The Offshore Voyaging Reference Site

Carbon Fiber Mast, Costs and Benefits

In the last post I explained why we replaced our old aluminium mast. This post gets to the real meat: How much did carbon fibre cost? And what did we get for that money?

The new mast, excluding some new rigging, cost about US$55,000, as against an aluminum replacement mast, which would have cost about $30,000; a lot of money to us, particularly since it was capital we were spending that came from the sale of our house.

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I’m confused… was the new mast 55k or 25k?



Hi John,

Any data on how long an aluminum rig will last? Ours is 30 years old and we are on the fence about just sleeving the area near the vang attachment that is cracked and re painting or maybe going with a carbon rig. It’s a lot of money to be tossing around when the diffemce could be a few years more crusing or the rig not holding up.


Mike R

Stein Varjord

I’d just like to support every word John says here, and throw in my 5 cents, or some. 🙂 I’ve mostly had my mast fracture problems on utterly extreme racing rigs. They are not directly comparable, of course, but they do tell you what works, and more frequently, what doesn’t. 🙂 What I’ll say, will to some extent repeat what John says, with some variations. I do that to keep the explanations complete.

First, when there are cracks in a mast tube, not only is the crack itself a weakness, but stuff has happened with the metal. Probably that whole part of the tube is quite brittle from fatigue loads. Making that “as good as new” is not possible, but it’s possible to make it work. A rather long insert that follows most of the inside of the tube is the main element. I’d say in a spot like that, I’d use a piece at least 1 metre/3 foot long. Preferably more. You probably have to make the insert from a piece of the same profile, cut off the rear end (with the sail track) and split it in the front. Use a file to round off the edges a bit. Makes the job easier. Do one side of the mast at a time. Spread some rather thick putty on the insert that will make the insert support the tube well. Epoxy is a good base that doesn’t get too brittle with time.

When the insert is in the right spot, have some means of pushing it hard towards the tube. I have found that threads in alu tend to corrode, so I don’t trust screws. I prefer “monel” steel pop rivets. Do NOT use aluminium rivets. Way too weak compressive force. Use the largest type, 6,4 mm. Make sure they are long enough. It’s smart to have two different lengths. You need a serious riveting tool. The amateur stuff won’t last the whole job. The hardening of the grip teeth isn’t good enough.

Put the first hole where the insert is already tight onto the tube. Gradually work your way out from that spot. Drill, rivet, drill rivet. This will use the rivet tension to pull the insert hard towards the mast tube. The pattern should be so that you try to avoid the perforated paper effect. Distance between rivets maybe 10 cm/4 inches, but that will vary with mast dimensions, metal thickness. There will be a lot of rivets! When finished, remember to hammer out the nail head from each rivet. Otherwise it will rust and damage the rivet.

An outside patch where the spot loads occur (like the vang attachment) will not increase the mast stiffness, but will spread the spot load so the mast can cope better. The patch doesn’t need to be very big. It also needs putty to make the mechanical contact good.

If my description didn’t already make it obvious, this is quite a lot of work with no guarantee for everlasting happiness. My advice would normally be: Get a new mast tube, but if that’s too expensive, this fix is something you can do yourself and it probably, but not certainly, will keep you sailing for a long time.


Hi John,

Thanks for the advice. The previous owner of the boat had made a new vang attachment years ago and the engineering was off causing stress cracks. Turns out the attachment/pivot pin was too far from the rig allowing for more leverage than was ever anticipated.

On the repair. We feel our rigger will be able to do a fine job. What we don’t like is spending half of what a new rig would cost on the refit of the old one. Cheap route is to go with the old but as you know that decision could be the expensive one in a few years.



Pete Rasmussen

Hi John,
I enjoy your website and have learnt a lot of very useful stuff.
I wonder if you have tried hoisting a bag of sand or some weight to ease the jerky motion mentioned in windless conditions?
I’ve reduced my halyards from 12 mm to 8mm and noticed a difference and this is on an 10 ton ferro double ender!
Thanks for the effort to make this site such a great read.

Dustin Doyle

Lifting a rubber coated weight to the top of the mast with a T slot attachment that goes into the main sail’s track should work, you can store it in the bilge area when not in use.

You could even make a fiberglass anchor attachment that would put the anchor into the main sail’s track, keep it from moving around, and protect the mast from scratches, and lift that as high as needed.


Hi. A novice here. I’m shopping for my first boat to refit on the hard for a few years. I’ve found a cat with a Aero Rig manufactured by Carbonspar. I’ve never seen this before (which is why I happened upon your site). Any feed back on this product? I see that you mention that cycling loads are the best indicator of wear, for any material. Any idea how much longer a carbon product will last over aluminum?

