30 Jun 2007 20:34:13
(PeteCresswell)
Comparing Sails

I think I've learned something new (to me, that is...): the
percent of carbon in a mast really does make a noticeable
difference.

I know a lot of people *say* that... Geeze, I've heard someone
claiming expertise say that we should replace hourglass joints
every year.

But my personal little epiphany is that carbon content is not
just industry marketing hype - it's for real.


To wit:

Last week, someone let me A/B a no-cam 6.5 against my Infinity
6.6 without cams. They warned me in advance that the sail was
old and the mast was only 55% carbon and the sail would feel
"dead".

I went out not really expecting to notice anything except the
purported additional low end of the test sail

Wrong! Beeeeeg dif.... the thing really did feel dead...
hopelessly, terminally dead.

A few days ago, I spotted somebody with the same board that I
have rigging a brand new no-cam 8.0 - same type I demoed
beforehand.

I put up my 7.5 Infinity without cams and started talking to the
guy. We wound up spending the better part of an hour swapping
boards/sails back-and-forth.

When he had my 7.5 up and I was on his 8.0, he was consistently
out-planing me. Ok, he was 20 lbs lighter.... but when I was
on my 7.5 and he was on the 8.0 we were planing at about the same
time - he had a little edge, but very little - absolutely nothing
anybody would buy a new sail over.

His mast was 55% carbon and mine was 75% (PowerEx Freeride/Wave
RDM)... and his new sail felt "dead" too - just like the
same-brand/model 6.5 that I demo'd earlier.

OTOH, he couldn't believe how "lively" my rig was. "Geeze!...
100% power that you can use... I'm spoiled now....".

My board was "wood" construction and his was Dram. We probably
should have swapped rigs but not boards.

But that can't be all - or even most - of it.

What I've taken away from these two little experiences:
---------------------------------------------------------------
1) I cannot compare two sails unless they're both rigged on
the same kind of mast I intend to use them on.
Anything else is futile.

2) 20% more carbon in a mast *really* makes a difference.

3) Any masts I buy in the future will contain as high a
percent of carbon as is consistent with being an RDM and
not being unduly fragile.
---------------------------------------------------------------

Anybody care to take a few shots at this little straw man?
--
PeteCresswell


30 Jun 2007 20:46:38
wind.sh@dow
Re: Comparing Sails

Nice post, Pete. I was using 50% carbon years ago, switched to 75% and
have been thrilled. I might have gone for 100%, but saw one too many
new or almost new masts snap on the beach.

On Sat, 30 Jun 2007 20:34:13 -0400, "(PeteCresswell)" <x@y.Invalid >
wrote:

>I think I've learned something new (to me, that is...): the
>percent of carbon in a mast really does make a noticeable
>difference.
>
>I know a lot of people *say* that... Geeze, I've heard someone
>claiming expertise say that we should replace hourglass joints
>every year.
>
>But my personal little epiphany is that carbon content is not
>just industry marketing hype - it's for real.
>
>
>To wit:
>
>Last week, someone let me A/B a no-cam 6.5 against my Infinity
>6.6 without cams. They warned me in advance that the sail was
>old and the mast was only 55% carbon and the sail would feel
>"dead".
>
>I went out not really expecting to notice anything except the
>purported additional low end of the test sail
>
>Wrong! Beeeeeg dif.... the thing really did feel dead...
>hopelessly, terminally dead.
>
>A few days ago, I spotted somebody with the same board that I
>have rigging a brand new no-cam 8.0 - same type I demoed
>beforehand.
>
>I put up my 7.5 Infinity without cams and started talking to the
>guy. We wound up spending the better part of an hour swapping
>boards/sails back-and-forth.
>
>When he had my 7.5 up and I was on his 8.0, he was consistently
>out-planing me. Ok, he was 20 lbs lighter.... but when I was
>on my 7.5 and he was on the 8.0 we were planing at about the same
>time - he had a little edge, but very little - absolutely nothing
>anybody would buy a new sail over.
>
>His mast was 55% carbon and mine was 75% (PowerEx Freeride/Wave
>RDM)... and his new sail felt "dead" too - just like the
>same-brand/model 6.5 that I demo'd earlier.
>
>OTOH, he couldn't believe how "lively" my rig was. "Geeze!...
>100% power that you can use... I'm spoiled now....".
>
>My board was "wood" construction and his was Dram. We probably
>should have swapped rigs but not boards.
>
>But that can't be all - or even most - of it.
>
>What I've taken away from these two little experiences:
>---------------------------------------------------------------
>1) I cannot compare two sails unless they're both rigged on
> the same kind of mast I intend to use them on.
> Anything else is futile.
>
>2) 20% more carbon in a mast *really* makes a difference.
>
>3) Any masts I buy in the future will contain as high a
> percent of carbon as is consistent with being an RDM and
> not being unduly fragile.
>---------------------------------------------------------------
>
>Anybody care to take a few shots at this little straw man?



