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#121
01-25-2005, 12:20 PM
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| Frank says: "The notion that the lower the CB the better has to have a limit. At some point lowering the CB is counter productive. " I'm going to take that one statement of yours, Frank, and show you how stupid it is. The CB of a boat SHOULD be as close to the waterline as it can be. Of course, this is because the CB is the Centre of BUOYANCY, not Gravity. The C_G_ (Centre of Gravity) should be as low as possible, although you can create an excessively stiff boat that way, but it will have beautiful RM curves. You see, Frank, you are not paying attention at all, and are using terms and acronyms that you do not understand, to describe conditions that you do not understand. One day, someone is actually going to listen to your "put the ballast as high as possible" lines, and (at the least) lose their boat, and I hope they come looking for you with the bggest frikkin' lawyer they can find. Over and out. Steve |
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#122
01-25-2005, 01:55 PM
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 Of course I am was chatting about CG. Pardon me for getting hot and bothered yesterday from all of the flame. One day, has come. I am listened to more than I should be. So here is the disclaimer. A sailor will always get his information from more than one source.Now we need to discuss more about "stiffness". A boat with a long thin fin with a bulb on the end does appear to be able to have a CG at the same place as the identical boat with a shorter fin but a heavier bulb. I am concluding that the major advantage of the long fin then is the ability of the identical boat to carry less weight. In other words the short fin heavier bulb vessel can have identical stability curves as the long fin less heavier bulb keel. I will not allow you to stop me from going further with the analysis because I am so confident that it is correct (which likely means it isn't ) I see this so very clearly. There isn't even any fog. Here it goes. I am serious.Given one can get the same stability curve on the same hull regardless of fin length just by adding weight to reach the same CG, and given the obvious problems with long fins in regards to touching down and prohibition of use from most all weather harbors, in the absence of an artificial racing design rule, you are better off putting the weight into the hull structure rather than on the fin. At the limit, all the weight can be moved off the fin and put into the hull except in the rare situation where the CG is below the hull. Now the question is. Does having the CG below the hull provide any speed advantage? I can not open the Church today owing to pressing business. Furthermore, we have determined that it is best for me to limit postings to a few per week. The aggrivation is to much for this old man and youngsters just can't handle the truth. So please someone else take the ball and run with it. The implications are so huge for design with the above clarity. For example why not put an engine as part of the hull structure and eliminate weight from the fin to get the same stability curves. Or why bother with a canter, why not just a retractable. Or why even have a weighted fin at all, why not a centerboard. The above is so profound that it is like the uniform theory of boat design. String theory. It explains the rational for lighter and lighter deck structures, why Cal 40s with their thicker than needed hulls perform so well, an why some boats do not benefit from lighter rigging. Stability really is everthing and the above explains it. What is wanted by a sailor is to use a (egad) Jim Taylor term, is Variable Stability. Only I doubt he sees that as I do. To me it means you want less stability in under 7 MPH winds (sorry folks this is how it is reported - not knots) In over 7 MPH you want more. The way you get it, regardless of design is via weight. More crew, more gear, more water ballast or weight distribution, more weighted fin length with same weight on fin, or less weight aloft - ie less sail. Sincerely Frank. |
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#123
01-25-2005, 03:01 PM
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| The stability curves of a keel boat and of a twin keel boat are going to be different. In fact the water ballast represented in the Mac26x has BETTER stability curves IMO. But of course I need the manufacturer to help me generate those curves. Steve. Of course you have to be technically correct. If the Mac26X has a point of vanishing stability of 90 degrees or more, I would be VERY surprised. She does. Roger MacGregor is on record with Practical Sailor as stating that the boat has 115 stability. But what does that mean on a centerboarder? What does it mean on any boat really. Once you add crew and gear you change the vanishing stability. You can make it better or worse. If you tip it upside down (that's with its centreboard pointing straight up, if it will stay there instead of falling back into its slot) will it turn itself back upright again? This test was required prior to allowing export of the Mac26x to Europe. The story I have been told, but can not confirm because I wasn't there, was that the testers would not allow the boat to be turned directly upside down with the water ballast full. MacGregor Yachts, desired to pass this test, and had anticipated that it would be allowed to fill the water ballast for the testing. The MacGregor Yachts legals were sharping their pens for action when Roger said: "well test her dry". She righted herself unassisted. If you touch its masthead to the water, will it come back up from that? I would be surprised. Watch the video or read the brochure. The vessel comes right back, ballasted or unballasted. In fact we are forgoing divers for bottom work, prior to racing now, and draw down the boat to her side for bottom scrubbing. This was recommended in the