View Full Version : Pros and cons with carbon masts

22nd January 2008, 04:36 PM
I wonder what the difference between 100% carbon masts and 50% carbon masts is. What are the pros and cons with 100% ?
Also, why is RDM better than SDM ? What's the advantage ?

Thank you in advance.

23rd January 2008, 01:03 AM
The two principle pluses with 100% carbon masts is that they are notably lighter and they offer far quicker/livelier reflex response. These factors maximize a sail's performance responding to the gusts, thereby offering optimum power and drive while letting the sail breathe to the best of its ability.

The distinct advantage that an RDM has over an SDM is a greater durability in a surf environment due to its greater wall thickness. However, that's not to say that an RDM offers better performance characteristics. The two distinct mast types do offer subtle differences even if they have the exact same bend curve, and that's related to the differing overall shape of the tube structures.

What's the best? That's hard to say because folks have different personal preferences. Also, much depends on the type of sails being used, to include the intent and focus of the sail's designer. Needless to say, it's best to use the mast type/brand specified by the designer.

Overall, if you can afford it, always go for the highest carbon content, regardless whether it's an RDM or SDM.

23rd January 2008, 01:32 AM
The very extensive Boards UK magazine of last year found that Skinny s improved the performance of AMOST all sails.
Totaly agree with steveC take, and myself found some sails are better with a regular dia mast, especially 460 and above and for sure 490. The Reduced mast will hurt more when you get hit in the head (wear a helmet and laugh) sink faster, rig faster thru the mast sleeve. You will have to purchase skinny mast extensions.
HotSails Maui has the HotRod skinny, and Powerex are both very highly rated. If the size was 430 and below I would get the skinny, 460 above get as much carbon as you can afford. Some sail makers design for skinny (Ezzy) some say both will work.
Cheers :)

23rd January 2008, 08:16 PM
Thanx for your answers.

I think I get it..but what about the carbon and bumbs ? Isn't 100% carbon more sensitive against hits etc ? You have to handle it more carefully right ?!?

23rd January 2008, 08:47 PM
If you're past "getting in the footstraps" stage, you'll be amazed of the performance difference between 50% and a 100% mast. Rig will be lighter, more responsive, more stable, everything. Go try one.
Yes it's more sensitive to knocks/bumps, but not drastically so. The only con is the price usually.

24th January 2008, 03:40 AM
I would certainly try any sails you intend to use on the 100% masts.(Before you buy)
Few seasons ago I upgraded (sort of) to 100% (SDM) (From C45)masts for sails 6 to 8.5.(Mixture of Tushingham and Pryde)
Found sails felt very hard and showed no improvement in speeds (GPS) . My 7 metre T Bird actually felt nicer on old C45. The 100% mast also came with a warning not to use in waves (How do you avoid them at coast ???)

Ended up selling the 2 100% masts and settling on C75`s (Tush)
Sails feel loads nicer and I have more confidence in rough water.Yep they might be a touch heavier but ???
I think on really big sails (9 plus) you might be better off with 100 and its stiffness/lightness but I reckon sails under 8metre are still designed around cheaper (sort of) masts.

Think its a different matter for RDM.430 and below I`ve gone RDM (100%) 460 and 490 have 75%`s.RDM needs 100% to get its stiffnes. All sails seem fine on this set up.

There is a lot of Hype around 100%(SDM) masts. I was very disappointed,but my biggest sail is 8.5.

24th January 2008, 08:35 AM
Hi Floyd,

I have to admit to still using my 400cm 30% carbon Windwing (Dynafiber) for my older 4.2 and 5.0 sails. Even though I bought the mast back in 1995, it has been an awesome product. I used Fiberspars for many years after retiring the old 400 around 2000 or so, but I been obliged to bring it back to life in 2005 due to mast breakages. Because it was the recommended bend curve for my sails both then and now, its viability has been without flaw, although it's a bit stiffer due the luff shape of later sails. Nevertheless, it performs incredibly well.

Also, I've had great luck with a 430cm 75% carbon Fiberspar. I've had the mast since 1999, and it's been a great product that's earned its spot in the van.

However, I'm using new 100% carbon RDMs for all newer sails all the way up to 490cm. The newer masts are totally right and more durable, and I'm good with my outlook for the future. The current performance is simply right on.

Really, I think that I'm better prepared for the future than ever before. I'm definitely stoked!

24th January 2008, 02:07 PM
As is indicated in the posts above, the number one thing with masts is that the sail you have fit them. Unfortunately, this can not be evaluated by just looking at IMCS numbers and such things. You have to try it out or maybe listen to somebody that has tried the particular combination out.

As for carbon masts being more sensitive, yes they can be, but it is in fact not so much the carbon itself being so much more sensitive. Th "problem" is that the stiffness of carbon is so high that you can use so little of it and still make the mast the right stiffness. Then, each single little fiber carries a bigger percentage of the load and hence any single litte damage will harm the mast more.