01 Jul 2007 12:10:51
Mamba
Re: Comparing Sails

"(PeteCresswell)" <x@y.Invalid > wrote in message
news:96sd831nr0r1mut36pcutcu5ut0q2pqffm@4ax.com...
>I think I've learned something new (to me, that is...): the
> percent of carbon in a mast really does make a noticeable
> difference.
>
> I know a lot of people *say* that... Geeze, I've heard someone
> claiming expertise say that we should replace hourglass joints
> every year.
>
> But my personal little epiphany is that carbon content is not
> just industry marketing hype - it's for real.
>
>
> To wit:
>
> Last week, someone let me A/B a no-cam 6.5 against my Infinity
> 6.6 without cams. They warned me in advance that the sail was
> old and the mast was only 55% carbon and the sail would feel
> "dead".
>
> I went out not really expecting to notice anything except the
> purported additional low end of the test sail
>
> Wrong! Beeeeeg dif.... the thing really did feel dead...
> hopelessly, terminally dead.
>
> A few days ago, I spotted somebody with the same board that I
> have rigging a brand new no-cam 8.0 - same type I demoed
> beforehand.
>
> I put up my 7.5 Infinity without cams and started talking to the
> guy. We wound up spending the better part of an hour swapping
> boards/sails back-and-forth.
>
> When he had my 7.5 up and I was on his 8.0, he was consistently
> out-planing me. Ok, he was 20 lbs lighter.... but when I was
> on my 7.5 and he was on the 8.0 we were planing at about the same
> time - he had a little edge, but very little - absolutely nothing
> anybody would buy a new sail over.
>
> His mast was 55% carbon and mine was 75% (PowerEx Freeride/Wave
> RDM)... and his new sail felt "dead" too - just like the
> same-brand/model 6.5 that I demo'd earlier.
>
> OTOH, he couldn't believe how "lively" my rig was. "Geeze!...
> 100% power that you can use... I'm spoiled now....".
>
> My board was "wood" construction and his was Dram. We probably
> should have swapped rigs but not boards.
>
> But that can't be all - or even most - of it.
>
> What I've taken away from these two little experiences:
> ---------------------------------------------------------------
> 1) I cannot compare two sails unless they're both rigged on
> the same kind of mast I intend to use them on.
> Anything else is futile.
>
> 2) 20% more carbon in a mast *really* makes a difference.
>
> 3) Any masts I buy in the future will contain as high a
> percent of carbon as is consistent with being an RDM and
> not being unduly fragile.
> ---------------------------------------------------------------
>
> Anybody care to take a few shots at this little straw man?
> --
> PeteCresswell

RDMs on any modern sail affect performance considerably as well. They allow
for more power and tunability, which can really be noticable in marginal
winds.




01 Jul 2007 19:28:46
a_macke@yahoo.com
Re: Comparing Sails

On Jul 1, 12:10 pm, "Mamba" <g...@nottoday.net > wrote:

> RDMs on any modern sail affect performance considerably as well. They allow
> for more power and tunability, which can really be noticable in marginal
> winds.

RDM's and SDM's tend to bend very differently - together with the
diameter differences (which have a huge impact on the luff curve),
that can really distort sail shape if you're using an RDM in a sail
meant for an SDM or vice versa. Some sails, however, will allow you to
use RDM's or SDM's, with the slight differences in tuning something to
be used to adapt a rig to your exact tastes. Sailworks Retros and
Huckers are an example - that's partially made possible by the fact
that the Sailworks RDM is spec'd for a bend curve that, when taken
together with the different diameter's effect on luff curve, is close
to how the SDM would set that sail.