Thanks, Greg


Hi Greg,
If you are thinking of a catamaran as a first boat, give my friend Kurt Hughes a call and pick his brain before you make that leap.

And if the aero rig cat that you are looking at is the one for sale south of Seattle that has had several million poured into it and never launched, you might want to invest in a pair of NIKE’s running shoes instead.

Stein Varjord

This is way too late for any advice on buying this specific boat. Also, I’ve never actually sailed an Aerorig. Still I have some comments on it.

I’m a multihull fanatic and loves the unconventional too, so I should like it, but I must say I think the Aerorig is a misunderstood solution to the wrong problem, and especially so if put on a multihull.

It’s great to be able to depower at any angle of sail. It’s also great to have the rig balanced so sheet loads are low. The aerorig has both, but the lack of supporting stays and shrouds mean the rig is ridiculously heavy, expensive and still very soft. This means it’s impossible to get a good and stable sail shape.

The claim for superior efficiency, is mostly quite significantly the opposite. The much narrower slot between main and jib means serious loss of efficiency. Downwind this is better, but it seems much of the thought behind this rig is based on a misunderstanding of aerodynamics combined with overconfidence in carbon fibre, which is an amazing material, but not magic.


Ciao Greg,
in the past i ‘ve been interested in the aerorig concept so i bought (super cheap)an open 30 sporting such a rig.Afther one summer in the med i was lucky enough to sell the boat without the rig wich is now burried 3 feet under ground in the Eolian island ,Sicily.My humble suggestion is to consider a different option

pete rasmussen

I’ve been experimenting with weight aloft because of a sharp motion in a beam chop. Mine is an Atkin’s “Thistle” though in ferro cement. Her mast is about 2 metres shorter than the Thistle as shown on the Atkins’s website.
So I hauled a 20 kg weight aloft on the staysail halyard and the difference to the motion is remarkable, much softer and slower. I will try a bit more weight to find the best compromise.
I’m considering building a new mast for her in timber most likely a Junk rig but also considering an unstayed mast cutter rigged.
Now it seems counter intuitive but my reading is indicating that more weight aloft is better for intitial stability, resisting knockdowns better so I’m thinking of adding a few metres to the mast and some weight which will make her motion much slower in a beam sea but may make her hobby horse some more according to John Vigor in ” The Seaworthy Offshore Sailboat”.
Its amazing how much weight aloft affects the motion, 20 kg on a ten ton yacht and the effect is remarkable!

pete rasmussen

Its pretty common knowledge how to engineer a freestanding mast and I’m trying to get it back to the size as drawn by Bill Atkins so can’t see too many problems in regards to strength. The weight is another matter and thats why I’m experimenting with weight aloft. I lash the ignot of lead to the inner forestay and hoist it with the staysail halyard. I’m aware of the dangers involved and take great care. SAD on this old girl is around 13! So she needs more ooomph in light air! She’s a bit like a Bonzai Tree, pruned to the wind force in Wellington , NZ which is something.
So I would like to find what affect various weights have and when I settle on a motion and performance I like I’ll try to build the mast to that weight. I’m thinking I’ll need to add weight, not try to build with less due to the lack of rigging. I’m concerned with making the rig too light and having to live with a really lively motion.
From this experiment I can see that a tube in the mast into which water can be pumped would make the yachts motion quite adjustable by which one could make her better to windward by draining the water, more comfortable at anchor or in a following or beam sea by having more weight aloft.
In regards to stability, a timber mast, unstayed, would float so making it more difficult to invert the yacht by adding positive buoyancy to the vessel at more than 90 degrees.
So lots of positives here John, more resistance to capsize, more comfortable motion and maybe less inclination to invert than an all metal rig plus more sail. Now if only I could figure how to make the mast rotating! 🙂


I enjoyed your post. You gave the pros and cons of the two different types of mast. And that is important.

Is there anything that could be done to reduce the uncomfortable motion when you have to motor?

Thank you



Fascinating thank you. Regarding motion and comfort, it sounds to me that you may have gained a significant comfort benefit from the yacht’s enhanced ability to punch through head seas rather than be stopped by them. In my experience the deceleration-acceleration cycle that results from head seas is much more likely to induce seasickness than any other form of motion.

Like many other commentators I started thinking of hoisting weights to slow down the roll when the seas are larger than the wind. I hear your arguments against it but perhaps lowering a centre-board is an alternative (for boats so-equipped).

A Boreal 47 with carbon mast is looking pretty attractive, albeit expensive [but not unjustly.] Will the [less expensive & smaller] A40 have a carbon mast?


