Hello,
The interview was done during 2010 and is now well out of date.
The only fellow I know who analysed many different brands of masts for their bend curves was a Mr. Peterman. You can still access his site here: http://www.peterman.dk/start-windsurfing-gb01.htm. You might be able to find the out-of-spec mast that Mr. Spanier was referring to.
Unifiber publish a list of mast bend curves, generally on a yearly basis: www.unifiber.net/en/masts-selector. You might be able to see your sail brand here and work out if the mast you are considering is compatible.
Hope this helps.
No. No issues for me. There are some sails with bend curves away from the mean curve.
There's a few.
The question , and what was addressed was ATYPICAL mast bend curve which means way out there, not representative.
The mast bend scale goes to about 20, which is very flex top, the scale doesn't really start at 1, a 8-10 is very stiff top, so the scale effectively goes from 10-20, each number is more important in values with change.
2010, saw Maui Sails, Naish, Gaastra as common stiff top. Soft top were several.
IMO NP aside from very long masts 490 and up, have been soft top, and having tried to make masts work on them, found that Hot Sails Maui, were the better option aside from a NP mast. of any sail NP has the strangest curve ever I encountered.
in the words of a brilliant sail maker, any mast will work in any sail, it depends on how much performance you are will to give up, using a non compatible mast, and how much range the sail had to begin with.
put another way, to adjust properly, you are killing its performance.
If using the Unifiber mast chart, look for the year published, as some ie Naish have changed curve.
At the time Barry was designing for Maui Sails. He was probably talking about the Maui Sails requirement for what he and Phil called the "stiff top" mast. Their race sails in the TR-x series prior to the TR-X, all required a stiff top-soft bottom mast. If you tried to rig those sails on a constant curve or soft top mast, they would not work correctly on the water.
At the time, nobody else that I know of was making sails for stiff-top masts. I think that's what Barry meant.
I have TR-4, TR-5, TR-6, and TR-7 sails, in sizes 10.0 to 12.0 for formula, and compatible stiff-top masts for them.
When they introduced the TR-X a few years ago, they went back to constant curve masts.
So, through the years, not counting what Maui Sails had been doing, pretty much everybody, except North, was making sails for constant curve masts. North was famous for requiring soft-top masts. Later, they also went back to constant curve.
Now, what about all these curves we talk about?
The Peterman chart below shows this information in the last three columns. Look at the third-last column, called IMCS bend characteristics. Note that the big Maui Sails SDM 550 mast shows a number of 6.4. This will depict the stiff top. The constant curve masts have values of something like 10-12. Numbers of about 14 and higher show the soft-top masts. These numbers are rough because different people made the measurements.
So, not only do you have to pay attention to the IMCS stiffness, but also the IMCS bend.
www.peterman.dk/masts-all-imcs01.htm
Select to expand quotesegler said..
At the time Barry was designing for Maui Sails. He was probably talking about the Maui Sails requirement for what he and Phil called the "stiff top" mast. Their race sails in the TR-x series prior to the TR-X, all required a stiff top-soft bottom mast. If you tried to rig those sails on a constant curve or soft top mast, they would not work correctly on the water.
At the time, nobody else that I know of was making sails for stiff-top masts. I think that's what Barry meant.
I have TR-4, TR-5, TR-6, and TR-7 sails, in sizes 10.0 to 12.0 for formula, and compatible stiff-top masts for them.
When they introduced the TR-X a few years ago, they went back to constant curve masts.
So, through the years, not counting what Maui Sails had been doing, pretty much everybody, except North, was making sails for constant curve masts. North was famous for requiring soft-top masts. Later, they also went back to constant curve.
Now, what about all these curves we talk about?
The Peterman chart below shows this information in the last three columns. Look at the third-last column, called IMCS bend characteristics. Note that the big Maui Sails SDM 550 mast shows a number of 6.4. This will depict the stiff top. The constant curve masts have values of something like 10-12. Numbers of about 14 and higher show the soft-top masts. These numbers are rough because different people made the measurements.
So, not only do you have to pay attention to the IMCS stiffness, but also the IMCS bend.
www.peterman.dk/masts-all-imcs01.htm
Select to expand quotefpw9082 said..segler said..
At the time Barry was designing for Maui Sails. He was probably talking about the Maui Sails requirement for what he and Phil called the "stiff top" mast. Their race sails in the TR-x series prior to the TR-X, all required a stiff top-soft bottom mast. If you tried to rig those sails on a constant curve or soft top mast, they would not work correctly on the water.
