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· Closet Powerboater
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Discussion Starter · #41 ·
Oma;
Boy, you are a snide little guy.

Time you educated yourself. All the info is out there. Lots has been presented here. We can't "make you" understand. It's not our lot to educate you. That's your job. You seem determined to stay in the dark when the light switch is right at hand.

Reach for the switch. Most of us did, years ago.
Bob, you're not really going to go after someone else for their snide or grouchy posting tone are you? ;)

As for your lot not being to educate us, I kind of hoped that you would make it your lot since you're one of the few high experts on the subject. With my opening post I posted a lot of BS about rigs, because when I DO try and educate myself, that's what I get back. A lot of dock-talk and eyebrow raising BS. I'm amazed at the sources sometimes too. A racer with a wall of prestigious trophies once told me that only real advantage of a fully battened main is "extra sail area." Really? I have a hunch there's more to it than that...

So, if not you, then can you help us find the right switch? Any good book recommendations? Good websites or Videos? Right now I am finding much more chaff than grain on this particular subject.

MedSailor
 

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Med:
I just can't do it. It would take a book to carefully go over all the varaiables here. I think it's a mistake to divide the the subject into two groups, i.e. masthead and fractional. There are so many sub-groups involved and that's without even mentioning hull shapoe differences in older masthead boats and movdern frac boats. I don't have the time to do it justice. Not sure I really know enough either.

I think there has been a lot of good material presented here and yes it has been clutterred with some less than accurate comments. But that's life and par.

With modern sail fabrics the entire picture has changed. The masthead rig of the old racer with its in line shrouds ansd super bendy stick was perfect with dacron sails as the rig could be shaped to change the draft characteristics of the sail relative to the conditions. With new, high tech sails, the shape you want is sown in from the start. You cannot stretch the sail to change the draft. If you need a fuller jib you can play with halyard tension and sheet lead but if you are seriously racing you'll put up a fuller jib. The LP may be the exact same as the flatter jib but the draft will be deeper. With the main you have halyard cunningham and outhaul to play with but with spreaders swept as much in some cases as 30 degrees you are not going to bend that "tripod" rig.

But if you go back 15 years you still had frac rigs that were effective but in those days mast bend was used and shrouds were in loine or almost in line. That's an entirely different situation.

Probably the biggest single factor to the success of the frac rig is we have come to learn that masive genoa overlap is not nearly as efective as additional luff length. Today it's all about leading edge.

Years ago the first of the Aphrodite 101's came to Seattle. About ten of theswe were ordered in Seattle. They came with a standard 100% jib. The class felt the boat would be underpowered in the light Seattle breezes. An overlapping genoa was built and two boats, one with 100% and one with genoa went out for two full days of testing in light air. The result was the 100% jib was just as fast as the boat with the genoa.

With squatty old CCA proportion rigs overlap was seen as a way to increase the SA/D. With the new frac rig the SA/D is much higher to begin with so there is little to gain from relatively inefficient overlap. Pragmatic advantage being you no longer need an "inventory" of genoas. I sail my frac rigged boat for 15 years with two jibs.

In summary (I hope) pretty much everything has changed. The question masthead or frac is multi dimensional and not just two dimensional geometry.

Racing FRANCIS last weekend we had a jib hal lead block failure resulting in a long beat in up to 30 knots AWS with an ugly looking, baggy jib. I was driving. We did the best we could with the jib and I tried to sail the boat mainly on the mainsail, our big sail, our driving sail. We did exceptionally well, walking away from the fleet upwind despite out jib hal handicap. This would not have happened with a masthead rig. Wewould have been crippled.

Sorry about being snotty. It's my vile nature.
 

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Thanks muchly Christian. I'm jammed today or I would have taken more time. Off to San Francisco tomorrow to give a talk at Saint Francis YC where I will have to act like an "expert". Getting ready today. Also doing my SAILING reviews today where I will once again have to convince myself that I am an "expert". No always easy to do. I'm still learning like everyone else.
 

