Sail design idea-vertical inflatable battens

[Hermit Scott]

Can you put a vertical inflatable batten in a sail to make the sail have a good shape when it is furled to say 50%? I have a 150 headsail and I would like to furl it to about 40 or 50% and have it have a good shape. The batten would go vertically almost the whole length of the sail and only be inflated when the sail is furled to the point where the batten is. It may be shaped like a long elispe to cause the airflow to be better. Are there inflatable sails or partially inflatable sails?
I know some here must roll their eyes when they see one of my "new idea" posts. Negative feedback for my stupid ideas is welcome.

 

[Don S/V ILLusion]

Already patented.

95,000 hits on google for a wing sail:

http://www.google.com/search?q=infl...s=org.mozilla:en-US:official&client=firefox-a

If it can be used on a spinnaker, anything is practical.

 

[Mulf]

Someone's already making them

http://www.airbattens.com/

 

[Hermit Scott]

http://www.airbattens.com/

Those are horizontal not vertical. They are the same thing as regular battens.
I was thinking more about a jib with a vertical batten runnning from the head to the foot. I know they have foam luffs that act simlar, but they are only one shape. Mainesail said he has one.
I would like to know if I can reef the 150 to any point as long as the luff is fulled out properly with different shaped battens for the shape required at each point. It doesn't seem complicated at all; a pocket sewn on to a sail with a bladder of the right shape.
I'm not looking for a wing sail, just a better shape for a large sail over furled.

 

[Brian M H23]

There are two competing effects. You need to roll up the sail around a larger diameter roller where it is baggier - this is what the foam luff is for. What also happens is you have a big giant disturbance (the rolled up sail) and a much shorter distance for the air to smooth out before the sail is gone. The sail shape effects screw you more than the roll of sail when reefing a small amount, because the sail roll isn't that large. If you roll it up more, having the foam luff in there makes the roll even fatter and the turbulence worse.

 

[Hermit Scott]

There are two competing effects. You need to roll up the sail around a larger diameter roller where it is baggier - this is what the foam luff is for. What also happens is you have a big giant disturbance (the rolled up sail) and a much shorter distance for the air to smooth out before the sail is gone. The sail shape effects screw you more than the roll of sail when reefing a small amount, because the sail roll isn't that large. If you roll it up more, having the foam luff in there makes the roll even fatter and the turbulence worse.

In drawing (a) there is no foam luff. The sail is baggy on the leading edge and poor sail shape. In drawing (b) there is a foam luff that keeps the leading edge in the right shape so no bagginess. But the fatter the rolled up sail is, the more difficult it is for the air to flow around it. IS this right???
If I could make the rolled up sail a more aerodynamic shape(like a cross section of a teardrop) would the fattness of the rolled up sail not be a problem then, or at least less of a problem?

 

[philwsailz]

For all points of furling or reefing, your teardrop proposal would present a greater area of disturbance for all degrees of rotation exxcept for when the "foil's" leading edge was exactly forward. That will be a pain, as your furling line will never set exactly where you want it or need it....

For your tinkering ever-creative mind, might I suggest someting along the lines of a Hoyt self-tacking jib boom, yet with the added benefit of being able to roll the FOOT...

Rolling the headsail foot in a traditional manner, (no jib boom) will have disadvantages as the weight of the rolled foot gets larger and heavier, but employing a boom for the jib allows an "outhaul" point for the jib, potentially eliminating the negative effects of the rooled "foot bag". At the same time, you eliminate the traditional foam luff roller-furling head sail, and the associated problems with bagginess with a severely furled, (not reefed) head sail.

If you decide to chase this with a patent search, and find it is clear art, just remember to credit this post as a source; I will like to share in the invention, (I am sure Garry is screaming FOUL right now... ). You have less chance of "getting a flat" with this idea when compared with your balloon idea...... hee hee hee

 

[philwsailz]

Oh, to point, for your C-30, the idea I throw out necessitates a head saill likely no larger than a 110 for everyday use, and an a-sail or some other large device for going downwind or off-wind... Not sure a self tacker will be very effective with a c-30's standard rig from performance standpoint...

 

[druid]

For your tinkering ever-creative mind, might I suggest someting along the lines of a Hoyt self-tacking jib boom, yet with the added benefit of being able to roll the FOOT...

I had a "reefable jib" on my Cal 25 years ago. It had reef points along the foot, just like a main, along with lines to tie up the roll at the bottom. Worked pretty well! Of course you have to go forward to reef this kind of jib...

druid

 

[Hermit Scott]

I don't want to patent any of this. I am going to buy a sewing machine, and if I could sew a pocket onto one of my headsails and insert a bladder in it that will make it roll up further with good performance, then I will. There's not enough potential money in this idea for me to pursue it.
If you really want to pursue a patenable idea, I will give you my list of patents. You can pick one and have half the business. All you have to do it develop the product(that is a final production ready device). Find all the money for marketing, employ salesmen and/or distributors. Find a manufacturer to build it, pay for the first shipment out of pocket. Go to the factory and make sure it's being produced right. And then when you sell a million of them service and warranty everything, and try not to go broke doing it.
An idea is only worth something if you can do all this.OR you already own a company that does all this, OR the idea is so earth shattering that someone with a company will pick it up and pay you a royalty. Then when they don't pay you, hire a team of lawyers to go get the money, this will potentially cost more than everything else so far.

