Tubular battens question

Technical discussion of ARC products
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DanBerger
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Tubular battens question

Post by DanBerger »

So this is going to sound a little stupid, but I haven't dealt with a lot of tubular battens. My question concerns the long ones--are there one piece long battens or are the long ones made from two smaller ones with one inserted into the other?? I inherited a cache of battens a while back that had all the long ones made that way, and I just got another batch that are all pretty much the same length and would require doubling them up to make the long ones.

I have a feeling that inserting one in another would seriously flatten out the bend characteristic in a batten..
Matt Haberman
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Re: Tubular battens question

Post by Matt Haberman »

Dan,

There are two different length tubular battens. On the larger boats (19+) it is necessary to splice some of the longer battens. This is done by sleeving a short segment of batten into the leech end of a full length batten. The overlap on the splice is only a few inches (4-6") and because it is out at the leech the batten is already quite stiff so you won't notice the splice.
Matt Haberman
Aquarius Sail Inc.
http://www.aquarius-sail.com
DanBerger
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Re: Tubular battens question

Post by DanBerger »

Thanks! I think the battens I got before were spares for a 22, so that makes sense. What are the lengths of the two different battens before splicing them? I have a feeling that I have a bunch of the shorter one and none of the longer one.
Bill Roberts
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Re: Tubular battens question

Post by Bill Roberts »

Dan,
The reason for the splice in the longer battens, bottom of the sail battens, is that in one piece they are too long to ship by UPS.
Splicing the long battens near the aft end is no performance compromise because near the aft end of the bottom battens is where you want the sail to be flat, no hooking leech. The taper in these battens is built on a special mandrel that causes them to naturally bend in an ideal airfoil shape. The round tube makes then light weight. Who builds better battens???? NOBODY!!!
DanBerger
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Re: Tubular battens question

Post by DanBerger »

I haven't had much experience with the tubular ones, I just never had any until recently. I used the fiberfoam battens in my 15 sail and thought they were pretty good. Now that I have put a set in a sail and actually inspected them, I think I am sold on them. I will probably get a new sail this winter and I'll go with the tubes.

It looks like if they break at the skinny end, there is no repairing them, right? The best way to repair something like that is to insert a tube and then epoxy the broken pieces back together and that would make for a very stiff section. That would completely change the bend characteristics.

Has Aquarius updated the battens in any way? I have a bunch of white ones that are probably 80's vintage. Would it be a good idea to get all new ones with a new sail?
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Re: Tubular battens question

Post by Matt Haberman »

Dan,

You are right that repairing a batten that breaks near the tip is pretty much futile.....
The bend characteristics of the battens are essentially unchanged from the original white ones. The materials and the process to make them has been improved over the years resulting in a batten that is much tougher then the original ones.
Matt Haberman
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Bill Roberts
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Re: Tubular battens question

Post by Bill Roberts »

Dan,
The SC and ARC battens are a very sophisticated bunch of sticks. First of all the battens have to be various lengths to fit the sail. Then they have to bend in concert with each other to form a correct airfoil at each batten length or position.
As a beam becomes longer, it becomes more bendy. As a beam becomes larger in diameter, it becomes stiffer. To make a set of battens that max bend at 30% of their length, for example, the batten length and the batten diameter and the batten range of diameters have to all be coordinated in order to make a proper, ideal, airfoil shape in the total sail. Sail battens for racing sails are a science all its own.
Properly made sail battens come in "MATCHED" sets.
DanBerger
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Re: Tubular battens question

Post by DanBerger »

Why did I KNOW you were going to say that, Bill?? Can't catch a break on cost, here, can I?

So, when you say 'matched' set, you don't mean that the battens have been cut at different places on the luff (small) end? Or, are they all the same (matched) battens just cut at the leech end?
Bill Roberts
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Re: Tubular battens question

Post by Bill Roberts »

Dan,
You can buy the cheapest sails and cheapest battens you can find and they will push your boat around. If that is all the customer wants, then go for it.

If you want the fastest sail and battens for your boat, then buy factory sails and battens.
Technical: Let's say we want, for example, a batten set that has max camber at 30% of the overall sail widths from the top to the bottom of the sail. We want this max camber location because we read a report that indicated a sail produces max forward thrust sailing to windward, max boat speed, with max camber located at 30% of the sail chord, width. The sail battens have the opportunity to influence the location of max sail camber at each batten. Therefore each batten regardless of length should have a natural bend that has max deflection at 30% of the length of the batten when loaded in axial compression. The forward end of the batten should bend more quickly and the aft end of the batten should be much straighter. These batten bend characteristics are much like the cross section of the top surface of an airplane wing, a glider's wing. For a tapered tube batten that means the range of diameters for each batten is different for different batten lengths. For a flat batten, it means the range of thickness of the batten is different for each batten and batten length.

There are a lot of sail makers and batten makers that don't want the "best" for their customers and they sell untapered battens. Untapered battens are cheap! They will work OK to push the boat around but not as fast as it could go. If this is what the customer wants, then that is fine. The customer just needs to know what they are getting.
Hobie sails have been supplied with untapered solid pultruded sail battens for years. These battens are cheap! They all have max deflection at 50% length. The short battens are too stiff and the long battens are too bendy. The boat owners don't know the difference, so this is fine.
DanBerger
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Re: Tubular battens question

Post by DanBerger »

Bill,

I think you misunderstood. I have a set of the old white tubular battens and was planning on using them, but Tom mentioned that there are new manufacturing techniques applied to all the new battens. I said that I was looking to buy a new sail (from Tom's sail maker) and then you mentioned that sails need a matched set of battens.

I have been using the fiberfoam (white outer with black foam core) tapered battens in my sail for years and have been very happy with them, they are tapered and seem to give a great sail shape. I went with those battens because 1) I had a full set (plus spares), 2) they were lighter than anything else, 3) they are tapered, 4) I didn't have a set of the tubular battens and 5) I wanted to go sailing and beat up on some Hobie 16s.

So, I read your post as meaning that I need to order a set of the new battens with the new sail. My question was if the battens are all the same, just cut down to length (from the big end), or if they were cut at the smaller end to move the camber of each specific pocket. If they are cut like the later, then that would be difficult to replace any of them.

I was hoping to save a little since I now have a set of the factory battens, that's all.

Now, I do agree that the Hobie battens aren't very good. A lot of the racers figured out the tapering part and spent many hours sanding down the battens to taper them and then many more hours picking the fiberglass out of their skin. The problem most people had was keeping the taper consistent and then trying to figure out the bend characteristics. The best most people could go on was just tapering each batten to a certain length on the batten and hope they got lucky getting it right. Once they had them tapered, the raw fiberglass would eat up the inside of the batten pockets and they had to (or should have) added that expensive heat-shrink sail-saving wrapping to all of the battens, which, I'm sure changed the bend characteristics all over again. Those battens weigh a ton, too. The Hobie 18s used a smaller jib batten for the top one which made it more bendy, but I don't think it was enough. I think the Hobie 16s should have adopted that practice.

But those are Hobie sailors. Bless their hearts.
Bill Roberts
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Re: Tubular battens question

Post by Bill Roberts »

Dan,
Starting with a set of specially tapered tubes from the vender, material is removed from either end or both ends to make a "matched" set of sail battens for an Aquarius product. The amount of length cut off from the blank and at which end or ends depends on the position of the batten in a factory sail.
DanBerger
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Re: Tubular battens question

Post by DanBerger »

Great, I hope the sail maker includes the measurements. I would hate to have to figure out a replacement batten by measuring against the broken one.
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