All that said - I think sometimes the 'craze' for RDM's is just that.
When I see 7.5+ freeride sails rigged on 490 RDM, I wonder if it's
worth it. Those rigs tend to look pretty soft to me - when a bigger
sailor pumps them, you often see them almost folding in half. I know
some people like a really 'soft' feeling rig, and for lighter sailors
that might make a lot of sense. But by the time you're using a 7.5+, a
little stiffness in the mast can help create stability in the rig,
which can translate into range. Getting that kind of stability and
range out of a soft noodly rig will require tradeoffs elsewhere. I
have yet to see a big freeride sail on an RDM that made me want to use
it - sure, they seem to work just fine, but why bother with just fine
if, for the same money, you can get really great?

-Andreas

http://g-42.blogspot.com



01 Jul 2007 20:41:59
Michael
Re: Comparing Sails

I recently switched from a SDM to an RDM 460 for my 7.0
(switched=broke my old 460). The 7.0 is a Naish Amp, and I weigh
165. While the sail seems to balance a little differently (I don't
know exactly what I mean by that...it feels different) it performs
just as well. Performance= early planing, top end speed, depowers
during jibes and duck jibes.

On Jul 1, 3:28 pm, "a_ma...@yahoo.com" <a_ma...@yahoo.com > wrote:
> On Jul 1, 12:10 pm, "Mamba" <g...@nottoday.net> wrote:
>
> > RDMs on any modern sail affect performance considerably as well. They allow
> > for more power and tunability, which can really be noticable in marginal
> > winds.
>
> RDM's and SDM's tend to bend very differently - together with the
> diameter differences (which have a huge impact on the luff curve),
> that can really distort sail shape if you're using an RDM in a sail
> meant for an SDM or vice versa. Some sails, however, will allow you to
> use RDM's or SDM's, with the slight differences in tuning something to
> be used to adapt a rig to your exact tastes. Sailworks Retros and
> Huckers are an example - that's partially made possible by the fact
> that the Sailworks RDM is spec'd for a bend curve that, when taken
> together with the different diameter's effect on luff curve, is close
> to how the SDM would set that sail.
>
> All that said - I think sometimes the 'craze' for RDM's is just that.
> When I see 7.5+ freeride sails rigged on 490 RDM, I wonder if it's
> worth it. Those rigs tend to look pretty soft to me - when a bigger
> sailor pumps them, you often see them almost folding in half. I know
> some people like a really 'soft' feeling rig, and for lighter sailors
> that might make a lot of sense. But by the time you're using a 7.5+, a
> little stiffness in the mast can help create stability in the rig,
> which can translate into range. Getting that kind of stability and
> range out of a soft noodly rig will require tradeoffs elsewhere. I
> have yet to see a big freeride sail on an RDM that made me want to use
> it - sure, they seem to work just fine, but why bother with just fine
> if, for the same money, you can get really great?
>
> -Andreas
>
> http://g-42.blogspot.com




01 Jul 2007 17:23:39
(PeteCresswell)
Re: Comparing Sails

Per "wind.sh@dow" <just lurking >:
> I might have gone for 100%, but saw one too many
>new or almost new masts snap on the beach.

Anybody know how far they can take carbon percent in an RDM and
still keep it bullet proof?
--
PeteCresswell


01 Jul 2007 16:36:12
wind.sh@dow
Re: Comparing Sails

On Sun, 01 Jul 2007 17:23:39 -0400, "(PeteCresswell)" <x@y.Invalid >
wrote:

>Per "wind.sh@dow" <just lurking>:
>> I might have gone for 100%, but saw one too many
>>new or almost new masts snap on the beach.
>
>Anybody know how far they can take carbon percent in an RDM and
>still keep it bullet proof?

No idea, but Powerex is well known for warranty support and they sell
100% RDM. I'll take a wild guess and say that if I told them I broke
a 550 RDM in the surf, they would think I was a moron for having that
mast in the surf. They could tell you what's a good idea and what's
not.


01 Jul 2007 18:32:13
Glenn Woodell
Re: Comparing Sails

On Sun, 01 Jul 2007 16:36:12 -0500, "wind.sh@dow" <just lurking >
wrote:

>On Sun, 01 Jul 2007 17:23:39 -0400, "(PeteCresswell)" <x@y.Invalid>
>wrote:
>
>>Per "wind.sh@dow" <just lurking>:
>>> I might have gone for 100%, but saw one too many
>>>new or almost new masts snap on the beach.
>>
>>Anybody know how far they can take carbon percent in an RDM and
>>still keep it bullet proof?
>
>No idea, but Powerex is well known for warranty support and they sell
>100% RDM. I'll take a wild guess and say that if I told them I broke
>a 550 RDM in the surf, they would think I was a moron for having that
>mast in the surf. They could tell you what's a good idea and what's
>not.

