Synthetic Headstay Weakness

Dyneema is a wonderful material for use on a sailing yacht for standing rigging. It is immune to rust and corrosion, and it is incredibly light weight! Placing it at the stem of your yacht, where salt spray and moisture are a daily fact of life is a wonderful idea as this powerful plastic will take the charge and never let you down.  

While it may seem that synthetic standing rigging has no weaknesses, this would be false. Synthetic standing rigging has one tragic weakness that can destroy it in a moment: chafe! 

In a gale, our 65 pound Mantus anchor broke out of its roller and gnawed on the deadeye for three days. The damage suffered to the headstay was extensive and precluded us from using our headsail as we limped along for 80 miles to return to shore. 

The shank of the anchor chewed and chafed on the dyneema deadeye while also mangeling the thimble inside the lower part of the deadeye.

If the damage to the dyneema had been less extensive, it would still had been risky to load this stay as the thimble was no longer in function.  

The purpose of the thimble is to smooth the bend at the bottom portion of the deadeye. Dyneema is strong, but sharp bends will cause the fibers to crack and break, leading to premature failure. 

We have a cutter rig, meaning that we have a second headstay further inboard, but it is by no means destined to resist the forces of the backstay and sails while trying to power to windward. These forces fall onto the headstay and are rather extreme, especially when the stay is further loaded with a large jib in high winds.  

Our rigging was crippled and we were 50 miles off the coast in a gale with another more powerful gale on its way! 

Now, to ensure this doesn't happen to you, there are a few suggestions I would like to make. 

First, if you are going off shore, stow the anchor somewhere away from the headstay. We keep various anchors that we use infrequently tied to the boat, and when heading off-shore, your bow anchor should be treated like any other anchor as you won't be using it for some time.  With your anchor secured and tied up very well, it won't be able to leap out of its roller and chafe away on your standing rigging.

Another trick would be to install a sacrificial piece in front of the deadeye. This would take the damage of anything that wants to destroy your rigging by getting destroyed first and hopefully you will find the problem and correct it before it gets worse. This line could be attached through the eye of the headstay and simply run down to a further forward hole in your stem fitting. 

To ensure that you will be able to make it home, it would be a good idea to carry a spare deadeye, already assembled with its thimbles and the fairleads needed to tension your rigging. If you lose your headstay, you are at the mercy of the currents! Having the tools and parts on board with you will grant you the ability to make it back to port on your own. 

The reason to have a deadeye already made is because they are rather tedious to make. I take about an hour to make one in calm conditions, at home, with no stress of a storm situation. Imagine trying to make one of these while out at sea as you worry about where and how fast you are drifting? Having it already made will also reduce the amount of time it will take to install the new deadeye, which sadly is a rather lengthy process. Headstays require a lot of tension and can take close to an hour to setup with a deadeye. 

Now, if you would allow me to lead by example on this front. This damaged headstay occurred on my own personal yacht that I rigged several years ago with synthetic standing rigging. I carry all the tools and parts needed on board to rig her again at sea if we needed. I also feel that I take every precaution possible to ensure the longest life for the rigging. This situation occurred and I can not guarantee that it won't happen again, so I am converting my headstay with a deadeye to a turnbuckle. I feel that a piece of bronze with stainless steel screws will hold up better should this freak occurrence happen again. We will certainly be restraining and stowing the anchor differently from now on to hopefully eliminate any other anchor related damages, but accidents are never planned and I feel that a piece of metal is a better security blanket than a piece of rope at the lower part of the stem. 

Synthetic standing rigging is awesome and deadeyes take away any fear or concern of corrosion, but the pulpit is a dangerous place when laying right next to the anchor. If you have a racing sailboat where the anchor is not stored on the bow, or your anchor roller is far away from your headstay, then by all means, keep with the peace of mind of deadeyes. If you have a similar setup to mine, then strongly consider setting it up with a turnbuckle and be sure to oil and inspect it regularly and frequently for any signs of corrosion. 

Combining Steel and Synthetic Stays

When converting your standing rigging to systhentic, you might feel inclined to change "some of the stays now, and some of the stays later" as the budget allows. I strongly recommend against this, as combining steel and synthetic standing rigging can lead to more problems than solutions.

Yes, changing the stays one by one as time and money allows may seem fine from a theoretical standpoint, but they will not play well together.

As temperatures change, steel and aluminum will expand and contract at a similar rate, meaning that the steel stays will always remain around the same tightness. Synthetic standing rigging actually expands when it cools, making the stays just a bit longer than they were when initially setup. As the air heats up, they contract and get tighter.

If you setup your rigging at 80F, and then decide to go sailing on a day that is 60F, you will find that your mast will be out of tune! The steel stays will be tighter than your synthetic stays, making the whole system out of whack.

