Main Sail Roller Battens


Jose Venegas
 

I am considering buying new sails for may SM2K and the sail maker suggested that the RBS Roller Battens could allow increasing the roach in the upper part of the sail, or at lest reducing the negative roach of the roller furled main and mizzen sails.  I had one of these battens on my hand and they are quite interesting:  They can support compression quite well but once they start to roll they flatten and allow easy rolling.  So, if they are placed perpendicular to the leach and not to the mast, they will roll as a corkscrew upward, without adding much to the local diameter of the furled sail.  Having had problems furling the main in no wind conditions, I imagine these battens would prevent the twisting of the leach that usually causes jamming of the main.  


 Question is: Has  any one direct or indirect experience with this type of batten?


Ipanema SM2K shrinkrapped in Boston Harbor, brrrrrr.


RBS Roller Battens | RBS Batten Systems



Dave_Benjamin
 


We sell Robichaud battens so I'm quite familiar with them. Romeo showed me a prototype for the roller batten when they were originally developing the product. For the most part roller battens have been used on genoas rather than furling mains. Vertical battens are a proven method to reduce leech hollow and I'd be hesitant to use a roller batten without some solid justification. It's important to understand that you cannot add roach to a furling main. All you can do is reduce or eliminate leech hollow. Some sailmakers have attempted positive roach in furling mains but I wouldn't suggest that for an SM. 

The real reason not to use roller battens in a furling main is that they are designed to be removed from the sail when the boat is not in use. I don't know too many people with an SM that want to drop the sail to remove battens, re-hoist, and then furl. Here is a direct quote from the Robichaud website:

"RBS suggests removing the roller battens from the sail when not sailing to ensure a longer and more responsive life.  The longer period that the roller battens are kept rolled up, the longer it may take for them to regain their proper unfurled shape. "

If you would like to work with a sailmaker who has owned an Amel and knows these boats, I'd be happy to speak with you. Brian Hancock works for us and is based in Marblehead, not far from you. Between the two of us, we can make sure you get the right sail and no dumb ideas along with it. 

Cheers,
Dave 



---In amelyachtowners@..., <jvenegas@...> wrote :

I am considering buying new sails for may SM2K and the sail maker suggested that the RBS Roller Battens could allow increasing the roach in the upper part of the sail, or at lest reducing the negative roach of the roller furled main and mizzen sails.  I had one of these battens on my hand and they are quite interesting:  They can support compression quite well but once they start to roll they flatten and allow easy rolling.  So, if they are placed perpendicular to the leach and not to the mast, they will roll as a corkscrew upward, without adding much to the local diameter of the furled sail.  Having had problems furling the main in no wind conditions, I imagine these battens would prevent the twisting of the leach that usually causes jamming of the main.  


 Question is: Has  any one direct or indirect experience with this type of batten?


Ipanema SM2K shrinkrapped in Boston Harbor, brrrrrr.


RBS Roller Battens | RBS Batten Systems



Dave_Benjamin
 

CORRECTION:

I should have said that the roller battens were more often used in non-overlapping headsails, not genoas. I would not use any sort of batten in a genoa as the pockets get destroyed pretty quick from tacks. 


Craig Briggs
 

The September Ocean Navigator magazine had an article on a newly developed roll up batten called Flattens. It's from a new UK company called Primrose Fry Technologies and the version for jibsails is being distributed currently to sailmakers by Challenge Sailcloth. The article showed it on the jib of a winning Key West race week boat.

I just got off the phone with co-founder Simon Fry who said they are now developing it for mainsails and have targeted it for release through Challenge by March, 2015. He went on to say that they expect to attain a positive roach of about half what a conventionally battened main would have - seems a huge improvement over our negative roach. 

Join SSCA for a free on-line subscription to Ocean Navigator. Oh, ok, you can just google Disappearing Battens to read the article.  Google PFT Flattens to get to the company's web site.

Craig Briggs, SN#68 Sangaris


Jose Venegas
 

Thank you both Dave and Craig,

The battens my sailmaker is proposing to use are not the ones I sent links on.  These are made of stainless steel and he has had good experience with them in other boats as long as there is enough space on the mast, as I said.

I know about the vertical battens, and would not even think about using that on my SM.  Imagine you have to bring the sail down with them in place!.  Also, if the furling is not exactly perpendicular to the battens, as somethimes happens when  the blade twists when furled under some wind conditions, the vertical battens will corck screw and jamming is almost assured.  A terrible sail shape after a little sail stretch is something else that I cant imagine seeing on my boat.  
The idea with the Roller Battens is not to create a huge positive roach, but to add some sail aloft.  So, it is not for use as full battens, but just for the last 3 or 4 ft near the lech.  I will chack that article, Graig,  thanks again

Jose


  The link is:


and they are called  "Roller battens" Page 41 of their manual


Craig Briggs
 

Correction - Flattens are distributed through Contender Sailcloth, not Challenge.
Craig on s/v Sangaris


Dave_Benjamin
 

Jose,

Our sail designer, who has 35 years of experience, has experience with the Rutgerson roller battens suggested caution with those. Very few sailmakers are using them. 