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man! cool to talk to you at least here

my experience with frac rigs is limited to dinghies and folkboats and hobies and the like and my limited experience tells me that frac rigs like to sail by the main and respond better to the main than a masthead rig, they also sail more like dinghies...

case in point my islander has a very small aspect main, bendy stubby mast with inline spreaders and will sail slow if using anything less than a 130 genoa...big overlap etc...

I have noticed that many 70s boats were all about the size of the jib with little importance given to the main

contessa 32, islanders,yankee 38, almost any ior boat of that era

in any case today Im completely lost in all the variations as Im always stuck boat wise 30,40 years back unless were talking dinghies...

anywhoo back to rigs
 

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Your numbers are a little off if the leech is 12% and the SMW is 1.8 on a J29. The mh downwind sail area is 667, the frac downwind sail area is 644. So a delta of 23 sq ft. Is this 23 sq ft enough to overcome the taller rig the frac j enjoys?

Upwind with blades the frac has an additional 3 sq ft, upwind with overlap the advantage goes to the mh rig (sorry, didn't bother to figure that delta) but again the frac has a taller rig and should be able to sail in more breeze and enjoy more shear.

But at the end of the day the mh is rated 6 seconds faster and is simply a better all around boat. My personal belief is the lower ce of the mh rig is a bigger advantage then initially thought. The mh boat stands up better.

Where is the frac an advantage? It's an easier boat to sail provided the extrusion/layup is strong enough to allow mh sails (codes through kites) and the spreaders are swept so runners and checks aren't required to keep the rig in the boat. Where is it a disadvantage? When more power is needed in the light stuff upwind a small j and I just doesn't give enough oomph with overlap. Hence the strong development of the mh codes and sprits. You can't simply add I because the geometry of the sail is structurally unfeasible, the aspect ratio doesn't work. So modern boats add j (sprit) and I (mast head sheave boxes) and essentially become a mh boat with a very big rig.

What's best? MH or frac? Looking at the J 29 the MH is best, looking at other boats, I don't know, there aren't many boats built as both MH and frac.
Shockwave,

The rates size for the J-29 spinnaker is 630sq feet (FH), 751 (MH) for a delta of 121sq feet. It's a pretty major upsizing relative to the boat. If you put a MH kite on the FH boat however the downwind sail area advantage would flip back to the FH.

My numbers indicate the FH is typically rates 3sec/mile slower than the MH, which in my eyes is directly relates to the size of the spinnaker. But I haven't had a chance to see the two boats side by side.
 

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Discussion Starter · #47 ·
Thanks Bob for the info. Don't worry about the San Fran talk, you're an expert compared to the audience, and that's why they're in their seats and you're up front.

I get what you mean about "convincing yourself that you are an expert." I would consider myself some kind of expert on a few things, but only because I've come to realize that there is no such absolute thing as an expert. Some just know more than others in certain areas of knowledge. It's part of why I added the qualifier "high expert". It's kind of like the term "smart", as in, "he's really smart". I find it such a useless and generic word. Show me a "smart person" and within 5 minutes I bet we can find a topic on which they know virtually nothing. I have a buddy who is a rocket scientist (really, he is) and he can be just as "dumb" as the rest of us mortals from time to time. ;)

Thank you for your rig primer. It has really helped me sort my question into many more sub-questions that will help me go forward. It also helps me understand why there are so many, seemingly conflicting opinions on the subject. Since rig evolution is a moving target, some info (from an "expert") may have once been good info, but is now outdated. Some info comes from big budget racing, small budget racing, or cruising perspectives.

I can also see that sorting out gains vs trade-offs for an individual gets complicated very quickly. Upwind gains are often race winning gains, but perhaps not for a cruiser. Also, your point about having different cuts of 100% jibs demonstrates the different requirements people have for their rig design and performance.

For me though it's all academic. I have a very limited list of boats I can choose from that fulfill all of the compromises that myself and my wife can live with. For now, they're all older masthead rigs. Still, I love learning and sailing is still my favorite subject to continue that learning.

MedSailor
 

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Your right, I transposed a number. The times I've raced on the 29 mh it seemed quicker all around then the frac, it's been a few years though... Not sure if it was the boat, the sails or the sailors.

