the headstay, and be transmitted as much to the bits. Of course some will be. I don’t know if that is what my headstay is set at. I am going to be ordering a Loos gauge and measure my rig before I dismantle it for the re-rig. I will report those numbers here. Since I don’t have roller furling I can measure my headstay Tension. But if anyone has a Loos guage you can measure your backstay. Since the angle to the mast for both headstay and backstay are very close the tensions should be about equal.
My rig is tuned fairly tight, with the lee shrouds taught. Loos recommends a tension of 1600lbs on a 9/32 wire headstay as a starting point. They have a very good discussion about rig tension here http://www.mauriprosailing.com/Loos-Co/Loos-PT-sailboat-tension-gauges.htm .
Hey sailors, wanna get lucky?
Well I really can’t help ya there. But I have started a blog to track the re-rig of Shanti with the synthetic rigging.
Plus I will be posting other BCC related goodies. And feel free to post comments. I value all your opinions. sorta.
Saturday morning and I have some interesting info. Many of you probably already know this if you have purchased a Loos Gage.
It?s always fun when you get a package with new gear in the mail. Especially when it is something that will make doing the job at hand fun, informative, and a little easier. I ordered a Loos PT-3 Pro tension Gage and a ATN Topclimber bosun?s chair.
I wanted to get the Loos Gage for not only tuning my new synthetic rig but also to measure what I had for tension in my present rig. I had tuned my rig the old fashion way. Push, pull, grunt, scratch ? and guess. I do have a bit of experience doing rigging work, but I have never had it put to a quantitative test before. My final adjustments on my present rig were done under sail. Tighten to the point so the leeward shrouds were snug.
What a surprise I received when I measured the tension on my present rig. My shrouds were tensioned near perfect.
Lowers 1220 lbs
Cap shrouds 1960 lbs
Intermediates 1540 lbs
Headstay 1660 lbs
The BIG surprise was the forestay and backstay. My forestay was at 300 lbs and my backstay was at 250 lbs. No wonder she wasn?t sailing to weather well! She had to have had a lot of forestay sag. This really messes up the ability to point. why was I so loose? I don?t know. I have come up with a number of reasons why?maybe. I just don?t know.
On Loos? web site they say a good starting point for forestay is 1600 lbs, shrouds at 1000 lbs. You usually want the longer shrouds (cap) set higher than the shorter shrouds (lowers) because of the stretch. This way when the load comes on the rig, your mast stays in column. Loos also points out that most people do not tension their rigs enough for fear of ?breaking something?. They also point out that the America?s cup boats tighten their rigs as much as the structure of the boat will allow.
A special note on using the Loos Gage on 316 wire. The Loos Gage is designed to be used on 302/304 stainless wire. Since 302/304 is stronger size for size than 316. The concept behind the Gage is based on the strength of the wire, not the actual size. So you can use it on 316 wire. You just need to find what size wire in 302/304 is equal in breaking load to the size 316 you have. For example - on the tension chart from Loos for the Gage it has listed the tension readings for 9/32 302/304 wire. The breaking strength of that wire is 10,300 lbs. The breaking strength for 5/16 316 is rated at 10,600. So I would use the readings for 9/32 302/304 for my 5/16 316 because the strengths are about equal. For the synthetic rigging the Gage will not work as far as measuring tension because the breaking strength is so large and is off the Loos charts. So it will only give me a reference point. I emailed Loos about this and they confirmed my thoughts.
Why is all this so important to me. It has a lot to do with the way I?m going to set up my roller furling. That post comes next.
Ok, I have to go clean my dinghy. Remember that a ship is known by her boats!
For more info see my blog at http://garyfelton.com/shanti
Thanks for the informative post. Your research and experience in this area is most helpful as I plan on following your lead with my rebuild project.
Since I am starting from close to ground zero I am also taking a look at replacing my Forespar Aluminum mast with a carbon fiber mast. However, there are apparently some downsides to consider … potential for damage from lightning strike is one I have heard. Price is certainly a biggy. Ouch! Maybe I should stick with the Forespar aluminum?
After having a carbon fiber mast put in a yacht I was running I came across some interesting information. I can’t remember which company it was, but there are some “lighter” aluminum masts out there. They can be almost as light as the CF. This is mainly because they fit heavy Stainless steel fittings on the CF and all they have to do on the aluminum is weld a tab on. So do some research on aluminum masts first before you spend the big bucks. Do a real weight comparison (with fittings). I would want to save another 45 lbs minimum to go to the expense of a new mast.
Yes, carbon is one of the BEST conductors of electricity I was in Ft. Lauderdale talking to the skipper that was running a yacht with the tallest mast in the world, at the time. It was carbon fiber. I was asking him about lightening strikes. He mentioned they had more problems when there was a BIG steel cruise ship in the port. They used on of those things that looks like an upside down broom at the mast head. We never had any lightening strikes on the yacht I ran. Most of the BIG sailing yachts today are using CF masts. Just has to be set up right.
Just found this video clip of a real Pilot cutter. She is using a bowsprit traveler and furler. Just what I want to do, but with a different furler. You have to look close as the scenes showing the bowsprit are short.