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Miter Cut Genoa

I'm about to start shopping for a new genoa and I was vacillating between cross cut in Marblehead and radial cut in Warpdrive. Hydranet would be nice but is a bit too costly. I have been told that crosscut furls flatter but I have no experience with a radial cut headsail and I'm not sure if that is really true. I thought that miter cut sails were old thinking that had become obsolete because of better materials but then I came across the claim that miter cut furls better/flatter than crosscut. A genoa that can be part furled and still retain a reasonable shape is appealing. Anyone have any knowledge or experience that they would share?

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post #2 of 10 Old 01-03-2019
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Re: Miter Cut Genoa

It depends on what you are doing with it. If you are racing, you should go radial. If you are cruising and plan on using your furler to reef, go with cross cut.

The cross cut sail is more tolerant of being roller reefed. It is easier to make, and easier to recut as it ages. The radial cut is probably going to have a nicer shape, and depending on the chosen material, less prone to stretch.

The Marblehead is just a basic crusing dacron cloth that has the same strength and stretch characteristics in all directions, which is why they can use a simple cross cut with it.

The Warp Drive has most of its strength along the warp of the cloth, which is why radial construction is used. The radial panels are aligned so that the stronger warp fibres are along the load paths of the sail.

If it were me I would go with the warp drive. It will be a much sexier sail imho!


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Re: Miter Cut Genoa

No genoa will furl flat after more than 20% or so, unless you had one cut flat for that purpose, in which case it would make a lousy sail when not furled...

Cross cut is cheaper but losses shape more quickly than the more expensive radial cut.

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Re: Miter Cut Genoa

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Originally Posted by SchockT View Post
It depends on what you are doing with it. If you are racing, you should go radial. If you are cruising and plan on using your furler to reef, go with cross cut.
Quote:
Originally Posted by sailingfool View Post
No genoa will furl flat after more than 20% or so, unless you had one cut flat for that purpose, in which case it would make a lousy sail when not furled...
These two comments really get to the heart of the issue - A couple of sailmakers, most notably Mack, claim that on a miter cut sail, as the material stretches, the draft remains further forward and the back of the sail remains flatter. This helps to retain the shape, even as the sail is rolled.

I am currently sailing with a 140% genoa that I got with the boat. It has horrible shape to start with and (obviously) only gets worse as it is furled. It is a handful in strong winds with lots of weather helm and spends a fair amount of time partly furled to reduce the overlap. I am going to go down to a 125 or 130 which means it will spend less time part furled and, being a new sail should have much better shape overall. But keeping the best possible shape when part furled is still appealing.

Just to make things more complicated, I just read that Crusader Sails (well respected in England) recommend a bi-radial, as opposed to the usual tri-radial, for furling applications when the furler is used to reef.

Quote:
Originally Posted by sailingfool View Post
Cross cut is cheaper but losses shape more quickly than the more expensive radial cut.
With cheaper dacron this is undoubtedly true but Hyde, for example, claims that cross cut in Marblehead retains it's shape better than tri-radial in Warpdrive. Tri radial starts out better but deteriated more quickly. Also comparing prices, again using Hyde as the comparison, there isn't that much difference
Crosscut Marblehead HA 9.77 9.1oz $3771
Tri-Radial Warp Drive Cruise 9.11 9.1oz $4274
I am looking at the more expensive sailcloths in the expectation (hope?) that it will retain a decent shape longer. Maybe I should just go cheap with the expectation that it will need replacing sooner. For further comparison
Crosscut Dimension Polyant 9.1oz $2657
CDX Cruise laminate $4281

Just to muddy the waters even more, Challenge have a new sailcloth, Newport Pro Radial, which uses the same 104 fiber as Marblehead. To quote, " Sailors who are looking for a performance upgrade from a crosscut sail, but still want the durability of a high quality woven will excel with Newport PR. The combination of technology in this line provides a strong alternative to a very expensive Warp-Drive Sail or a Cruising Laminate Sail".

Initially I thought I'd have to choose between tri-radial or crosscut and then pick a loft. But now I have to decide between Tri-radial, bi-radial, miter-cut and crosscut. Multiple sailcloths and not all loft offer all options. Maybe I should just convert to Junk Rig or buy a stink pot.

