Chris Williams Foiling Moths Homepage

Improvements

2010-03-25T14:54:00.002-04:00

We at North Sails are always looking to improve our product. After a season of hard work we have looked at our 2009 sails and how they wore out and then made some small changes to our sails construction which should have a big improvement in the way the sails last.

Moth sails take a real hammering when rigging and carrying boats out to launch. With the sails already built from tough base sail cloth I think a moth mainsail is going to wear out from time spent rigging rather than time spent sailing.

Below is an image of the new light weight rubber bumper on the head of the 2010 sails. This provides better chafe protection than thick webbing we previously used which tends to get torn up on concrete.

The batten ends, especially on the top battens wear out quickly and risk having the orange tension line which loops over the batten wing tips wear out and break. All battens now have rubber bumpers on both sides of the batten pockets as in the image below:

With the stiffer masts comes higher downhaul loads. Some boats are even using 8:1 downhauls. Originally our sails had press rings, then we switched to webbing loops on the luff sleeves. However, after more testing we decided to put the press rings back in the sail. With the high loads we have added a web loop for safety to ensure the ring does not pull out of the sail:

To make the sails easier to rig up we have added side zips to the cams. This is a popular feature which can really take the headache out of rigging up. All luff sleeves are now made from a more durable Dacron than the 2009 sails which had a square weave low stretch Dacron which was prone to tearing. Additionally the front seam on the sleeves is now reinforced with a Teflon tape to ensure that the mast will not tear through the seam and add a little more ruggedness when your sail decides to flip itself over on the pavement while rigging!

With the winter weather starting to take a break in the US testing is about to begin in earnest with hopes of further improvements making it into the product.

Below is an image of the 2009 model V8 on a Southern Spar in 12kts TWS. The new 2010 sails are slightly more draft forward throughout with more front% (Slightly more knuckle) in the lower sections and more reactive to downhaul in the head for when the breeze comes on.

Please feel free to drop me a note anytime with questions on our sails. We are always open to suggestions and possible improvements in our product.

Tuning Guide

2010-03-19T17:46:00.000-04:00

Successful couple of weeks for North Sails. Following Chris Graham's win at the UAE Nationals Rob Gough won the slalom. Brad Funk then got the most out of his V8 to get 3rd in the Worlds. Not as good as 2009 with the win in the US Champs and the 2nd in the Worlds, but we will take it considering the conditions and expecting more out of the sails as the wind builds.

After about 5 months of development I have finally had some time to put ideas on getting the most out of the North Sails.

Upwind technique:

-More vang improves VMG upwind. With a 16:1 you should need moderate tension once up and foiling and very tight tension upwind once fully powered up.
-Less vang is better for speed, IE when trying to get to one side of the course or for getting through another boat.
-Once fully powered up, IE TWS greater than 14-15kts max vang
-Downhaul should be fairly loose in marginal conditions, as the TWS increases the downhaul should be pulled until you can sail with a full sail. If your weather tell tales are luffing then you need more downhaul, if your leeward tell tales are luffing ease the downhaul.
-Once fully overpowered upwind max downhaul and vang as hard as you can pull
-Outhaul about 150mm off boom in light winds and 100mm in breeze, never tighter than 100mm
-Shroud tension tighter for power, looser if overpowered, typically leeward shroud just loose
-Flat to slight heel to weather in light wind to power rig up as much as possible. More heel to weather as the windspeed increases. Heel to weather more for high mode and flatter for fast mode. Keep in mind that more heel reduces the apparent wind angle and the effective sail area.
-Ride height as high as possible without rudder ventilating

Downwind technique:

-Outhaul eased LOTS. Probably foot of the sail 200-250mm from boom, 8mm bungee wrapped around leech helps the outhaul ease, as does Ultra High Molecular Weight Plastic Tape under your boom and large clew tie lines or a Velcro strap.
-Vang cracked, but not too much. Just enough to make gybing easier seems about right.
-C-Ham eased till there are just wrinkles on luff in light wind, a little less in breeze.
-When heating up for speed add a little more downhaul especially if fully powered up.
-Hike when enough pressure to hike against and still feel good apparent wind pressure, but don't make it a priority to hike unless you can hike hard to increase speed and carry the building apparent windspeed down to a similar angle as a non-hiking angle.
-Heel is flat in most wind conditions, but slight to weather once hiking hard
-Ride height as high as one dares depending on the windspeed

Taking a page from big boat racing, a good set of targets can be helpful. I am using this as my starting point. Obviously a good guess is required on the approximate windspeed. Downwind Speeds are a little more approximate, maybe the top guys are a few knots quicker downwind as the breeze increases:

I'd be happy to hear peoples comments on what makes them go faster.

Congratulations to Simon, Amac and Brad

2010-03-14T09:44:00.000-04:00

Congratulations to Simon, Amac and Brad. Three very worthy competitors, hard working sailors and three really great guys who have used their experience to finish atop a tough field in even tougher conditions.

Thanks to the DOSC, Puma, CST, Chris Graham, Glenn Raphael and Sailing Anarchy for organizing another great Moth Worlds.