At the time, nobody else that I know of was making sails for stiff-top masts. I think that's what Barry meant.
I have TR-4, TR-5, TR-6, and TR-7 sails, in sizes 10.0 to 12.0 for formula, and compatible stiff-top masts for them.
When they introduced the TR-X a few years ago, they went back to constant curve masts.
So, through the years, not counting what Maui Sails had been doing, pretty much everybody, except North, was making sails for constant curve masts. North was famous for requiring soft-top masts. Later, they also went back to constant curve.
Now, what about all these curves we talk about?
The Peterman chart below shows this information in the last three columns. Look at the third-last column, called IMCS bend characteristics. Note that the big Maui Sails SDM 550 mast shows a number of 6.4. This will depict the stiff top. The constant curve masts have values of something like 10-12. Numbers of about 14 and higher show the soft-top masts. These numbers are rough because different people made the measurements.
So, not only do you have to pay attention to the IMCS stiffness, but also the IMCS bend.
www.peterman.dk/masts-all-imcs01.htm
Ezzy wonder why some use stiff top...
But one thing, top NEVER can be stiffer than bottom,it is imposible to flex more bottom than top,because top is allways smaller in diameter so when you put 30kg in the middle of mast,top will allways bend more...
So, what is your point? ... bring up allot of old information about masts but nothing seems relevant. Unless you are just trying to take a dig at Neil Pryde? Puzzling.
Select to expand quotefpw9082 said..segler said..
At the time Barry was designing for Maui Sails. He was probably talking about the Maui Sails requirement for what he and Phil called the "stiff top" mast. Their race sails in the TR-x series prior to the TR-X, all required a stiff top-soft bottom mast. If you tried to rig those sails on a constant curve or soft top mast, they would not work correctly on the water.
At the time, nobody else that I know of was making sails for stiff-top masts. I think that's what Barry meant.
I have TR-4, TR-5, TR-6, and TR-7 sails, in sizes 10.0 to 12.0 for formula, and compatible stiff-top masts for them.
When they introduced the TR-X a few years ago, they went back to constant curve masts.
So, through the years, not counting what Maui Sails had been doing, pretty much everybody, except North, was making sails for constant curve masts. North was famous for requiring soft-top masts. Later, they also went back to constant curve.
Now, what about all these curves we talk about?
The Peterman chart below shows this information in the last three columns. Look at the third-last column, called IMCS bend characteristics. Note that the big Maui Sails SDM 550 mast shows a number of 6.4. This will depict the stiff top. The constant curve masts have values of something like 10-12. Numbers of about 14 and higher show the soft-top masts. These numbers are rough because different people made the measurements.
So, not only do you have to pay attention to the IMCS stiffness, but also the IMCS bend.
www.peterman.dk/masts-all-imcs01.htm
Ezzy wonder why some use stiff top...
But one thing, top NEVER can be stiffer than bottom,it is impossible to flex more bottom than top,because top is always smaller in diameter so when you put 30kg in the middle of mast,top will always bend more...
But Dave Ezzy also recommends mixing mast halves, and when he does it's always the half from the longer stiffer mast that goes on top and the shorter softer half on the bottom. Does that not pretty much emulate a hard top mast?
Nope, just trying to explain mast bend curve information. Bend curve matters. You have to match the mast to the sail requirements.
Back in the TR-4 days, it was difficult to avoid paying exhorbitant prices for MS masts when hardly anybody else made them with the same curves. Turns out, some models of the Gaastra Ignition matched the MS bend curve at a much lower price. You can see this on the chart. (They tell me that the 2002 Ignitions were made on the same tools with the same layups and cure cycles as the MS masts.)
To answer the comment about the bottom never flexing as much as the top, you have to look up how they tool up and bend the masts to make the measurements. It is a standard procedure that everybody follows. I know Sailworks has measured all the masts they ever sold.
See this:
www.unifiber.net/en/windsurf-masts
Yes, a windsurfing mast of any type ALWAYS flexes more in the top half.
If it did not, the bend curve difference % would be 0 (Zero). Even the stiffest top masts are 6-8%, which means the top half bends 6-8% more than the bottom half when the test weight is applied to the centre.
But the simple fact is that all masts vary a bit in their curve and stiffness. All manufacturers or sailmakers will specify a tolerance for both stiffness and bend curve. (For example, 1% either way, and 0.5 IMCS stiffness number either way). The differences in practice are minimal, but a very sensitive sailor can often find different masts, in the same brand, and even in the same model, can change the feel, 'set' and performance of a sail. I find my most powerful tuning tool is trying different masts in the same sail, admittedly, usually slightly different spec masts. Even some masts that test almost identically in the IMCS test, can actually show differences when rigged in the same sail.
