Is the Unifiber chart correct?

The 2011 chart shows Severne as hard top. The 2015 chart shows Severne as on the cusp between hard top and constant curve.

Can anyone quote an accurate percentage bend?

yes it is correct

I've got measurements on Severne, Gaastra and Naish masts (RDM's only) old and new. The measurements I've done give the older naish and severne (redlines ) masts a 8-9% curve, the severne HD's from 2010/11 a 9-10% and the current ones 2014+ at 11-12%

why are sail companies doing this to us ??
one finally decides to "commit" to a sail combo that is out of the norm - hard top or flex
and then they go towards what others were saying all along ?
that may bring new fans, but upset previous ones

joewindsurfer.blogspot.com/2016/03/have-mastssails-all-gone-cc.html

Can't please everyone all the time

yes I know. I had a whole set of gaastra masts 2x 400 2x 430 1x370, which were optimal for my 2010 blades and still work ok with my 2013 & 2015 blades, however I'm slowly swapping them over (at a cost). Both Naish and Severne have changed, more or less at the same time and the curves are very very similar.

It drives me mad and stresses me out when I come to changing my sail quiver (due to age); as will the feel still be similar? if not what brand will? if its another brand will I have to change all my masts over as well?

As a result I don't really by new current season anymore, but new last seasons. Saves money plus you know (from reviews etc) what you are in for

I just got a 2014 Naish Bullit and the charts had said it was combatable with the severne hardtop masts so I was using my severne mast which wasn't that great.. Finally swapped to a Sailworks CC ( luckily I had an old one ) and that helped..means I have to carry an extra mast around though..

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Lindz1510 said..
Can't please everyone all the time

actually what is upsetting is - some companies spoke against the clew cutout, CC masts, etc
those same companies now have cutouts and are going to CC
why bother being a loyal customer when it seems all just P.R.
i was hard top and tried some flex top, but now feel the wisest choice was always to go with the flow i.e. CC
that is why i now recommend going CC, SDM over 460 and even going away from monofilm
so, which CC company does one recommend - people seem to love their Ezzys and they seem bomb-proof
never tried one though ...
sorry to vent

^^^ I've always been glad I started out on constant curve gear. I am dismayed the way some companies are fooling around with their curves now, destroying backwards compatibility in their own brand.

I'm a recreational sailor so I'm happily in the Ezzy family. The sails go forever. This one has done at least 5000km and still sets beautifully:

I agree with KJ, it's a worry when purchasing new model sails, particularly whole quivers. The logical thing would be for manufactures to publish and/or print the bend curve figures on their sails and masts. This (plus the existing length/luff and IMCS specs) will give a complete picture of a given product's characteristic and buyers can make a better informed choice about keeping their existing masts, buying the recommended manufacturers mast, or buying a cheaper alternative. From my understanding, heavier sailors of CC sails normally like to run a harder top mast in their sails, so this missing spec would allow them to tune their rig "off the spec" so to speak (ie: buying a different brand mast for a given sail to perform the tuning).

What would really be good (this may be an engineering impossibility or not practical due to the harsh environments masts undergo) is to be able to fine tune a mast towards hard or flex top by maybe 2-3 +/- units. This will give experienced users greater tuning ability, but also allow for variations in bend curve across the years.

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jn1 said..
I agree with KJ, it's a worry when purchasing new model sails, particularly whole quivers. The logical thing would be for manufactures to publish and/or print the bend curve figures on their sails and masts. This (plus the existing length/luff and IMCS specs) will give a complete picture of a given product's characteristic and buyers can make a better informed choice about keeping their existing masts, buying the recommended manufacturers mast, or buying a cheaper alternative. From my understanding, heavier sailors of CC sails normally like to run a harder top mast in their sails, so this missing spec would allow them to tune their rig "off the spec" so to speak (ie: buying a different brand mast for a given sail to perform the tuning).

What would really be good (this may be an engineering impossibility or not practical due to the harsh environments masts undergo) is to be able to fine tune a mast towards hard or flex top by maybe 2-3 +/- units. This will give experienced users greater tuning ability, but also allow for variations in bend curve across the years.

