
Question from 2005 and earlier
Send
your questions to the editor
Sail
Away
Today
Drew Petrou of Staaf
Sails answers these Ask Someone questions.
Enjoy.
Q1:
I am currently purchasing a new Dufour 40 with
the tall rig. I am looking to purchase sails
for use in the middle East principle for fast
cruising and some racing. The temperature can
reach 50C in the summer and the UV is generally
high to very high. What sail material and cut
would you suggest. Winds are generally 10-15k
but can quickly rise to 40K. Seas when rough
are short and steep.
A1:
The sail cloth that resists UV the best is carbon
fiber. It costs a bit more than other laminate
sail cloth but the UV resistance properties are
worth it. Dimension-Polyant has a great line
of laminate sailcloth that uses carbon fiber
as the primary load bearing fiber and a layer
of taffeta on both sides of the fabric. This
cloth is available in many different weights
or denier as we look at laminate cloth, and a
suitable blend for your boat is a combination
of GPLX 7, GPLX 14, and GPLX 21. This cloth is
very strong and well suited to rapidly changing
conditions. Ill attach a cloth brochure
that will detail the cloth construction and application
range.
Q2: Asymmetric
sails come in a number of different cuts depending
on the wind angle. Is there a cut suitable for
a very wide range of wind angle?
A2: This
is a great question and everyone is looking for
the
all-purpose A-sail. To answer your
question: Yes we can design an all purpose sail
that you will be able to sail in a broad range
of wind speed and over a large range of wind angles.
But in truth you will never be able to sail as
high as a flat cut reaching spinnaker or code 0
and probably never be able to sail as deeply a
large running kite. Sails can be optimized to perform
over a large range of conditions or specialized
to fill a hole in your inventory There is always
a best of both worlds solution if you
are willing to overlook the extremes.
12/21/05 |
Farr
Follow-up
Q: I
appreciated Russ Bowler's frank "VOR
Perspective"
piece in today's Anarchist. But while he hinted
at concerns over the upcoming Southern Ocean
leg, his comments beg the real question: Given
the ability for designers/ sailors/ /sponsors/et
al, to agree on a box rule that could provide
safe, yet exciting, competitive ocean racing;
and given the state of the art in grand prix
racing boat design and building...Why on Earth
did everyone agree on a rule that created boats
that almost certainly will have catastrophic
failures, very high odds of crew injury - or
worse, crew being catapulted out while the
boat flies along at 30-40 knots in 30-40 foot
seas at night with green water continually
blasting over the decks all the way back to
the helm? Is is likely there is no harness
capable of withstanding the shock loading of
such an event, or if the harness does sustain
the load it will break out whatever fitting
was provided for attachment. Perhaps all crewmembers
will need to be permanently harnessed to the
standing rigging, allowing them to stay attached
to the boat and be drowned...as there will
be no way to recover them at these speeds while
the boat is in effect a submarine. It certainly
appears that the survivors will have had an
indeed exciting ride, but hard to see where
the fun, exhilaration, thrill, etc. of sailing
will have been part of the experience. It is
also obvious after leg one night one that the
boats are likely to have structural failure,
indicating bad strength/weight tradeoffs, again
with the crews' lives at stake. Leg one night
one was surely a warning shot, but why would
Farr and the rest need this warning shot -
which was fired on a night with conditions
not as severe as expected conditions in the
design brief for this race? I suppose I should
also be asking why the crews of Movistar, with
many miles of offshore experience on their
boat, and the other boats have agreed to continue?
I cannot understand this and would love to
hear the rationale.
A: Certainly
a lot of very good questions raised by your
reader. It is difficult to produce an event
that is both safe and exciting as he suggests.
From a pure engineering perspective if the
boats were built to the 12 meter Rule with
scantlings according to Lloyds Rules for Ships
then as an engineer my job would be relatively
easy and risk free and I could sleep soundly
knowing that the boat was over designed and
never going to meet a wave at speed and crews
were safe as long as they could keep the bilge
water under control. However, there would be
no interest from sailors or sponsors for such
an event.