Both Powerrex and NoLimitz have made masts for Ezzy in recent years.
Both were 91% RDM and both were guaranteed in breaking waves but none
went as long as 550.

They do break but I don't think I'll be breaking them anytime soon.

Glenn


01 Jul 2007 15:56:03
The Dog
Re: Comparing Sails

On Jul 1, 4:23 pm, "(PeteCresswell)" <x...@y.Invalid > wrote:
> Per "wind.sh@dow" <just lurking>:
>
> > I might have gone for 100%, but saw one too many
> >new or almost new masts snap on the beach.
>
> Anybody know how far they can take carbon percent in an RDM and
> still keep it bullet proof?
> --
> PeteCresswell

Wall thickness...

Dog



01 Jul 2007 19:44:45
Florian Feuser
Re: Comparing Sails

> Anybody know how far they can take carbon percent in an RDM and
> still keep it bullet proof?

Carbon percentage usually tops out at 100%, unlike personal effort in
figure skating and NASCAR racing, which for some reason goes to 110%.



--
florian - NY22

http://www.kasail.com/windsurfing/team/florianfeuser.html


01 Jul 2007 20:19:27
wind.sh@dow
Re: Comparing Sails

On Sun, 01 Jul 2007 18:32:13 -0400, Glenn Woodell <letsrig@cox.net >
wrote:

>Both Powerrex and NoLimitz have made masts for Ezzy in recent years.
>Both were 91% RDM and both were guaranteed in breaking waves but none
>went as long as 550.
>
>They do break but I don't think I'll be breaking them anytime soon.
>
>Glenn

Ezzy may have this warranty, but now I see this on
http://www.powerexmasts.com/aboutPowerex/warranty/:

"Only Z-Wave and Prepreg Wave masts will be replaced if broken in surf
conditions. "


01 Jul 2007 21:23:12
Glenn Woodell
Re: Comparing Sails

On Sun, 01 Jul 2007 19:44:45 -0400, Florian Feuser
<florian@SPAMTRAPfunnygarbage.com > wrote:

>> Anybody know how far they can take carbon percent in an RDM and
>> still keep it bullet proof?
>
>Carbon percentage usually tops out at 100%, unlike personal effort in
>figure skating and NASCAR racing, which for some reason goes to 110%.

And don't forget the Space Shuttle that can go to something like 104%
which is "full throttle".

I', employed by NASA and even did some work with the main engines and
never understood that one.

Glenn




01 Jul 2007 20:30:50
wind.sh@dow
Re: Comparing Sails

On Sun, 01 Jul 2007 19:44:45 -0400, Florian Feuser
<florian@SPAMTRAPfunnygarbage.com > wrote:

>Carbon percentage usually tops out at 100%, unlike personal effort in
>figure skating and NASCAR racing, which for some reason goes to 110%.

This reminds me of Spinal Tap. "Most amps's volume only goes to 10,
but we had our amps modified to go to 11."

110% carbon sounds like an inside joke.


02 Jul 2007 10:03:01
Dan Weiss
Re: Comparing Sails

On Jul 1, 7:44 pm, Florian Feuser <flor...@SPAMTRAPfunnygarbage.com >
wrote:
> > Anybody know how far they can take carbon percent in an RDM and
> > still keep it bullet proof?
>
> Carbon percentage usually tops out at 100%, unlike personal effort in
> figure skating and NASCAR racing, which for some reason goes to 110%.
>
> --
> florian - NY22
>
> http://www.kasail.com/windsurfing/team/florianfeuser.html

Coach: "You people don't know how to win. It takes 110% effort 100%
of the time. I want you to redouble your efforts from this point
forward."

Wise-ass student athlete: "But if we redouble our efforts, isn't that
400% 100% of the time? Or is it OK if we give 200% twice as often?

Coach: "OK Einstein, apparently you're so smart you don't need to go
to college. Johnson, get your butt over here and take Johnson's
position. Johnson, you just calculated your way to the bench."

-Dan



02 Jul 2007 13:27:26
sergio kapul
Re: Comparing Sails

I've started switching to RDM masts (all 90-100% carbon) 370-460 about 5
years ago, last one is 460 for a Naish race sail bougth couple of months
ago, for a light weight person, i think it's a better fit, my weight is
under 140lb, sails just feel more responsive, etc... no down side (my SDM
were all 100% carbon), someone would have to pay me serious money to switch
back to SDM for any sails under 8m2, I do have 520 SDM
for my jumbo race sail...