Shockwave,

The rates size for the J-29 spinnaker is 630sq feet (FH), 751 (MH) for a delta of 121sq feet. It's a pretty major upsizing relative to the boat. If you put a MH kite on the FH boat however the downwind sail area advantage would flip back to the FH.

My numbers indicate the FH is typically rates 3sec/mile slower than the MH, which in my eyes is directly relates to the size of the spinnaker. But I haven't had a chance to see the two boats side by side.
 

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Your right, I transposed a number. The times I've raced on the 29 mh it seemed quicker all around then the frac, it's been a few years though... Not sure if it was the boat, the sails or the sailors.
No worries... And it yet again proves the difficulties in these conversations. I could take either a MH or a FH load it with the right sailors and smoke the other one doesn't matter which. Because the boats really were designed to the same performance ( J boats intended the two to race OD with each other) it is fun to look at how they played with the numbers to try and get that result. What's equally interesting is what people would do today... Larger higher aspect mains, asymmetric chutes, Code zero's (which really change the whole game), MH spins on fractional jibs.

Oh so many fun games to play.

What I think needs to be carefully reserved is that just because a FH may be better on a windward leeward race course may have little do to with how it works out on a cruising boat. The harder you are willing to work the boat and sail inventory the better a fractional looks. If you are just going to fly white sails then a MH starts to average out better.
 

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bob, if you won the race in a crippled boat, that doesn't reflect anything on the rig type. It just means someone designed and built a fast boat. Or, it was "take your kids to the races" day on the other boats. Or, if she also won on corrected time, Francis isn't rated correctly.(G)

So far I've seen no one post anything objective. An AC boat might have the wing (a real wing, not a sail) end two meters down from the masthead simply because more sail that high would only help it capsize faster--a real issue for them. Or, it might have been too tall to transport at that point. Just looking at it, without knowing the facts, is meaningless speculation.

Similarly, all the comparison of masthead to fractional rigged vessels ignore the larger questions of whether the "faster" rig is being compared apples-to-apples to the entire boat design having the same balance (fore and aft) and same sail area (main and fore and aloft) and without those things being apples-to-apples, all we have is what a dog knows about elevators.

Huh?

Yeah, I get up in the morning, and my master puts us in a box, and then he opens the door, and the whole universe is changed! And then we get back in, and he opens the door again, and the whole universe is changed back! I don't know how he does it, he's obviously God.

Well...that's how the dog sees it. Motors, cables, switches, Otis brakes...the dog knows nothing about those, he only thinks his master is remaking the universe.

From what I've seen, the question of rig type comes down to "This is what the boat comes with. This is what the grumpy old man, ergh, distinguished marine architect (G), says makes this boat work, and I'm not gonna argue with him."

Funny thing is, there's someone designing both kinds of rigs, somewhere, sometimes, isn't there?

Argue with the designer, and he'll give you a yawl like the Pearson 424. You know, where the yawl boom keeps trying to take off the helmsmen's head?
 

· Closet Powerboater
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Discussion Starter · #52 ·
Hello:
I'd respond but I'd need a translation first.

I am currently working on:
One frac rig
One ketch rig
One masthead sloop that just became a frac rig.
Ahhh... but is the ketch fractional? :D Can I have a mashead main on my ketch with a fractional mizzen please? I think that would be the perfect rig.

Medsailor
 

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Very interesting discussion. There are many variables that come into play when making such a comparison that to me saying a fractional rig is better that a MH rig has little meaning. Fluid dynamics was not my favorite subject in college since much if not all is based on emperical data whereas I always needed to go back to basic theory to understand what was being observed. Thank you Mr. Newton. I should spend some time reading Gentry's articles as RichH suggests, but doubt if I could grasp the information. Look at some of the improvements and innovations in aerodynamics over the past decade. Large commercial planes (and even smaller ones) now have a vertical component on their wing tips to enhance performance. The AC series boats have a main with the head no longer pointed but now it has a long horizonal component. The stealth fighter with all its odd shapes was thought it would not fly efficiently, but yet it does.

As time goes on other improvements to get better performance out of fluid dynamics will take place and I'm sure that some will seem contrary to present day understanding. My 2 cents. :)
 

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I think the future will bring us back to full on mh rigs, giving up I is giving up power, with a row of window shades. Pick the power you need, be it a frac or mh, upwind or downwind. The open 60's have moved the butt back to allow enough j for mh upwind headsails tacked to the deck, not the sprit.







New cruising boats are following with multiple headsail options, Tartan being one. But I'm curious how many cruisers really want to work that hard?

No worries... And it yet again proves the difficulties in these conversations. I could take either a MH or a FH load it with the right sailors and smoke the other one doesn't matter which. Because the boats really were designed to the same performance ( J boats intended the two to race OD with each other) it is fun to look at how they played with the numbers to try and get that result. What's equally interesting is what people would do today... Larger higher aspect mains, asymmetric chutes, Code zero's (which really change the whole game), MH spins on fractional jibs.

Oh so many fun games to play.

What I think needs to be carefully reserved is that just because a FH may be better on a windward leeward race course may have little do to with how it works out on a cruising boat. The harder you are willing to work the boat and sail inventory the better a fractional looks. If you are just going to fly white sails then a MH starts to average out better.
 

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Whew- I'm still at the stage of learning how to sail my boat efficiently. But appreciate these posts as inspite of myself did learn something. My impression has been for dilettantes like me it's easier to get close to best trim with a MH than a frac. ? Am I fooling myself in thinking the MH is more forgiving? We have non stretchy, crawly sails. We fool with halyard,out haul, and back stay.
 

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Shockwave,

I am not sure what IMOCA rules are on sails and rigging so I am not sure how that drives their sail selection. They also have permanent reaching struts which make large jib better in more conditions since they can be trimmed properly.


Outbound,

I don't think the rig matters much in terms of trimming, it is just different. The size of the jib matters more. So a FH 155% vs a MH 155% is pretty much the same trimming the sail (trimming the rig is very different). But a lot of FH don't carry large overlapping jibs, they use a massive main and just a small blade for a jib. Just enough really to balance the boat.

My trimaran for instance can barely sail under main alone because the main is so powerful it will drive the boat head to wind no matter what you do. A little bit of jib even if it's trimmed badly solves this.
 

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Have solent rig. Once over~10-15K AWS find boat does just as well with solent as with genny except downwind. I guess a demonstration of the lack of effect from overlap. Then downwind find better to use genny on a pole up to ~20-25K AWS even if means a reef in main.
Use a parasail so the comments about spinnakers/code zeros etc. don't apply. Think for cruisers the old saw "gentlemen don't go to weather" applies. Think it's much harder to get to your polar predictions in light/moderate air then heavy. Think swept back spreaders and running backstays make for a more complicated rig. Don't put the main on the spreaders downwind so think I would give up some with swept back spreaders. Understand the fractional rig makes more sense in theory and for racers but for the type of sailing I do and intend to do like being just under 64'. Like only needing to rig the running backstays when weather demands and when I deploy the removable stay for the stormjib. Like that my rig doesn't pump. Like not having jackstays to maintain.
Still as Bob says current generation of sails don't stretch and masts with swept back spreaders don't bend much so a lot of what I was taught to do no longer applies. Always learning. Thanks. Boat got 2 new coats on her bottom. At my level of sail trimming that will probably make more difference than anything.
 

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Thought one of the big pluses of frac rigged boats was you got a lot more out of adjusting the backstay beyond increasing fore stay tension. ?Is this still true?
 

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Thought one of the big pluses of frac rigged boats was you got a lot more out of adjusting the backstay beyond increasing fore stay tension. ?Is this still true?
It depends on the boat and the rig. Generally the backstay is just to play the top of the main, and it leaves the jib tension alone. But then you have a lot of fractional rigs without backstays with just runners, or some that don't worry about anything but prebend.

This is where rig design gets really fun. Since you can design a boat without needing to absorb all the backstay tension you can design a different hull. The J-35 for instance sailed best upwind with about 3500psi of backstay pressure. But the boat wasn't designed to take this much pressure and the hull would start to flex. On the fastest boats reinforcing the hull became necessary to offset the mast pressure.
 
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