Rule
evolution does not generally come from complete
agreement between sailors, designers, sponsors,
rule authorities et al. It usually springs
from, and is controlled by, one of these sources
and certainly among designers there is often
a wide variety of opinions on what new rules
should produce. In the case of the VOR 70 I
believe everyone had a good idea of what they
were developing and understood the risks and
rewards.
I
don't believe the VOR 70's are experiencing
anything that is a higher risk than that experienced
by the ocean going multihulls or the Open 60's.
I'm not sure this makes it right but the point
is that to keep up with the development of
ocean sailing the Volvo race organizers had
to move to something that would interest the
sailing community. In the next 3 months we
will see if the readers conjecture on the dangers
is validated. From my observations, I am impressed
how the crews are working hard at understanding
and managing their boats and the dangers they
present. Don't let leg 1 night 1 be the sole
basis for your judgment. Give them another
leg or two.
Regards,
Russ Bowler
Farr Yacht Design, Ltd.
12/19/05 |
Tanked
A
boat builder
question and answer this time, the
answer provided by Jeff Kent of Composite
Solutions Inc.
Q: I have
an older Lindsay 505 hull with wood tanks and
deck that are in very bad shape. Provided the
weight of the boat is good and the hull is
structurally sound I would like to make carbon
replacements for the wood structures. I was
thinking of making a mold off the tanks and
decks. Is this a project that is possible by
the average Joe or am I insane? Is this a reasonable
technique to resurrect this boat?
A: The
real question I think is how bad are the tanks
gone? If the were of ply and the outer veneers
are gone but the geometry is intact there may
be hope to remove a few of the plies evenly.
and then replace with on layer of 200gsm 2x2
twll carbon fabric and epoxy. if carefully
done, this can be done without a vacuum, just
bublebuster rollers and peel ply carefully
applied. If any voids can be filled to make
it air tight, do so, then use a vacuum bag.
The
above method is probably the least invasive
to the geometry of the hull. If tooling was
made from the existing tanks, it could work
but it would take a lot of time and materials
just to get tools. Then you would have to make
the tanks with carbon skins and a core of Nomex
honeycomb or PVC foam. This is all much to
do and I don't believe it to be worthwhile
unless time and funds are unlimited. One option
is to see if Mark Lindsay would be interested.
He is at Boston
Boatworks in East Boston MA. Hope this
helps!
Regards,
Jeff Kent
12/13/05 |
Men
of the Cloth
This
sailmaking question is answered by Quantum's
Larry Leonard.
Q: Now
that we have laminate sales, multi directional
cloth, seamless welding, carbon fiber etc.,
etc., what is the next evolution of sail
design going to be?
A: We
believe the next big step in sail development
will be called Smart Sail Technology.
This concept was developed by Quantum following
extensive research in the area of upwind sails
using aero-structural coupling. This study
was undertaken to expand on the simple
lines of stress model being used by most
of the sail manufacturers employing custom
fibered membranes. Through this research it
quickly became apparent that loads within a
sail are dynamic, varying endlessly, as any
one of the following, wind speed, wind angle,
lead position, sheet tension, or halyard tension,
changes. To address these changes, Quantum
locates fiber not only in the primary direction
but also in the secondary and tertiary directions,
creating a fiber matrix, with many crossings,
eliminating the bias load, normally carried
by Mylar film.
In
addition, now that it is possible to predict
the deformation of a membrane or sail, and
fiber can be placed in any direction in any
density, then logically it must then be possible
to engineer a sail that deforms in a positive
manner, enhancing the speed of the yacht, as
opposed to past designs that became inefficient
as a result of improper structure. This results
in a smart
structure that has the potential to flatten and
twist as desired in higher wind ranges automatically
eliminating some of the normal movement in lead
position to accomplish the same effect. This
has become our goal and is the next logical step
in sail development.
For
those of you that enjoy the science of sailmaking,
you may view the research paper that inspired
this development here.
12/06/05 |
Fabricated
Today's
Ask Someone is regarding sail cloth and is
answered by Moose McClintock from Dimension-Polyant
Sailcloth Technology.