I'm not sure why you're that concerned with the vertical battens. You don't need to go full length and they're arranged so there's no overlap between the battens when we do them. Personally if I owned a boat with a furling main, I'd skip the battens entirely. My Maramu had a conventional rig. But I have a client with a good sized Oyster with vertical battens and he's been happily referring people to us. 


---In amelyachtowners@..., <jvenegas@...> wrote :

Thank you both Dave and Craig,

The battens my sailmaker is proposing to use are not the ones I sent links on.  These are made of stainless steel and he has had good experience with them in other boats as long as there is enough space on the mast, as I said.

I know about the vertical battens, and would not even think about using that on my SM.  Imagine you have to bring the sail down with them in place!.  Also, if the furling is not exactly perpendicular to the battens, as somethimes happens when  the blade twists when furled under some wind conditions, the vertical battens will corck screw and jamming is almost assured.  A terrible sail shape after a little sail stretch is something else that I cant imagine seeing on my boat.  
The idea with the Roller Battens is not to create a huge positive roach, but to add some sail aloft.  So, it is not for use as full battens, but just for the last 3 or 4 ft near the lech.  I will chack that article, Graig,  thanks again

Jose


  The link is:


and they are called  "Roller battens" Page 41 of their manual


Dave_Benjamin
 

Craig,

Sounds intriguing but with someone who has been around this business most of his life, I've discovered the pioneers are often the ones getting the arrows. I won't put an unproven product on a voyaging boat. We need to test them on boats that get sailed a lot but not out of range of a repair loft. 

And remember, all you can do is regain a bit of leech hollow. I can get far more performance out of an Amel with other sails than the incremental improvement that battens in a main offer. 


Jose Venegas
 

Dave, can you be more specific about the problems your sailmaker had with with the Rutgerson roller battens ?  Is it a problem with durability or jamming?  I had the chance to play with them and I thought the idea was briliant.  

Thanks agin for your answers

Jose.


Dave_Benjamin
 

Jose,

He and I are both sailmakers but he's a third generation sailmaker and older than I am. His experience was that the battens ended up breaking and causing damage to the sail if I recall correctly. Those roller battens have been around for quite some time and every sailmaker I've spoken to that tried them had issues. 

One tip I can offer is this. If you don't see sailmakers using a product on their own boat, don't use it on yours.

And if you want battens, there's several on this forum who have used vertical battens in the leech without a problem. Most of the problems I see with furling mainsail battens are on common production boats that use inexpensive spars. The Amel mast is much better engineered.  


Jose Venegas
 

Thank you for the info Dave,  I can see how over time the battens, particularly if they are left partially rolled in heavy air can have high dynamic stresses and cause fatigue on the stainless steel.  Althogh the stainless ribs are covered with cloth, if not replaced eventually they will break through damaging the sail.

Something to be aware of and I will run some tests on my lab to see how many times they can be flexed before they break.

I will keep you informed.


Dave_Benjamin
 

I look forward to seeing what you come up in testing. I'm more concerned about the sail damage than the batten itself failing. You could certainly carry a spare set as well. Personally I'm a lot more comfortable with a set of beautiful epoxy battens with my friends at Robichaud. Those will last for a couple of circumnavigations. 


Jose Venegas
 

Dave, that makes me feel better bacause I am not at all concerned about sail damage.  These battens, once the tip is flexed, become very easy to roll creating minimal friction between the sail and the mast slot.  Just see how flexible becomes a slanley measuring tape once you have beent it backwards.

Jose


Dave_Benjamin
 

Jose,

Good luck. Let us know how it works out. Every other sailmaker I know who has tried them won't recommend them. But maybe your guy knows something those guys with a few hundred years of combined experience don't know and we will all learn from him. 

The issue is the steel coming out of the protective covering and damaging the sail. That's been the recurring problem with these battens. I I were to use one, I'd go with Robichaud. They're a small company and the service I receive from them is phenomenal. 


Jose Venegas
 

David,

That is a very important observation that makes a lot of sence.  As the batten is flexed the steel in the inside will move relative to the one in the outside creating extra force against the end of the the protective covering.  Fortunately this potential problem can be completely prevented with proper design. 1) make the inner part of the batten a little shorter than the one outside and don't use long battens: if used perpendicular to the leach they will be smaller than the vertical or horizontal ones for the same leach.  2) making sure the ends are rounded and covered with plastic to prevent the shafe.  3) never leave them partially furled as they will continuously be flexing and likely will fatigue.  This is a true draw back as it puts a design limitation on the infinite number of reefs that the in mast furling sail can have without battens or with vertical battens.