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post #5 of 10 Old 01-04-2019
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Re: Miter Cut Genoa

There is a lot to unpack here. First of all, the whole idea behind radial construction is to minimize stretch by aligning the predominant fiber orientation more closely parallel to the highest forces within the sail. Since elongation and bias loading shorten the life of a sail, radial construction also produces sails which typically are much more durable than cross cut sails, especially for genoas rather than working jibs. The reduced stretch results in a much wider wind range for the sail, less heeling, the need to adjust the sail less frequently, better pointing ability across the wind range and better speed.

Radial construction is not the same as miter construction. Miter construction tries to do a similar fiber orientation to radial construction, but with a greatly simplified cutting pattern resulting in less stitching (i.e. Labor) and less wastage, but produces a sail with more stretch and therefore a little shorter lifespan and narrower wind range before it needs to be furled.

Cross cut sails are easier to broad seam accurately, so before today's sophisticated computer cutting programs, they tended to have a more predictable flying shape in light to moderate air, but would stretch much more than the two other fabric layouts above. It still is fine for working jibs since the loads on a working jib are much more vertical than on a genoa and so a single the fiber orientation is less of a problem. But genoas have much higher diagonal loadings. As a result cross-cut sails tend to have much higher bias loads and therefore stretch a whole lot more and so need to be adjusted more frequently and be furled sooner, will make the boat heel more in a breeze, and also will have a much shorter lifespan in terms of maintaining its shape.

All three sail fabric patterns should furl about as easily, but the cross cut sail would tend to stretch more and so have a much worse flying shape when deeper (more than 10%) reefed than the other two approaches to sail panel layout. These days sails that are intended to be flown partially furled are fitted with foam luffs. These are shaped so as to purposely take some of the fullness out of the sail when it is flown partially furled. Before foam luffs you could maybe furl a genoa 10% before the shape of the sail was so bad that it seriously hurt the ability to sail to weather and created large drag and heeling forces relative to drive. Foam luffs in theory improve the flying shape so that the range is increased to perhaps 15% before the sail shape starts to deteriorate with some foam luff sails purposely made to allow a little larger amount of furling without killing sail shape.

I would be very concerned about buying sails from Hyde if they are saying that a miter cut sail will stretch more than a cross cut sail of the same weight fabric. That suggests that either they did not explain things as clearly as perhaps should have been the case, or else there is something wrong with their cutting patterns, or both.

In terms of making a decision, you are replacing your current sail since it has poor shape even though it is still a 'white triangle'. That tells me that you care about the aerodynamic shape of your sails. A cross cut genoa will permanently lose its shape much faster than a well designed and properly made radially cut sail. In a discussion with a reputable sailmaker on this topic, the difference was huge. My take away is that a radial cut sail is well worth the money if you sail in a venue with period of lots of wind, very changeable conditions, and you care about how well your boat sails not only in terms of speed and pointing ability, but also heeling.

Jeff
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Re: Miter Cut Genoa

Thank you for this, Jeff.

I think that regarding the theory, and how that translates into performance under full sail, I have a good grasp of crosscut vs miter vs radial. It's furling and shape retention where I still have some uncertainty.

Just to be clear on one point, Hyde has never said that a miter cut sail will stretch more than a cross cut sail of the same weight fabric. What they do indicate on their website, is that a crosscut sail in Marblehead has lesser initial performance but better shape life than a tri-radial in the same weight of Warpdrive. Everyone seems to agree that Marblehead is the best woven polyester sailcloth so I assumed, perhaps erroneously, that Marblehead stretches less over time i.e. better sailcloth is more important for shape life than better cut. Judy from Hyde Direct liked your post so maybe she will comment on this.

I am going to go with a tri-radial for my next main and, were it not for the fact that we intend to head down to the Caribbean in a couple of years, would probably think seriously about cruising laminates for both sails. In that my main (and most others) reef from the bottom, the tri-radial layout seems to maintain better load paths as it is reefed.

I am less convinced regarding a genoa which reefs from the luff. I am moving away from mire-cut but, if you look at the layout of a bi-radial vs a tri-radial, and think about the load paths, a tri would tend to be better aligned to the load paths initially but a bi would tend to maintain those load paths better as it is furled. I hope that makes sense - images below.

Quote:
Originally Posted by Jeff_H View Post
My take away is that a radial cut sail is well worth the money if you sail in a venue with period of lots of wind, very changeable conditions, and you care about how well your boat sails not only in terms of speed and pointing ability, but also heeling.
This is very reasonable. This boat came from Long Island Sound which Is well known for light wind and sails very nicely in those conditions. When the wind picks up it is a very different story.