Q: Are
there any new cloths coming out?
A: We're
doing a new line based on easier construction
techniques that should translate into less
expensive sails for the sailor. Over the spring/summer
we started developing FLX2, a crosscut laminate
with a double "X" pattern for bias
stability. This has been used for most of the
summer with very good feedback, it's currently
targeted for the weeknight and casual weekend
racer who wants higher performance but knows
he's not going to be able to afford the membrane
style sails or the higher performing but more
costly tri-radial sail. While currently being
done as an Aramid style only, we'll be introducing
this as a Pen style in both racing (film only)
and cruising (taffeta on both sides) styles
in late December.
We're
also in the process of reintroducing our racing
nylon style, our Formulon line, which has a
unique coating process to ensure non-porosity
and long term stability. We've had it out in
limited production and results have been beyond
expectations with a Pan Am games win, several
NA and Mid Winter wins and overall exceptional
feedback. Ask your sailmakers for more info
on both lines.
12/02/05 |
Yacht
Design
Here
we have questions for a designer, these kindly
answered by designer Rob
Shaw.
Question
1:
With regard to the boats designed with huge mains,
fractional jibs masthead kites, and no backstay
(i.e. the new Shaw boats), how much support does
the main provide when running as deep downwind
as possible?
Question
2:
Will the mast stay in the boat with the main
down and the kite up?
A: It
really depends on what your rig configuration
is. The Shaws have 30 degree raked spreaders
with the caps running right to the mast head,
which provides the mast head all the support
it needs to run the masthead gennaker. All
the main might have to offer is to lock the
mast in with some pre-bend so you don't have
it inverting, but with raked spreaders that
shouldn't be a problem. We run the gennaker
on a tight reach with the main inside out often
so it's not doing much for you then. A few
of the guys have run home after post race drinks
at the club with just the gennaker up and had
no problem. Also you will probably get a lot
of lee helm, downwind the main is just providing
you with some balance with all the drive coming
from the gennaker.
11/28/05 |
Model
Builder
This
one answered by weather and navigation
guru Bill
Biewenga. Enjoy.
Q: Everyone
knows about grib files, and that software like
MaxSea and others integrate grib file info
for display over cartography, but also for
input into routing algorithms. I am interested
in evaluations, recommendations, and understanding
the consequences of which particular numerical
models produce the grib files which I can get.
Talking weather here, such as wind, pressure,
waves, possibly precipitation. There are numerous
numerical models producing grib files: AVN/GFS,
Theyr, Navy, NOAA WavewatchIII, etc. I understand
some predict over land as well as sea, some
are finer grid than others (just interpolation?).
Is there any systematic evaluation of which
models predict best under what conditions or
over what geographical areas? I sail in mainly
in the western north Atlantic. A comprehensive,
well organized, and detailed answer would be
wonderful! Thanks. A good answer to this question
would take SA to a new level in my opinion.
Increase the info to BS quotient! Again, thanks.
A: I'll
try my best to increase the info to B.S. quotient.
GRIB stands for "GRaphics In Binary",
and as you mentioned, GRIB files come in a
variety of flavors from an assortment of models.
From my perspective, the GFS model seems to
work best on average for the sailing you're
doing in the North Atlantic. None of them are
perfect everywhere. Some are better in the
tropics and others are better in extra-tropical
areas. That's why, when I'm using computer
generated models - whether they're in a GRIB
format or printed out - I also try to look
at weather information that has some kind of
human intervention involved. That might be
a weather routing company such as Commanders'
Weather or it might be weather maps that I
get from the Ocean Prediction Center, either
by weather fax or from the Internet.
The
models come in various resolutions, most often
in 1 degree grids. A variety of computer generated
models at various altitudes - including the
surface - can be found at: http://www.arl.noaa.gov/ready/cmet.html.
The models do, however come in higher resolutions.
RAMS data as an example is available for a
few selected spots. It's very high resolution
and even graphically forecast a storm approaching
the Olympics in Atlanta when they were being
held there and indicated which parts of the
city would be most severely affected.