Thank ou for a nice book about carbon rigging!

I am going to change my alu-mast for carbon. Which typ off standing rigging do you use with your new mast? Rod, Dyform or …….. We are planing sail away the summer off 2017.


Thank you for swift reply

My rigg is just 6 years old, so we do not need to change. But last year we did som service on our boat, and we had to remove the mast. The weight did shock me, and I decided to chance for something lighter; carbon.

We do not have to change the rig, but I want to do it before our trip.

We do have a local firm doing nice rig-jobs. They are normaly working with Sparcraft and selden, but when we started talking about carbon they told me that we should get a new rig from a producer who knew carbon. They also liked Hall, so we are going to talk to them.


And why do you like Dyform better than rod?


Hi again

Thank You for your advice. I will consult the designer ore the shipyard.

My boat is a RM, a very stiff and strong boat, made of plywood. She is light and fast, designed by Mark Lombard.


Another alternative that might complement your carbon mast at a cost about the same as Dyform and less than rod.



I have never heard about Dynex Dux fiber rigging before. I am not sure that I would go for a product that unknown for me. Who are selling this stuff, and who produce and sell it?

Stein Varjord

Hi Markus H (Gamenius) 🙂
I’ve also not heard about the brand Dynex Dux, but I’d guess it’s just a branding of normal Dynema rigging. This has become the standard in extreme racing like the ORMA 60, 75 and IMOCA 60 classes. These boats go pedal to the metal solo even non stop round the world. The reason often given for choosing fibre rather than metal is better reliability and easier to inspect.

They do need exchange approximately in half the time compared to a good steel wire rig, but since fibre rigging is cheaper to buy and easier to rig, total cost in the long run is normally about the same.

You know Marius Rosvold. He’s used Dynema shrouds on his 40 foot cat for about 10 years, and knows a lot about fibres in general, including carbon masts, as he used to manufacture some of them. Talk to him about the experience. I got his phone number etc if you want it.

Eric Klem

Hi Richard,

Do you have first hand experience with Dux rigging? If so, I would love to hear how it worked out. We will need to replace our standing rigging in the next few years and I definitely plan to look into it. While I don’t like the idea of the extra windage, we have a very heavy rig which contributes to the boat pitching more than I would like. Realistically, I will likely ended with regular wire again due to not being an early adopter type but if it really is proven by then, I would be very interested.



Hi Eric,
I have no personal experience with Dux— that is why I included a link to someone who does. Brian Toss in Port Townsend has also rigged several boats with it and is well respected.

Eric Klem

Thanks Richard. I occasionally, look at the stuff the Brian Toss posts on it. He seems to think that it is the way of the future which is interesting and he clearly is quite knowledgeable. Once the number of installations is up and a lifespan is established, I will feel a lot more confident in it. It would be interesting to see what the insurance companies think.



For me the amount of rough use that the material has undergone as bottom trawl line weighs in as strongly as typical yacht use— ie sitting in a marina.

Doesn’t seem to have taken the yacht world by storm , but that could be because it isn’t shiny or found on Beneteaus rather than whether it is a good material or not. And insurance companies are the last ones I’d rely upon for materials engineering. My experience is that they are good at extortion and lawyering their way out of paying, but not much else.

Stein Varjord

I agree on your comment about well tested. On that note, it’s worth mentioning that the extreme racers like IMOCA 60, that all use fibre in their standing rigging, will sail a longer distance in a couple of months in a non stop round the world race than most normal cruising sailboats (not long distance cruisers) go in a lifetime. The waters they sail are the toughest in the world and they push the boats way beyond what any sane sailor would consider. The solutions they have are chosen because they are superior on reliability.

Racing boats and long distance cruisers are very different beasts, which is of course also a trawler bottom line, but I think they are still very convincing testing platforms. The solutions we actually use on cruisers cannot endure those same punishing tasks without failing miserably, while at the same time being more expensive and heavier.

It’s hard to know why it’s not entered the cruising market more yet, but I actually think the main reason is that a fibre rigging needs more frequent inspection and an interest for keeping an eye on how things are. I’d guess boat builders and riggers alike are a bit afraid they will get into trouble with warranty etc if they give the normal cruiser this responsibility.

Markus Gamenius

Hi Stein

I know of Rosvold and his fast TRT1200. I am not sure that Dynema is the right rigging for a long distance cruiser. But I might be old fashion.

The reason for me considering carbon mast is the weight saving. I was shocked to see the weight of ma alu mast. It was heavy! But I would like to have a rig that I could easily maintain in the pacific, far away from professional riggers.

