Sport Today

by **Neau** » Mon, 17 Nov 1997 04:00:00

Does anyone on this newsgroup have experience with the Delta mast
available from Multisail? It's a 460 or 500 cm mast (carbon fiber content
of 60 or 100%) of which the bottom 40 cm can be removed. It is made by
Powerex. While the Delta mast was designed to make changing sizes of the
Multisail easy, I notice that Windwing is offering fixed length 40 and 60
cm mast base extensions in their 1998 catalog, and suspect this is
basically the same idea. I believe Windwing masts are made by Powerex now.

If you have experience with the Delta mast, I'd appreciate hearing your
opinion.

L. D. Lide

by **Bill Hanse** » Mon, 17 Nov 1997 04:00:00

Quote:

> Does anyone on this newsgroup have experience with the Delta mast
> available from Multisail? It's a 460 or 500 cm mast (carbon fiber content
> of 60 or 100%) of which the bottom 40 cm can be removed. It is made by
> Powerex. While the Delta mast was designed to make changing sizes of the
> Multisail easy, I notice that Windwing is offering fixed length 40 and 60
> cm mast base extensions in their 1998 catalog, and suspect this is
> basically the same idea. I believe Windwing masts are made by Powerex now.

FYI: The use of the fixed 40cm carbon base extension will convert a
460/25 (MCS and IMCS) 12% constant curve to a (measured) 490/22 MCS 11%
constant curve (IMCS 25). I measured this set-up as a 490 for comparison
with our 490/26 (IMCS 29.5) made by Powerex as an alternative to buying
a 490 for our larger sails. The overall stiffness is less, IMCS 25 vs.
29.5, and the mast is 1% softer at the booms. For lightweight sailors in
sails with ample luff curve and multiple stiff race-type battens, i.e.
our Synthesis and Race CS models, this arrangement will work reasonably
well adding pumpability and attendant low-end power with a slight loss
in overpowered stability. It isn't recommended for aggressive
heavyweights. Our 9.0 Race CS is designed for use of a fixed carbon base
extension (or other suitable extra long base) and a 490/26 mast.

Bill

by **TomBuckO** » Wed, 19 Nov 1997 04:00:00

Quote:

>Does anyone on this newsgroup have experience with the Delta mast
>available from Multisail? It's a 460 or 500 cm mast (carbon fiber content
>of 60 or 100%) of which the bottom 40 cm can be removed. It is made by
>Powerex.

L.D.

I purchased one this summer and thought it was a great design idea. I am not
real technical, but I am always looking for a way to minimize the amount of
gear I have to haul around, and this mast fits the bill. I use it for
everything from 5.2 up to 8.2.

No problems so far . . .

Tom O'Brien - Chicago

by **Keith Mede** » Wed, 19 Nov 1997 04:00:00

Quote:

> FYI: The use of the fixed 40cm carbon base extension will convert a
> 460/25 (MCS and IMCS) 12% constant curve to a (measured) 490/22 MCS 11%
> constant curve (IMCS 25). I measured this set-up as a 490 for comparison
> with our 490/26 (IMCS 29.5) made by Powerex as an alternative to buying
> a 490 for our larger sails. The overall stiffness is less, IMCS 25 vs.
> 29.5, and the mast is 1% softer at the booms. For lightweight sailors in
> sails with ample luff curve and multiple stiff race-type battens, i.e.
> our Synthesis and Race CS models, this arrangement will work reasonably
> well adding pumpability and attendant low-end power with a slight loss
> in overpowered stability. It isn't recommended for aggressive
> heavyweights. Our 9.0 Race CS is designed for use of a fixed carbon base
> extension (or other suitable extra long base) and a 490/26 mast.

> Bill

Bill,

As always thought, as you stated above, that a softer mast gives you
better low-end power, but that you would be sacrificing higher wind
range and stability. But in Peter Hart's Speed with Style video, filmed
at the World Speed Trials, some of the pros were talking about using
softer masts so that they could extend the range of their sails and go
faster in really strong winds.
Since I already have a Powerex 490/29 that fits my 7.3m and I have the
Powerex 40cm carbon extension to use on my 8.3m, that I could experiment
using a 460/25 with the 40cm extension on my 7.3m to get that softer
feel and I was hoping the softer mast would make the sail twist off even
better in the higher gusts.
Maybe you can set me straight.

