I think 'gust response' can happen without a square top sail.

Anything with a lot of roach will surely de-power as the wind loads it, bends the mast more and the leach falls away?

Doesn't tthst happen a little with a triangular sail, except it's the middle of the leach which falls away, not the top where it's wanted?

Cynically, I think the move to square top rigs is 90% about 'looking modern' by apeing the skiffs.

The skiffs I think partly use square tops for the same reasons Merlins have 4-sided sails, it's the most area within class rules and more of it is up where the wind is?

There's also an element that lots of sail development is done in the big money 18ft skiffs, a lot of knowledge gained by direct comparison in racing. So probably a class looking to tap into the latest thought on sail design will do well to tap into that and follow the skiffs?

Probably true that it's cheaper and easier to tune battens than masts?

Carbon masts can be made with all sorts of characteristics, which is less easy to achieve by tapering extruded ali tube. The carbon is also lighter so maybe springs back quicker for a given 'spring force' and the characteristics of the resin perhaps affect the damping?

Don't forget there is a lot of history with glass tipped masts in the B14 and AFAIK Finn and maybe OK? Likewise some catamarans have used carbon battens as well as glass.

For a cheapskate club sailor like me, I think some of these sails have a lot of stress in them, resulting in shorter usable life than you get from a more traditional roached sail?

And don't forget, the elliptical plaform is supposed to be most efficient?

(Blah Spitfire Wing blah......)

I'd be interested to know more about it, not sure what's been pubished since Bethwaite?

Mozzy makes some good points.

 

I'd  add that cats developed their rigs mostly without the masthead asy's that need a lot of stays to resist the forward halyard tension.

The upper shrouds on a skiff rig should be making the mast tip move back and not to leeward?

These issues make a lot of pre-bend in the upper mast a sound approach?

If you're thinking about e.g. Dart 18, there is no kicker, but high leach tension with a 6:1 main sheet on a traveller? Easing sheet is more like easing the vang on a dinghy?

Originally posted by ChrisI There's no question that for us a square top rather than a pin head is not fashion but a key part of the design - in light wind conditions and esp when tide and wind are from the same direction we go forwards when other boats are going backwards.

That's just area high up though?

You can think of a square top as either a triangular sail with roach added by a long top batten, or as a triangle with the top cut off.

You could get the same light air performance with a taller mast and more triangular sail?

It's all comparative and with a SMOD you don't really have a sensible framework to say square top is 'better'.  Better performace per sq ft of sail? Better performance within the limits of mast length? Better performance within a £ budget?                                                                         

                          

In a development class, we're talking about best performance within an arbitrary set of rules which 'tax' roach to arbitrary degrees.                                                    

                          

So what baseline do we use when evaluating a square top's all round performance?                                                                  

Presumably what we want is a rig which keeps the heeling moment constant as the wind increases above the design point of the crew hiking/trapezing to the max? Is that more about the squareness of the top or the characteristics of the mast etc? Can an elliptical sail ever be as good in this respect?                       

          

 How do we model this when designing a rig? How many rigs are actually rigorously designed and how many are just a case of sketching a sail and see how it goes?

See the old thread I bumped.

I also found a thread about the re-hash of the RS400 rig, when they tried a square top main and rowed back to just changing the cloth:    

 

https://www.yachtsandyachting.com/forum/forum_posts.asp?TID=7237&PN=4&title=rs400-proposed-changes

    

Divided opinion. some were very positive about the square top, but as I recall, it looked very nice but got spanked by Merlins around the cans?

What are the symptoms of it 'not working well' in light winds?

The boat feels "sticky" in light winds, essentially its easy to stall the rig in light winds. We have had to learn how to flatten the fully battened sail so that the flow remains attached. This has been achieved by reducing rig tension to straighten the mast whilst also experimenting with kicker to control the roach twist. Put another way - when the H2 first came along it seemed like we could sail to our PY in medium or heavy winds but when it went light we got a total kicking in PY racing but after several years of trial and error we have found some new "gears" that keep the boat powered up as the breeze falls. Hope that helps?