Of the same reason I am a little bit sceptic to rod. If it fail it fails fast. No forewarning, I belive. But a lot of people I am talking to tell me that it would be stupid to pay for a carbon mast and not use rod ore some new fiber rigging. They compare it to install a V12 engine in an old VW Beetle. Am I stupid, just wasting money?

Stein Varjord

Hi Markus.
I think being a bit old fashioned is smart when planning long distance sailing, both cruising and racing. As frequently mentioned on this site, what has been tested by many sailors will offer reliability. Also old well-tested solutions are sometimes just better than newer ones.

Traditional sailboats mostly used rope for all standing rigging, lashings rather than shackles and no rigging screws. The most extreme racing boats on the planet have returned to exactly those designs because it’s lighter, stronger and most important: It’s way easier to inspect and maintain. A shackle can suddenly break without warning, maybe because of fatigue. A rope lashing will always show clear signs of wear and fatigue is not possible. It’s way better at tolerating overloads and unexpected pull angles.

I think rope in standing rigging is much safer than steel, but only if inspected and maintained regularly. Many sailors treat their boats like their cars. Do nothing until it won’t work, then call the mechanic. With that attitude, definitely choose steel. I know that’s not your attitude, so I’d definitely look at Dyneema or such.

The claim you’ve been told that you need rod to get the real benefits of carbon is just plain wrong. Rod is only smart if:
1. The boat has a quite narrow base for its shrouds, and
2. It’s a pure racing boat.
If you remove any one of those conditions, another material will do a better job. As mentioned, the fastest racing boats on the planet use no rod, but they all have carbon masts. With your boat, none of the conditions are applicable.

Rod rigging is very cool for two reasons: It’s very stiff, meaning not stretchy, and for a given load, the rod is considerably thinner than realistic alternatives. Thickness matters on a racing boat because it means less drag, especially upwind. On a long distance cruiser, thickness matters much less. You can easily get the strength and stiffness you want from several other materials. I would say that you have two good options: Dyform or rope. Both will match a carbon mast very well.

The really big problem with rod is making terminals on them. The only really good alternative is a special machine that swages the end of it so it gets bigger and can’t pass the terminal. Most riggers don’t have such a machine and rely on inferior methods.

The cool thing about Dyform is that it’s almost as stiff as rod and almost as easy to handle as normal wire. Normal wire is made from hot rolled steel. Dyform is made from a higher steel quality and then cold forged. The latter gives the hexagonal shape that makes a denser wire and the metal gets very much stiffer. I’d avoid swaging. The process tends to damage the effect of the cold forging, making the exit of the swage an even bigger weakness than with normal wire.

A carbon mast is mostly easier to fix than an alu mast. If it breaks, it can be repaired to 100% of new, which is impossible with alu. The repair takes some knowledge, but the amount of work and skill is less than for the alu mast repair I described further up in this thread. You would need normal woodworking tools, suitable carbon fibre, epoxy, adhesive tape, gloves, etc. Easy enough to bring, and much less space and weight than what you need to fix an alu mast. To find a rigger that is actually competent in repairing an alu mast, is not easy anywhere, and as mentioned, will never be a fully good mast. Go for carbon without doubts of suitability. The cost is considerable however, so if it’s worth exchanging a well functioning alu mast is a valid question.

Stein Varjord

Just want to add a bit to the above post, in spite of it already being ridiculously long. 🙂
When I say “rope rigging”, I do of course mean stuff like Dyneema, PBO, the mentioned DYnex Dux or similar tings specifically meant for standing rigging. Normal “rope” is not suitable for this type of use.

Many of the extreme racers that use some sort of fibre rigging have no spreaders. Just like traditional rig types. This makes the rig very simple and is possible on very wide boats, which almost all extreme racers are now.

Most cruising monohulls are too narrow to make this possible. One can still use Dyneema etc, but I think I’d mostly go for Dyform if I wanted to optimize the standing rigging of a normal cruising monohull. On a multihull I’d never be in doubt: Choose “rope”.

Stein Varjord

Rereading my long post above I notice that I have written another word than I meant to write. In the part about making end terminals on rod, I say the good method is to use a machine that will “swage” the end of it. What I meant to say was “forge”. I have to admit I’m not even sure that’s the right word. English is not my first language, so I make some mistakes like that.

The process I’m thinking of is reshaping the steel by brute force without heating it. This will make the steel more “compact” and increase strength ans stiffness. Both rod and Dyform have already been treated this way, so terminals need to be right.

Markus Gamenius

Hi again

I got the last edition of “Mechanical and Electrical Manual” by Nigel Calder some days ago. It is all new. I have read the second and the third edition, but I did really missed an update. Now the forth edition is here!