 Thank you for bringing up this key point .  I will be happy to be a guiney pig with this design as I cant see myself puting rigid vertical battens on my amel.  

Some times innoavation comes through those who are willing to take the risks.

Jose


Dave_Benjamin
 


Jose,

If you're using the Rutgerson, the results are quite predictable. They will fail and damage the sail. If you use short battens, you'll be limited as to the amount of leech hollow you can eliminate. You will also have excessive wear at the inboard ends of the pocket. If you look at any of my conventional mains, you can see that the partial battens are about half the girth of the sail. Most sailmakers have gotten away from the short leech battens for that and other reasons. 

I don't know what will occur with making the pockets at a 90 degree angle to the leech, but it will be interesting to see. 

As a sailmaker, if I owned a SM, I probably wouldn't bother with battens of any variety. My old Maramu had a conventional rig which suited me fine. 

Vertical battens have proven to be an acceptable compromise so it's a mystery to me why you would go to great expense and have ongoing repair needs just to reduce the leech hollow somewhat. 




---In amelyachtowners@..., <jvenegas@...> wrote :

David,

That is a very important observation that makes a lot of sence.  As the batten is flexed the steel in the inside will move relative to the one in the outside creating extra force against the end of the the protective covering.  Fortunately this potential problem can be completely prevented with proper design. 1) make the inner part of the batten a little shorter than the one outside and don't use long battens: if used perpendicular to the leach they will be smaller than the vertical or horizontal ones for the same leach.  2) making sure the ends are rounded and covered with plastic to prevent the shafe.  3) never leave them partially furled as they will continuously be flexing and likely will fatigue.  This is a true draw back as it puts a design limitation on the infinite number of reefs that the in mast furling sail can have without battens or with vertical battens.

 Thank you for bringing up this key point .  I will be happy to be a guiney pig with this design as I cant see myself puting rigid vertical battens on my amel.  

Some times innoavation comes through those who are willing to take the risks.

Jose


Craig Briggs
 

Hi Jose,
Just another data point for your experiment is that the fellows that developed the Flattens I posted about last week said they are installed at Luff-90 - perpendicular to the Luff, not the Leach. That way when they roll up they actually make the sail roll tighter - like the measuring tape analogy you used wherein the tape rolls up on itself, not crosswise to its natural cupped shape.  Anyway, will follow with great interest - sounds like a good idea, notwithstanding our resident sailmaker's doubts. Keep us posted.
Cheers,
Craig


Jose Venegas
 

I hope this will end the already long discussion and explain the reasoning behind my willingness to try something different from vertical battens on my SM.

My experience as a mechanical engineer is only 40 years but I have always evaluated critically every modification I have made to my boats.  In principle, I see the vertical battens as a bad design waiting for disasters like those experienced by Michael.   I do understand that sail makers are by definition conservative and thus Dave’s skepticism.  Sails have been around for thousands of years and worked well with minimal changes.  Adding new features always brings the risk for failures and, if I made sails for a living, I would also be skeptical and conservative.


However I am not sure these roller-battens have been used in the manner we plan to do it. I can see how the roller battens, installed as full battens and perpendicular to the mast as shown in the website, can have problems.  Using them like that in addition to making wider the folded sail, they exacerbate the problem brought up by Dave : as the sail is furled, each turn will make incremental motions of the inner part of the stainless batten relative to the outer part.  The more turns the more this happen and the greater the force the tip of the inner half of the batten will do against the batten cover.

By putting the roller battens perpendicular to the leach it makes them shorter than if they were placed horizontal or vertical,  and thus they will have less turns and make the furled sail less wide.  In addition, when placed perpendicular to the leach with a length such that only 40% of them extends over the leach, the sail damage when battens are too short will be prevented. More important, the widening of the furled sail will be reduced because the battens will roll in a corkscrew shape.  I am also expecting that they may reduce the likelihood of the leach folding on itself and jamming the sail when it is furled with little wind.

In any case I am willing to take the chance, knowing that if I am wrong it is for reasons that I am still not aware of.  So far Dave’s skepticisms has been very helpful  to identify key potential problems and for formulating solutions. Unless he or any other person identifies additional problems with the roller-batten idea I will proceed with the project, keep an eye on the battens, and will keep you posted on my progress or failure.


Jose


Dave_Benjamin
 

Jose,

I'd suggest you start with the mizzen. It's a small inexpensive sail and if it is irreparably damaged, you can keep sailing. 

You could also consider having a prototype made out of some relatively inexpensive Dacron. If the plan is to perfect the concept and then build a sail for the long term, your prototype should be under $1000 not including the battens. When I do prototyping, I usually just run those projects at my cost plus 10% to cover administrative expenses. I'm not volunteering for this one since you're not local to us.

Those Flattens look interesting. Those might not add that much thickness to the roll if installed perpendicular to the mast. Another way to design a sail like this would be to set the pockets parallel to the foot.