If you follow that logic, it is not hard to see that 100%rdm masts are actually not (necessarily) very sensitive since here you use a smaller diameter to lessen stiffness and hence be able to add more material. There are 90-100% carbon rdm that are stronger than ANY sdm and also less sensitive to mistreatment off water.

But just as with sdms, when if you try to make an rdm super light (ie go significantly lower than say 1.5kg for a 4m mast) you will again approach the limit were the mast will become sensitive and not very strong.

Its not only the weight though. Designing and constructing a mast is very difficult. Also seemingly very similar mast can be very different when it comes to strength. Its all about eliminating weak spots.

24th January 2008, 03:50 PM
I partly agree with Floyd (btw I also use Tush 400 75% mast and like it very much). Depending on your intended use/sail type, there maybe be significant improvement though. Especially with bigger race/freerace cammed sails, I think it's usually the case.
Matching bend curve from another manufacturer (although IMCS is nominally the same), can be a nightmare. Have you seen this, please help if you've used an Arrows:


24th January 2008, 03:58 PM
What do you mean when you say that the mast is more resonsive ?

25th January 2008, 01:34 AM
While sailing, the mast is actually quite active along with the sail responding to the gusts and lulls encountered. When the mast is deflected, the time it takes to return to a neutral or normal state is viewed in terms of frequency response. As the percentage of carbon content increases, the frequency response becomes quicker, or more responsive in nature. Conversely, as the percentage of fiberglass content is increased as part of the structure, the frequency response becomes slower, or less responsive in nature.

Of course, this is a very generalized explanation. What it really comes down to is the structural properties of the materials in concert with the design shape. Although carbon fiber can create a very stiff shape, it's quite susceptable to damage. Fiberglass, on the other hand, is less stiff in use, but it's not as susceptable to impact damage. By mating fiberglass and carbon, one can balance the inherent properties of the two materials and benefit by the compromise. I think that the 75% carbon mast is an excellent result of this type of balance or compromise. If one was considering using freeride or wave sails, the choice is a very good one. Yet, if one was considering top of the line race oriented slalom or formula sails, the 100% carbon mast is the way to go to extract the maximum performance potential possible.

25th January 2008, 01:48 AM
Reacts quicker; feels more controlled but forgiving. ,springy but damped.Pumpable.
My sails felt harsh and ungiving on 100%C SDM`s.

Just as an add on. I love feel of my NP Alpha`s on 100% RDM`s.

25th January 2008, 08:37 AM
This should answer most questions on masts .


28th January 2008, 06:39 AM
Forgive my cynicism, but I recon this stuff about frequency response is just a clever marketing pitch invented by Fiberspar and has just been absorbed into windsurfing folk law as fact.
One can certainly feel the difference a light mast makes to swing weight, especially when the rig is being bounced over chop, but I don't know that this 'frequency response' thing is anything more than feeling that lack of swing weight.

My experience is that lighter (SDM) masts usually feel better until they break but the biggest benefit is a mast that suits the sail perfectly and that is not always the lightest one.
I have some 55% masts that rig my speed sails far better than 70% and 100% masts just because they have a slightly different curve, and the weight difference becomes insignificant compared with the benefits of the better shape. SDM 100% masts are just too fragile in my experience (comes back to the thin walls to stop them being too stiff) and I wouldn't buy anything more than 70-75% for normal use.
Didn't some of the big mast manufacturers have big failure rates with 100% racing masts a year or two back?

For RDM's or skinnies it is a different matter. They must have much thicker walls to gain the correct stiffness so 100% carbon works extremely well. The only downside with that is cost but since they generally last very long and well it is worth paying for.

29th January 2008, 01:00 AM
Sail Quick
When a mast is deflected it stores energy. When deflection force is removed force will be used to return mast back to its original (and beyond if poss) position.
Two forces are resisting the motion to return.
A) The weight (mass) of sail and mast
b) The dampening effect of sail

If you reduce the weight the thing will fly back quicker.(ie the force stored is acting on less weight) since Force = Mass x Acceleration: if you half the weight you will double the acceleration (back to norm) On top of this 100% masts are not only lighter I suspect they are also stiffer;(regardles of IMCS) compare a 490 100% and 490 75%. I have hung weights from them.The 100%C is always stiffer(and lighter))) so they store even more enegy (IMO) compounding the effect.

In archery a carbon bow will match (in speed of arrow terms/length of flight) a fibreglass one with only 70% of its draw weight.Because it has a faster reflex.It is not just a sail /mast term its physics/materials concept.

I also think (not sure of this one though;cant quite remember it from uni days) that carbon fibre has very low hysterisis.(ie very low internal daming;some materials show resilience to returning (polymers in MTB suspenion) some show very little (Spring steel/carbon fibre)

29th January 2008, 09:13 AM
Yes Floyd, that pretty much sums it up I recon.

I too have done a bit of IMCS mast testing and have noticed the same as you. Quite a few time the SDM 100% masts from the same factory were actually stiffer than the lower % ones and usually over what the specified IMCS claimed. For a lighter weight sailor like myself this was a problem. The 100% masts were noticeably thinner walled (as one would expect) and seemed much more susceptible to damage from mishandling and accidents. I was particularly concerned at the effects on durability concerning wear from cam rubbing and the boom clamp on an already very thin section.