In the section about standing rigging Calder writes a lot about Dynex Dux. Both he and his son has used it on this boats. They liked it, but it creeps and they need to tension often. It is also prone to chafing. The main thing is 1/5 of the wire weight. Twice the strength for the same diameter. Easy to inspect, change and repair.

The big questions are if the Dynex riggs will hold up as long as wire and that creep does not be an issue under normal use.

I am tempted but not convinced

Markus Gamenius

Radar and carbon

I have my Simrad Broadband 4G-radar on the arc all the back on my boat.

Someone told me that carbon is a bigger issue for the radar than aluminium. Will the mast be a problem for the radar signals?

Matt Marsh

Carbon is generally a bit less reflective to radar than aluminum is, but not enough to make any difference to the performance of your radar. You can usually see past either kind of mast without a problem.
Incidentally, the Simrad FMCW units are sensitive enough at very close range that you can sometimes see the mast on the radar display. I even saw one once that picked up the boat’s own fishing outriggers, along with the individual pilings of the pier.

Markus Gamenius

Hi again

To day I have a trysail on a separat track. I would like to keep the trysail, but I do not like the weight of the extra track. Harken offer a system called “Trysail switch”, where the trysail uses the mainsail track. Is this any good, ore should I look for another solution?

Markus Gamenius

Thank you for all your replies

So you have a separat trysail track? Then the mast should be prepared for that track? It is not something you can add later on a carbon mast?

Stein Varjord

I support what John says, and would also say that I would feel a bit uncertain about that thingy actually being able to work in really bad weather. That lack of trust got a lot worse when I read in the description: “Cars must not be under load in curved section.” When a trysail is needed, you’re probably quite stressed because of a lee shore, big waves and way too much wind. All slides will be under load most of the time, sometimes very high load from flapping. I’d feel very uncomfortable having to rely on a little gadget like this.

Markus Gamenius

What is the real weight saving?

I have been reading “some” posts about carbon rigs. Some of them are claiming that the real weight saving is not big at all. The reason for this is that the standing rig is heavy and that all terminals connecting the standing rig to that mast are heavy to. So all in all you will at best have a weight reduction of 20, but probably not more than 10-15%. Is this correct?

Stein Varjord

I’ve also heard the objection with how many percent of what is saved. My opinion is that it’s a completely irrelevant comparison. The point is just that getting 200 kilos off the rig is great, no matter what other weights are there. The percentage is meaningless as an expression of effect. A story from our own Norway illustrates that:

Our present King Harald has been an eager racer his whole life, and good at it too. In the eighties the IOR classes were the hottest, and the IOR One Ton was definitely king on the hill. 🙂 Harald was Crown Prince at the time and launched one of the best racing campaigns in Norwegian history, aiming to win the World Championship in Kiel. This contained a huge amount of preparations and considerations, but one little detail was quite interesting:

Wind instruments was seen as an “of course!”, until the designer said “are you really really sure you need them? The sensor thingy at the mast head is 0,7 kilo and the wire up there is about the same. It’s really far up!” The answer most thought of was in the line of “yeah, but on a mast this big and with all the wires, sails and stuff up in it, that’s nothing!” But then the designer said that “OK, but to compensate for that, I have to add 76 kilos at the bottom of the keel, and I should reshape the bow and stern some to compensate the heavier pitching.” There were no wind instruments on the boat and they went on to win the championship. That single choice wasn’t the reason, but that line of thought was.

I have a suspicion that many sailors want to have the feeling that they have the best possible solutions on their own boat. When discussing other solutions, they tend to make an effort to discredit them. I can’t see any other explanation for bringing out the point about the percentage of the total rig is saved. I kinda wonder why they also don’t point out how small a percentage it is of the whole boat weight. “Just one percent maybe? And how much were you going to pay for that tiny percentage?”

In this case we have to keep the topics separated. Saving weight up there is extremely much more effective than anywhere else in the boat. If the rig as a whole, including sails, have then actually become only 10% lighter, it sounds little, but that will actually make your boat behave at least 10% better and 10% faster, etc. That’s pretty impressive!

In the nineties there was a rush of racers that changed from aluminium to carbon. I was amidst that and it was interesting to look at numbers and effects. I didn’t take notes, but I’d say as a general guideline the mast tube would lose between 50 and 60% of its weight and still be much stronger.

One boat I sailed (Formula 28 trimaran XOZ) had a 105 kilo Proctor alu rotating semi wing. We changed into a Marstrøm mast with the exact same shape (developed for our boat). It was 28 kilos and still a lot stiffer than the alu tube. Marstrøm did use higher modulus carbon on that one though. Much more expensive. It’s possible to make ridiculously light stuff that will take a serious beating, but it will cost.