02 Jul 2007 13:43:43
Florian Feuser
Re: Comparing Sails

> Anybody know how far they can take carbon percent in an RDM and
> still keep it bullet proof?
> -- PeteCresswell

Pete,

I think your question deserves a serious thought; sorry about coming
back with nothing but a wise-crack the first time.

The structural strength of a mast is not necessarily diminished upwards
of a certain percentage of carbon. Inversely, you don't gain strength
but you rather loose some by replacing a portion of your load-bearing
fibers with materials of different stiffness. In theory, a 50% carbon
mast would bend with fewer carbon strands taking a greater portion of
the load, without the remaining glass fiber seeing any significant stress.

A different problem, however, is that the carbon fiber is sensitive to
point loading and shattering aa a result of its material stiffness.

Additionally, any load is very effectively tranmitted to weak spots or
discontinuities where strands have been broken during manufacturing or
because you've dropped it on a pebble in the parking lot. 100% Carbon is
simply more sensitive, but ultimately it should outlive and outperform
everything else.

If I am informed correctly, the 90& carbon marking on nolimitz and
powerex refers to a protective layer. The load-bearing part is still
100% pre-preg carbon. I am using a 90% carbon powerex and 100% carbon KA
masts. They both perform great, but I wouldn't drop either.


--
florian - NY22

http://www.kasail.com/windsurfing/team/florianfeuser.html


02 Jul 2007 14:10:40
Florian Feuser
Re: Comparing Sails

> And don't forget the Space Shuttle that can go to something like 104%
> which is "full throttle".
>
> I', employed by NASA and even did some work with the main engines and
> never understood that one.

Maybe they just calling it 104% to make the astronauts feel better?
...kind of like that guitar amp?


--
florian - NY22

http://www.kasail.com/windsurfing/team/florianfeuser.html


02 Jul 2007 19:03:32
brett
Re: Comparing Sails

agree. RDM makes very little sense for large sails and flat water.

1- In 7.0 + sails you lose power with an RDM - you get less perimeter
tension, and they don't pump as well.
2- Unless the sail is cut for RDM, the leading edge is less stable. The
sail feels "softer" which is nice for waves, but bad for speed and pointing.
3- in a 460 or 490 an RDM weighs more than a standard diameter mast of the
same carbon percentage.
4- Long RDMs have slower reflex response.
5- You are not using big masts in surf, so deflection to failure is not an
issue.

I would never use anything but RDM in the waves, but I would not use RDM in
a race sail, or longer than a 430, period. Beyond that, quite a bit depends
on the specific sail. Some sail makers like Naish and Hot have freeride
sails made for RDM, and those work well. Others suffer. For
instance Retros and most Neil Prydes feel like poo on skinnys IME.

As with so many things, mast / sail interaction is complex, and has many
variables. It is not a case of RDM being "better" than standard. They each
have pros and cons. Consider the intended use. They same is true for X-Ply,
but I digress...

<a_macke@yahoo.com > wrote in message
news:1183318126.186793.305610@d30g2000prg.googlegroups.com...
> On Jul 1, 12:10 pm, "Mamba" <g...@nottoday.net> wrote:
>
> > RDMs on any modern sail affect performance considerably as well. They
allow
> > for more power and tunability, which can really be noticable in marginal
> > winds.
>
> RDM's and SDM's tend to bend very differently - together with the
> diameter differences (which have a huge impact on the luff curve),
> that can really distort sail shape if you're using an RDM in a sail
> meant for an SDM or vice versa. Some sails, however, will allow you to
> use RDM's or SDM's, with the slight differences in tuning something to
> be used to adapt a rig to your exact tastes. Sailworks Retros and
> Huckers are an example - that's partially made possible by the fact
> that the Sailworks RDM is spec'd for a bend curve that, when taken
> together with the different diameter's effect on luff curve, is close
> to how the SDM would set that sail.
>
> All that said - I think sometimes the 'craze' for RDM's is just that.
> When I see 7.5+ freeride sails rigged on 490 RDM, I wonder if it's
> worth it. Those rigs tend to look pretty soft to me - when a bigger
> sailor pumps them, you often see them almost folding in half. I know
> some people like a really 'soft' feeling rig, and for lighter sailors
> that might make a lot of sense. But by the time you're using a 7.5+, a
> little stiffness in the mast can help create stability in the rig,
> which can translate into range. Getting that kind of stability and
> range out of a soft noodly rig will require tradeoffs elsewhere. I
> have yet to see a big freeride sail on an RDM that made me want to use
> it - sure, they seem to work just fine, but why bother with just fine
> if, for the same money, you can get really great?
>
> -Andreas
>
> http://g-42.blogspot.com
>