owners manual. The only trick is to use the jib and not main haulyard. However, I do carry an extra 300 lbs of gear stowed low in the boat. The M has 300 lbs of solid ballast and it made sense to me. Almost every fin-keeled racing yacht out there will, with the possible exception of an older style of Swan 50-something which has - you guessed it! - a centreboard instead of a fin keel. PLEASE do yourself a favour and read up a bit on what makes a sailing boat stay upright, which is the same thing that gives it power, and that thing is righting moment. Think of the fin keel, and the ballast in it, as the person on the other end of the seesaw, and yourself as the wind in the sails. If the other person moves close to the pivot (like putting all your ballast inside the boat) then you will hit the ground hard (capsizing), when you are both at the same distance (or have the same moment relative to the pivot), then everything is balanced. Just think about it.... I think mostly about what makes any boat stay upright. The notion of a fixed fin in the water stopped making sense to me when I learned that the canters do not get lateral resistance from the keel fin. They rely on forward rudders instead. If you do not know what is meant by the word "moment" in this context, then you should not open your mouth about stability until you have proved that you understand the concept. Really. Steve I know that all boats can capsize in sufficient sea, regardless of righting moment. I also know that lubbers added several tons of led pellets to perfectly well designed sailboats because they didn't like the feel of the sea. I also know that a "tender" boat is made less so by reducing sail and that roller furling is the greatest sailing invention of the modern age. Steve, it doesn't take lessons of "moment" to ride a bike. Neither does it take such lessons for sailing. Are you really saying otherwise? I suspect the undersanding of "moment" is something every human has since learning to walk. That doesn't mean we are able to articulate it. But I will try later. I do appreciate the comments. |
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#124
01-25-2005, 04:10 PM
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One observation, even at anchor Samba rocked a minimum of 5 degrees. A smaller vessel probably would rock less. The Mac26x really would have performed well there. Rules require that to add a vessel to the island fleet you must remove a vessel with similar carrying capacity. You can not land a panga (dinghy) without a licensed naturalist aboard, so I do not think it productive to plan a Mac26x voyage or any voyage for that mater to the Galapagos. This is a place best cruised by charter. The Book Sailing for Idiots is oriented to keel boaters. Think about that. |
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#125
01-25-2005, 04:11 PM
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#126
01-25-2005, 04:22 PM
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#127
01-25-2005, 04:59 PM
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| D'ARTOIS, I object further to a number of points Mr Mighetto: That continuously snapping at designers in general - there are good ones and there are lesser good ones, just like in any other profession. One mark of a profession is that usually a license is required. We do not have that with boat designers and likely not with NAs. Sometimes you might say that in the absence of a license at least a degree is evident as a requirement but unfortunately even that does not hold true because many racers become designers and the most successful often do not hold licenses or degrees. The most important defining characteristic of a profession is that members of the profession are willing to speak out against those practicing that are doing wrong. Only Taylor, an NA out of Michigan, spoke against the popular Jim Teeters. He stated in really an unqualified endorsement of the vessel that the Mac26x can be operated safely. I assume he did the stability calculations and if they were filed, they will be available for public review eventually. Taylor likely is a profesional. Perry I put in that class. You are right there are some, but there is much work to be done. Management is more of a profession than boat design is. A second issue is the fact that this poor Mr Martin is put for 10 years in jail next to the fine and communal work he has to perform. How can anyone defend such a man? He had a fellony conviction prior to the disaster. BTW, his legals have set up an argument for appeal. It involves vertigo. The defense, which is not uncomon in drunken cases, is that Martin's slurred speech is explained as well as the oposite reaction than a sober man would make to an incident, by a medical condition. If you had said, I know that the 26x is a rickety, unstable vessel, and that it might quite possible that whilst powering and being overloaded, a sudden movement had tipped the boat. Eight adults, three children, no testimonies in the press of what had caused the tipping over. Overloaded may be with overweight people on a rickety boat, the accused Mr Martin must have had really the public opinion against him. Not a very good lawyer did he have as well. The owners manuals and warning placards had been removed from the boat by the time police could investigate. "Very good lawyers" are known for that kind of thing. Martin appears to have learned at the cost of two lives. Designers have a chance to learn about a revolutionary design. I was dissapointed in the judge because she wavered on the 10 year sentence, going with 6 instead. This sends the message that in any drunk case you can at least reduce the sentence by dragging the manufacturer into the case. No I think Martin had very very good lawyers because two deaths is two more felonies in my book and in the US three felonies usually means life in prison without parol. In such a circumstance you do not say......Anarchy.com is expecting...... .......and I have to come