If you need a new mast, there is no doubt that carbon will serve you a lot better than aluminium, but if your present mast is goood, I doubt that it’s economically smart to change it. It will definitely make your boat better though, to a degree you will have zero problem noticing.

John seems to be a man not prone to exaggerations. In his description of how Morgans Cloud became a better boat when she got a carbon pole, he says very clearly how good a choice that was. I think that verdict has a credibility rating of “sky high”! 🙂

Eric Klem

Hi Stein,

Great story. I can now use this as an excuse as to why we have no wind instruments. The only problem seems to be that my wife insists that I chronically underestimate the windspeed. I really like the tall rig on our boat in most conditions but we have a lot of weight very high up and I am convinced that this is a major contributor to the pitching we experience.



Partly inspired by this thread I switched from an in mast aluminium furling mast to a carbon mast with slab reefing and a canoe boom. It was a radical step to take, when strictly the mast didn’t need replacing, but it was at a tipping point. She needed new sails, standing rigging, in mast furling motor had failed, mast needed stripping and painting as the anodising was reacting to the stainless fittings. All the fittings had been installed before Duralac so were bonding to the aluminium. And the mast pumped more than I was comfortable with. She sailed well before – now she is just much more enjoyable and faster. She weighs 21 tons, but she accelerates rather than heels in the gusts. Points 30º/35º apparent. Yet she’s perfectly balanced with minimal weather helm. 300kg out of the rig with the changes to the mast, standing rigging (rod rigging now) and switching to 3Di North Sails. Increased the main by 200 square feet. Financially tough to deal with, but glad I went through the pain. It does seem to be one of those performance improvements that is win win all the way round. Even sailing close hauled isn’t so much of a chore, and it’s satisfying overhauling those who are motor sailing with ease. In the Caribbean winter 2015, (doing the ARC). I’ll try and do a video for those interested.
All best, David

Markus Gamenius

Hi David

You did take a bigger stepp up then I am going to. I do have a slab reefing and I am going to keep the geometry of the rigging, so I can keep my sails. The rigg is 6-7 years old and OK. It is the weight that is my biggest concern, so I am going to change to carbon.

I am getting prices from Axon, Hall and Selden. Who did you go for?

David Higgs

Went with Axon, installed by Advanced Rigging (Hamble Yacht Services) in the Hamble, UK, and very happy with the quality. Eric Duchimin does know his stuff. Think their setup is cost effective, French company, masts built in Romania. If you place an order at the right time of the year and are not a rush order you can negotiate. The one tip I’d give is sit down at a proper Autocad workstation to check out the details. Trying to do it off print or PDf’s isn’t that effective. The canoe boom I wasn’t sure of, but now I’ve got used to it – it works well. The ability to walk along the boom, sort out reefing lines, flaking the sail, sail cover etc is not to be underestimated. If you go carbon, think you also have to go hydraulic with vang and backstays. Till you have a carbon mast, you don’t realise how easy it is to adjust the sail set with these tools. It’s taken us a while to work out the correct trim for a reach, close hauled was easier and ironically faster for a while. When you do replace the sails – have a look at 3Di. They do perform well with a carbon mast.

Markus Gamenius

Hi John, Stein and all of you

Just want to say thank you! It makes life and sailing easier when people are sharing good thoughts and their experience.

I am going to order my new mast in a few weeks. I want Hall, but they cost much more than Axxon and Selden. Axxon are, like Hall, a composite only mast producer. Bur they are very french, just like my boat 😉

For me Selden is aluminium masts, carbon, I do not know.

Stein Varjord

Hi Markus
I have no knowledge of Selden carbon masts, but they are a big company that probably understand that they need to make good products to survive in the future, so I wouldn’t worry too much about competence compared to “no name” makers.

On the other hand, there is a point most customers lack a proper understanding of. Saying that an object is made of “carbon” is as precise as saying that an object is made of “metal”, but not if it’s steel, aluminium or gold.

Carbon exists in a very big variety of types. The properties and prices span extremely wide. The normal measurement is E-module (elasticity) given i MegaPascals. Normally the types are put in groups Standard, Intermediate, High or Ultrahigh Modulus fibre. I norally found it more illustrating to talk about elongation at break. Good quality E-glass (normal type) is about 5-7%, Standard modulus carbon normally is around 2%. The higher qualities can go as low as 0,02% or possibly even less. The price goes up very dramatically though.