So clearly I am not going to win the blog worlds with my last blog post. Never has a truer statement been made than Dave Lister's Mothcast comment, "You blog, you lose." At the time I thought Dave was talking about losing races. I have been loosing races for 25 years before blogs were invented- so what's to loose? Obviously a blog sets oneself up for a faux pas.

It is interesting how a blog is in it's simplest for a diary or a way for people to express their opinions. The problem with opinions is that everyone has them and usually 50% of the population is going to disagree with you. More to follow on NORTH sails in the future.

Sail Development

2010-03-12T13:03:00.000-05:00

It has been a very interesting worlds, especially looking at how different sails are performing. I think all the sail designers have concentrated on having one sail which suits all winds- this is always compromise in some conditions and some sails do this better than others. The Hyde sails perform well in marginal foiling conditions, the Raptor sails are high wind sails, and the KA and North Sails more all purpose designs.

Brief Summary Moth Sails from a designers perspective:

Raptor- These sails were all the hype coming into the worlds. Unfortunately, my friends, Bora, Dalton and Bear are under-performing relative to the more competitive worlds of 2009. The reality is two boat sail testing can lead to different shapes than race testing- we learn this in the America's Cup and in keel boats all the time! I guess building 18 free sails tends to build up loyalty. The Raptor sails are pushing the limit of flattness for racing in light winds. The Raptor sails are also close cousins to windsurf designs. Remember the only similarity between moth sails and windsurf sails is that both sails use cams. Windsurfers have about a third of the righting moment, very soft unsupported rigs, unlimited sail area, limited sail adjustments, rarely go upwind and are used in more wind than moths would likely rig up in- the net result is flat, large (Relative to the available righting moment) twisty sails, and lots of sails in ones quiver.

Hyde- Hats off to Mike for making it to the worlds and putting in a good performance so far. Clearly these sails are the opposite to the Raptor designs and are performing well in the lighter winds. The original North Sails started out with very similar depth distribution as the current Hyde sails and by the time the 2009 worlds came along the North sails evolved to be deeper down low and flatter up high.

KA Sails- What can one say, nothing beats strength in numbers! With half the fleet using KA sails it is going to be hard for KA not to have another great result. Amac, as always, has done his homework several years ago and keeps a lot of the top guys running his gear. Next week we will post some pictures and scans showing the differences between the KA and V8 sail shapes on the water.

North Sails- The North Sails team has taken a bit of hit this year with Rohan, Nathan, Kevin Hall and Morgan Larson out of Moth sailing for 2010. Hopefully we see them back sometime soon. Much appreciation for Brad Funk, Chris Graham and Rob Gough helping tune our product and putting in some good results! Clearly Chris and Brad are moving the right direction relative to 2009- keep it up.

The 2010 North designs have evolved into slightly flatter and more draft forward sails with an improved twist profile. Some of these changes are due to the progression of stiffer masts over the last year. After the worlds we will have to decide if this was taken too far or if the light air of Dubai is an fluke. We have also dropped the V6 design to help reduce the choice of sails available- quite frankly this was pretty confusing for some sailors to decide what to buy. The demise of Bladerider and hopefully the end of sailors trying to use the soft Bladerider masts also propagated this change.

Next week we will also outline some of the improvements to the 2010 North Moth Sails. Apart from the ongoing shape development, a lot of work has been done to help increase the durability of the North Sails in collaboration with Kai Hopf from North Windsurf. These are very expensive pieces of equipment and we want to make sure our clients get the best value for their sails.

Good luck to everyone for the final days of the worlds.

Southern's Foiling Moth rig explained

2009-10-15T16:46:00.000-04:00

Nice article copied from Sail-world.com

Southern's Foiling Moth rig explained

''Mr Foiling Moth' Rohan Veal flying with a Southern Spars rig at the 2009 Int Moth Worlds' Sean Trew (Pacific Fog) ©

During the recent CST Moth Worlds held in Oregon, Southern Spars new rig design was put to the test. Results are in, and 10 of the top 20 competitors were using Southern Spars kit.

So what makes up the Southern Moth rig?

The key objective was to produce a rig that would fit the range of sailor weights now common in the Moth class. After a collaborative R&D effort between Southern Spars and North Sails that included analysing mast stiffness characteristics and current sail designs in the class to the nth degree, it was decided that two spar options would be produced.

Southern Spars developed its two masts: the standard P1 mast suited to all sailors, as well as the aptly named Phatboy mast for the heavier sailor. The rationale for developing two different masts is that larger sailors apply more force through greater righting moment and consequently force masts to bend more than a smaller sailor. Therefore, it made sense to design two masts with different levels of stiffness that would bend equally regardless of the size of the sailor. This evens out the playing field for a larger sailor by allowing them to make better use of a standard sail design.

Both spars are two-piece masts made from high modulus carbon - laminated to give the most consistent bend possible; they are joined with a spigot. The mast plugs are made of lightweight Acetyl plastic, while the spreader attachment is carbon and the stay attachment is a small lightweight alloy fitting – presenting less windage than the previous mast.

The new high modulus oval boom is approximately 25% stiffer than its predecessor making vang changes more decisive; it also offers less windage and weight. The mast package has absolute minimal weight at approximately 2kg fully rigged.

