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What makes a boat weatherly?
What makes a boat weatherly?
What is the best keel type, hull form, and rig type? What can you do to improve weatherliness on an existing boat? Back you your answer with an explanation. Bart Senior |
What makes a boat weatherly?
"N1EE" wrote in message om... What makes a boat weatherly? What is the best keel type, hull form, and rig type? What can you do to improve weatherliness on an existing boat? Back you your answer with an explanation. Bart Senior Define "weatherly" please |
What makes a boat weatherly?
What makes a boat weatherly?
What is the best keel type, hull form, and rig type? Bart, I think more people here would take part in your sailing queries if you'd frame them within a hypothetical sailing story. It;s more interesting than just popping a Q&A. RB |
What makes a boat weatherly?
That's an easy question:
http://www.americascupcharters.com/2us17.htm "N1EE" wrote in message om... What makes a boat weatherly? What is the best keel type, hull form, and rig type? What can you do to improve weatherliness on an existing boat? Back you your answer with an explanation. Bart Senior |
What makes a boat weatherly?
N1EE wrote:
What makes a boat weatherly? What is the best keel type, hull form, and rig type? What can you do to improve weatherliness on an existing boat? Back you your answer with an explanation. IMHO the first step is to explain what is commonly meant by 'weatherly' other than the 12-Meter America's Cup defender. Usually it refers to a sailing vessel's ability to make good speed to windward, ie maintaining above average (or at least, better than the vessel being compared) VMG. In some senses, it can be taken to mean being able to make good to windward under adverse conditons. What makes a boat 'weatherly?' Firstly, an effective rig... most importantly one that can be shaped and sheeted inboard for maintaining drive at an angle close to the wind. Secondly, an effective underwater shape or foil, which will allow the boat to go forward easily but resist leeway. Third, the boat must generate enough righting moment to keep the rig & underwater foil at efficient angles instead of just laying over. In different conditions, effectiveness of rigs and especially hull shapes & underwater foils vary greatly. In moderate air and smooth water, a very high aspect rig and keels like glider wings work amazingly well. If the chop increases and flow in both air and water gets turbulent, they loose their efficiency and lower aspect rigs, and keels that are stubbier & swept back are the best. Another point to keep in mind is that relative areas of rig & underwater foil make a big difference. To improve the weatherliness of any boat, start first with the rig. The mast should be straight & vertically centered... you'd be amazed at how many sailors, even racers, are breezing around with crooked and/or slanted masts. Next, the condtion of the sails and the sheeting arrangements should be looked at... some are OK, some need improvement. One big improvement that can be made in many production boats is to put on a proper jib/genoa sheet track to bring the sheet lead inboard. Sheeting to the toerail ain't gonna get it (in most boats). Then pay attention to the underwater surface, if the keel & rudder foil sections are bunged up then that can be worked on. In some cases, a keel redesign (like Ol' Thom did) can help dramatically, but most of the time the designer knew what he was doing and unless you are making changes in the rig, you won't benefit from changing the keel IMHO. Lastly, buy spiffy new racing sails and get the sailmaker to come for a trial sail with you. Watch him carefully and take notes on everything he does & says. