fractional rig vs mast head

[Old Salt]

john farnsworth I think you are mistaken

Backstay tension can be used flatten the main . Also it tightens the forward stay which allows the boat to sail higher.Without going into detail here I will just list a few of the dozens of references & links on just how tightening the backstay actually "flattens" the main sail which is usually done with increasing winds."Flattening the curvature of the sail will make it less aerodynamic and reduce the "pull" on the leeward side of the sail. This can be done by tightening the backstay (flattens the upper 2/3 of the sail), and by tightening the outhaul of the mainsail (flattens the lower 1/3 of the sail). Tightening the backstay will bend the top of the mast backward and the mid-portion of the mast forward. This will flatten the upper two thirds of the mainsail and depower the sail"http://www.sailingusa.info/sail_shape.htm"Fore and aft mast bend changes the shape of the mainsail in two ways. One is that the mast either pushes fullness into the body of the mainsail when it straightens, or pulls fullness out of the mainsail when it bends more..."http://www.onemetre.net/Build/Rig/Rig.htm"Mastbend is the primary adjuster of mainsail fullness. As wind increases, so should backstay tension....."http://www.towndock.net/sails/maintrim.htmlhttp://www.practical-sailor.com/tools/boat_clinic.htmletc etc

 

[Joe]

Sorry, John... your common mistake is wrong...

First... I refer you to Tom Whidden's "Art and Science of Sails" pages 208 through 219. (as in Tom Whidden aka North Sails, Americas Cup, etc.) Many boats are designed with bendable masts to affect mainsail shape. Backstay tension is a primary control in achieving mast bend, whether it be a masthead or fractional rig. To make a long story short....On a fractional rig the backstay bends the mast through "leverage" where the forestay acts as fixed pivot point while the backstay pulls the top of the mast back. On a masthead rig, where the opposing forestay will not let the top of the mast bend backwards, backstay tension helps bend the mast through "compression" . Running backstays are often used to control and limit mast bend.On a rig with a stiff or unbendable spar, backstay tension mainly alters forestay tension, thus having a dramatic affect on headsail shape but very little effect on the mainsail.I have quoted my source, if anyone has issue please call Tom Whidden, president of North Sails, and tell him he hasn't got a clue.

 

[newly anonymous]

outdated information

Yes, mast bend will flatten the main on flexy masts, the type we all used to sail before the sailing community discovered that running backstays are not only evil but largely unnecessary. Sportboats aside, we moderns tend to sail with a far stiffer mast supported by swept spreaders designed to eliminate mast pumping. Backstay tension, at that point, does a lot more to reduce headstay/forestay sag--thus flattening the jib--than to bend the mast.Regardless of what Tom Widden may have recommended in the past millenium, go out to your own boat next weekend and play with backstay tension. If you bother to look up, you'll find that you're doing a heck of a lot more to flatten/deflatten the jib than the main.It all comes down to how your mast was designed to perform. Back when Widden wrote that book I used to sail a boat with runners in which the mast was designed as a tool to effect sail shape. When racing, an entire crew position was devoted to the runners, in effect "trimming" the main via the mast. I, for one, grew tired of having to make that extra sandwich every Saturday. My last two boats, as a consequence, have had a mast specifically designed to resist that type of flexing. The masts on most production boats, even boats in the cruiser/racer categories, have been designed this way for at least the past decade.Widden's book, THE ART AND SCIENCE OF SAILS, was published in 1990. For those not keeping track, that was 17 years ago, which in terms both of mast and sail design was a very long time ago.

 

[newly anonymous]

while we're on the topic of outdated info

For those of you who are using laminated sails, assuming they're not worn out, introducing luff tension via the halyard and/or cunningham will no longer move the draft forward to help the sail point higher. At least not significantly. Your sails have been designed very specifically to reduce that type of stretching. This is true for both kevlar and carbon reinforced sails regardless of what all the old sail trim books in your yacht club's library tell you.The good news, for those of us still using dacron sails, is that luff tension will still effect the draft, especially on older sails. The more tired your sails get, the more important luff tension becomes. Of course, for those of us with furling mains, the entire discussion of luff tension is moot.

 

[Old Salt]

Outdated ?! LOL Thats funny *o

If anything that is "Updated" information. This is what people are doing on "newer" better performing boats.Tell what you wrote to all the newer J Boat owners out there and they'll laugh you into next week. I know you put that "caveat" in there by saying "putting Sportboats aside", but I don't buy that and to say its outdated is ridiculous.Its pertinent for all boats its just that its effect is not as noticeble on some boats as others http://www.jworld-sailing.com/ullman-mainsail-trim.htmBut then again I guess you are the world wide expert on sailtrim.

 

[Ross]

With my 1968 style rig and a full keel boat I am

surprized that it will still sail when the wind blows. Maybe with all of the modern methods of sail trim boats will sail without wind.My old boat has a forestay and a back stay single spreader upper shrouds and fore and aft lower shrouds. It even has outboard chain plates.

 

[MoonSailer]

Sail trim for the last 5% of performance

In my experience a sailboat will sail when the wind blows. Unless you are really doing something very wrong you can get 75% of your performance without much effort. Some effort gives you 90-95% and then you have to be a little crazy to get that last race winning bit of performance. Usually I am more concerned with watching the birds or drinking a beer to be too worried about sail trim. Sure sometimes I'll get real focused trying to get around a point without tacking but mostly I like to relax and enjoy. Also usually the wind waries enough in strength and direction to require constant triming to have a perfectly trimed sail. I've been known to sail 20 miles or more without adjusting the sails.

 

[Charisma]

test, test only no message

Just a test to see my avitar

 

[Charisma]

Question for Joe

Hey Joe, Just chcked and was right, how did you end up using My avitar? That is a photo taken of our H26 on lake Pueblo CO. According to your bio you have a Catalina 27, and sail out of mission bay CA. What Gives? If you need a photo of a Catalina 27 I can supply one. Chris

 

[Joe]

sorry john....

....you must then qualify your statement to boats of a more recent vintage... Whidden's book being published in 1990 is fine with me... since my boat was built in 1977. Sorry that all of us are not "modern" sailors, but your statement did not discriminate between older vs modern, cruiser vs racer, etc. so I chose to bring that to everyone's attention.I also will venture a guess that most of the sailors in this forum still use dacron sails, at least while cruising. I will also go out on a limb and say that the majority of us do not have in-mast furling. So... your comment/advice doesn't apply to my case....

 

[Joe]

to charisma....

Sorry Dude, I'm not sure what you're talking about. I certainly didn't steal your avitar, why would I want to do that. FYI, my avitar is a portrait of Admiral Lord Nelson. Check your computer.

 

[Ross]

Joe That Ain't what shows on your recent posts.

check your work.

 

[Alan]

to be fair...

... the forums have had issues with avatars lately. You may want to check with Phil and see wasup.

 

[GeorgeB, s/v Freya]

Slightly Different Experience

In regards to Arimids and composites, I have trimmed both Kevlar and a Polyester/Pentex “laminate” sails and I can shape and move the draft using a combination of halyard and/or Cunningham. Perhaps I’m putting a little more meat on the winch or that we are running T-900 halyards (no stretch there!) These sails are a lot less stretchy than Dacron and the halyard/Cunningham adjustments are a lot more subtle as is the sheet adjustment (Spectra sheets). It has been taking us almost half a season to truly dial-in one of these sails but well worth it. Even for cruisers there is no comparison to the average modulus Dacron. The boat is stiffer, faster and more powerful – just what one wants in the San Francisco Chop.Call me old fashion, but I really like my backstay. Even with my masthead rig, It really does the job of taking out the headstay sag and flattens the genoa. I don’t think there is much of a selling point for the B&R rig in regards to adding roach to the main. The roach still needs to conform to PHRF. We sailed with a PHRF legal extended roach without a backstay crane and could tack without the roach catching the backstay in everything except a light wind. And in that instance, we would back off stay tension. O.K. almost the same hassle as running backs, but hey, this was a sled, not the family station wagon.John F., it sounds like you might have some experience with UK Tapedrive? Can you give me some pointers and advice? I’ve been told that carbon tapes can delaminate over time, is this true? I’m torn between the tapedrive and the load bearing D4 Membranes (a.k.a. “string” technology) such as Doyle’s Stratus, UK’s Ultra and Sobstad’s Genesis. But there again, I’m not so sure about their longevity.

 

[s sauer]

Backstay Adjuster AND B and R Rig

I feel fortunate to still have my 'outdated' masthead B&R rig on our '86 Hunter 28.5. Last weekend the wind piped up a bit and I wanted to point a little better and depower a little. I flatened out our 3 year old loose footed dacron main with full outhaul and, the backstay adjuster 'on' about four inches and sheeted in our tri-radial laminated 135 Genoa about six inches off the spreaders, heeling about 15-20 degrees. It's nice to have the 'racing' controls to make quick easy adjustments for comfortable 'cruising'.

 

[Greg Jobson]

S. Sauer How dare you !

John F says what you are doing is outdated. You should learn how to sail.Don't you know you can't flatten your main with a backstay?You should sail like John F. With a baggy mainsail that causes you to heal so much that you must reef at 15kts. ;-)

 

[Wanderer138]

Backstays and jumpers and runners, oh my!

As an occasional racer of a boat with the so-called "bendy" rig (fractional ZSpar mast with tapered top and swept spreaders) I think I can add some comments:1) as mentioned earlier, a running backstay (aka "runner") is NOT the same as an adjustable backstay.2) All backstays, whether adjustable or not, are considered part of the standing rigging. They are almost always made of wire and attached to the aft end of the masthead.3) Running backstays are attached to the rear of the mast, usually at the same height as the forestay. There is one on each side of the mast and usually only the windward runner is used. When the boat tacks, the formerly windward runner is eased and the formerly leeward runner is tensioned. They are made of some type of ultra-polymer line (probably Spectra) and are considered part of the running rigging. My (limited) understanding is that they are used to adjust forestay tension (and headsail trim) while under way. They're very useful but usually show up only on hard-core race boats with lots of crew.4) Fractional rigs with swept spreaders can have a certain amount of prebend dialed into the mast with ZERO backstay tension. This is why the B&R rig works. Most people fail to realize that swept spreaders allow the chainplates to be situated aft of the mast foot. The shrouds pull DOWN and BACK. A single set of lower shrouds and the forestay are enough to support the mast.5) Lower shrouds are attached just below the spreaders (about mid-height up the mast) so in addition to keeping the mast centered athwartships, they also regulate the stiffness of the mast (more lower shroud tension, stiffer mast).6) The uppers are attached at the forestay. In addition to supporting the mast athwartships like the lowers, they also bend the mast fore and aft. More upper tension. more pre-bend. Actually "pre-bow" is more appropriate, as the mid-mast (where the spreaders are attached) moves forward like a bow as the masthead moves back. The forestay acts as the fulcrum. Since the uppers aren't attached to the masthead, the unsupported top of the mast can also bend off to leeward, which helps depower the main and reduce heel in gusts.7) Mast bend on a fractional rig controls mainsail draft AND leech tension simultaneously. Increased mast bend pushes the middle of the sail forward, reducing draft. At the same time, the masthead moves down and back, reducing leech tension. This "opens" the leech and increases mainsail twist. 8) Increased twist is very useful in heavy or gusty air and waves. It keeps airflow attached to some part of the sail and depowers the main, reducing heel and weather helm in heavy air.8) The appropriate amount of mast pre-bend for a given day's wind conditions can be set at the dock by adjusting upper and lower shroud tension, i.e., less bend in light air, more in heavy air.9) If the backstay is adjustable, more bend can be added to a fractional rig while under way. When sailing upwind, the apparent windspeed is higher so the mainsail may need to be depowered, e.g. if the boat is fast, or more twist may be needed to reduce weather helm or if waves are starting to slow the boat. Increase backstay tension until the mainsail and boat are working optimally. The trim stays the same on either tack. Off the wind, apparent wind is lower, and the mainsail needs to be powered up. Easing backstay tension takes the extra bend back out.With this understanding, I've managed to do OK on my boat with one crew or single-handed. However, if I missed something please let me know. Fair winds.PeterH23 "Raven"

 

[Joe]

avatars....

Ross, it looks the same as it always has. Check my work? What work? I haven't been anywhere near the setup file for ages. Sorry it's irritating everyone but I think the problem is elsewhere. Send your complaints to the webmaster.

 

[Ross]

Joe , the Avitar on your last post is a white

sloop seen from the port side. It don't look nothin like Lord Nelson.

 

[Alan]

Peter

You pretty much hit the nail on the head. One small point, the runners attach to the side of the mast at or near the hounds, not at the rear."Check-stays" attach to the mast further down near the center of curve of the bend. They are used in conjunction with the runners to pull the bend out of the mast that the runners induce. In so doing the main sail shape and headstay tension can be controlled independently.