Go Back   Starboard Forums > Free Forum

Reply
 
Thread Tools Display Modes
Old 25th January 2008, 02:34 AM   #11
steveC
Member
 
Join Date: Aug 2006
Posts: 639
Default

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.
steveC is offline   Reply With Quote
Old 25th January 2008, 02:48 AM   #12
Floyd
Member
 
Join Date: Sep 2006
Posts: 459
Default

Responsive.
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.
Floyd is offline   Reply With Quote
Old 25th January 2008, 09:37 AM   #13
honk
Member
 
Join Date: Aug 2006
Posts: 28
Default

This should answer most questions on masts .

http://www.bluefinz.com/jm/index.php...1&Itemid=10001
honk is offline   Reply With Quote
Old 28th January 2008, 07:39 AM   #14
sailquik
Speed Demon
 
sailquik's Avatar
 
Join Date: Aug 2006
Posts: 37
Default

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.
__________________
The older I get, the better I was.
sailquik is offline   Reply With Quote
Old 29th January 2008, 02:00 AM   #15
Floyd
Member
 
Join Date: Sep 2006
Posts: 459
Smile

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)
Floyd is offline   Reply With Quote
Old 29th January 2008, 10:13 AM   #16
sailquik
Speed Demon
 
sailquik's Avatar
 
Join Date: Aug 2006
Posts: 37
Default

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.
__________________
The older I get, the better I was.
sailquik is offline   Reply With Quote
Old 29th January 2008, 04:13 PM   #17
steveC
Member
 
Join Date: Aug 2006
Posts: 639
Default

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.
steveC is offline   Reply With Quote
Old 29th January 2008, 07:27 PM   #18
Papounet
Member
 
Join Date: Oct 2006
Posts: 213
Default

Quote:
Originally Posted by Screamer View Post
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:

http://www.star-board.com/forum/showthread.php?t=3285
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 ?
Papounet is offline   Reply With Quote
Old 29th January 2008, 09:06 PM   #19
Ola_H
TEAM
 
Join Date: Aug 2006
Posts: 1,191
Default

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.
Ola_H is offline   Reply With Quote
Old 30th January 2008, 12:17 AM   #20
Unregistered
Guest
 
Posts: n/a
Default

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 .)
  Reply With Quote
Reply

Bookmarks

Tags
None

Thread Tools
Display Modes

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +7. The time now is 01:01 PM.