Quick question. Why do sail making companies often design sails with a luff of, lets say 429cms and then recommend a 400cm mast? All that does is result in you needing to use a long extension (I don't like doing this in waves with an RDM).

So, why can't they design the sail with a luff 1cm longer and take into account that it'll be rigged on a stiffer mast?

Or is it simply a way of selling more masts?!

'tis a good question.......

whats a 430 mast?

It is more to do with the stiffness of the mast.. It is not always obvious, but the wrong stiffness mast can kill a sails performance and wind range.

Some masts allow you to mix and match so with a luff length of 429 you can make a mast of 415 (400 bottom, 430 top).

I do this with my 5.2, it works well

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Brett Morris said...

It is more to do with the stiffness of the mast.. It is not always obvious, but the wrong stiffness mast can kill a sails performance and wind range.

Brett, I'm not saying "I'm going to stick a bigger mast in the sail", I'm saying "why not design the sail around a mast that will be slightly stiffer". It surely can't be that hard!

Nebbian, fair point but as I said to Brett - this was a question of - why don't the sail makers design more specifically to mast length, knowing that they usually come in 370, 400, 430 etc...

I agree with Nebbs that mix n match is good, but I do wonder that it leaves too many tuning options - with his 5.2 Ezzy he could choose 400 + lots extension, 415 (with mixed bits) or his 430 with more extension. Any would work well and only one will be spot on for his sailing style, weight, etc.
Too hard to decide what may work best.

I agree that the current situation is weird as if a 5.2 has 429 luff why not just design it for a 430/21? Maybe they are trying to maximise the number of sails you can get on one mast but it would appear not as
(1) they want to sell more masts!
(2) at the other end of the spectrum there are a lot of 4.0 - 4.2 that could be designed to fit on a 400 but they deliberately cut them on a 370. I think that kinda rules out that they are deliberately trying to get a 5.2 on a 400 to help us all out



Be really interested to hear from a sail designer....

the sail is softer by using a smaller mast - usually preferable for the average weight sailor.

your overall rig is lighter by using a smaller mast.

the swing weight is less for doing loops etc. that is why a lot of companies are making more compact sails. i would never use a sail now where a 4.7 doesnt rig on a 370 for that reason.

The most extension my Koncepts have is 120mm, 5.0 to 7.5 so some designers are working to a mast length

Maybe designers want to reach better performance in e.g. waves (where lower part of the sail has less power), by catching more wind in the upper sail area, that's why longer luff, but the sail prefers softer feel and that's why shorter mast is required...

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Crash Landing said... "why not design the sail around a mast that will be slightly stiffer". It surely can't be that hard!

Nebbian, fair point but as I said to Brett - this was a question of - why don't the sail makers design more specifically to mast length, knowing that they usually come in 370, 400, 430 etc...

I don't want to use a 400 in my 4.7, I want to use my 370.. But there are people out there whose smallest sail is a 4.7 and they don't want to buy a 370 for it...

I also want to run my 5.6 with 32cm extension on a 400 mast because masts don't come any longer than 400..

I have no problem running a 30cm extension in surf.

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sideskirt said...

Maybe designers want to reach better performance in e.g. waves (where lower part of the sail has less power), by catching more wind in the upper sail area, that's why longer luff, but the sail prefers softer feel and that's why shorter mast is required...

nah.

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Crash Landing said...
All that does is result in you needing to use a long extension (I don't like doing this in waves with an RDM).

Get a proper extension and you'll be fine. Sail designer may also try to use one mast for as many sails as well. 400 for 4 sails or so.

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barn said...

sideskirt said...

Maybe designers want to reach better performance in e.g. waves (where lower part of the sail has less power), by catching more wind in the upper sail area, that's why longer luff, but the sail prefers softer feel and that's why shorter mast is required...

nah.

Dunno actually :) I just know I have my ICE 5.3 on 400+35 and it works good anyway...

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Rob11 said...

Crash Landing said...
All that does is result in you needing to use a long extension (I don't like doing this in waves with an RDM).

Get a proper extension and you'll be fine. Sail designer may also try to use one mast for as many sails as well. 400 for 4 sails or so.

My response to this would be that I used to think that mast manufacturers advised to not use a 30cm extension - not because of the extension but because of the mast (RDM specific).

My second response is that I'm not actually asking about mast lengths, quality of extensions etc - I think Mark gets it: why make a sail with a 429cm luff when you could make it 1cm longer and designed to fit the stiffer mast? That's it. Simple.

Thanks for the responses - but I haven't got the answer yet!

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Crash Landing said...

Rob11 said...

Crash Landing said...
All that does is result in you needing to use a long extension (I don't like doing this in waves with an RDM).

Get a proper extension and you'll be fine. Sail designer may also try to use one mast for as many sails as well. 400 for 4 sails or so.

My response to this would be that I used to think that mast manufacturers advised to not use a 30cm extension - not because of the extension but because of the mast (RDM specific).

My second response is that I'm not actually asking about mast lengths, quality of extensions etc - I think Mark gets it: why make a sail with a 429cm luff when you could make it 1cm longer and designed to fit the stiffer mast? That's it. Simple.