I don't want to put anything on the headsail that requires me to go forward to tend it.
I don't think a jib boom would work well with a 150. I am looking for an idea that will enable me to over furl the 150, with out complicated things going on. If I can do it with a bladder that will be simple enough to be worth doing it.

 

[David in Sandusky]

Modern furlers

I have read that some modern furlers wind in the middle of the sail first, thus reducing the bagginess of the furled sail without the added turbulence from the bulk of the foam luff.

Personally, I think it is unlikely that any furling technique will give you a usable sail beyond 25% furled.

So how about this idea:

A 110 jib furling on the forestay for heavy weather, and
A single line reefed screacher or other sail mounted ahead of the forestay for light winds.

We use a variant on this scheme, flying an asymetric in light air, and a 110 for heavy weather. We have to go forward to drop the spinnaker, but it's a lot faster than changing foresails. In light air, the spinnaker will not allow us closer than 60 degrees off the true wind, but that is about as close as we can sail with our shoal draft keel, and sheeting ourtside the shrouds. I believe that there are light air sails that will do better into the wind, and operate off the modern single line reefing set-up. That is you wind them around a luff rope that becomes the halyard, rather than around the forestay. You could then leave it up while furled, or go forward to drop and bag the reefed sail.

 

[RichH]

There isnt any sail on this planet that can be roller furled much beyond 30-35% (LP) and still have any decent shape, most all the 'broad seaming' is in the first 30%... after that a sail is all mostly 'flat' (no broad-seaming).

 

[sailingdog]

I have read that some modern furlers wind in the middle of the sail first, thus reducing the bagginess of the furled sail without the added turbulence from the bulk of the foam luff.

Personally, I think it is unlikely that any furling technique will give you a usable sail beyond 25% furled.

So how about this idea:

A 110 jib furling on the forestay for heavy weather, and
A single line reefed screacher or other sail mounted ahead of the forestay for light winds.

This is a pretty reasonable compromise, especially if you have a screacher that is relatively flat cut and allows you to point fairly high.

We use a variant on this scheme, flying an asymetric in light air, and a 110 for heavy weather. We have to go forward to drop the spinnaker, but it's a lot faster than changing foresails. In light air, the spinnaker will not allow us closer than 60 degrees off the true wind, but that is about as close as we can sail with our shoal draft keel, and sheeting ourtside the shrouds. I believe that there are light air sails that will do better into the wind, and operate off the modern single line reefing set-up. That is you wind them around a luff rope that becomes the halyard, rather than around the forestay. You could then leave it up while furled, or go forward to drop and bag the reefed sail.

I believe David is talking about a sail on a furler using a wire luff. The wire luff (sometimes a synthetic line, like dyneema is used) allows the sail to be furled using a roller furling unit, but does not allow the sail to be reefed. It is hoisted with a halyard, like a spinnaker, but the wire luff does not become the halyard.

 

[Hermit Scott]

Does anyone put multiple furlers on multiple stays side by side, like on bigger sloops or cats? I have only seen them behind each other, like a cutter. But I have never seen one with a jib on one, right beside a 150 on another.
I'm not going to do it on a 30' sloop lol. I will on my 40' cat I am going to buy when I am rich though.

Everything is a compromise. I will probably get a new 110 and just be happy with what it does.
David-I like the idea of having a spinniker for the light wind, and a 110 on the furler. That is a good solution.

 

[Joe]

Before some of you guys try to reinvent the wheel.... here's some ideas other sailors have run with... most involve the code zero loose luff sails on detachable, continous line furlers. It seems that everywhere I look I see multiple headsail rigs, twin furlers, code zero... but not side by side Hermit.. What do you do with the sheets?

http://en.wikipedia.org/wiki/Spinnaker

http://www.ukhalsey.com/sails/CodeZero/

Here's well known cruiser, Evans Starzinger's set up:
http://www.bethandevans.com/sail_combinations.htm

Always lots of discussion on this in the sail mags too:
http://sailmagazine.com/boatworks/sails-and-rigging/downwind_sails_for_cruising/

A more traditional cruising yachts point of view:
http://www.pearson40.org/best_sail_inventory.htm





My suggestion is to think "closehauled vs reaching" rather than "heavy air vs light air" when looking for a practical reason for mounting a spinnaker like sail on a furler in front of a furling jib. That way the convenience of switching between the two sails is easy to justify just by changing boat direction rather than waiting for a weather change.

 

[DannyS]

This is from Beth and Evans Starzinger's description of their former boat, Silk.
"Silk had two side-by-side head stays, one fitted with roller furling and one for hank-on sails. This arrangement makes it easy to set twin headsails on tropical downwind passages."
Not twin furlers side by side, but something similar.