29th January 2008, 03:13 PM
I have to admit that I had a 100% carbon Gulftech 490 SDM (originally made at their Texas facility) in the late 90s that ultimately failed due to cam wear. It broke above the boom on the outside at Coyote Point, but I was able to sail back on the remaining 2/3rd left with a folded over section banging on the boom. Admittedly, I was quite lucky to be able to sail it in.

Despite my misfortune, it was an absolutely awesome mast until it died. In fact, I still have the unbroken section, to include the 7.7 sail that was damaged by the break in the mast.

Although there appears to be some dissatisfaction with high carbon content masts, I have to say that all mine have been great. Not all of them have lasted forever, but I always got at least 3-4 years before failure. Even though I'm a bit of a lightweight (70 kgs), I must admit that I have been able to leverage well off these masts.

Overall, I had to say that my experience with 100% carbon masts has been very positive. However, I have to be frank that I wouldn't invest in a 100% carbon NP mast. No reason to gamble on a historically questionable product. I think 2006 was undoubtedly a black year for NP. It's hard to recover from such a poor show.

29th January 2008, 06:27 PM
Matching bend curve from another manufacturer (although IMCS is nominally the same), can be a nightmare. Have you seen this, please help if you've used an Arrows:


The responses : http://www.peterman.dk/start-windsurfing-gb01.htm

- A little essay about masts
- A selection of results of mast measuring
- The IMCS anything better ?

29th January 2008, 08:06 PM
On carbon "flex response": Just as Sailquick, I SERIOUSLY doubt damping properties of carbon vs that of fibreglass has any noticeable effect here. Weight (mass) is what matter the most and then we have to quite common effect of the high end carbon mast simply being stiffer.

I believe that the bow example depends on the same thing, carbon bow being lighter in this case. Its not hard to imagine that there is actually more matter that has to be accelerated in the bow itself than in the arrow. So light weight will matter a lot.

If the actual damping has anything to do with it, I would bet that the type of layup, how fibers and matrix are packed, matter more than the choice of fiber (weight/stiffness effects aside). It may be the case that high end high carbon masts, also sports a "tighter" laminate.

29th January 2008, 11:17 PM
But surely if reduced mass of bow can increase its reflex speed the same will happen with a mast.
Whole point of high carbon masts is to increase reflex response.
(ie otherwise a heavier fibreglass would offer same performance but just heavier.Which it does not .)

30th January 2008, 04:54 AM
Poster #20, I'm not sure you got the distinction. One claim is that faster "reflex speed" is due to lower weight primarily. Another claim is that is is properties of the carbon fiber itself that causes the faster reflex.

Under the first clam (which is what I believe in): if you build one mast in 100% carbon fiber and another one with identical weight and stiffness using less carbon and more glass, they will have virtually the same reflex speed (and if you compare say a 55% standard diameter freeride mast with a 100% rdm wave mast you in could in practice come out with rather similar stiffness and weight data).

People that believe in the second claim will think that the 100% carbon mast will have a faster flex response in this case.

30th January 2008, 06:08 AM
Hi Ola_H,

It's my thought that comparing SDM masts with RDMs might be taking certain liberties on the scheme of things, regardless of differing carbon contents. As I'm sure that you're aware, different sail designers taylor their designs around different diameter mast types, and that doesn't even begin to address preferred bend curves.

To be fair in a broad sense, I'm inclined to think that comparing SDMs to SDMs and RDMs to RDMs makes for more sound comparative data. I still have an interest in SDMs (with different masts of carbon fiber contents), and I know without a doubt, that much thought considered right is truly subjective in nature, especially considering varying sailing interests and respective design formats.

If one starts contrasting apples with oranges, its my thought that things ultimately have to get much more complex when considering different disciplines and preferences out there.

30th January 2008, 12:33 PM
The SDM/RDM thing was just to indicate that it _could_ be possible to build masts with different materials but similar weigh properties, not meant to be a real basis for comparison.

In practice it is of course impossible o build on glass mast and one carbon mast and have both weight, stiffness and geometry identical (since carbon is stiffer in the same weight).

The argument from the start is that it is the is is the weight difference that is responsible for the reflex difference, not the the material choice per se. In theory this is a clear distinction, but in practice the two effects get kind of hard to isolate (and keeping everything except geometry the same is probably the closest you gonna get towards isolating material choice).

30th January 2008, 04:10 PM
Hope you havent got it ?? (Hysterisis)
Anyway ; it was me that mentioned it and I agree I dont think it has any real effects in this case.Inernal damping differences between C and glass will be tiny. ( I would imagine)

I cant see how it woul be possible to build two masts of equal stiffness; equal weight ; one of 100%C and other 50% C (yet same reflex ???)

Lighter masts of equal stiffnes must have quicker reflex.
The equal weight lower carbon would be softer.

I just think for sails under around 8 metre 100% masts are too stiff (Unless they are RDM)