Southern’s Composite Rigging have also developed EC6 carbon stays for the Moth. The new stays are 1.9mm in diameter and weigh just 29g apiece. This is considerably lighter than both PBO and wire rigging, which weigh in at 44g and 128g per stay respectively.

by Brenna Pringle 5:59 AM Thu 15 Oct 2009

Worlds Lessons

2009-08-30T14:18:00.009-04:00

So the Moth Worlds are over, I finally have had a chance to take a well deserved rest from Mothing and have started reflecting on what can be done better in my own personal sailing as well as what North Sails can do better for the 2010 worlds.

For me it is simple, more time in the boat is the only way I will be able to compete with the level the class is heading. Clearly speed is not all that is needed to win these days, good starting, good tactics, good boat handling and reliability are all essential. These are the items I will focus on in the next six months in that order. Nothing new to sailing, but defiantly more important in moth sailing than ever before. Maybe I should listen to Dave Lister and stop blogging?

Now onto the sails. Always room for improvement in sails as well. I think overall we have to be very pleased with the way the North Sails performed. Our goal was to have 5 boats in the top ten which was realized. Obviously Nathan won the US Championships and we also had 5 boats in the top ten for the US Champs too.

Below is a list of the gear table I made after the event of the top 30 sailors (Obviously some sailors used multiple gear, but I think this is the best representation of what everyone used):

As with all sailing, the best sailors placed well and I am sure Bora would have been able to win in any boat, mast or sail combo. Unfortunately we did not have our sails on many Mach2's (Only Nige who used our sail from time to time with good effect). Interesting is that the first 9 of 10 Bladeriders used North Sails.

Top 11 Bladeriders

Back to the subject here, what did we learn about making the sails better? It was clear that the stiffer carbon battens are critical, esp as the wind increases. Some sailors used the carbon battens in the top three battens and others used them in the lower battens. I personally used the carbon battens in all of the battens and felt that my sail looked pretty good and matched the Southern Rig well. We will test some new sail shapes, which are a slight modification on the current theme, but taking lessons from the V6 which really seemed to be the best all around performer. North will also spend time looking at how to make the sails more robust without adding weight, esp in the luff sleeve which like all moth sails tends to get hammered rigging up and carrying out to the launch site.

Kevin Hall had a test V10 design which was closer to the V6's molded shape with a reduced luff curve to fit on a super stiff Southern mast, this shape maybe adapted for the stiffer masts anticipated for the worlds in Dubai.

My feeling is that mast development will be where we see the most development going into the next world championships with Southern and CST working on the fine line between light weight, stiff and robust spars. Stiffer masts will be key and of course nobody is going to want to carry heavier rigs or risk failure which will make getting the right amount of off axis carbon dialed perfectly.

Rohan, Bora and Nathan in the US Champs

Kevin Hall leading race 1 of the US Champs

Typical race start at the worlds, short line only the top ten boats had a clear lane, after the start if you did not nail it you had to wait for the top ten boats to clear out before you could put the bow down and send it.

Yours truely yet again overstanding the top mark.

Rohan, Rob, Chris W, Adam and Chris G

Rohan and Nathan leading in the US Champs

Nige proving he still has it, nothing goes better to weather than Nige in 20+ knots!

Fleet of North Equipped Moths following Bora around the top mark at pace

Of course the most important lesson of all was how cool all the moth sailors are and what a great group of sailors who I can now consider my friends, nice to meet everyone!

Photos from Sean Trew at http://www.pacificfog.net/mothworlds2009/ ubercool guy and I am sure everyone in the moth class appreciates Sean taking time out of his life to document our crazy addiction to share with the world.

Also, thanks to our sponsors, esp CST, Zhik and West Coast sailing. Last but not least to the Columbia Gorge Racing Assosiation and all their volunteers who made for the best ten days of sailing I have had in many years- Thanks!

Stay tuned to see what is going to be the next developments from North Sails and Southern Spars to improve your boats performance.

Sailor Guide

2009-07-29T20:44:00.007-04:00

While the gear guides are cool and of course Moth Sailors are "Gear Heads" when you really get down to it, I think the lineup for this years World Championships is what the class should be talking about. While maybe small in numbers the list is pretty impressive in quality, quick Google search came up with the following:

Scott	Babbage	2006 29er World Champ, 2nd Moth Worlds
Dalton	Bergan	2006 49er NA Champ	2005 49er NA Championship 2nd
Anthony	Boscolo	2008 29er US Champ	1996 US Double Handed Champion, Bemis Trophy
Sean	Couvreux	2001 Rolex Olympic Classes 49er 2nd
Rob	Gough	2009 Victorian State Champs, 2nd
Bora	Gulari	2008 NA Champion	2008 PCC Champion
Kevin	Hall	2005 Finn US Champion, Olympian
Hans	Henken	2008 29er Euros Bronze
Morgan	Larson	2007 49er NA Champion, 3x 3rd Worlds
Andrew	McDougall	2008 World Championships 2nd
Charlie	McKee	2001 49er World Champion, Bronze Olympics
Jonathan	McKee	2001 49er World Champion, Gold Olympics
Nigel	Oswald	2000 UK National Champion
Nathan	Outteridge	2008 49er World Champion, 2009 too
Simon	Payne	2006 World Champion, 5x Euro Champ
George	Peet	2005/2006 Volvo Ocean Race
Arnaud	Psarofaghis	2008 European Champion, 2009 too
Chris	Steele	2007 Optimist World Champion
Rohan	Veal	2005 World Champion, 2007 too
Tim	Wadlow	49er Olympian, 2nd 2007 49er NA's

Surely there are people with great sailing achievements I forgot or whom I have not met yet.

See everyone at the regatta.

Pimp your ride

2009-06-09T11:10:00.007-04:00

The following sails are available:

Production V6- Best for CST 351, 352 and 353 or Standard Bladerider mast. Used ONCE for 10 minutes- make offer.
Production V8- Best for CST 352 or 353 or Southern Spar. Used 10 times, cloth in great shape, luff sleeve a little tattered, but I can fix- make offer.
Production V10- Best for CST 354+ or Southern Phat Boy. Brand New
Development Sail v7AP. Slightly deeper sail, suitable for larger sailor and best on softer mast- used twice, make offer.

Also available in time for the Worlds are:

North Sails Narrow Mast Cams (Compatible with North, KA or Bladerider sails)
North Padded Spectra Hiking Straps (For that "Locked in" feeling with your machine)
North Carbon Batten Sets at 400g
Carbon Shrouds- gucci!

Please inquire with me at: chris at design dot northsails dot com

Another Championship

2009-06-09T10:16:00.002-04:00

TNZ sailor Kevin Hall winning the Oregon State Champs in the gorge- photo credit to Pacific Fog

Been too busy to blog over the last couple weeks with North Sails Design services finishing some Virtual Wind Tunnel and VPP studies for the 100' Alfa Romero, VPP/CFD development for a canting keel 80'er in build at McConaghy Boats and load annalyisis for a 90' Cat. Hopefully my lack of blogging does not get me kicked out of the Moth Class!

The US Fleet just finished a tune up regatta in the Gorge. The West Coast fleet has been getting pretty impressive where half the racers were former olympic sailing team memebers. Kevin Hall used his North Sail with Southern Mast in the 1st half of the regatta to devistating effect. Adam Lowry also used the V10 mainsail to great effect and posted a 5th (Did I mention Adam is 6'6" and 89kg).

Nice Video, also from Pacific Fog of the racing- check out Kevin motor by everyone off the line.

Southern Spars Kit

2009-04-23T21:55:00.005-04:00

Big week this week, got my new Southern Spars mast and boom. These are some seriously nice pieces of equipment. The mast sets up perfectly with the V10 mainsail and should be good with the V8 too. The main difference between the Southern Rig and the CST rigs is a slightly smoother taper which makes for a stiffer tip. This allows for the mainsail to blade off very smoothly in the head rather than the traditional head dumping open which we have all become accustomed too.

Below are some pictures:

V10 Mainsail with moderate downhaul on Southern Rig and Boom

V10 mainsail with high downhaul and vang on Southern Mast and Boom

Oval boom is 25% stiffer making vang changes more effective

Vang cleanly ends internally for less windage

Normally I hate metal fittings on race boats, but the hounds attachment on the Southern Rig is very sexy, a well engineered stainless fitting for minimum windage, maximum reliablity and comparable weight to a carbon end

Spreader attachment fitting- very small, very strong, very light

Mast joint with recessed set screw

Sweet package!

If you would like more info on the Southern Spars, please feel free to drop me a note at:

chris at design dot northsails dot com .

Pricing for the rigging is as follows:

Mast 1550 NZD 871 USD 662 Euro 594 GBP
Boom 920 NZD 517 USD 393 Euro 352 GBP
EC6 shrouds 756 NZD 425 USD 323 Euro 290 GBP

(Headstay, Shrouds, Backstay) Shrouds and loops are 28g vs 120g for standard wire rigging. Carbon rigging is 2mm diameter vs about 3mm for wire.

If you are interested in a sail, please visit:

http://www.bladerider.com.au/

http://www.northsailsod.com/

Silver Bullet?

2009-03-22T10:16:00.012-04:00

Moth front and center at North's Headquarters

Great start for the North Sail's International Moth program. Our V7 and V8 designs have been used in only three championships to date. In each of these three events only one sailor has used the North Sail for the entire event. However, in each of these events the lone sailor with a North Sail convincingly won the regatta:

2009 Australian Championships- 1st Place Nathan Outteridge (North Sails V7 MH)

2009 US Midwinter Championships- 1st Place Chris Williams (North Sails V7 MH)

2009 Victorian State Championships- 1st Place Rohan Veal (North Sails V8)

This past weekend at the Vic States Rohan raced with the new V8 design. Rob Gough from Tasmania also used a North V8 in the first two races, taking a 1st and a 2nd with the sail before heading back to Tasmania. Both Rohan and Rob were using new Bladerider VRX's which have been immaculately constructed. Rohan was using Bladerider spars and Rob was racing with a CST 353 mast.

These two new V8 sails were having a slight problem keeping the cams rotated, we are looking at a couple different details to solve this problem (Changing battens stiffness, stronger luff sleeve material and revised orientation, batten angles, etc). I am sure both Rob and Rohan would have been even faster with sails that had better cam rotation. Once the sails are 100% we will be starting our first production run of about 50 units.

The first batch of Southern Spars masts and booms have been shipped out. A few of these rigs will be tested in Hawaii as well as the first North Sails V10 design.

Winning equation for everyone to think about: Bladerider + North Sail = Silver Bullet

What's on YOUR mast?

Southern Spars

2009-03-18T21:34:00.010-04:00

MemBrain Model of Southern Moth Rig

I always enjoy working with Sparmakers, it was one of my favorite parts of the AC design and luckily a very large part of North Sails Design Services work.

One of the things I find fascinating with mast analysis is that simulations can be checked with hand calculations pretty easily. This is something which is not possible with sail design, maybe this is one of the reasons that sail design still is very much a mix of art and science where mastmaking, while still a very creative process, is a pure engineering exercise.

Working with Southern Spars is always great, they have more engineers in-house than most of the other mastmakers combined (I don't think that is an exaggeration)! So there are always new tricks to learn. As everyone will soon know (Or should have figured out by reading the sail selection chart) the new Southern Rigs are a little stiffer than most other moth rigs.

Right now we are developing the V6 and V10 designs. North Sails Cape Town has built a lot of test sails so far for the Moth, so it was important to try to model the Southern Rig carefully to get the luff curve perfect in order to keep our prices affordable. Therefore a lot of homework was done to hopefully get the V6 and V10 designs perfect on the 1st couple prototypes.

The above graph is the measured deflection and predicted deflection of the CST 351 tubes. This test was required to calculate the EI's (Stiffness and Stiffness distribution) of the most common skinny mast.

Two Southern Spars tubes are being offered, the Standard P1 tube and the Phat Boy tube for sailors above 85kg or so. The theory is that larger sailors apply more force through greater Righting Moment and therefore force masts to bend more than a smaller sailor.

Therefore it is possible to design two different stiffness masts which will bend the same if a more powerful sailor is using the stiffer mast. This is critical for North Sails because by understanding this relationship we can make a mainsail design which should work for both rigs as long as sailors choose a rig which is appropriate for their size and fitness. This also gives larger sailors a more level playing field as they will not loose as much power through added mastbend than the average mothie.

The chart above shows the total mast deflection of a CST 351, Southern Spars P1 and Southern Spars Phat Boy rigs. Also shown is the Southern Phat boy rig with an additional 10% more downhaul which is a good measure of the added mastbend the stronger sailors can exert on the mast (Mostly through side bend) than the average mothie.

Side Bend of spars modeled in MemBrain

Fore/Aft predicted bends

Please feel free to contact me if you are interested in a Southern Spar for your Moth and I will put you in contact with your closest Southern dealer. Prices and info on the Southern Spars Element C6 micro carbon rigging to follow...

Moth Midwinters

2009-03-06T15:57:00.010-05:00

Just back this week from the Moth Midwinters (20 hour drive down and 30 hour ride back home through a snow storm). We had a small fleet (Only 3 Boats) but had a great three days practice before the regatta where we all were able to try some new things. Most importantly for myself, I was able to try the V7MH design which is the same sail that Nathan won the Australian Nationals with. The sail setup great on my CST 352 rig, but I am looking forward to giving it a try on the Southern Spar as soon as it arrives.

In other news, the 1st batch of V8 sails left for AUS, although they just missed delivery for the Adelaide International Regatta. Hopefully we will have news to report on the new designs next week. We will then go straight into production of the V6 and V10 designs.

Also note that there are two V7 AP designs left for sale. Please drop me a note if you are interested. One sail is unused and the other only used three times. These would be good sails for larger or stronger sailors with a standard bladerider rig, Fastacraft Mast, C-Tech or a CST 351 mast.

Details will be announced for the Volvo Ocean Race Moth Expedition regatta in Boston next week. Posibility of a dozen boats making it the biggest event on the East Coast to date.

Enjoy the pictures from testing before the midwinters. As always, hospitality in New Orleans was once again amazing. Next years regatta will be Feb 17-20th.

Sail Model Guide

2009-02-14T13:16:00.008-05:00

Overlay of the V6, V8 & V10 mainsail designs, note similar mold shape

In the latest Mothcast Bruce McLeod and Luka Damic raised the point that the new North Sails V-Series of models is a bit confusing (Thanks for pointing this out!). Obviously our intention was not to confuse the market, so I have tried to clarify things for potential customers. (By the way, if anyone ever has questions, please feel free to send me an email: chris at design dot northsails dot com.)

Concept- As stated before our concept and North Sail's philosophy is always to offer only the highest quality and fastest sails possible. After months of research and testing, we concluded that due to the range in rig stiffness and sailor sizes that a single sail design will never be able to compete against sails which are more optimized for a specific mast. Furthermore we we did not want to force our clients to buy a mast to match our sail design (Similar to what is done with windsurf sails).

Therefore we identified a range of luff curves for the various moth masts and then modified the sail designs to suite these masts. The V6 design therefore has 10mm more luff curve than the V8 and the V8 has 10mm more luff curve than the V10 design.

By tailoring a design to a specific range of mast stiffness we can then adjust the head width and sail shape. For example, a stiffer mast can support more girth in the top easier- which is easy to accomplish with the area saved by taking out a little luff curve.

See the image below to understand the effect of luff curve on the head width:

Similarly a sail design optimized for a softer mast needs to be slightly finer in the molded shape in the front to prevent the sail from being too draft forward in lighter conditions. This effect can be seen in the image below:

Further optimization- In a perfect world our lighter clients will sail with slightly softer masts than our heavier clients. Therefore lighter sailors would end up using the V6 design and heavier sailors using the V10 design. However, as one can see in the images, the sails are not radically different from each other. A rider who wants to have a more customized quiver of designs may end up with a V10 design for lighter conditions and a V8 sail or stronger winds. This would allow the V10 sail to setup with less downhaul in light winds for a given sail depth. We will continue testing these concepts as time goes by and can help our clients decide what is the best designs for their needs.

Over the next couple weeks we will be testing different mast/sail combos and we will give our suggested setup once we have more data.

Cloth Matters

2009-02-09T12:21:00.009-05:00

X-ply monofilm (left) vs. ODL04 (right) used in the V-Series North Moth Sails

Instron Testing ODL04 at nearly 100kg

Instron Testing X-Ply (Fill test shown, warp, fill and bias are tested)

In sailmaking the shape and design of a sail are very closely related to the cloth used in a sail. Likewise the performance of a sail has a lot to do with the cloth it is made from, which is why we feel it is important to use cloth that costs 3 times more than film.

Below are the results from tests this week of standard X-ply monofilm vs. ODL04 Technora used in the V-series Moth Sails. It is not surprising to us that the ODL04 is 1.39 times more resistant to stretch in the warp at 1% strain even though it only weighs 56% the weight of monofilm. With sailcloth the old saying, you get what you pay for is very true.

ODL04 1mil film results.

Smaller Stretch numbers are better, larger Loat at 1% strain are better

X-Ply test graphs

Sail Sale

2009-02-03T22:39:00.008-05:00

North Sails and Bladerider are offering a sail sale to introduce the North V8 Moth mainsail. Buy two mainsails with the carbon batten upgrade and receive 20% off retail (Team up with a buddy and save some cash)! Contact your nearest North Sails loft or click here.

The big question lately is, "What is the different about the North mainsail?" The original concept of the North Sail was to have a powerful design which made tacking, gybeing, starting, etc easier. However, over the last several iterations of the design, the shape has evolved to a sail which has greater top end speed potential through flatter sections and good takeoff power with an improved twist profile. As you can see in the image below, the sail is straighter in the back for low drag when foiling and has a tight mid leech for improved upwind pointing and early foiling.

North Sails philosophy has been simple for the past 50 years. Build the highest quality, best engineered and fastest sail shapes available- no shortcuts and no compromises. The V8 mainsail design is no exception to the North Sails philosophy with only the best material used on the body of the sail (1mil Dimension Polyant Technora Scrim), low friction Dimension Polyant Square Weave Dacron bias cut luff sleeve, RBS Epoxy or Tapered Carbon Fiber battens, shroud chafe protection, internal downhaul webs, adjustable head loop, tell tales, etc. The result is a very light, sail which is easy to use and has incredible top end speeds.

We also have a list of about 10 early test sails which are for sale for anyone who is interested. Mostly deeper sails which would be suitable for heavier sailors or lighter venues when just getting up is the key to winning and high top ends speeds are not necessary. E-mail me if interested- chris(at)design.northsails.com, or phone- 1-203-907-9323

Australian Moth Nationals Success

2009-01-28T21:49:00.006-05:00

Australian Moth Nationals Report

Last week the Australian Moth Class held their National Championships in conjunction with Skandia Geelong Race Week. Most people agree it was the most competitive moth regatta to date with many of the top finishers in the World Champs finishing out of the top 5.

Over the last five years KA Sails has built a nearly 90% market share in the class with the top 10 boats in the last two world championships. This was the 1st major regatta for North Sails. Nathan Outteridge was the only rider to use the North mainsail the whole regatta and won the regatta by a 6 point margin counting a 1st, six 2nds and a 3rd out of 42 racers. Not only was this the first regatta for the new North Sail, it was also the first regatta for Nathan, a newcomer to the Moth Class (But as the current 49er world champion and Olympian, his pedigree is without question).

Nathan used the v7MH design built at North Sails South Africa. This design has been developed by Chris Williams in conjunction with two time Moth World Champion Rohan Veal and European Moth Champion and North Sails Suisse designer Arnaud Psarofaghis.

We are currently finalizing the design for the production sail. We plan to offer three models based on the sail Nathan used in the Nationals but fine tuned for sailor weight and rig stiffness:

V6 - slightly more luff curve and less seam shape suited to bendier masts, +18 knot winds and sailors weighing less than 65kg. (Available April 2009)

V8 - all round sail suited to most common masts and sailors weighing from 65kg to 75kg. (Available March 2009)

V10 - less luff curve and slightly more seam shape suited to +75kg Mothies using a stiffer mast. (Available April 2009).

Retail cost will be $1390 USD FOB North Sails Cape Town. Optional upgrade to carbon fiber battens is available for $95 USD.

Please contact Chris Williams or Rohan Veal with any inquires

Congratulations to Nathan and many thanks to Rohan and Arnaud for the help.

Arnaud's Sail

2009-01-18T07:19:00.004-05:00

After three months of development North Sails is confident we have the shape of our new mainsails dialed in. After the Australian Nationals we will be finalizing the details for the production sails and some subtle refinements in the sail shapes if needed. Instructions will also be posted on how to order your new sails and options which are available.