In a mast it’s probably smart to not use too much standard modulus. Probably intermediate will give you a dramatically stiffer mast for the same weight and it will be more reliable too, but the fibre will probably cost at least twice as much. In the total cost of the mast though, the fibre cost increase isn’t too horrible. Comparing the different producers, I would ask for some pretty exact details on fibre types and layup processes. Some use single filament buildup with a machine. Do NOT go for that. Totally unsuitable for masts. They need to use mats that they wrap on or in a mould. They should also use prepregs, not wet layup. They should use a high temp cure system, at least 90 degrees Centigrade, preferably 120. They should use an autoclave, an oven with very high pressure, that compresses remaining air bubbles in the laminate, while vacuum will expand bubbles. Such bubbles are possible future weaknesses. Hall might even give you “more mast per dollar”, but to find out, you need to pester all the producers with detailed questions about the above topics and anything else you don’t feel you get quite.

I would also include at least two mast producers I know of. Marström They have more knowledge and experience with carbon than most other companies on the planet, as they started in the eighties. They have a “check” on all the mentioned points and can do things most other producers comment by “What? How did they do that?!” They built the majority of the Olympic Tornado catamarans, all the Extreme 40 cats, the Seacart 30, thousands of dinghy masts, big numbers of masts for bigger boats (their first one was for us, XOZ, which they later bought) parts for fighter planes, etc. I have been at their spots up through the years (but long time ago now) and they do serious stuff! The founder and owner, Göran Marström is an Olympic silver medallist (Tornado 1980), son in law of iconic Poul Elvstrøm (the most winning olympic sailor in history) and a smart and cool old guy.

Torbjörn Linderson used to work for Marstrøm and is now working for Southern Spars in Spain, or at least he was until a year ago or so. I can ask. They are certainly a very serious producer too, and he certainly knows all there is to know about carbon. I’ve used quite a bit of carbon myself, but compared to the serious mast guys, I have no clue. Southern Spars made the masts for extreme maxi raters like “Comanche” and “Wild Oats”, and all the Volvo Ocean Race boats. Should be good enough for credentials. 🙂

Markus Gamenius

Hi Stein

It seems that Southern Spars do not “like” small boats. They are so expensive that I think they are saying “no thank you” to customers like me.

I called Marström and did have a long talk with Per Wärn, who are working with technical sales and production. He told me that, as far he did know, most of the known carbon rigg makers did use good fiber and good production techniques. He gave me some good input on several things, like installing a lightning rod and copper strand, that is connected to the keel, installing a separat try-sail track, and so on.

I like small companies that have time to talk to the costumers! We are asking them to send us and offer to.

It would be cool to have a scandinavian mast!

Stein Varjord

Hi Markus.

Per (Pær) is a calm and nice guy and has been a core person with Marstrøm forever, so he’s worth listening to. He would never criticise his competitors. That will always backfire and leave a bad impression. He’s probably mostly right too. In the nineties there were some mast makers that had no clue and just wanted the cool carbon brand. Nowadays I think most have the knowledge and morale to make good products. Not all use an autoclave though, and not all use 120 degree C cure systems.

What I meant with my talk of different types of carbon is not to say that “Standard modulus” carbon is bad stuff. It isn’t at all! All carbon I’ve ever come across is really great stuff. I have no reason to think any mast maker would try to fool you. I think they will all be completely honest about all you want to know, if you ask.

What I did want was to give some basis for questions or specs. When you get price quotes, the fibre in the mast might be higher modulus in some expensive masts, even though they might not say that immediately, because they’d expect you wouldn’t understand the meaning of it and it might cause confusion. If you ask directly, they will of course tell you. A more expensive carbon is not better quality. It’s just stiffer, so you get different properties from your mast, like lighter.

Masts are perfect spots for using more expensive fibres, because the payoff in boat behaviour and speed from reduced weight is so great, and because they work under mostly compressive loads, which greatly favours very stiff materials. Less flex combined with less inertia means a stiffer mast gets lower local loads if all other factors are the same. Rudders and daggerboards are better in standard modulus fibre, since they need some flex to reduce peak loads.

I will send a message to Torbjörn Linderson at Southern Spars. I spoke with him less than a year ago and have sailed with him and known him for decades. It’s interesting to know from him if they are not interested in normal boats, or if they have a reason for being prohibitively expensive. He knows he can’t give me bullshit. 🙂

About installing a copper thread in the carbon mast. That might be smart, if Per says so, but it surprises me. Maybe I misunderstand? Maybe he thinks of the copper wire from the mast foot to the keel bolts? Carbon fibre is an extremely good conductor. Actually better than Gold, and naturally way better than aluminium. Maybe there is a problem with the epoxy still getting fried? If a copper wire is to be installed, one would need a seriously thick copper wire to make a difference. Right?