Select to expand quoteNotWal said..fpw9082 said..segler said..
At the time Barry was designing for Maui Sails. He was probably talking about the Maui Sails requirement for what he and Phil called the "stiff top" mast. Their race sails in the TR-x series prior to the TR-X, all required a stiff top-soft bottom mast. If you tried to rig those sails on a constant curve or soft top mast, they would not work correctly on the water.
At the time, nobody else that I know of was making sails for stiff-top masts. I think that's what Barry meant.
I have TR-4, TR-5, TR-6, and TR-7 sails, in sizes 10.0 to 12.0 for formula, and compatible stiff-top masts for them.
When they introduced the TR-X a few years ago, they went back to constant curve masts.
So, through the years, not counting what Maui Sails had been doing, pretty much everybody, except North, was making sails for constant curve masts. North was famous for requiring soft-top masts. Later, they also went back to constant curve.
Now, what about all these curves we talk about?
The Peterman chart below shows this information in the last three columns. Look at the third-last column, called IMCS bend characteristics. Note that the big Maui Sails SDM 550 mast shows a number of 6.4. This will depict the stiff top. The constant curve masts have values of something like 10-12. Numbers of about 14 and higher show the soft-top masts. These numbers are rough because different people made the measurements.
So, not only do you have to pay attention to the IMCS stiffness, but also the IMCS bend.
www.peterman.dk/masts-all-imcs01.htm
Ezzy wonder why some use stiff top...
But one thing, top NEVER can be stiffer than bottom,it is impossible to flex more bottom than top,because top is always smaller in diameter so when you put 30kg in the middle of mast,top will always bend more...
But Dave Ezzy also recommends mixing mast halves, and when he does it's always the half from the longer stiffer mast that goes on top and the shorter softer half on the bottom. Does that not pretty much emulate a hard top mast?
I think the curve on a 400 vs a 430 is near the same. So stiffer ,I think not. Thinking a longer ie 430 could flex more.
His intend I feel is a mast that requires less mast extension, with the longer section used in combo.
Emulate, no, the mast bend curve would need to change a few points, towards the stiff top.
What you have written may be correct, but I think not. I've asked David.
Interesting that HotSails like a combo ie 430/400, but recommend short mast on top.
Mast Stiffness:
Think of mast stiffness as the skeleton in an animal. The bigger the animal, the bigger and stronger the bones need to be. Every size sail will have an optimum mast stiffness.
Mast stiffness is described by MCS and IMCS.
MCS stands for Mast Check System. The MCS number tells how stiff a mast is. The MCS is obtained by supporting the mast 5.0cm in from either end and hanging a 30 KG weight in the center of the mast. The maximum deflection is measured and divided into the length of the mast. That means a 520 mast with an MCS of 27, bends 19.26 cm when 30 KG of weight is suspended from the center. So, the higher the MCS number, the stiffer the mast. The problem with the MCS number is that it is specific to masts of the same length only. A 460 with an MCS of 25 is stiffer than a 400 with an MCS of 25.
IMCS stands for Indexed MCS. It allows you to compare the stiffness of masts of different lengths. In effect, the IMCS is saying, if you stretched (or shrunk) your mast to a 460, this is what the MCS would be. That's why a 430 with an MCS of 25, has an IMCS of 21. And that's also why a 460 has an MCS of 25 and an IMCS of 25.
In case you are interested, here is how you calculate IMCS: IMCS = (mast length)^3 / (midpoint) x 460^2
What happens if your mast is too stiff or too soft:
- If a mast is too stiff, the sail will require more downhaul. This will move the draft further back and decrease the forward drive, while at the same time making the sail feel twitchy and slightly draft back.
- If the mast is too soft, the sail will require too little downhaul, making the sail less stable.
The two basic rules for Ezzy Sails are:
1) Less than 28cm of extension is acceptable, more than 28cm of extension means the mast is too soft. The problem is not the amount of extension, but rather shorter masts are usually softer than longer masts, so the length is pretty good indication of the stiffness.
2) Dropping the sail down at the head more than 8cm, means the mast is too stiff.
Mast stiffness vs. sailor's weight:
Some people think a heavier person should use a stiffer mast and a lighter person a softer mast. This is kind of true and kind of not true. The mast stiffness must be matched to the sail size, not the person's weight. So generally, a heavier person is using a bigger sail, so they will be on a longer and stiffer mast.