Bi-Radial or Tri-radial, Warpdrive or Newport Pro Radial. The field is narrowed.

I think I'll get some quotes before I decide further. Thanks to all, especially Jeff - any other thoughts or comments are very welcome.

Geoff
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head_tri_rad.jpg   head_bi_rad.jpg  

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Re: Miter Cut Geno

Quote:
Originally Posted by Geoff54 View Post
These two comments really get to the heart of the issue - A couple of sailmakers, most notably Mack, claim that on a miter cut sail, as the material stretches, the draft remains further forward and the back of the sail remains flatter. This helps to retain the shape, even as the sail is rolled.

I am currently sailing with a 140% genoa that I got with the boat. It has horrible shape to start with and (obviously) only gets worse as it is furled. It is a handful in strong winds with lots of weather helm and spends a fair amount of time partly furled to reduce the overlap. I am going to go down to a 125 or 130 which means it will spend less time part furled and, being a new sail should have much better shape overall. But keeping the best possible shape when part furled is still appealing.

Just to make things more complicated, I just read that Crusader Sails (well respected in England) recommend a bi-radial, as opposed to the usual tri-radial, for furling applications when the furler is used to reef.



With cheaper dacron this is undoubtedly true but Hyde, for example, claims that cross cut in Marblehead retains it's shape better than tri-radial in Warpdrive. Tri radial starts out better but deteriated more quickly. Also comparing prices, again using Hyde as the comparison, there isn't that much difference
Crosscut Marblehead HA 9.77 9.1oz $3771
Tri-Radial Warp Drive Cruise 9.11 9.1oz $4274
I am looking at the more expensive sailcloths in the expectation (hope?) that it will retain a decent shape longer. Maybe I should just go cheap with the expectation that it will need replacing sooner. For further comparison
Crosscut Dimension Polyant 9.1oz $2657
CDX Cruise laminate $4281

Just to muddy the waters even more, Challenge have a new sailcloth, Newport Pro Radial, which uses the same 104 fiber as Marblehead. To quote, " Sailors who are looking for a performance upgrade from a crosscut sail, but still want the durability of a high quality woven will excel with Newport PR. The combination of technology in this line provides a strong alternative to a very expensive Warp-Drive Sail or a Cruising Laminate Sail".

Initially I thought I'd have to choose between tri-radial or crosscut and then pick a loft. But now I have to decide between Tri-radial, bi-radial, miter-cut and crosscut. Multiple sailcloths and not all loft offer all options. Maybe I should just convert to Junk Rig or buy a stink pot.
Quote:
Originally Posted by Geoff54 View Post
Thank you for this, Jeff.

I think that regarding the theory, and how that translates into performance under full sail, I have a good grasp of crosscut vs miter vs radial. It's furling and shape retention where I still have some uncertainty.

Just to be clear on one point, Hyde has never said that a miter cut sail will stretch more than a cross cut sail of the same weight fabric. What they do indicate on their website, is that a crosscut sail in Marblehead has lesser initial performance but better shape life than a tri-radial in the same weight of Warpdrive. Everyone seems to agree that Marblehead is the best woven polyester sailcloth so I assumed, perhaps erroneously, that Marblehead stretches less over time i.e. better sailcloth is more important for shape life than better cut. Judy from Hyde Direct liked your post so maybe she will comment on this.

I am going to go with a tri-radial for my next main and, were it not for the fact that we intend to head down to the Caribbean in a couple of years, would probably think seriously about cruising laminates for both sails. In that my main (and most others) reef from the bottom, the tri-radial layout seems to maintain better load paths as it is reefed.

I am less convinced regarding a genoa which reefs from the luff. I am moving away from mire-cut but, if you look at the layout of a bi-radial vs a tri-radial, and think about the load paths, a tri would tend to be better aligned to the load paths initially but a bi would tend to maintain those load paths better as it is furled. I hope that makes sense - images below.


This is very reasonable. This boat came from Long Island Sound which Is well known for light wind and sails very nicely in those conditions. When the wind picks up it is a very different story.

Bi-Radial or Tri-radial, Warpdrive or Newport Pro Radial. The field is narrowed.