Keith Meder
Plano, TX

by **Neil Frenc** » Thu, 20 Nov 1997 04:00:00

Quote:

> > FYI: The use of the fixed 40cm carbon base extension will convert a
> > 460/25 (MCS and IMCS) 12% constant curve to a (measured) 490/22 MCS
> 11%
> > constant curve (IMCS 25). I measured this set-up as a 490 for
> comparison
> > with our 490/26 (IMCS 29.5) made by Powerex as an alternative to
> buying
> > a 490 for our larger sails. The overall stiffness is less, IMCS 25
> vs.
> > 29.5, and the mast is 1% softer at the booms. For lightweight
> sailors in
> > sails with ample luff curve and multiple stiff race-type battens,
> i.e.
> > our Synthesis and Race CS models, this arrangement will work
> reasonably
> > well adding pumpability and attendant low-end power with a slight
> loss
> > in overpowered stability. It isn't recommended for aggressive
> > heavyweights. Our 9.0 Race CS is designed for use of a fixed carbon
> base
> > extension (or other suitable extra long base) and a 490/26 mast.

> > Bill

> Bill,

> As always thought, as you stated above, that a softer mast gives you
> better low-end power, but that you would be sacrificing higher wind
> range and stability. But in Peter Hart's Speed with Style video,
> filmed
> at the World Speed Trials, some of the pros were talking about using
> softer masts so that they could extend the range of their sails and go

> faster in really strong winds.
> Since I already have a Powerex 490/29 that fits my 7.3m and I have the

> Powerex 40cm carbon extension to use on my 8.3m, that I could
> experiment
> using a 460/25 with the 40cm extension on my 7.3m to get that softer
> feel and I was hoping the softer mast would make the sail twist off
> even
> better in the higher gusts.
> Maybe you can set me straight.

> Keith Meder
> Plano, TX

I don't understand. Most people say it is bad to use an adjustable
mast base extension extended out to 30-40cm. It could break your mast.
But it seems to be OK to use a fixed mast base extension. What's the
difference. An explanation would be appreciated. Thanks.

Neil French
Norman, OK

by **The Do** » Thu, 20 Nov 1997 04:00:00

Quote:

> I don't understand. Most people say it is bad to use an adjustable
> mast base extension extended out to 30-40cm. It could break your mast.
> But it seems to be OK to use a fixed mast base extension. What's the
> difference. An explanation would be appreciated. Thanks.

> Neil French
> Norman, OK

What's happening is when you adjust that Chinook extension
out to its longest, there's not that much extension inside
the base of the mast (what.. maybe 3-4 inches). Where as
the fixed extension will have maybe 6-7 inches of ferrule
up in the mast. Plus, the base extension that I have was
made by the same folks who made the mast. It fits much
more tightly, so the load is distributed over a wider
area. It's engineering, my good man.

The Dog
--
Brian "The Dog" Cunningham
signature under construction
Don't blame Alcatel, they didn't know.
Dog House: web2.airmail.net/bcunning

by **Bruc** » Fri, 21 Nov 1997 04:00:00

probably because the fixed extension will fit the mast better and won't
point load it, whereas ordinary bases by their nature will not distribute
the load well.
--

Quote:

> I don't understand. Most people say it is bad to use an adjustable
> mast base extension extended out to 30-40cm. It could break your mast.
> But it seems to be OK to use a fixed mast base extension. What's the
> difference. An explanation would be appreciated. Thanks.

> Neil French
> Norman, OK

by **TomBuckO** » Fri, 21 Nov 1997 04:00:00

The fixed estension is constructed exactly like the joint in a two part mast -
so the pieces match up exactly. Unlike a mast extension.

Tom O'Brien - Chicago

by **NLW TFW** » Mon, 24 Nov 1997 04:00:00

Plus, jacking a mast up can place the boom in an unreinforced area if the mast
isn't designed to be jacked up that high.
Mike \m/
Never Leave Wind To Find Wind

by **Bruce Peters** » Mon, 24 Nov 1997 04:00:00

A critical point to watch out for in coupling any section of mast or
mast base together (whether fixed base, adjustable base, or even a
2-pc mast) is the fit. Sleeved tubular sections need at least 2 1/2
times their diameter to correctly transfer the load. This is
predicated upon having a good low tolerance fit between the sleeved
sections.

The fit between the sections becomes more critical the longer the
extension becomes. Loose fitting connections allow the base extension
(or lower half of the mast) deflect slightly before the load is fully
transferred. Within the confines of the luff curve (defined by the
sail's mast sleeve) this amounts to a kink in the mast bend and a loss
of rig tension. The kinked curve will cause a tight spot on the
leading edge and associated wrinkles behind it. While the loss of rig
tension by the loose fit will draw out depth from sail and reduce
power. Neither is desirable.

Bruce Peterson
Sailworks R+D

by **Barry Ritche** » Mon, 24 Nov 1997 04:00:00

Applause, applause. Someone designing sails so we don't have to buy a
mast for each size of sail in the quiver. Thank you Windwing!!

-Barry (Windwing boardhead of course)

Quote:

>...snip...
> Our 9.0 Race CS is designed for use of a fixed carbon base
> extension (or other suitable extra long base) and a 490/26 mast.

> Bill