For
your purposes, however, I think the GFS models
- offered for free through www.saildocs.com -
will probably offer you generally provide you
with what you need. Keep in mind, though, that
computer generated models and GRIB files do
have limitations. They tend to smooth the data,
as you imply with your question about the resolution
of the data. And some are better in different
situations than others.
11/18/05 |
Yacht
Design
Here
is one about yacht design, answered by
Tim Kernan of Kernan
Yacht Design:
Q: I
Have a late 1/2 tonner with the genoa tracks
next to the cabin sides. Other similar boats
have the tracks further outboard by about 3-4" and
I was told by a sailmaker that I'd be faster
doing the same. I have always been told that
tighter sheeting angles allowed one to point
higher. What gives?? Should I move the tracks
outboard or pull the traveler car higher to
keep the slot open??
A: We'll
need to know what the actual sheeting angle
is, measured from centerline, with the clew
as the origin. Older generation wisdom was
to shoot for 8 degrees, sometimes you would
see it even lower at 7 degrees. Current thinking
is up to 10 degrees, but you have to factor
in that most current boats are set up with
inhaulers. So at standard setting, the slot
is more open, but inhaul for height when you
need it. Definitely you will need to be able
to get to 8 degrees at a minimum for height,
particularly on an older generation IOR type
hull. It is probably not worth moving the tracks,
but your best bet is to check the actual angle,
then go from there.
11/17/05 |
Ask
the Sailmaker
Papa
Roach
Q: Dear
SA,
I
have the following question for Harry. I'm
looking to replace the cruising main on my
32' fractional rigged cruiser/racer (no running
back stays). What would be pros & cons
of replacing the existing conventional triangular
main with a fully battened massively roached
sail?
Kind
regards,
William
Burville
Plymouth UK.
A: The
decision of whether or not to replace you
current main with a very large roached main
will depend on several factors. First consider
how the boat balances in its present configuration;
do you have weather helm, neutral helm, or
lee helm. Adding more sail area in the roach
of the main will increase weather helm.
Next,
determine how the new main will work in conjunction
with your current rig. If you have a permanent
backstay the amount the roach will overlap
the backstay needs to be taken into account.
And finally consider the type of sailing you
will be doing the majority of the time.
Offshore
sailor Steve Daschew is a big proponent of
very large roached mainsails. We worked with
Steve and John Conser in developing and building
the mainsails on the "Sundeer" line
of yachts that Steve designed and built. The
idea is to add a substantial amount of very
efficient sail area, mostly for offshore sailing
where you may sail for days or weeks on the
same tack. Having more sail area in the main
provides a lot more power without making the
rig taller and is especially useful when doing
a lot of trade winds reaching. It also allows
you to sail with smaller, more easily handled
headsails, and as the wind increases it is
easier to reef the main than it is to change
headsails.
The
only downsides are it may add more weather
helm than your boat needs, and it may make
the mainsail harder to raise and lower. Not
only is the sail heavier because of the extra
area and the battens, but it also puts more
load on the luff cars. You may find it necessary
to upgrade to some type of low friction luff
track system such as the Harken, Fredrickson,
or Tides Marine Strong system. Generally increased
weather helm can be taken care of by reefing
the main in conditions when it is present.
The mainsail should also be designed with a
first reef that is positioned such that the
roach will pass through the backstay triangle
when reefed. This is very important if you
are day sailing or sailing in an area that
requires frequent tacking.
If
you are looking to add more sail area to your
boat, especially if you tend to do extended
passages, it is a very good way to go.
Harry
Pattison
Elliott / Pattison Sailmakers
949 645-6697
On the web at www.epsails.com
11/10/05
|
Ask
the Sailmaker
Butch
Ulmer from UK/Halsey tackles
this one.
Q: I
sail in two classes. One exotic, one very traditional.
The traditional class has a rule that insists
on "woven", i.e. not laminated sail
construction. What is best within that very
limited rule box?
A: Many
classes insist on woven material (Dacron or
polyester) for their working sails. Usually
(as in this case), they are more traditional
boats. The two major benefits that accrue from
this requirement are lower cost and improved
longevity. The major drawback is loss of performance
as woven materials are typically stretchier,
particularly after the sail has been used a
fair amount.
To
cut down on the amount of stretch, cloth makers
add resins to woven materials. The resins (as
long as they remain in tact) glue the woven
yarns together and make the fabric behave more
like a laminate. (A good analogy is wire reinforced
glass think of the wire as the yarns
and the glass as the resins). Heavily resined
woven fabrics have low stretch (particularly
when new) but they are stiff, hard to handle
and tear easily.
The
right fabric in this case depends on how traditional
the boat in question is and how much the person
in question wants to win!
10/17/05 |
Ask
the Sailmaker
This week's answer provided by Harry Pattison from Elliott/Pattison
Sailmakers.
Q:How about a
review on sail cloth- carbon was the rage the last few years,
but now I see a lot of kevlar and carbon/kevlar combo's.
At least in our area (RI). The D4's are now a combo of carbon/kevlar.Thoughts
please.
A: Carbon is still
the number one choice for primary load bearing yarns in sails.
The carbon fibers have the lowest stretch, with the best
UV resistance, of anything currently being used. The carbon
being used in today's sails has a modulus of about 1400 grams
per denier, while the higher end aramid fibers come in at
around 880 grams per denier.
The
GPL line of fabric from Dimension - Polyant has been
the staple for the last three or four years and really
set the standard. It does have some differences from
the new generation "load path" sails that you
see out now, (D4, 3DL, Fusion, etc.). Even though GPL
fabrics may look like they are 100% carbon they are actually
blends of carbon and Technora. Technora is the trade
name for a Japanese version of aramid, which is black,
like Kevlar is the Dupont trade name for its aramid fiber.
In
GPL fabrics the carbon yarns are wide, flat
ribbons rather than bundled yarns which you
see in the warp direction. They are inserted
over the top of a Technora scrim and then laminated
between mylar films. The advantage of this
construction is that the carbon ribbons have
no sizing or adhesive applied to them. You
can see this when you cut into a piece of the
fabric. The carbon is soft and supple. You
can bend it, beat it, tie it in knots; and
it retains it strength. It is this characteristic
that gives the GPL's their great durability.
I have yet to see a GPL sail that suffered
a catastrophic failure; the carbon yarns just
don't break down.
The
downside to this construction is that it is
not possible to really pre-tension the carbon
ribbons during the lamination process, which
means the fabrics have a little bit more initial
stretch than fabrics made with pre-tensioned
yarns. To overcome this they use the Technora
scrim as a base which is pre-tensioned. This
does two things. First the Technora warp yarns
take care of any initial low load stretch;
just to the point where the carbon yarns become
loaded. Second, the Technora fill yarns provide
the needed structure and strength in fill direction.
In
any of the "load path" sails all
of the yarns are laid down under some pre-tension
and bonded to the full size lower mylar skin.
Current technology does this with a "stringing"
machine which is basically a computer controlled
overhead gantry with a head that will lay down
a pattern of multiple yarns in each pass it makes
over the lower mylar skin. In this process all
of the yarns have to have adhesive applied to
them as they are laid down, and usually have
a fair amount of sizing to keep all the fibers
in each yarn bundled together. The adhesive and
sizing stiffen the yarns and reduce their flexibility;
and the flex properties of carbon go down quite
a bit The result is that in most cases designers
have gone to a combination of carbon with either
the yellow or black aramid in somewhere around
a 60:40 to 80:20 blend. The idea is to have the
carbon take the primary load while the aramid
yarns, which are now better in flex than the
stiff carbon yarns, provide for some extra protection
against catastrophic failure. In this scenario
the better choice is to use Technora which is
the best of the fibers in flex.
Aramid fiber is still quite a bit less expensive
than carbon, and it is certainly strong enough
in lower load applications. In "load
path" sails the ratio of carbon to aramid
is based both on cost and high load performance.
There is little if any advantage to building
a sail for a 25' boat in carbon. Generally
speaking the higher amount of aramid you
have the less the sail costs, but the more
it will stretch. Over the next few years
you can expect to see sails built with less
and less aramid. The aramid yarns in the
fill direction don't add much to the shape
holding ability of the sail because as long
as the carbon hasn't broken down it stretches
less than the aramid, so the aramid never
gets really loaded. Already some designers
are starting to make sails that are 100%
carbon in the primary yarns. You will probably
see more and more of these, especially in
the America's Cup sails where strength and
weight are more important than long term
durability.
10/3/05
|
Ask
the Sailmaker
Main,
Man
.
This week's answer courtesy of James Heckler
of Lidgard
Sails
Q: I'd
like to know what if any the difference is
in the main battens being perpendicular to
the leech or the luff.
A: The
main purpose of having battens in your sails
is to help support the sails shape. The number,
placement, and orientation of the battens will
affect how well they work.
Most
of us are a bit crazy about weight aloft. So
we want the battens to do their job, with the
minimum amount of weight up there, and get
maximum benefit. We also mostly like sails
with lots of roach - we need more sail!
To
support roach you either need a rounded shape
(like in a Spinnaker) or battens - the better
your battens are the flatter the sail will
be "out the back". Most sails use
a combo of shape and battens to give the support
you need. I have attached a picture of a typical
mainsail chord for a Dacron sail. You can see
that the shape is a little rounded in the back
- not dead straight.
Battens
need to go beyond the roach into the body of
the sail to be effective. If you put your battens
on at 90 degrees to the leech (or more importantly
90 degrees to the straight head clew line)
then the length of batten needed to get into
the supported part of the sail is at a minimum
- which is light. Also, if you are talking
about a cross cut Dacron sail you are also
lining up the battens with the fibres in the
cloth. So when you pull tension on the battens,
you are loading the cloth in a less damaging
way than if you had the battens square to the
luff.
If
you put short battens square to the luff then
you need a longer batten to get the same support.
But, it makes the sail quicker to flake up
and put away - so maybe it spends a little
less time flogging in the breeze when you drop.
Full
length battens are almost always installed
perpendicular to the luff. This is because
they carry compression load all the way to
the mast and this load is most efficiently
passed into the mast at this angle. It also
becomes pretty much impossible to deal with
the sail when raising and lowering if they
are not close to 90 degrees.
Full
length battens have a whole range of benefits
to sail shape and life - but they have been
covered in other posts. My personal opinion
is that they are worth it for most boats;the
increased weight is more than covered by the
improved performance and sail life.
Some
class rules specify batten layout - and there
can be area advantages for going angled or
square. In the end a lot comes down to preference
and the type of sailing you are doing.
James
Heckler
Sail
Designer
Lidgard Sails
Auckland
09/19/05 |
Ask
the Sailmaker
A
couple weeks back we ran a picture of a Quantum
Farr 40 Code 2 jib. One of you Curious George's
had a question about it, so here is the answer.
Q: The
sail in the picture looks like a 100% which
I assume would be for heavier winds, the draft
looks more forward for heavy winds but the
depth looks full which would seem to indicate
light winds? Please comment on the sail shape
and the conditions it is being used in.
A: This
is a Code 2 Jib for a top level Farr 40 team.
The wind range is 8-14 knots. These depths
with the appropriate entry and exit have proved
to be quite fast in the class. Photographs
are a great way to analyze sail shapes and
an excellent way to document your inventory.
By creating a pictorial history of each sail,
you will be able to document fast sail shapes
and then can extend the performance life of
your sails by predicting when a re-cut is necessary.
Best
regards,
Larry
Leonard
President Quantum Sail Design Group
09/12/05 |
Ask
the Sailmaker
Here
Mark Reynolds from Quantum gives
the skinny.
Q: I
have just taken delivery of a new Pentex sail
for my 6.5 metre sportsboat. The mast has quite
a bit of mast pre bend to take mast head spinnakers,
which I knew would cause some problems with
the cut of the new sail. The new sail has creases
from mid way up the luff to the clew ( the
boom end ). Do I straighten the mast or put
more pre bend in it???? There is some flutter
on the leech telltales also.
A: Sounds
like the classic over bend wrinkles. The
mast is just bending more than the sail
can handle. You either need to take out
some bend or add some luff curve to the
main so they fit each other. Its
hard to say without looking at how extreme
your pre bend is to say which would be
better. If its easy to straighten
the mast a bit Id look at that first.
When the breeze is on good and the mast
bends even more you want to be just starting
to see these over bend wrinkles. If they
come to early straighten the mast or add
some luff curve to the main.
08/31/05 |
| Ask
The Sailmaker
Q: I
would like to ask Larry Leonard from Quantum
Sails the following question: The rumours
are saying that you are using the very old
Genesis string machine (used by Sobstad Sailmakers
and Peter Conrad back in the old days) when
you are making Fusion sails. Is this true?
Regards
Jan Johansen
A: While
we did inherit a laminating machine from Sobstad
we do not use any of their stringing machines.
We've invested quite heavily in the plant in
Malaysia in both the site and in the equipment.
All stringing is done by new equipment and with
heads that can lay 12 fibers at a time. Sobstad'
original equipment could only string one fiber
at a time. The laminating machine has been totally
refurbished.
To give you a feel for the quality of the product
I have attached a photo of a Farr 40 Code 2 Jib.
Best regards
Larry Leonard
08/17/05 |
Ask
The Sailmaker
Q: I
just got a a new set of racing sails, made
of Bainbridge DIAX-LSP sailcloth. My question
is can I use my roller furler to store my
jib when the asymmetric is hoisted, or will
this damage the laminate
Regards,
Dick Sanders
A: Diax
LSP is a Pentex based laminated which is a little
worse for UV degradation than regular polyester
so you certainly would not want to leave it furled
without a cover for long periods of time. But
to leave it furled while you are sailing downwind
with the asymmetric up is not a problem. This
answer courtesy of Harry
Pattison, E/P Sails.
08/15/05 |
Ask
the Sailmaker
Mast
Bend
.
Here is the first one with the answer courtesy
of Doug
Christie, UKHalsey Sailmakers.
Q: We often
hear about the pros and cons of straight mast versus
a mast with prebend. With a typical one design or race
keelboat i.e. with a reasonably bendy mast, what are
the decision parameters and what advantages does one
style have over the other. - David Cattle.
A: David,
There are a few considerations.
1. It is generally best to have as straight
a mast as possible as this allows your sail designer
to put a better % of any given girth measurement
into roach rather than luff curve. With modern
fabrics, long battens and full battens it is
very easy to support this roach. The logic behind
this is to help create helm and also projected
area downwind.
2. Some classes have restrictions on position
of mast at step, partners and rake. Rigs with swept spreaders
are often forced into a situation of requiring pre-bend.
I still try to get as straight a mast as possible through
rig tune, then design around this set up.
3. Some soft masts with limited fore and aft support
need prebend to ensure any pumping goes the correct way.
Inversion is bad. The sail designer just has to hit a
moving target with luff curve making his job a little
tougher.
4. A straighter mast also ensures that more of
the backstay tension goes into fore-stay tension rather
than being lost in compression. This allows your sail
designer to build gruntier headsails. In combination
with the flatter more forgiving main this is a good starting
point for an easily trimmed setup.
5. Whatever the amount of pre-bend a stable mast
is fast. Reducing pumping allows a more consistent
sail shape.
Hope this helps,
Cheers,
Doug.
08/09/05 |
To:Hans
Fogh
Question:
What
was the development of the laser sail
like? Did you use the Finn sail as a
reference when you designed the sail?
Thanks Hans!
Hans
Replies:
I
worked 10 years for Paul Elvstrom and
sailed against him in the Finn. I also
sailed 5 Finn Gold Cup. We made many
sails for the Finn and also for the OK
Dinghy, so I had a lot of experience
making sails for a non stayed mast. I
used some of those
ideas but because the Laser did not have
sail tracks for mast and boom we came up
with a fixed sleeve for the mast and loose
footed for the boom. Over the last 2 years
I have just designed the Mega Byte sail and
have used a top full batten which if I had
to design the Laser sail today, I would do
the same.
Thank you for your questions.
Best regards from Hans Fogh
December 4, 2001 |
Tom
Whidden
Question:
Please
ask Tom Whidden about the threats to
the Volvo/ AC programs that if they did
not by North's downwind sails they would
not be sold 3DL's. I would love to hear
his explanation.
Regards,
BEN
Tom
Replies:
Dear
Ben....Thankyou for giving us an opportunity
to respond to your question about Volvo
and AC campaigns sail buying policies.
First and foremost, North does not ask for
or require exclusivity from a campaign either
verbally or contractually. We are happy for
them to buy sails from any competitor at
any time. In fact, we feel that presents
us with a chance to learn and test against
other ideas and technology and to improve
our own. Secondly, I know of no campaign
that would ever grant us complete exclusivity
whether or not we are speaking of upwind
or downwind sails. If any AC or Volvo campaign
decided to build their downwind sails elsewhere
we still would be thrilled to offer and build
the 3DL upwind sails.
The greater irony is that we at North Sails
feel that our greatest competitive edge today
lies in downwind sail technology. Certainly
our ability to sell every Volvo group and
all but one AC group proves that we have
taken R & D and exhaustive testing seriously.
Believe me, we could threaten all we wanted
but I don't know one AC or Volvo syndicate
that would agree to buying North downwind
sails simply for the right to buy 3DL sails.
Regards....Tom Whidden
November
24, 2001 |
Paul
Cayard
November
20, 2001
Question:
With
Paul Cayard seemingly on the bench for
the AC. I'd like to know if he's thinking
about trying for the Olympic team once
again in the Star.
Signed, A. Rhody
Regardless
of how AC 2003 plays out for me, I am
thinking of the Olympics in 2004 and
have just bought an new Star with that
in mind. Next spring I will sail in the
Miami Olympic classes regatta and then
the Bacardi Cup, then the Worlds in Marina
del Rey in August. Star sailing in the
sailing that I enjoy the most. I think
it is the best of pure sailing skill.
|
Three
Questions for Mark Reynolds:
I
am a new owner of a Melges 24.
- What
are three areas an amateur helm should
concentrate time and attention to best
improve results (any pracitice tips)?
- What
is the best mechanism in your opinion
or steps (in order) for depowering
the main and maximizing pointing on
a Melges 24 (rig tension, main sheet
tension, vang sheeting, backstay)?
- Third,
what is the corresponding result of
vang sheeting on jib shape (what are
the necessary adjustments to jib when
vang sheet hard to flatten the main)?
Thanks,
Scott Gregory USA # 378
Mark
Replies:
-
I've
been doing a lot of practicing the
in M-24 over the last few months. We
do a little of everything, 2 or 3 boat
tuning, various drills, practice starts
and short races. I would suggest doing
the same. You need to work on your
boat speed (helm technique and tuning),
your boat handling (short races and
drills like tacking and gybing) and
tactics (practice racing and
regattas).
-
To
depower the main I start off with some
backstay and then quickly go to the
traveler. There's a range when you
have to use a mix of the two with some
mainsheet thrown in and the tiller
so you really need 4 hands! Then when
it's really windy you have to just
go to the mainsheet. You can also use
a bit of vang depending on the cut
of your main.
-
Perhaps
you've noticed vang sheeting affecting
the jib shape. In most boats that don't
have rock hard rig tension (a tight
leeward shroud) you have to be careful
about going to vang sheeting to quickly.
When you use the vang to get leech
tension you are not pulling back on
the rig like you do when you use the
mainsheet to tension the leech. The
result can be a little more luff sag
resulting in a fuller jib, not generally
what you want. With the deck stepped
mast in the M-24 we just use the vang
sometimes to dial in a little extra
bend and to take over the leech when
the mainsheet is eased way out in strong
wind.
November
15, 2001 |
|