out smelling like roses...... Only a fool can not see that I have a following. I am just one of many thinking thoughts that those who pretend to be professionals would prefer not to have expressed vocally. Yet only through such expression will any good come. This is a very, very sad occasion and Mr Martin is definately not the only one to blame. I sincerely wish you will refrain from expressing any further nonsense explanation about stability and related topics. The sample of Mr Martin's accident is absolutely not the right one Martin and any drunk operator of a boat or car do not deserve the courtesy of shared blame. I agree that few things are black and white - except when they are written down. Martin will do his time. He is lucky that the judge will allow the US population to forgive him at completion of his debt. We are obliged to forgive him at that time. But the colateral damage - the halt of production of the Mac26x and the continued disinformation tracable to Jim Teeters and the Top Down approach used until recently at US Sailing has not been dealt with. Hopefully Taylor's review of the stability characteristics of the Mac26x was submitted to the courts in writing. The GP RWP did much to support the design as well. I sincerely wish that you could see how I have come to expressing stability and related topics in relation to the Mac26x. The arguments supporting Jim Teeters when they should be supporting Taylor just boggles my mind. Where does Teeter's get all his support from? Folks should be cutting off all ties to the fellow. His career ended with the end of the TP52. |
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#129
01-25-2005, 05:25 PM
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| Frankie says: "I also know that a "tender" boat is made less so by reducing sail " I was going to reply to this one, but honestly cannot bring myself to reply to such a blatant ignoramus, especially one who refuses to learn. Frank, I may not have a "license", but I spent 3 years at college studying yacht design at th Southampton College in England, and have spent 20 years designing since, including commercial vessels and round-the-world racing yachts. If you think you know what makes a yacht work better than I do, then good luck. You are now the first and only person in my "Ignore" list on this site. Have a nice life. |
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#130
01-25-2005, 06:13 PM
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| skinny boy woodboat, very good question as to why 216. Some of the answer I suspect is in observations you made about the bpat already. For one it is tender, the sail area on it is pretty small but standards. The Mac26x was given a 216 PHRF in what I have come to believe was a punitive action after the Newport Ensenada race where Mac26x Lady Katy Too! sailed in the cruising class to victory. Cruising class allowed some motoring at that time and it is my belief that her operator used the motor to reach plane in less than planing conditions, then shut the engine down, gaining significant advantage. The MacGregor Yachts company treated this event as it had been intended - a fun race, but I think serious racers were very upset, still are. On tender... A tender boat will stagger in gusts. This is not the behavior of the Mac26x. Part of the explanation for why the uninitiated say a boat is tender is that they have never observed one sailing in gusts. The use of flexible rigging, that acts like a spring in gusts to keep the boat on her feet is often not considered by those overusing the word tender. A boat with hard side chines like a Thunderbird or the Mac26x and a boat with a flat bottom, like the Mac26x and several planing sailboats are not usually described as tender. This is because at rest they are far more stable than a rounded hull, the stability coming from the flat portion of the hull. These boats harden up when heeling with the hard side chine contributing to keeping the vessel from crabbing. IE the chine provides lateral resistance as well as the fins. The generally accepted SA/D for a sportboat that would easily plane AND have the horsepower to plane under sail is >30 upwind and >75 downwind. The boat has an upwind SA/D of 19. Even adding a spinnaker downwind runs the SA/D downwind to only optimistically about 40. This puts its sailing horsepower in the same category as most traditional designs and one would not expect it to plane under sail very often. What the? See the calculator on http://www.eskimo.com/~mighetto/p11.htm. These boats can be expected to plane and do in normal wind fully ballasted. The same is true for the M. The math shows that both vessels are capable of breaking from displacement speed and reaching a true plane with the standard jibs. This is indicated by the displacement/length ratio being under 150. The X is significantly better at planing; her D/L is 137.59 vs the M's at 145.61. It probably will take abnormally strong wind (20 knots perhaps) for the M to plane fully ballasted where that potential in the X is evident in 12 knot winds, perhaps less depending on the point of sail. The X has a planing Dribbly style hull form. The M has more of a traditional rounded River sailboat form. But so what. Almost all of the US Sailing accredited schools teach you not to plane. This is my frustration with the training you get at US Sailing schools. Furthermore almost all of the buoy courses are purposefully designed so one can not plan in normal wind. Now I blow you away. Rerun the calculations without the water ballast or with the Genoa. Suddenly you have Melges class. Next you have the actually hull form, the foils are not exactly lifting so the weather performance of the boat is not likely to be any better than most other trailerables and will have substantial leeway which will in turn result in a higher rating. The rear foils most certainly are lifting foils on the Mac26x. There is substantial hardware involved. Hardware that after a few years of