Tushingham have Bend Curve % on their masts, just need all brands to do it & print it on the sails so there's no guesswork.
Surely that's not hard.

So... if I have this right, my older Severne masts will be slightly more stiff top on my newer Severne sails. I have a couple of SSR 100% (2006-8?) masts with 2013-14 sails. If I have it right in my head (highly unlikely) this would mean a tighter upper leach and flatter through the mid/low section. What I see in practice is the opposite. If anything the upper leech is looser by a tad than I would expect. Mine are SDMs... I have heard that the RDMs are more a different curve but have no experience with them.

However...

The whole mast bend curve is one of the stupidest things in the industry. Clearly there is no significant design advantage as proved by the slalom PWA results. So why not just agree on constant curve and stop picking customers around! It's a bit like a stamp duty tax, all it does is stop people from moving house more often. Selfish manufacturers trying to keep a big slice of a small pie instead of trying to grow the size of the pie.

/rant_over

My data is only RDM masts so I can't really comment on the SDM's.

The other thing to bear in mind is that not all masts are the same (from the same manufacturer). This is what got me into measuring them, as I brought two mast (the recommended ones for the sails) a 400 and 430 and couldn't work out why the sails on the 400 set like crap. The bend curve on the 400 was 13% and the 430 was 9% (9% was the correct curve).

What also complicates it, is that two masts may the same % curve figure, however have a difference in where the curve occurs.

@VIC - How do you measure the mast curve diy style at home?

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southsea said..
@VIC - How do you measure the mast curve diy style at home?

lmgtfy.com/?q=windsurfing+measure+mast+bend+curve

Thanks Mat, I was asking how do it at home and get the calibration percentages - I understand the principle and industry method - ping me over a link for that ;-)

Severne have not changed their mast curves at all over the last 6 years or so.

The variance people are finding is often due to how they measure the curve. Severne measures their masts over seven points, while many "testers" measure at three. Any slight variance to the measuring mechanism over 1 mm or so will give you a different result. It is often the case that website Lists are stating curves that are inconsistent with the manufacturer own design and testing. This can only be due to the method of measurement as no brands are going to work with one curve in design and sell differently as it would cause major grief.

Some brands do change their curves when they have a new method of design they wish to explore or by a new designer joining the company. Usually they will inform their customers as many brands have done so in the past.

We at Severne maintain that the best mast for your sail is the one it was designed on. Your rig will feel different if you use different carbon percentage masts, different weight masts or older more "worn in" masts, last loose their original form over time. But the appropriate curve shape for the design of your sail will rig the right way.

Manufacturers often have tolerances in the construction process that can vary for mast to mast by a SMALL degree. This is true of many products.

Ultimately, there is no right way to design something so if ideas are different amongst designers, you may find it hard to get a consensus on which curve is the right curve.

For best results Severne sails are best on Severne masts that each model has been recommended with for use with in our Catalogue and online.

Enjoy your sailing.

3 or 7? You can measure at 100 points if you want but the deflection at 25% 50% and 75% of length will always be the same.

I think the chart (the ones measured by others) may be wrong ........ possibly due to error in where they took the measurement, you only need a little lateral movement to make a difference in the deflection amount. But 7 points will not change whether it is hard top or CC surely..?

I like sails on the manufacturers mast too, dunno why people have to complicate things. Just use the Severne mast !!!
But it would be nice if manufacturers used a set bend curve, we would not like fins with 9mm, 10mm and 11mm thick bases at random and they may or may not fit. We got a standard years ago.

We want and love the newer and better sails. The improvement in performance sometimes comes at the expense of a fixed mast structure?

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SeverneSails said..

You're one of the few companies that reply on this forum and you have my respect for doing this. Not many co's would take that risk. What I write below isn't intended to upstage/embarrass. You are the bleeding edge of innovation in the industry, that is pretty cool. If users want your products to be the most optimised, then they have to have to use matching equipment “year for-year”. I accept this. If users use an older model mast (like me) in the latest sail, they deviate away from optimality. I accept that as well. I just want less confusion. I come from a technical background, and in this sport their is a lack of technical info (not just Severne).