Thanks for the responses - but I haven't got the answer yet!

easy answer, they save 75 cents having it 1cm shorter

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Rob11 said...

Crash Landing said...
All that does is result in you needing to use a long extension (I don't like doing this in waves with an RDM).

Sail designer may also try to use one mast for as many sails as well. 400 for 4 sails or so.

As I said above I don't think they do. If a 5.2 has a 428 or 429 luff and they cut it so it works on a 400 then your theory is fine - but then why have a 4.2 in the same modelthat fits on a 370? Why not cut it for a 400 so they fit as many sails on one mast as possible

Thus I don't think they are trying to fit as many sails on one mast as possible - they want to sell you more masts too.

I wonder if it might be easier design wise so that's why I'd like to hear from a sail designer.

Although to partly contradict my post in reply to Nebbs sometimes it is nice to have choice. My 5.2 has a 428 luff and recommended mast is a 400. But as a heavy guy i preferred it on the 430. When I lost weight and/or if it is going to be really gusty I like it on the 400

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choco said...
easy answer, they save 75 cents having it 1cm shorter

And you save $$$$ not having to buy a second mast...

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Crash Landing said...
why make a sail with a 429cm luff when you could make it 1cm longer and designed to fit the stiffer mast? That's it. Simple.

I see ready to be a sail designer...

Sail designers have a particular sail shape in mind, for a given model and they often design/test a specific size and mast type.

In the modern era, they translate the design onto a computer or old-school style using templates. To make different sizes, they then just resize the templates, usually by about 10% or so - which then usually suits the next mast size too.

So simply speaking, the designers often arn't thinking about mast lengths specifically... Some sail designers do consider mast lengths -> the 2008 KA Koncepts had luff lengths that were attempting to match mast lengths... they were lengthened the following year.

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Crash Landing said...



My response to this would be that I used to think that mast manufacturers advised to not use a 30cm extension - not because of the extension but because of the mast (RDM specific).

My second response is that I'm not actually asking about mast lengths, quality of extensions etc - I think Mark gets it: why make a sail with a 429cm luff when you could make it 1cm longer and designed to fit the stiffer mast? That's it. Simple.

Thanks for the responses - but I haven't got the answer yet!

I gave you an answer (well I thought so!)..

If you can't fit your 430 into a 429 luff then your doing it wrong, If you expect my bigger sails to be designed for a 430, then I will buy something else.

Feel free to run your 430 in a 429 luff.. zero extension, its sorted.. You'll have your sail with a stiffer mast..

But...

I DON'T WANT MY 5.6 DESIGNED TO BE RUN ON A 430 MAST.. it has a 432 luff, it runs with a 400.. 430 masts are crap, they are to stiff, and I don't own or want one..

does this answer your question?

I actually was a sail designer, not for windsurfing but yachts and I can tell you that a 400cm mast with a 30cm extension is not the same as a 430cm mast. It's all about twist profile and even though they look the same, the sail will set up differently on each mast. You can use these differences to tune the sail for different weight ranges but after using the wrong mast in race sails I can definitely vouch for the differences. You have to trust that the guys designing the sails actually know what they are doing and it's not just a matter of hitting the scale button on the computer...

I think everyone here is missing the point.

Like Jethrow - we know that a 400 +30cm extension is not the same as a 430. The point is that a sail with a 430 luff can be designed to work on a 400 + 30cm ext, or designed to work on a 430.

If you make a range of sails and the 4.2, 4.5 and 4.7 all fit on a 400, and the 5.2 has a luff of 429cm why not just make the 5.2 sail to suit a 430 (stiffer) mast? They already have to make other sails in that range set well a 430, like the 5.5 and 5.7 for example.
Why have all the sails in one range use between zero and 15cm ish of extension but have one size sail need 29cm of extension?

I think this is pertinent as wavesailors tradionally don't have long extensions - most go to 25cm ish - so to need a 30cm extension means buying another one.
I can understand the 6.2 kinda size needing lots of extension as some wavesailors want to have one big big sail for grovelling and you'd not want to have to buy a whole mast for that one sail. But considering just about all of us have a 400 and 430 masts, and 4-5 sails, why make the middle size need a sh!teload of extension when it is easy to have it designed so it works on a 430 with no extension?

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Crash Landing said...

Quick question. Why do sail making companies often design sails with a luff of, lets say 429cms and then recommend a 400cm mast? All that does is result in you needing to use a long extension (I don't like doing this in waves with an RDM).

So, why can't they design the sail with a luff 1cm longer and take into account that it'll be rigged on a stiffer mast?

Or is it simply a way of selling more masts?!

Asked KA designer Andrew McDougall a number of years ago if a KA 5.3 Koyote (423cm luff, recommended mast 400/IMCS19) would work ok on my NP X6 430 SDM mast and his response was 'IMCS 21 mast would compromise it'. Appears to be mostly about stiffness, though I have used the 430 X6 as well as my current Ezzy 430 RDM for three seasons in the 5.3 and am quite happy with the way the sail rigs on the stiffer IMCS 21 mast (hate using extension when I don't need to!).

Another thing to be aware of is that some sails are much more mast specific than others of the same size, even when they're made by the same manufacturer!