 

[RichH]

There is a great problem with multiple headstays - differential (unpredictable) tensions in each forestay when one or both sails are flying. This somewhat relegates the use of multiple headstays to downwind sailing where the shape of the luff isnt important.

For upwind where the luff shape MUST match the expected sag (to leeward) of the wire, one really needs a means to quickly vary the stay tensions to 'match' the luff hollpw curve that the sail maker cut into the sails. Without such means, and with two stay 'sharing' the reaction loads from the backstay(s) the shape 'result' is always god-awful - draft aft, powered-up, inability to point, very slow boat and a boat that aggressively heels. Hyfield type levers dont have the rangeability to accomplish the varying tension requirements. Multiple head stays really require 'additional' backstays, running backstays, or complicated other means to adjust the stay tensions - especially underway. Multiple headstays are for boats that primarily 'go downwind', such as boats that are 'on passage'.

With two headstays, the windloaded sail always transfers it stay load to the 'furled' stay thus always becomes 'unloaded'. Plain vanilla tensions in EACH forward stay should be in the range of 15% as that what a sailmaker EXPECTS it to be. When you have 2 forward stays, and one backstay at 15%, the result is both the forward stays will be at ~1/2 that tension (7.5%) .... and the SAG in each wire will be well beyond what the sailmaker cut into the leading edge of the sail (luff hollow), expecting 15% stay tension. Not a good match between the stay sag and the luff shape; hence, deplorable foresail shape & operating performance.

 

[Hermit Scott]

There is a great problem with multiple headstays - differential (unpredictable) tensions in each forestay when one or both sails are flying. This somewhat relegates the use of multiple headstays to downwind sailing where the shape of the luff isnt important.

For upwind where the luff shape MUST match the expected sag (to leeward) of the wire, one really needs a means to quickly vary the stay tensions to 'match' the luff hollpw curve that the sail maker cut into the sails. Without such means, and with two stay 'sharing' the reaction loads from the backstay(s) the shape 'result' is always god-awful - draft aft, powered-up, inability to point, very slow boat and a boat that aggressively heels. Hyfield type levers dont have the rangeability to accomplish the varying tension requirements. Multiple head stays really require 'additional' backstays, running backstays, or complicated other means to adjust the stay tensions - especially underway. Multiple headstays are for boats that primarily 'go downwind', such as boats that are 'on passage'.

With two headstays, the windloaded sail always transfers it stay load to the 'furled' stay thus always becomes 'unloaded'. Plain vanilla tensions in EACH forward stay should be in the range of 15% as that what a sailmaker EXPECTS it to be. When you have 2 forward stays, and one backstay at 15%, the result is both the forward stays will be at ~1/2 that tension (7.5%) .... and the SAG in each wire will be well beyond what the sailmaker cut into the leading edge of the sail (luff hollow), expecting 15% stay tension. Not a good match between the stay sag and the luff shape; hence, deplorable foresail shape & operating performance.

So if one did have side by side stays, it would only work well if you could unload the tension on one stay at a time?

I hope to be buying sails in the next 30 to 45 days. I would like to PM or email you(RichH) and ask some specific questions for the sails I should buy.
Joe-The problem of what to do with the sheets on a side by side doesn't seem to be as bad as the problem of tacking when you have one behind the other and you are using the fore most sail. I have read where some people do a 270 backwards tack and clear the sail in front of the the stay instead of behind.
I guess if you want to switch sails alot then configure the sail arrangement for close hauled vs. reaching. I was thinking more for convienent cruising, where the weather doesn't change as much as the direction of the boat. But I am glad you proposed that, I had never thought of that before.

 

[Joe]

This is from Beth and Evans Starzinger's description of their former boat, Silk.
"Silk had two side-by-side head stays, one fitted with roller furling and one for hank-on sails. This arrangement makes it easy to set twin headsails on tropical downwind passages."
Not twin furlers side by side, but something similar.

Yes, twin headstays are not uncommon. In fact my slip neighbor's 1966 Columbia 26 Pilothouse is rigged with twin headstays. Designed to be used for twin headsail downwind, or upwind sail changes.... like twin luff groove foils. I, myself have tacked my wire luff, tall staysail next to the fixed headstay with hanked on jib for twin headsail action. There are many things you can do and try... my impression of hermit's comment was that he would rig two roller furling sails side by side, somewhat far apart, rather than placing the larger unit forward of the smaller, like some of the examples I linked. I just think that side by side, the size of the furler parts, and the confluence of the sheets and control lines would constitute more confusion and unnecessary stresses on the rig than could be justified. Go with something that is a proven winner.

Hermit, the forward sail is either jibed with the sheets flying outside the other rigging, like a spinnaker, or... as many cruising spinnaker users do... rolled up first, then tacked, then rolled out on the other side. The inner jib or staysail is tacked throught the foretriangle in a normal manner.

In a cutter configuration, where there is a couple of feet between the head stay and the inner forestay, the forward sail can be tacked normally with the headsail sheet passing between the two stays... delaying the staysail's release a bit, untill the forward sail is across, will prevent the headsail sheet from getting tangled on the inner stay.