experience was significantly enhanced. This is not the case on the Mac26m. The M has rudder hardware more similar to the Mac19. It is less advanced in my view owing to that and the builder will tell you that where the X is meant for planing, the M is meant for short durations of planing, called surfing. You see that in the rudders. I will add some photos to the log. Anyway the hull form provides lateral resistance as well as the rudders. You can lift a rudder, as the manufacturer instructs and in most cases there will be no additional leeway. The over 17 MPH and under 3 MPH conditions are the exception. Here you do notice leeway. Sometimes you want that to make a mark. The forward foil is self gybing. This is why the Mac26x points better than any trailerable. (well at the time of the brouchure printing anyway) Perhaps a beter pointing boat has been developed since 1999. It is not the M. Combining this and other small details such as seakeeping and the fact that the manufacturer doesn't want people out of the cockpit meaning no hiking to increase righting moment results in a generally slow performing boat. The manufacturer definately tried to come up with a design where hiking out was not necessary. But with this specific X model, there is an unusual midship rail seat. The stanchions at the mid seat rail put your butt out there. Of course you can hang your rear outside any life line as well and I have seen Mac26x crews doing so. Hiking out is not allowed on many race courses. But certainly the Hobie Catters might rig something on an X and this is rumored to have been done. It is not necessary or advised. The boat planes in normal wind anyway. When you put it in waves it compounds that upwind as the entry is quite broad and will tend to pound and due to weight will slow. Acually there is a fine initial entry on the Mac26x bow. However there is a powerboat belly forward of midship. I tend to agree that this boat is stopped dead by a wave. We work around it by weaving through them, as do many sailboats. Only the heavy cruisers can crash through waves with little momentum impact. The lack of sail power will then make it slow to accelerate after being slowed by a wave. Power out of a tack is not a problem, though the broad buttocks is. Power after being slowed by a wave comes from the rig. This is acting like a big spring. Here we try to use gusts to advantage and fall off. There is no way that a Mac26x can beat a WinLee boat on a close reach by following the same course. One possibility is to pretend the boat is a multi-hull and sail the course more as a multihull would. IE more tacks to the mark but at planing speeds. The other way is down wind. We are allowed to move the water ballast off the boat and it is not needed for down wind work. Obviously, the design is not well suited for windward/leeward buoy work - except that the ability to drop ballast on down wind runs coupled with eventual relaxation of the rule preventing foil retraction will eventually make the boats competitive on the longer windward leward courses. Dropping ballast in PHRF NW races is already allowed. The canters will eventually give centerboarders the oportunity to remove the board retraction restriction. When that happens, we will get the same number of tacks up wind as a WinLee boat by sailining longer tacks into shallower water than the fixed fin boats can handle. Why Mighetto defends it could be buyer's remorse or could be just having a good go at stirring a bunch of people up by posting ridiculous claims, not unheard of on the Internet for sure, or maybe he is just delusional if you read the threads he has been into you find he has no real experience and doesn't even have experience on this boat in a wide range of conditions and speaks always hypothetically as he has not done anything that he speaks about. He also seems to have a fetish for certain people on the east coast which I am not sure what that is all about. I have a sailing resume stronger than most and certainly more experience in a water ballasted machine than most. The east coast is the least coast for sailors. My frustration with them has been some what eased by the great work the NYYC has recently done regarding centerboarders and IMS. The biggest gripe I have is the notion that bulbed fin fixed keels represent more than a recent and failed experiment in boat design. Nothing in history supports that and as of yet no NA or boat designer has been able to articulate anything good about them. Yet we still see new models rolling out with the sexy? testicle design I do hope we got through our differences, I was actually trying to be helpful to you and maybe I was not as descriptive as necessary in the first two posts, but did think I was answering your questions. I hope this helps. The helpful chat - even flame. The bashfull hang back or email me at mighetto@eskimo.com. |
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#131
01-25-2005, 06:26 PM
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#132
01-25-2005, 06:31 PM
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#133
01-25-2005, 06:43 PM
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OK Frank I can't freaking take it any more !! Why don't you tell the good people of this forum what your experience really is. No dodges, no bullshit, no garbage about other experiences applying to sailing, just give us a real number of miles or days or years or any other form of measure that most of us can recognize. If you can't do that then just shut the **** up!! You can't ---You won't--because you know you are full of it right up to your eyebrows Period. |
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#134
01-25-2005, 07:25 PM
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 Thanks so much for clearing that up. It's nice to know so many of us are helping to make this a wonderful, informative forum. |
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#135
01-25-2005, 07:41 PM
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