Re H2

Yes that's helpful.

Maybe that's general to sails with a lot of roach rather than being specific to flat-head, I've seen a few sails which are hard to make sense of when the wind gets too light.

Some boats you can leave the kicker off  in light air because the sheet gives the right blend of pulling the boom across and leach tension.

A lot of factors than can't be isolated from one another, too many variables.

Many of the Broads cruisers have jackyard tops'ls, some now have them permanently fitted, so their only reefing is at the bottom..

The H2 was a new class designed with a square top from the outset. The rig was designed by Jim Hunt from HD sails and not a man I would use the words "aesthetics or commercialisation" in connection! Of course it is possible that you are a respected founder of a sail loft and multiple world champion TT - I know I am not - but I reckon Jim designed a rig that he felt would work well rather than look pretty.

The H2 has a PN of 1034?

The Phantom, with almost no roach at all, 1004.

Blaze with a big round roach, 1033.

Dzero 1029

It's not looking like sailing's answer to nitrous oxide is it?

With respect;

I"ve spent a lot of time researching design history, and there seems to be little evidence that squaretops and gaffs have much to do with each other at all.

The traditional gaff rigs almost never used gust response in anything like the way we do, and that comes from a LOT of reading of books and articles from the 1800s and early 1900s. 

The gaff's advantages were due to low centre of effort, fewer problems in keeping the stick aloft and things like that. After reading many hundreds of pages (my mag collection dates back to 1894) I can find no information that indicates that gust response was seen to be better with gaffs than with contemporary bermudans.

The gaff rigs were almost always low aspect, whereas squaretops tend to be fairly high in aspect ratio. The gaffs normally had too much twist, way more depth than we use, and were sailed at wider angles of attack upwind and downwind.

In cats like the Taipan 4.9, which has a very big and stiff wingmast even for a cat, the former large roach gave way to a squaretop over a decade ago, and the class opinion was that the gust response was very much better. To give an idea of the stiffness of the 4.9 mast, Glenn Ashby (who was a champ in them before he was famous) told me that the mainsheet load on the 96kg 16' Taipan 4.9 was higher than that of the vastly larger Tornado - and yet the very flat squaretop on the 4.9 gives good gust response. You don't need much movement when the head is already very, very flat.

Incidentally the Taipan's co-designer Greg Goodall is credited by many (like sailmaker Ben Hall in an old article in US mag Sailing World) with introducing the true squaretop in an A Class that his brother used to win the worlds in back in the '80s. Greg followed on by also winning two world titles in the class, but if I recall correctly he reckons the increase in squaretop area is (like so many things) largely down to improved materials that allow sailmakers to make sails that don't distort and therefore suffer from leaches that either blow open or slam shut. I haven't seen him in years so this is just from memory.

Nope, or not from my experience owning and sailing a couple of them. The cat don't need as much gust response as their higher upwind speed means that a gust is a lower percentage of apparent windspeed. They also (as far as I can recall) use flatter sails than skiff types, so it needs actual less twist and mast bend to create a similar depowering effect.

I've never seen my F16 or F18 clew rise or come in to windward, personally. The mainsheet loads are way too high. We took the mainsheet off our old 20' cat and stuck it on the 36' 5 ton offshore mono we have, and it's easier to work on that than it was on the cat!

The proof may come in A Class cats. They have had extremely light carbon wingmasts, rather than stiff alloy rigs, for eons. Despite the fact that they could probably design in as much bend as they want (ie by shifting from carbon to 'glass etc) they have extremely straight masts - so straight that they don't use halyards at all but just push the sail straight up the mast from the bottom because there is basically no luff curve to create resistance.  But (AFAIK) the mainsail chord is so flat that the minimal amount of mast bend created by downhaul pressure is enough to completely flatten the sail when needed. Mono sails are still deeper (AFAIK) so have more draft to be taken out so need more mast bend.