03 Jul 2007 04:28:52
Matt
Re: Comparing Sails

>>For instance Retros and most Neil Prydes feel like poo on skinnys IME<<

I've been very happy with the low end performance of my PowerEx 460 RDM/7.5
Retro combo. Pumps on a plane nicely in really light air. The Retro still
pulls like a truck and is very stable. I can't speak about it's higher end
performance cause that's when I use the RDM for a 6.8 power wave sail and
small board.

I just bought a used 8.5 Retro and 490 SDM to increase the lower end planing
threshold. I have no intentions of buying a 490 RDM.

"brett" <brett@southport-rigging.com > wrote in message
news:8_bii.36112$G23.34438@newsreading01.news.tds.net...
> agree. RDM makes very little sense for large sails and flat water.
>
> 1- In 7.0 + sails you lose power with an RDM - you get less perimeter
> tension, and they don't pump as well.
> 2- Unless the sail is cut for RDM, the leading edge is less stable. The
> sail feels "softer" which is nice for waves, but bad for speed and
> pointing.
> 3- in a 460 or 490 an RDM weighs more than a standard diameter mast of the
> same carbon percentage.
> 4- Long RDMs have slower reflex response.
> 5- You are not using big masts in surf, so deflection to failure is not an
> issue.
>
> I would never use anything but RDM in the waves, but I would not use RDM
> in
> a race sail, or longer than a 430, period. Beyond that, quite a bit
> depends
> on the specific sail. Some sail makers like Naish and Hot have freeride
> sails made for RDM, and those work well. Others suffer. For
> instance Retros and most Neil Prydes feel like poo on skinnys IME.
>
> As with so many things, mast / sail interaction is complex, and has many
> variables. It is not a case of RDM being "better" than standard. They
> each
> have pros and cons. Consider the intended use. They same is true for
> X-Ply,
> but I digress...
>
> <a_macke@yahoo.com> wrote in message
> news:1183318126.186793.305610@d30g2000prg.googlegroups.com...
>> On Jul 1, 12:10 pm, "Mamba" <g...@nottoday.net> wrote:
>>
>> > RDMs on any modern sail affect performance considerably as well. They
> allow
>> > for more power and tunability, which can really be noticable in
>> > marginal
>> > winds.
>>
>> RDM's and SDM's tend to bend very differently - together with the
>> diameter differences (which have a huge impact on the luff curve),
>> that can really distort sail shape if you're using an RDM in a sail
>> meant for an SDM or vice versa. Some sails, however, will allow you to
>> use RDM's or SDM's, with the slight differences in tuning something to
>> be used to adapt a rig to your exact tastes. Sailworks Retros and
>> Huckers are an example - that's partially made possible by the fact
>> that the Sailworks RDM is spec'd for a bend curve that, when taken
>> together with the different diameter's effect on luff curve, is close
>> to how the SDM would set that sail.
>>
>> All that said - I think sometimes the 'craze' for RDM's is just that.
>> When I see 7.5+ freeride sails rigged on 490 RDM, I wonder if it's
>> worth it. Those rigs tend to look pretty soft to me - when a bigger
>> sailor pumps them, you often see them almost folding in half. I know
>> some people like a really 'soft' feeling rig, and for lighter sailors
>> that might make a lot of sense. But by the time you're using a 7.5+, a
>> little stiffness in the mast can help create stability in the rig,
>> which can translate into range. Getting that kind of stability and
>> range out of a soft noodly rig will require tradeoffs elsewhere. I
>> have yet to see a big freeride sail on an RDM that made me want to use
>> it - sure, they seem to work just fine, but why bother with just fine
>> if, for the same money, you can get really great?
>>
>> -Andreas
>>
>> http://g-42.blogspot.com
>>
>
>




03 Jul 2007 01:03:57
rod.r
Re: Comparing Sails

I have Simmer zero-sevens, 7 batten RAF sails, designed around the
Powerex SDM masts.
I had the opportunity to buy a Powerex 460 RDM at a good price so
asked the sail
designer what he thought.