I think I'll get some quotes before I decide further. Thanks to all, especially Jeff - any other thoughts or comments are very welcome.

Geoff
Hi, this is Judy from Hyde Direct. Just to be clear, I’m not the Hyde representative who has been talking to Geoff. I agree with much of what Jeff wrote. My opinion differs only a little in terms of degree. I agree in principle.

In general, a radial design Genoa made of Challenge Warp Drive, will hold its shape better than a crosscut or mitre cut made of Marblehead.

Challenge Newport Pro Radial isn’t really new. It’s an updated version of the old Challenge Radial. Challenge renamed a lot of their products for their 2019 catalogue.

Newport streches more than Warp Drive because it’s the warp threads in the Newport have a lot more crimp to them. Higher crimp means more stretch in the direction parallel to the thread. Warp drive is the superior cloth vs Newport. It’s in a completely different league.

Durability and service life depends to a great extent on the size if the threads in the off-load direction for both cross cut and radial cloths. They are the threads that are exposed to the UV which is significant in tropical and subtropical climes. They also are the threads that take the brunt of the punishment from flogging. The bigger the Genoa, the more it gets flogged ( in general)

I’m curious, which Hyde rep have you been talking with?
And what boat do you havel., and what size Genoa are you talking about?

Judy

Judy B
San Francisco Bay and Delta
F24 Trimaran

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Re: Miter Cut Genoa

Hello Judy - Thank you for your input, especially as you are off cruising. I have also sent a PM.

Quote:
Originally Posted by jblumhorst View Post
Newport streches more than Warp Drive because its the warp threads in the Newport have a lot more crimp to them. Higher crimp means more stretch in the direction parallel to the thread. Warp drive is the superior cloth vs Newport. Its in a completely different league.

Durability and service life depends to a great extent on the size if the threads in the off-load direction for both cross cut and radial cloths. They are the threads that are exposed to the UV which is significant in tropical and subtropical climes. They also are the threads that take the brunt of the punishment from flogging. The bigger the Genoa, the more it gets flogged ( in general)
That's very useful insight. I hadn't come across Newport PR before and the idea that it would be more UV resistant was attractive. If Warpdrive is that much better, I am inclined go that route.

To answer your questions, it is a Catalina 42 MKII and, if going Warpdrive, 125%. We mostly sail double handed out of Buzzards Bay but intend to take the boat down to the Caribbean soon. From my previous post
Quote:
Originally Posted by Geoff54 View Post
I am currently sailing with a 140% genoa that I got with the boat. It has horrible shape to start with and (obviously) only gets worse as it is furled. It is a handful in strong winds with lots of weather helm and spends a fair amount of time partly furled to reduce the overlap. I am going to go down to a 125 or 130 which means it will spend less time part furled and, being a new sail should have much better shape overall. But keeping the best possible shape when part furled is still appealing.
Still a little undecided about bi vs tri - now can I afford a new main as well?

Thank you all for the input.

Geoff

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Re: Miter Cut Genoa

Thank you to all who contributed to this thread - I just ordered new sails so I thought that I would post a quick update.

After lots of research I finally opted for a 125% genoa and a full batten main, tri-radial in warp drive 9.1. I'm still not completely convinced that tri-radial is that much better for non-racing, but sooner or later you have to just go for it. When I started this thread I was thinking tri-radial or maybe miter cut. In the end it came down to tri-radial in warpdrive or crosscut in marblehead. I would have liked to gone for hydranet but it was just too expensive.

I ordered from National Sail Supply / Rolly Tasker. I would have preferred to have gone with someone local so that, if there is a problem, I have someone local to deal with, but the price difference was just too much to justify it. The local loft for the brand that Jeff favors were many thousand of dollars more and, quite frankly, weren't very responsive to my request for a quote. National Sail weren't the cheapest but very close, seem to have a good reputation and provided a quote a few hours after I emailed the request.

Did I make the right decision? Only time will tell. I'll let you know.

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Re: Miter Cut Genoa

I made a real mistake in not getting a radial cut IMRF main like the old one when I got a new main. I was just being cheap in the wrong place! The RFIM main had a much better shape as a radial cut, and I imagine a jib will too.
Especially for RF sails, smaller fabric panels means less stretch and easier furling and longer lasting, IMO. I won't be buying any other cut in the future.
Sadly, the PO got talked into tape drive sails and they are just garbage if anyone suggests them to you.

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