This is just my belief and there are many people who know much more; I'll grab one of them when our season starts again.

I bought another Tasar the other week, just to sell it within the club in the hopes of generating more boats. Unlike our good Tasar, it only had dacron sails.

We took it out for a race to see how it went and it was very interesting to drop back into dacrons from the flatter, bigger, roachier Mylar sails the class now has. The old deep dacron main required vastly more mainsheet and traveller work in gusts to keep the correct amount of twist. The mylar's bigger roach and larger, flatter shape has far more gust response and it was a shock to go back to the old way. IMHO the fleet closed up with the Mylar sails because they required less work to optimise twist.

BUT..... the Mylars stay in top "championship podium" shape for longer and then lose structural integrity far faster. The old dacron sails, unless flapped and crunched, can't be killed with a stick. The Mylars, no matter how well cared for, will tear a decade or so before dacrons would start to lose any noticeable strength.

I'm still far from sure that moving to Mylar was the correct choice for the class overall.  It's not conservatism (I've had Mylar sails for decades, and love my amazing membrane yacht headsails to bits) but as you imply, for a SMOD the durability of less-stressed pinhead dacron sails makes a lot of sense.

I don't think I have ever considered the sail shape on the H2 to be about maximising speed as such, its a concept that tried to balance out all the factors that people wanted from the boat. But as you raised it the H2 sail area is 9.3 sqm and the Blaze is 10 sqm and we sail off virtually the same PY and are similar lengths and widths so I would say that in this case the H2 rig would seem more efficient than the blaze one.

Originally posted by ChrisI .....And re the A Class and ultra straight masts - I guess that shows they are experiencing the flip side of 'gust response' which is lost energy from the wind, which they don't want.

If the mast is a spring without much damping, the energy of a gust is stored rather than lost. The energy is recovered as the gust eases.                                  

                                         

I think to some extent modern materials mean the flexing is better handled in the battens and sails than the topmast.

Or maybe the hull design is significant, the Blaze having a lot of wetted surface and a generally 1990s air about it? not to mention being made out of slate.

Well the blaze and H2 are closest in terms of hull dimensions and wetted area of the examples you gave - the Phantom and D0 are considerably different concepts. Besides - as stated, I am not advocating that a square top main is really about maximising power; in the H2 it fits the designers desire for a well balanced boat that is both easy and fun to sail.

Butr isn't the point supposed to be that square top will give better gust response, make the boat easier to sail efficiently and hence give better performance around the course? I don't think any is saying it's about more peak power, apart from the river sailors who want to poke more area above the bushes, as British Moths were doing before any skiff or cat sailors were thinking about 'square tops'.  If the H2 rig is genuinely more 'automatic' it should be easier to sail well and have a lower PY. So why is it significantly slower than a Phantom? Does anyone race those against one another in conditions where gust response matters? Is the superior planform of the square top simply trumped by the amount of multi-sailmaker development that's gone into Phantoms? Or would the PYs just be wrong if you put the two boats around a course in F3 gusting F5 or whatever? The two boats must have pretty similar LWL and SA/Disp(loaded).?

I really do not want to get into a PY discussion, I think we have done that to death. I do sail against Phantoms at my club, they destroy me in the light and I often beat them over the water in medium or strong wind in part because my rig is so much easier to control. Perhaps my preferred point of reference is the opinion of my informal "training partner" who has been national champion in both Phantom and H2 as well as in many other classes who always comments on how sweet the rig is on his H2 when he takes it out to do some two boat tuning with me!

Waterline length is the same, within mm?

The only way would be  to test rigs on the same hull and even then some rigs suit certain hull shapes and conditions.

Any way please IGNORE my ramblings and carry on  Its been a great thread so far .

The Blaze keeps getting mentioned here ... and not necessarily by its owners !  Funny that - might make you think that its got something going for it.   A very different paradigm of course.  My summary ? - It would be a very boring world if we all liked the same things- I'm personally happy that people sail or race anything frankly..  Most Blaze owners refrain from comparing it to other approaches here because it is so different.

A few leave us for 'greener pastures' each season of course, but then a very high proportion do return within a couple of years.  Don't just compare boats on forums via your keyboards  - just sail them.   Go on ...Try the lot for real, you've mostly got the time and any good proactive class will willingly assist !!

Indeed, I'm looking at the H2 hull and can't understand why it would be slow in light air.

I recall a conversation a few years ago about Harrier dinghies, forefather of the H2 (?) which allegedy went well with a rig from a Phantom, in light air. Of course transplanting rigs is only going to work if the mast step happens to be in the right place.

When we go PY racing, we inevitably end up comparing with other classes.

Blaze seems like a fairly useful benchmark.

Not new, but not really 'oldskool'.                        

Not a particularly heavy or light person's boat.                 

Enough of them about that most have sailed against them.                  

In the right PY group to be on a lot of people's radar.                                    

There's not actually very many una rig s/h classes which tick all those boxes

I just raised it as being a fair example of a big curved roach rig, midway between the Phantom and the H2 conceptually.                       

It was 50 years ago!  Hull shape looks quite nice. Don't mention the weight!

Originally posted by JimC No, it was awful for 50 years ago too. Untapered mast, Solo sail planform with a extension above the top batten, we knew better even then too.

Fair comment, I sometimes tend to forget most of the junk I remember from the 70s was made in the 60s. Some of it before the 60s.

FWIW, I quite like the look of a square top sail; and if someone can tell me why it's a performance benefit, I'd happily believe them.

I think in theory a square top should be a good idea for dinghies for a given mast height. In light winds when you have more RM than power you can generate lift up high where there is usually more wind and cleaner winds. Then when the breeze pick up and you have all the power you RM can balance you can dramatically lose power from up high, which lowers the CoE in sails which allows your available RM to hold down more power. 

In practice, generating power up high in light winds may sound great, but is limited by tip losses. If you force the wind to do something hard where nearby there is an option to just go around, it will usually just do that. Similar to setting a really deep foot and them all the wind dropping out under the boom. Obviously the theory to elliptical sail shapes is to taper off toward the tip as it becomes increasingly inefficient to try and generate lift toward the end. 

If you could end plate the sail against the deck, and put wind lets on the head then it would be really nice... but both are impractical in many cases.  

The most recent Blaze sails are made by Hartley 'in-house' - and are cosmetically more of a 'square-top' than the pre-existing North one.  The informal talk within the class has suggested that they are 'better' for the lighter crews in the fleet (esp in higher breeze) as they do shed power more easily - however the results are still mostly inconclusive and very mixed.   At my own weight (80ish KG) they seem almost identical in terms of performance - but as times go on the newer sails will no doubt dominate the front as the North supplied ones age. 

   

Difference between that and the H2 is not so much the angle of the very top, but more the chord at say 80% height, which on the H2 looks to be a very big % of the foot?

Or in other words, the H2 sail is a big % area of luff x foot ?

Nearly a rectangle?

I suspect what matters is developing the whole thing to work together, mast, sail, battens, other controls, not just picking the best planform.

Sailmakers have learned a lot across dozens of classes and dozens of yearly iterations in some of those classes, so radically moving away from what we know works pretty well is a big risk.

Mike , looks like the top batten is different? If it is , that’s a little more than ‘ cosmetic’ . 

As it makes damn all difference to performance either way it's main real benefit may be that it is apparently lower cost to produce..  Some like the darker material, some do not...  This picture was taken about a year ago and today about 50+% of boats at Stone SC currently for the Nationals will most likely sport a 'new' version  (10th to 12th inclusive).  At my weight I cannot see any advantage/disadvantage against a 12 month old North - I'm lucky as I like both sails equally. ... But erm .....slightly maybe less lucky in that I have to be at a wedding tomorrow !!

Another alteration to the Blaze that makes no difference to performance? There's been a few of them over the last 12 years or so. 

Without mentioning the elephant in the room (it start with P and ends with Y) it's difficult to discuss this any further I guess

Quick question that's been asked before: When does a one design become a development class?

Totally agree with you , that doesn’t happen often does it . All one design have to adapt or die/ or become a niche boat. 

But the thing is not all moderate improvements are voted on democratically by a class in a open and honest manner. 

1) Some are just waved though by a class. ( which is not necessary wrong )

2) Some are forced on a class by a manufacturer that owns the design rights. Like the new mk3 cockpit design on Lightning 368 or the weight change to the Supernova. Don’t get me wrong , I am not saying the changes were wrong just the fact the class had no control over the change .  

When individuals are able to make changes to hull, rig, foils etc without needing a class vote.  You can’t put any mast you like on a Blaze, or any sail, or indeed any sailmaker.  You can’t put a different rudder on the back.  You can’t design your hull or pick your builder.  Name a class that has never updated anything?

You can do all of those things, it just means your 'Blaze' ceases to be a Blaze Class Dinghy.

Like you can put a Rooster 8'n'a bit rig on a Laser and race it as a PY boat. You can put foils on it if you want. The owners of the 'design rights' can't control what owners do with it. Class associations may be embedded with manufacturers, but there's nothing to stop a bunch of owners forming a new class association where people race hulls sold as Lasers, or RS600s with foils. You can buy a class yacht like an X-99, change the rig and race it under IRC. Some CA's are bound by the RYA or WS due to being adopted National or International Classes. When you buy a boat to race, if you want to go beyond club PY races, you need to buy into the class's 'ethos' and rules and MO, or pick a different class.

Err these days the py system is quick to react as they use real race time data. So if a class really gets faster is shows . As I mentioned Supernovas, they took 25 pounds out of the boat and loads of slow sailors joined the class so the py got a little better 

Ah now, this I agree with!

Originally posted by Grumpycat  Err these days the py system is quick to react as they use real race time data. So if a class really gets faster is shows .

It seems to be a self drainer. Am I correct?

If so yes massive advantage, just capsize pull it up and sail off, no worries!

If it's windy enough for the top guys to capsize, the transom flaps do the trick fairly quickly.

Most series have a discard, so maybe the odd disastrous capsize doesn't change the trophy winner very often. Even in self draining boats (RS 400, Laser,....) some people recover from capsize much quicker than others, I could point out people who capsize more often than I do, but lose less places from it.  Self draining really comes into its own in those comedy capsize events when there's not enough wind or space to sail the boat dry. I know a few handy Ent sailors, I don't hear them whining about the self draining boats being unfair, I do hear them liking more 'improving' sailors in the fleet and congratulating them when they finish a breezy race despite capsizing. Self draining doesn't make capsizing fast. My Dad used to have an Ent with a bow bag, no tanks at all, in the 2020s, we really don't want to be sending people to sea in that kind of thing!

Article by Bethwaite the younger here:

https://bethwaite360.com/square-head-vs-pin-head-rigs/

Reckons the ultimate sail design is still a carefully shaped pin head, but that it doesn't work so well with carbon masts .. which are lighter.  So if you want the benefits of the light but stiff carbon then you might need a fat head main.

This is annoying as my new boat has a carbon mast but a very pointy main sail ... worst of both worlds?

within the narrow field of dinghy racing, or more specifically drifting in dinghies inland and making it vaguely competitive, maybe not; but on wider social issues, I doubt we're that dissimilar on outlooks. 

I note your points though about feeling like a builder is pushing through changes, not something I've not experienced it personally and any time I've been around a class when changes were proposed I've never considered them bad for the class... XD controls being my most memorable I guess.  

I think it's worth pointing out that there's also some discussion around one designs and how it affects PY:

"let's upgrade our sail plan / move to carbon spars to rig the PY system" said no class chairperson or dinghy builder ever.

Usually it's all about making a boat they love to build and/or sail just a bit nicer with the technology that becomes available.  I doubt it's even really about performance in its purist sense.

Totally agree , what ever the set up between CA and a manufacturer, boats have to be sold and money needs to be made . 

Re the two examples of manufacturers (Lightning and Supernova )  forcing change ( in the nicest way ) I gave.

1) The Lightning 368 sold more boats in the 18 months after the cockpit mould change that they had sold in the preceding decade. 

2) The Supernova now regularly gets over 100 at their nationals .

So looking back , who am I to say these decisions were wrong or taken in the wrong way 

Originally posted by Sam.Spoons Just got back from the Blaze Nationals and interested to note the event was won with a North sail not the latest Hartley version.

It can be a little sophist to say things like that with no background.

Was the sail a big deal? Noticeable edge in any way?

Or was it by any chance one of the lightest boats with one of the better helms who sailed a great series and deserved to win?

It's like back in the Jurassic era of Lasers, certain sails were thought to have tiny advantage, which became a huge issue to some people because when everything is identical apart from X, X is king, even if in reality, it only makes less difference than the drag factor of the helm's hairstyle.

With a Blaze, there are a lot of variables. Your man with the North sail might just have his rig set up to work well with the sail, rather than the sail itself being 'better'. He might just be better at windshifts, starts, waves etc.

But very few people ever got laughed at for choosing North Sails.

This was more of a reply to the suggestion that the claim that all updates to a SMOD class must automatically be performance enhancing and that new Blaze sail must be faster than the old. And, yes, the sailor using it is a past National Champion and was sailing a fairly recent epoxy boat.

Take the sail manufacture in-house and make more cash, or enable sub-contract manufacture from whichever source is cheaper for the next batch and slap your own label on it.

 

 

 

Not necessarily a bad thing, some savings might even get passed on to sailors....

when given the choice, I would choose HD over North; but I fully accept North are an exceptionally good loft.

If no choice is on the menu, then I'd happily take North over other some other well known options from SMODland.  (I thought the D-Zero sail was very, very good and easy to tune in my non-expert opinion)

I now live on same street as a North Sails retail shop... it's right preppy garb around here. 

I think it's a bit of both, the new sail, built in house, is a little cheaper (about 8%) than the North but AIUI the North had been getting more expensive with every batch. Hartley Boats do have a new sail loft, sailmaker and some very expensive machinery to pay for so hopefully they'll be able to keep costs down over the next few years as last year's capital expenditure gets absorbed.

Hope the sizing was correct  .

North once brought five sails to the British moth nationals . Four didn’t measure , so North took them away and recut them and brought them back a couple of days later. Three were ok and one still didn’t measure . The sailor concerned let them have one more go at correcting it but it still didn’t measure. North then offered to make him a new sail or have his money back and keep the first sail . He took the second option and he went to HD sails who made him a new sail and recut the north so it measured.

I am not saying anything about Norths customer service which was second to none but perhaps the original problems shouldn’t  have happened in the first place . 😀

Crumbs - this is a statement I never thought I'd see on this forum !

I buy a car because it fits a specific purpose not because of the advertising. I can buy many T shirts That fits the purpose of the  North one, that don't advertise and cost much less.

I built my own boat, Wood, Plywood, Fibreglass, resin, paint, screws.. No one can tell what companies supplied the stuff.. The only things that have  logos are the sails and  I could remove the advert in the corner...

The only things that I have deliberately bought with a logo on them, are Three Rivers Race polo shirts, various sailing and model railway association / event shirts to support their activities, and The British Legion Poppy which is a logo in it's own right.