He told me that the sail would work at about 50% of maximum using an
RDM. He also said
he'd recommend most other brand high carbon SDM masts before a 30%
Powerex SDM.



03 Jul 2007 10:15:31
wind.sh@dow
Re: Comparing Sails

On Tue, 03 Jul 2007 01:03:57 -0700, "rod.r" <rod@sraa.co.nz > wrote:

>I have Simmer zero-sevens, 7 batten RAF sails, designed around the
>Powerex SDM masts.
>I had the opportunity to buy a Powerex 460 RDM at a good price so
>asked the sail
>designer what he thought.
>
>He told me that the sail would work at about 50% of maximum using an
>RDM. He also said
>he'd recommend most other brand high carbon SDM masts before a 30%
>Powerex SDM.

I find this last part confusing. Did he specifically recommend OTHER
BRAND high carbon over Powerex high carbon, or did he just recommend
going higher than 30%?


03 Jul 2007 13:16:43
Mamba
Re: Comparing Sails

<a_macke@yahoo.com > wrote in message
news:1183318126.186793.305610@d30g2000prg.googlegroups.com...
> On Jul 1, 12:10 pm, "Mamba" <g...@nottoday.net> wrote:
>
>> RDMs on any modern sail affect performance considerably as well. They
>> allow
>> for more power and tunability, which can really be noticable in marginal
>> winds.
>
> RDM's and SDM's tend to bend very differently - together with the
> diameter differences (which have a huge impact on the luff curve),
> that can really distort sail shape if you're using an RDM in a sail
> meant for an SDM or vice versa. Some sails, however, will allow you to
> use RDM's or SDM's, with the slight differences in tuning something to
> be used to adapt a rig to your exact tastes. Sailworks Retros and
> Huckers are an example - that's partially made possible by the fact
> that the Sailworks RDM is spec'd for a bend curve that, when taken
> together with the different diameter's effect on luff curve, is close
> to how the SDM would set that sail.
>
> All that said - I think sometimes the 'craze' for RDM's is just that.
> When I see 7.5+ freeride sails rigged on 490 RDM, I wonder if it's
> worth it. Those rigs tend to look pretty soft to me - when a bigger
> sailor pumps them, you often see them almost folding in half. I know
> some people like a really 'soft' feeling rig, and for lighter sailors
> that might make a lot of sense. But by the time you're using a 7.5+, a
> little stiffness in the mast can help create stability in the rig,
> which can translate into range. Getting that kind of stability and
> range out of a soft noodly rig will require tradeoffs elsewhere. I
> have yet to see a big freeride sail on an RDM that made me want to use
> it - sure, they seem to work just fine, but why bother with just fine
> if, for the same money, you can get really great?
>
> -Andreas
>
Yes, my blanket statement is a vast oversimplification. My theory is that
even sails that are not specifically designed for an RDM, they may offer
more power in marginal conditions. This might be due to the additional
"pocket" allowed by freeing up additional luff material over the height of
the sail. I had not considered an apparent extra softness of an RDM would
impact this feeling as well. However, I have always beleived that a stiffer
mast would allow more sail shape, which I would equate to better low end
power in marginal conditions.

My sailing experience with RDMs is also very limited to smaller sized B&J
sails that will work with either SDM or RDM. I find the same sail exhibits
more grunt when rigged with the RDM. I am ~ 160#.

Cheers
Gary




05 Jul 2007 00:17:01
rod.r
Re: Comparing Sails

"I find this last part confusing. Did he specifically recommend OTHER
BRAND high carbon over Powerex high carbon, or did he just recommend
going higher than 30%?"

Sorry, I wasn't too clear. What he said was he recommended any other
high carbon
COMPATIBLE mast to a low carbon Powerex mast, even though the sail was
designed around the powerex.

As long as the mast had a compatible bend curve, high carbon ruled
over low carbon with exactly correct spec.



05 Jul 2007 08:06:27
wind.sh@dow
Re: Comparing Sails

Got it. Thanks, Rod.

On Thu, 05 Jul 2007 00:17:01 -0700, "rod.r" <rod@sraa.co.nz > wrote:

>Sorry, I wasn't too clear. What he said was he recommended any other
>high carbon
>COMPATIBLE mast to a low carbon Powerex mast, even though the sail was
>designed around the powerex.
>
>As long as the mast had a compatible bend curve, high carbon ruled
>over low carbon with exactly correct spec.