IMCS and the MCS only tell part of the story. They do not describe anything about the bend curve.
Bend curve:
To describe the bend curve, you divide the 1/4 point deflection into the midpoint deflection and come up with a percentage. You do the same for the 3/4 point.
Ezzy masts are: 1?4 point = 62%
3?4 point
-
-
-
-
-
= 77%
The lower part of the mast bends at 62% of the center.
The upper part of the mast bends at 77% of the center.
This falls within the "constant curve" category.
A 3?4 percentage of 80% or more would be considered "flex top" A 3?4 percentage of less than 75% would be considered "hard top"
Hard top bend in Ezzy Sails:
A "hard top" bend means the mast has more bend in the lower section and is stiffer in the upper. When using this combination in Ezzy sails, the sail will require more downhaul, which will flatten the luff and make the sail less powerful and twitchy feeling. In addition, the hard top bend will make the sail flatter in the boom area and fuller in the top, which moves the center of effort up in the sail.
Mix and Match:
The reason we mix the tops and bottoms is to get the optimum bend curve and stiffness for the sail size.
Shorter bottoms and longer tops:
We combine shorter bottoms because the bottom is the stiffest part of the mast. So, as you go smaller in sail size, you want a shorter bottom to keep the correct flex and a constant curve bend. If you use a longer bottom and a shorter top, the curve gets more "flex top". This makes the head twist more, but does not flex enough in the middle of the mast. You want flex in the middle of the mast for comfort and performance in strong wind.
Mix and Match has its limitations:
It works best when you combine only one size smaller bottom. If you combine a bottom that is two sizes shorter than the top, the bend gets more "hard top".
- Our standard length masts have a "constant curve" bend of: 1/4% = 62%
3/4% = 77%
These numbers indicate how much the mast bends 1/4 of the way up the mast and 3/4 of the way up the mast relative to the middle.
So, higher percentages mean softer and lower percentages mean stiffer.
When we combine a top with one size smaller bottom, the bend numbers change as follows:
? 1/4%: goes up by one to 63%
? 3/4% goes down by one to 76%
? This is still in the constant curve range.
If you jump down two sizes on the bottom, then the 1/4 and 3/4 go to:
? 1/4%: goes up by two to 64%
? 3/4% goes down by two to 75%
? This more "hard top" in bend.
I have an HSM Qu4d which can rig on either a 370 or 400. Every mast I've tried on the flex top side of CC has set and handled well.
Using the 370 gives a bit more reactivity and bottom end, the 400 more stability and top end.
Sometimes I use the 370 top on 400 bottom which is probably as close to HSM bend curve as I can achieve, it's a definite blend of the two.
Usually I stick with the 370 for foiling and the 400 for waves.
On the other hand Sailworks and Northwave really dislike anything flex top, even Ezzy masts aren't quite right.
So my only conclusion is that there are sails which are mast tolerant and ones which aren't.
Select to expand quoteGrantmac said..
I have an HSM Qu4d which can rig on either a 370 or 400. Every mast I've tried on the flex top side of CC has set and handled well.
Using the 370 gives a bit more reactivity and bottom end, the 400 more stability and top end.
Sometimes I use the 370 top on 400 bottom which is probably as close to HSM bend curve as I can achieve, it's a definite blend of the two.
Usually I stick with the 370 for foiling and the 400 for waves.
On the other hand Sailworks and Northwave really dislike anything flex top, even Ezzy masts aren't quite right.
So my only conclusion is that there are sails which are mast tolerant and ones which aren't.
You don't say what the 370 or 400 masts are? HSM sails are tolerant , but flex top side. Northwave, work best on a CC,like what they sell, NoLimitz ,( NW is a Hood River sail, prob not many outside the USA )
....and then there is the effect of production and rigging variations .
Some real world measurements.
1/4 1/2 3/4 % bottom % top character IMCS
11 17.2 13.2 63.9 76.7 12.7 21.85
11 16.8 13.0 65.4 77.3 11.9 22.36 mast rotated half turn
10.6 16.3 12.9 65.0 79.1 14.1 23.05 tip changed, same brand, model and size
10.6 16.3 12.7 65.0 77.9 12.8 23.05 mast rotated half turn
If you're looking for consistency, It pays to mark the spigot position and rigging orientation.
Nice for the pros to be able to test with a load of masts.
Select to expand quoteTe Hau said..