When I converted to synthetic standing rigging, I switched all the shrouds except for the check stays (that run aft from the height of the inner forestay). I didn't swap these stays out simply because I ran out of time before we were going on a long sailing trip. I figured that I would swap them out when we got back.

It seemed that I had to tune the rigging as the temperatures changed, especially the cap shrouds. As fall approached, the check stays (which attach about 3/4 of the way up the mast) remained the same tightness while the cap shrouds at the top of the mast were a bit looser. This meant that the mast would be in column and then bend sharply at the check stays. All I had to do was tighten the cap shrouds and this issue would resolve! The problem was this tight bend that was occurring at the check stay tang.

I was worried that if the temperature was cool enough and the shrouds loose enough, that the mast might bend far enough to buckle and cause serious damage to the spar! This kept me always adjusting and tuning the rigging for quite some time.

Eventually, I replaced the check stays with dyneema and all these problems disappeared! Now, all the shrouds expand and contract at the same rate, meaning that the mast will always remain in column.

On warmer days, the mast is obviously straighter as the rigging is tighter. This gives us the ability to point very well! On cooler days, the mast leans over slightly until the windward stays become tight and the leeward stays hang limp. The headstay also hangs a bit slack and our ability to point is degraded slightly.

While mixing steel and synthetic shrouds is not ideal, there seems to be no problem with having steel or synthetic headstays. Our setup is currently a synthetic headstay and backstay, with a steel inner forestay.

The reason the inner forestay was not replaced with the rest of the rigging is it is still new! The inner forestay was only 3 years old when I converted to synthetic standing rigging, and the cost of materials to swap out that additional stay just wasn't justifiable! When the inner forestay reaches 10 years old or starts to show signs of deterioration, it will then be replaced with a synthetic stay. Until then, it will remain.

On our setup, where we are a cutter rig with all synthetic standing rigging (except the inner forestay) the mast is able to remain in column and we are able to sail very well in all conditions! Having an adjustable backstay is a huge help for taking up some of the slack in the headstay on cooler days while trying to beat to windward.

Synthetic standing rigging is a wonderful and easy setup that you can create and install yourself. The weight savings will make your yacht less tender and the resistance to corrosion will give you peace of mind. If you decide to make the switch, make sure that you convert all your shrouds at the same time and not a few at a time to see how it works on your yacht.

Oversizing Your Rigging

You often hear people suggest that you should oversize the stays of your yacht if you want to go ocean voyaging. They make it sound like if the stays are the weak point and making them larger will turn any sailboat into a blue water yacht.

The reasoning behind this is in the ocean, you will encounter storms with no place to hide. You will be forced to sail through weather you would only encounter in a nightmare, and your rigging will need to hold all of this abuse. By increasing the size of your stays, you are also increasing the strength of the wire, making the entire system stronger! Or so the common thought would lead you to believe. 

The problem with increasing the size of your steel standing rigging is two fold. First, the added wire size directly translates into added weight aloft. This will make your yacht much more tender and life during a storm will be far less than deplorable. The second reason is the wire size of your rigging is not the weak link in your standing rigging. Your entire rig is a calculated design where everything shares the responsibility. Increasing the wire size but not increasing the size of the clevis pins that hold the terminals is pointless. Now you have heavier rigging of the same strength! Remember, a chain is only as strong as its weakest link, so increasing the size of one link will not make the chain any stronger. True upsizing of your rigging would entail increasing the size of everything involved in your standing rigging. 

With steel rigging, there is a severe weight penalty for increasing the size of the wire. Synthetic standing rigging doesn't carry such a weight penalty; instead it carries a financial penalty. Increasing the size of the line used will increase the cost per foot dramatically! For example, 6mm New England Ropes STS-HSR costs $2.79 per foot. 7mm New England Ropes STS-HSR costs 3.49 per foot. That is a $0.70 increase for each foot of line you need to buy! If you take it a step further and go to 9mm New England Ropes STS-HSR, you are now looking at $6.09 per foot! Now you are looking at an increase of $3.30 for every foot just so that you can upsize your rigging by 3mm! 

Windage is another concern with increasing the size of your synthetic standing rigging, as it is suddenly a larger stay to pass through the wind. This is only a real concern for racers, as the average cruiser has enough junk on the deck to nullify any penalty from larger stays. 

After the financial burden, increasing the size of your synthetic standing rigging does offer one major advantage, it decreases the amount of creep you will experience. Having larger stays means that each stay will be loaded a lower percentage of its maximum. If you apply a static load to synthetic standing rigging, it will creep. If the load is greater than 10% of its maximum breaking load, you will experience significant creep. If the load is less than 10%, you will experience less creep. As you increase in size, the strength of the line increases dramatically, and so would the decrease in creep. 

Increasing the size of your steel rigging is pointless, as this will simply add weight aloft and cause you to heel over more while sailing. Increasing the size of your synthetic standing rigging will cost a lot more but it will also give you less creep. 