Example:
2011 5.3 Severne Gator 436cm luff
Recommended mast - 430/21
Compatible masts - 400/19 & 460/25

2011 5.3 Severne Blade 432cm luff
Recommended mast - 430/21
Compatible mast - 400/19

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GazMan said...

Crash Landing said...

Quick question. Why do sail making companies often design sails with a luff of, lets say 429cms and then recommend a 400cm mast? All that does is result in you needing to use a long extension (I don't like doing this in waves with an RDM).

So, why can't they design the sail with a luff 1cm longer and take into account that it'll be rigged on a stiffer mast?

Or is it simply a way of selling more masts?!

Asked KA designer Andrew McDougall a number of years ago if a KA 5.3 Koyote (423cm luff, recommended mast 400/IMCS19) would work ok on my NP X6 430 SDM mast and his response was 'IMCS 21 mast would compromise it'.

Yes of course it would. The 430 would be stiffer, plus you'd be extending the head strap to drop it down 7cm (into the stiffer part of the mast) making it even more stiff!

The point is that he could choose to make a sail with 423 luff rig on a 430 if he wanted to (dunno why he would as that is an extreme example) ..... so we want to know why some sails are designed with a 429 luff and are designed for a 400 mast when maybe 430 would make more sense so we don't all need to buy a long extension for ONE sail in our quiver...

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Jethrow said...

I actually was a sail designer, not for windsurfing but yachts and I can tell you that a 400cm mast with a 30cm extension is not the same as a 430cm mast. It's all about twist profile and even though they look the same, the sail will set up differently on each mast. You can use these differences to tune the sail for different weight ranges but after using the wrong mast in race sails I can definitely vouch for the differences. You have to trust that the guys designing the sails actually know what they are doing and it's not just a matter of hitting the scale button on the computer...

Interesting comparison tests of NP X6 masts vs next smaller X6 mast in range, extended by 30cm:

www.peterman.dk/windsurf-NP-X6-mast-study-extensions-780gb.htm

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Mark _australia said...

GazMan said...

Crash Landing said...

Quick question. Why do sail making companies often design sails with a luff of, lets say 429cms and then recommend a 400cm mast? All that does is result in you needing to use a long extension (I don't like doing this in waves with an RDM).

So, why can't they design the sail with a luff 1cm longer and take into account that it'll be rigged on a stiffer mast?

Or is it simply a way of selling more masts?!

Asked KA designer Andrew McDougall a number of years ago if a KA 5.3 Koyote (423cm luff, recommended mast 400/IMCS19) would work ok on my NP X6 430 SDM mast and his response was 'IMCS 21 mast would compromise it'.

Yes of course it would. The 430 would be stiffer, plus you'd be extending the head strap to drop it down 7cm (into the stiffer part of the mast) making it even more stiff!

Possibly 0.00000001% stiffer?

^^^ Gaz I think it would be more than that.... but all the little bits add up.

Lets not get off track - My point was that they can choose to make a sail set well on different masts but they all seem to choose to make a sail with 428 - 429 luff set on a 400 and crashlanding and I ask why?

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GazMan said...

Crash Landing said...

Quick question. Why do sail making companies often design sails with a luff of, lets say 429cms and then recommend a 400cm mast? All that does is result in you needing to use a long extension (I don't like doing this in waves with an RDM).

So, why can't they design the sail with a luff 1cm longer and take into account that it'll be rigged on a stiffer mast?

Or is it simply a way of selling more masts?!

Asked KA designer Andrew McDougall a number of years ago if a KA 5.3 Koyote (423cm luff, recommended mast 400/IMCS19) would work ok on my NP X6 430 SDM mast and his response was 'IMCS 21 mast would compromise it'.

Unfortunate that I have to resort to quoting my own post!

Response from KA designer was probably out of context. Checked email, full response was:

The 5.3 has a fixed head. We did this as putting it on IMCS 21 would compromise it.

When I eventually brought the 5.3, it came with an adjustable head!

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Mark _australia said...

^^^ Gaz I think it would be more than that.... but all the little bits add up.

Lets not get off track - My point was that they can choose to make a sail set well on different masts but they all seem to choose to make a sail with 428 - 429 luff set on a 400 and crashlanding and I ask why?

Yeah, agree totally, only takes one email to either KA, Severne or Ezzy which would save a lot of this sorta 'chit-chat'. Have done it a few times, David Ezzy particularly gave me some great info about mast compatibility. So who is gonna cut to the chase?

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Mark _australia said...

..... so we want to know why some sails are designed with a 429 luff and are designed for a 400 mast when maybe 430 would make more sense so we don't all need to buy a long extension for ONE sail in our quiver...

Maybe the 400 makes more sense so we don't all need to buy a 430 mast for ONE sail in our quiver?

Barn if your biggest sail is a 5.2 or 5.4 and all your sails are on a 400 you are a lucky fella

I have 4.0 - 6.2 for wavesailing and even if I was a bit lighter I reckon it would be the same



S like it or not, I have to have 2 masts.

If the 5.2 was cut for a 430 I'd only need one extension but as it is currently I really need 2 extensions