Regarding the recommended masts catalogue/online. is the excerpt below what you are referring to ?




I own a 2009 or 2010 (I'm not sure what year, as their is no indication on the mast) 430 RDM Blueline. In your above reply, you said that you have changed your bend curves, so what does this mean ?. If I wanted the latest Gator, I would have to buy a new mast for it. Is this correct ?. I can't see Blueline model on your lists or on your site.

Severne out source the manufacturing of their masts to an external mast maker. Therefore, you would have to provide this mast manufacturer a formal specification ?. Why not make this data publicly available ?. The intent of this is for existing Severne owners to determine how compatible their masts are with the latest model sails (or match earlier model sail). I'm not sure if you are aware of this, but many sailors at my sailing spots don't have much spending capacity for this sport. They can afford if they are lucky $500-800 at new gear every couple of years. For Severne gear, that's basically a clearance sale model or a few 2nd hand sails. Their masts are rarely Severne. There are a couple of cashed up sailors in this state that roll up with a trailer full of the latest and greatest Severne gear year after year. They have done exactly what you have told them to do. I am in between these two economic groups. I can afford 3 sails, or 1 sail + 1 mast every couple of years. So for me, it's really important to know compatibility as I would like to buy as many sails as I can and not have to replace a mast if it doesn't need replacing. If data was published on your site (a graph, or some sort of figure of merit like the 3-point bend curve method) that would allow me to determine how compatible masts are to the latest models and justify replacing a mast based on hard data. $1195 RRP is a lot of money !. This data would also give me the flexibly to source the most compatible clearance sale model/2nd hand model to achieve not replacing my mast in times when I can't financially do this. Another valuable thing would be to start printing the year date on your masts and sails for easier matching (I have noticed you have done this on your 2015 Blade Pro sail bag, so that is a good start).

I hope you understand my argument and don't take this as an attack. I've been a Severne user pretty much since I started Windsurfing. It's just that the current method of ringing up a dealer and asking them for their opinion isn't reliable enough.

Its pretty simple logic. For a typical slalom sail, the cost of replacing all rig components is as follows:

Sail: $1200
C100 Mast: $800
Carbon Boom: $1000

This is prohibitive. Booms and masts last much longer than sails. I basically keep them until they break. I have one Loft mast that has had 3 owners, including myself and is 8 years old. Sails on the other hand stretch, wear out and get damaged over time affecting their performance. So I replace more regularly - every 2 or 3 seasons depending on use. I don't want to be limited to one sail manufacturer, so I've chosen to source my sails from manufacturers who design to fit constant curve masts. I've successfully interchanged masts and sails from Loft, KA, North, Naish and Gun.

If any of these manufacturers change their design philosophy, then they are taken of the potential buying list. For this reason, I've never considered purchasing NP or Severne

I think those last two posts have some very worthwhile comments in them.


I sailed a Severne sail for the first time today. Looked great, felt great, just the sort of thing that I would purchase at some future stage. I too am restricted financially and the masts I already own are something else.
Would I save up all my peanuts and go the sail/mast combo in one purchase? Yeah, I might. Would I much prefer to have direct and clear information about bend curves and such so that I can make an informed decision about possibly splitting the purchase into two events to ease the pain? Definitely.

How I solved this recently... The very nice people at windsurfnsnow let me loose on the shop floor with the recommended mast for a sail and also an alternative. I was welcomed to rig and de-rig several times with each mast and was thus able to see for myself just how much difference it actually made. I bought the alternative mast and am very happy with the result.
My other sail was custom built for me and I asked the sailmaker to make it to fit the mast I already owned, which he happily did.

I think it's all well and good to say 'use the recommended mast', clearly that would be best and negate any uncertainty. The reality though, as mentioned above, is that a lot of the time alternative masts are used, many of them working very well in place.
Providing decipherable, clear and direct information I think would allow people to purchase with more confidence and less negative feeling of having to swear faithful to a single manufacturer. It wouldn't surprise me if the net result of removing the confusion would be more sales all around and a general growing of the sport which would be good for all.