Ideally, you should try to keep your yacht's rigging at the designed size. When the rigging was designed, the designer factored in the heeling forces of the wind and the ballast in the keel. Altering from this would mean deviating away from an expertly calculated state into an experimental state.

Dealing with Winter's Stretch

Dyneema, used in synthetic standing rigging, is remarkably strong and light weight. This makes it an excellent choice for standing rigging, as it supports the mast without adding unwanted weight aloft.

The dark secret about synthetic standing rigging is that the dyneema has a negative coefficient of thermal expansion, meaning that it actually elongates as it cools. Aluminum, a common spar material, has a positive coefficient of thermal expansion, meaning that it will shrink while cooling.  Stainless steel rigging also has a positive coefficient of thermal expansion, so it will shrink along with the aluminum at roughly the same rate.

As winter approaches, the mast will shrink ever so slightly, as will steel rigging, meaning that it will all stay roughly the same tension. This is why steel rigging seems to stay the same tightness year round, as it expands and contracts with the mast. 

Synthetic standing rigging, on the other hand, becomes rediculously loose as winter approaches. The mast contracts ever so slightly, while the dyneema expands a bit. The combination is a longer than normal stay on a shorter than normal mast! You might be tempted to simply tighten the deadeyes during winter, that way the standing rigging is tight again, but the problem is that once summer returns, the mast will expand slightly and the dyneema will contract drastically.

It is very fair to say that synthetic standing rigging is temperature sensitive. I prefer to tune synthetic rigging at 80*F. I find that this gives you wonderful sailing in summer, when it is much hotter, and rigging that is still functional into the cooler times of spring and fall. In the dead of winter, it is not uncommon to find that your headstay has expanded a full 1/2 inch (12mm). 

While it might look as if the rigging is lost during the winter, you must admit that no one wants to go sailing when it is 20*F outside! As the weather warms up, the rigging will all go back into its place without any need for adjustments or tuning. 

This works well for fair weather sailors who only sail when the weather is inviting. What happens if you need to sail in the winter? Should you tighten your rigging for the sail and be sure to loosen it as the weather warms? What if you forget to loosen it and the contracting stay becomes too tight and breaks a fitting or rips out a chainplate? 

While I have yet to go sailing with synthetic rigging in the winter, we are probably going to be encountering this scenario soon. Maddie and I have set out cruising and we will be crossing the North Atlantic in the winter. We hope to arrive in the Azores by December and may be sailing over to Portugal in February! The winds will certainly be cold and the rigging will become slack! 

I have the standing rigging tuned to perfection at 80*F, and I know that if I tighten it during the winter, I will have to go through all the trouble of re-tuning the rigging as spring rolls around. If only there was a way to mark the 80*F position on the lashing! 

There is! Our plan is to setup a secondary lashing that will run over the current lashings to tension the rigging without disturbing the current setting. The current lashings will remain, but the new lashings will go over them and pull the stay tight once again. With the new lashings pulling everything tight, we will be able to safely sail during the winter to reach our next destination, and simply untie the new lashings as spring approaches. As soon as we untie the new lashings, the old lashings will take over and allow the stays to contract to their old settings! 

This idea has not been tested, but it is my solution to winter sailing on my own boat as we cruise the North Atlantic in the winter with synthetic standing rigging. 

How Tight is too Tight?

When setting up your rigging, it might be very tempting to tighten each stay until something breaks! The problem with this protocol is you would then have something break.

The truth is, your standing rigging only needs to be tight enough to hold the mast straight and upright. The looser your standing rigging can be, the less stress you will put on all the fittings that are associated with the rigging. The removal of unnecessary static loads will greatly prolong the life of your rigging and your yacht.

It is important to remember what each stay does, and therefore, how tight it needs to be. The cap shrouds need to be the tightest of the shrouds, as they keep the tip of the mast in place. Due to leverage, this stay needs to withstand a lot of load. If the stay is slack at rest, the top the mast will move to leeward as the weather builds. Eventually, the stay will become tight and the mast will stop moving. The less you want the masthead to move, the tighter this stay needs to be.

The further down you go, the less stress each stay will experience, and the looser it can be.

On cutters, check stays will be present to counteract the inner forestay. These stays do not need to be tight at all, as all these stays do is stop the inner forestay from pumping the mast. As the inner forestay pulls forward, the mast will bend forward slightly, and the check stays will become tighter.

At rest, however, these stays may appear to be "too loose."

The headstay and backstay are another stay of constant debate. If they are tighter, you can point upwind better. Looser and you can reach better. The correct answer for the tension in these stays is "enough to point what you need." If you are a gaff rigged cutter, you will not point very well due to the sailplan, so there is no reason to overstress your fittings by having a bar-tight headstay. On the other hand, if you have a fin keeled racing sloop, the headstay should be akin to a banjo string!

Standing rigging is only there to hold the mast up. The goal is to accomplish this task with the loosest stays possible.