We would like to wish all of the competitors in the Australian Nationals best of luck and thank Arnaud and Rohan for their help with testing new sail designs and offering feedback for improvements.

Below are some photos of North Sails Suisse sail designer and 2008 Moth European Champion Arnaud Psarofaghis testing the new v7 Medium/Heavy Aramid Scrim mainsail in Geelong.

North Sails VPP Action

2008-12-04T18:07:00.016-05:00

While news on the North Sails Moth developments are a little slow (Testing is still ongoing with our Version 6 designs shipping to Melbourne next week) I thought I would show moth sailors a little bit of what we have been working on with larger yachts.

While this may not seem applicable to Moths, in general Mothies are also techies and so maybe this will be interesting. Also, in the very near future we will have the VPP setup to rank moth sail designs and trims in a similar manner. What is interesting about making a VPP for a moth is that it may actually be a little easier to tune and acheave accurate results. Mainly because if we concentrate on foiling conditions, it is easy to calculate the foil drag as they produce a known amount of lift (Yacht and Crews mass minus any lift from the sail due to weather heel). Therefore with a known amount of lift, the drag can be established easier for a given boatspeed than a traditional yacht which has more variables.

What follows is a bit of background put together for the division of North Sails known as the Design Services Group (NSDS). NSDS is where I work, in a nutshell we provide designers and yacht teams with answers using technology developed for the AC. There are some pretty interesting projects from rig tuning and development, to sailplan optimization, load studies, etc.

Anyway... North Sails Design Services provides yacht designers and projects access to tools for independent analysis which can be used to evaluate different options effecting performance. While North Sails is not in the business of designing yachts, North Sails does believe that a understanding of the entire yacht/rig system and how the aero forces effect the hydro side of the equation. Understanding the whole system allows us to develop faster sails and help designers improve their yachts.

The North Sails VPP System is unique in that it is the only 100% CFD based VPP which is available for designers to use. Why is a CFD based system better than standard empirical and coefficient based systems? Traditional VPP systems use either empirically based or formula based techniques to calculate hull drag and a sailplan’s forces. For example, a standard VPP may use a formula based analysis of a hull (IMS Style or Delft regression formulas) to estimate the hull drag on a yacht. This leaves quite a lot of room for error, especially when testing different hull forms or sizes which are dissimilar to the hullforms which the delft regression series arrived from.

Usually the sailplan’s aero forces are coefficients (Usually from wind tunnel measurements) that have been tuned by reverse calculating the VPP performance estimates to match real life measurements. Therefore both sides of a traditional VPP’s equation leave some room for error when scaling from one yacht to another.

By using CFD for both the Aero and Hydro sides of the VPP equation, errors from scaling & adjusting the form factor of the Hull and Sailplan are reduced. Below is a validation study where the hull and sails of the Transpac 52 Platoon (2008 J/V Design) were modeled in CFD. These results were plotted against logged data from races which the Platoon won in the 2008 Audi MedCup series.

As you can see the VPP appears to be more accurate than the onboard instrumentation of the yacht (State of the art BravoRacing package of electronics- same as used by Alinghi). Besides the wide scatter of data, the instruments also appear to have overestimated leeway (Although I am looking closer into this- could TP-52's sail with 4+deg of leeway and still win races?) this has effected the recorded TWA (Sightly wider) and results in a slower VMG. The formula used by the instruments to calculate leeway is: LEEWAY = (12 * Heel) / BOADSPEED^2 .

What should be interesting for many yacht designers should be the fact that the North Sails VPP system is capable of making accurate predictions of yaw balance and rudder angles. This is the result of testing many variables such as sail meshes, sail force calculation options, vortex modeling, hull meshing, foil analysis, etc before fully understanding how to best use Flow/DasBoot/VPP to provide the most accurate yaw balance predictions. The tests with the Transpac 52 did not have any adjustments or changes to the rig position, but if a designer wanted to test yacht balance, the VPP allows for easy adjustment of rake and rig position relative to the yacht to test different balances. The VPP would then give results of the changes including performance and rudder angles.

Flow/MemBrain is the design suite which North uses to very accuratly predict sail shapes. These shapes are then tested in CFD and forces are created. Flow is a Vortex Lattice CFD Code which is used to calculate sail forces and pressures for the VPP and the FEA solvers. MemBrain is a Non-Linear FEA model incorporating the rigs longitudinal stiffness, transverse stiffness, the JG and EA as well as the running and standing rigging’s EA’s. The stiffness properties of the sails are modeled based on the actual layouts , fiber modulus and yarn distributions exactly matching the sails that will be built.

MemBrain balances the internal stresses of the rig and sails with the external loads from Flow or other CFD programs such as CFX. Internal stresses such as rig pretensions, sheet adjustments, sail controls, etc can be adjusted as in real life to ensure that the sail shapes tested in Flow match the same trim as expected onboard. This reduces the need for estimates on sail area reduction coefficients (Reefing) or sail trim coefficients such as (Flattening) used by most VPP’s.

The above image is of the rig tune used in a recent project. Rig tune can be adjusted at an extremely high degree of accuracy. This applies to the moth rig as well.