....and then there is the effect of production and rigging variations .
Some real world measurements.
1/4 1/2 3/4 % bottom % top character IMCS
11 17.2 13.2 63.9 76.7 12.7 21.85
11 16.8 13.0 65.4 77.3 11.9 22.36 mast rotated half turn
10.6 16.3 12.9 65.0 79.1 14.1 23.05 tip changed, same brand, model and size
10.6 16.3 12.7 65.0 77.9 12.8 23.05 mast rotated half turn
If you're looking for consistency, It pays to mark the spigot position and rigging orientation.
Nice for the pros to be able to test with a load of masts.
Oh dear! 
That last thing the mast makers want is someone actually testing stuff! 
I have to admit I have been down that rabbit burrow and it nearly did my head in! 
Eg. The same mast tested and measured 5 times with 5 different answers! 
Select to expand quotefpw9082 said..
So who is sail desinger that Barry talking about?
It seems obvious he was talking about Neil Pryde sails so...
Select to expand quotegorgesailor said..fpw9082 said..
So who is sail desinger that Barry talking about?
It seems obvious he was talking about Neil Pryde sails so...
So NP these years use the softest top in market...today also use flex top..
I think this is AA wish/claim, obviously he prefer soft feeling rather than hard mast like point7,Severne or some years Mauisails .
Select to expand quotefpw9082 said..gorgesailor said..fpw9082 said..
So who is sail desinger that Barry talking about?
It seems obvious he was talking about Neil Pryde sails so...
So NP these years use the softest top in market...today also use flex top..
I think this is AA wish/claim, obviously he prefer soft feeling rather than hard mast like point7,Severne or some years Mauisails .
I think The bend curves suit the design philosophy of the designer. They could design the sail to set on constant curve but are afraid to change. It is clear that it really doesn't matter, since all sail brands with different bend types having winning sailors at different times. The sails are all fast. IMHO, There is no clear advantage of one bend curve type over another despite what designers may say. One caveat - I was told by a mast manufacturer(who makes many different masts) that it is harder to build a strong Stiff Top mast - especially Race masts & that the CC/FT masts were generally stronger.
Select to expand quotesailquik said..Te Hau said..
....and then there is the effect of production and rigging variations .
Some real world measurements.
1/4 1/2 3/4 % bottom % top character IMCS
11 17.2 13.2 63.9 76.7 12.7 21.85
11 16.8 13.0 65.4 77.3 11.9 22.36 mast rotated half turn
10.6 16.3 12.9 65.0 79.1 14.1 23.05 tip changed, same brand, model and size
10.6 16.3 12.7 65.0 77.9 12.8 23.05 mast rotated half turn
If you're looking for consistency, It pays to mark the spigot position and rigging orientation.
Nice for the pros to be able to test with a load of masts.
Oh dear! That last thing the mast makers want is someone actually testing stuff!
I have to admit I have been down that rabbit burrow and it nearly did my head in!
Eg. The same mast tested and measured 5 times with 5 different answers!
Yea, but good enough to differentiate between for example CC and hard top. Need a pretty good mount for the tips to get consistency and also consistent loading method. These variations with rotation are very normal and was very noticeable in the days of Formula boards and 520, 550 masts, the sail behaved very differently with the mast rotated. I always turned mine 180 for light air setting.
Select to expand quoteTe Hau said..sailquik said..Te Hau said..
....and then there is the effect of production and rigging variations .
Some real world measurements.
1/4 1/2 3/4 % bottom % top character IMCS
11 17.2 13.2 63.9 76.7 12.7 21.85
11 16.8 13.0 65.4 77.3 11.9 22.36 mast rotated half turn
10.6 16.3 12.9 65.0 79.1 14.1 23.05 tip changed, same brand, model and size
10.6 16.3 12.7 65.0 77.9 12.8 23.05 mast rotated half turn
If you're looking for consistency, It pays to mark the spigot position and rigging orientation.
Nice for the pros to be able to test with a load of masts.
Oh dear! That last thing the mast makers want is someone actually testing stuff!
I have to admit I have been down that rabbit burrow and it nearly did my head in!
Eg. The same mast tested and measured 5 times with 5 different answers!
Yea, but good enough to differentiate between for example CC and hard top. Need a pretty good mount for the tips to get consistency and also consistent loading method. These variations with rotation are very normal and was very noticeable in the days of Formula boards and 520, 550 masts, the sail behaved very differently with the mast rotated. I always turned mine 180 for light air setting.
Quiet right. 