Markus Gamenius

Hi Stein

I have not been in contact with Southern Spars my self, but the firm I use in Norway have asked for offers on some project and they tell me that they do not do that anymore. Southern Spars are always the most expensive alternative, by far. But it would be interesting to hear why they are so expensive. It is hard to belive that they should be of much higher quality than Hall.

And you are right about Pär at Marström, he does not speak badly about his competitors. I really got the good “trusty” feeling when we did speak on the phone, so my gut feeling is that we are going for a Marström mast. But we have not seen any price, though we talked to them yesterday.

It could be me that misunderstood the details around the lightning protection Pär explained to me. But Pär had the same view about carbon masts and lightning as Hall has. He told me that they have some masts that have been hit and they survived just fine.

Markus Gamenius

I ordered my new rigg earlier this week.

We did get offers from Selden, Axxon and Hall. Wa also talked with Marstrøm, but though we wanted a complete solution we did leave them out. They seamed like a good and serviceminded company, but in the end they wanted to make the mast tube and leave the rest to others.

We did find the communication with Axxon to slow so we left them out and continued the dialog with Hall and Selden. I got the feeling that I was choosing between two very different products.

Selden being the smart choice. Lower price (wrong to call them cheep), good quality, easy to get spare parts (using their standard parts) and many service places around the globe.

Hall being the choice of hart. High price, superb quality, maybe harder to get spare parts (they claim that “nothing will brake”) and most important the guys at Hall are real experts. They know rigging and we are getting answers and feedback fast.

So in the end I followed my hart, we are going for Hall. I really got the best feeling for their solution, even the higher price.

Chuck B

Hi John, I recently heard an opinion critical of carbon fiber as a spar choice that it could be challenging to find capable work/repair in remote locations. First, how true is that in your experience? Second, how often have you in practice found yourself needing work done on your CF mast in any location, remote or not?

Thank you & best wishes,


Chuck B

Thank you John, I had my suspicions but have no experience with carbon fiber – great to hear it confirmed by your experience. The open sharing of knowledge and especially experience makes your site such a valuable resource!


Bob Miller


In 2010, we switched to a carbon fiber mast for our Mason 44. One of the best decisions we made. Like you, we ended up working with Hall Spars which was a great experience.

Don’t know if you saw the latest news, but Hall Spars has closed their US facility. Lots of talented and very good people impacted.

Hope they can regroup.

Thanks for your website.


P D Squire

I wonder if carbon would allow a narrower mast than alloy, and if the difference could reduce overall drag, and improve leading edge mainsail airflow to any significant extent?

Eric Klem

Hi PD and John,

The way I see it, you are trying to balance windage, weight, strength and stiffness. Windage is complicated as it is very geometry dependent and weight is a very straightforward calculation.

Strength all depends on how the rig is designed including its supports (what engineers call boundary conditions). My understanding is that generally if you don’t have a stay failure, the weakest mode of a mast is compression but I have never actually run any numbers on it. If you think about a disc of material and applying a given compressive load, then the only things that matter are the material’s compressive strength and the diameter (how much material there is). However, once that disc becomes tall, you also have to watch out for buckling too. Buckling is proportional to the moment of inertia, the height, the load and the boundary conditions. Inertia is by far the most important factor as it is not linearly proportional but much higher, for example with a round solid mast, it would be proportional to diameter^4 so a 19% increase in diameter yields a doubling of inertia. In truth, we deal with non round sections that are hollow so you have to actually do the math but overall size and therefore inertia are super important. They are also important because as there are bending loads on the mast such as from the mainsail luff, to solve for stress you again use your moment of inertia. You do have to watch really thin wall structures, especially when there is torsion on them and if you have to connect to them.

Stiffness is a function of the geometry and the modulus of elasticity of the material. Carbon fiber has a wide range of modulus depending on construction but you can generally assume it is at least twice and likely more than 3X. While that is a big factor, geometry can easily trump this as discussed above where moment of inertia is more important. Racers don’t want too much stiffness but most cruisers tend to do better with a high stiffness rig especially as this provides some safety margin with things like inverting.

Because carbon masts have significantly higher material strength, it is possible to decrease the geometry but the decrease is not as much as you might expect thanks to that pesky moment of inertia. Alternatively, the designer can keep the mast section the same and thin out the walls provided they account for attachments. To actually optimize it, you would need to run the real optimization problem, stuff like changing from 2 to 1 set of spreaders would make a significant difference. The real point of writing all of this is to say that not all factors are equal and some are proportional to powers as high as 4.