Downwind sails can be modeled using CFX to test sails at wider AWA’s or which are likely to be turbulent. CFX can couple with MemBrain in the same manner as Flow.

North Sails design services also has access to one of the best free surface Hydro CFD programs in the world. DasBoot is a Potential Flow, Free Surface Code used by Alinghi, J/V Yacht Design for their TP-52’s & Volvo 70 development for Mean Machine. DasBoot was written by Michael Richelsen who also wrote Flow, MemBrain & the North Sails VPP. Originally DasBoot was written for the Illbruck IACC Challenge and later refined during the design of the Volvo 70 Mean Machine (Which unfortunatly ran short on money). The results from DasBoot are used to generate hydro resistance files for the North Sails VPP. (DasBoot is a potential flow free surface code. Doublet & Source singularities. But unlike most hull codes DasBoot has a boundary layer model)

2008-11-24T12:47:00.006-05:00

North Sails Suisse sail designer and 2008 Moth European Champion Arnaud Psarofaghis testing the North Sails v3 mainsail in Geneva. Temperature was -5deg c but results from this and other tests are leading to even further development in the North Sails Moth Mainsail designs. New designs will be tested at Sail Melbourne with final designs ready for the Australian Nationals.

Look for some clever features on the next designs and more news as sails developments happen.

Onboard photo- v3 Mainsail 8kts TWS

Onboard photo- v3 Mainsail 12kts TWS (Little Downhaul, tight sheet)

Video of sail from off boat about 8-10kts TWS

Onboard video- 12kts TWS upwind

North Sails Mainsail

2008-10-18T11:16:00.009-04:00

North Sails South Africa has completed the 1st stage of Moth sail development with America's Cup Sail Designer and Mothie Chris Williams. The goal of the project is to offer the fastest sail shapes in three different price levels and designs suitable for all sailors:

Step-up MonoFilm- 4mil/3mil combo All Purpose Design $915 USD

Dimension Polyant Aramid- ODL04 1mil Scrim Mainsail $1,198 USD

Cuben Fiber- CN13F.5 0.5mil AutoClaved Laminate $1,578 USD

The Cuben Fiber and Dimension Polyant mainsails offer approximately 1050g and 750g weight savings over the KA MSL-13 mainsails respectively.

***Prices are FOB Cape Town***

In addition to three construction styles, there are three designs to chose from:

All Purpose (AP) Mainsail- Designed for the club racer in a very forgiving shape with maximum power in lighter conditions with the ability to depower for high wind strengths

Light / Medium (LM) Mainsail- Designed for earlier foiling than the MSL-13 which can be translated to higher pointing ability in lighter winds and deeper angles downwind. Target windspeed 5-16kts.

Medium / Heavy (MH) Mainsail- Still powerful for maximum power off start lines, and good tacking / jybing performance, but more forgiving shape to allow control in strong conditions. Target windspeed 10+ knots.

Design Notes- The most obvious difference between the mainsails over the competitors sails is the profile:

While shifting the area higher up in the sail and reducing the foot length offers a slight advantage downwind and in lighter conditions, it is not the most important development. Using Norths advanced FEA/CFD suite of sail programs, the rig was carefully modeled in MemBrain to understand how the mast behaved in all conditions:

(Mast modeled in FEA with 30kg weight)

(Mast / Mainsail simulated in MemBrain)

Using these advanced tools has allowed the mainsail to be designed smoother and fairer than using traditional techniques of empirical development as well as learning how different controls affect shape and trim:

(Image showing effect of 1cm C-Ham on sail Shape)

In addition, forces from Flow (CFD) allow forces from many models to be compared to each other for easy validation of different sail designs.

(Prototype Mainsail onboard upwind aprox 12kts)

(Mainsail onboard downwind aprox 10kts)

Detailing

Weight has been a very important driving force in the development of the North Sails moth mainsail. Only the best materials have been selected. For example the square weave luff sleeve costs twice that of other materials, but is stronger and allows for less friction when adjusting the C-Ham (Esp if the sail is wet). Numbers and insignia will be offered as stenciled ink to save further weight.

Monofilm mainsail

(Prototype mainsail v2 on way to winning race 1 of the Heineken HPDO regatta by over 1 leg, windspeed aprox 5-7kts)

More photos from HPDO Regatta- Special thanks to PhotoBoat.com

PhotoBoat.com
PhotoBoat.com
PhotoBoat.com
PhotoBoat.com

Cuben Fiber prototype AP Design testing in South Africa

History- Originally North Sails was going to offer a 3DL mainsail for the Moth. However, due to technical issues with the 3DL Drum (3DR) we have decided that Cuben Fiber is a better solution for the time being. Below is an image of the 1st North 3DL Moth Mainsail.

Development- Our intention is to continually develop the mainsail design and construction, keeping a limited stock of sails. Therefore please feel free to contact me for further info or future developments and of course feedback is always appreciated.

Testing- While always ongoing, we are planning on some testing sessions in November 2008 to get feedback from the worlds top moth sailors- stay tuned for notes from these tests.

Ordering- Contact Chris Williams or your nearest North Loft to buy your own North Mainsail:

Chris Williams
chris(at)design.northsails.com
1-203-907-9323

http://www.northsails.com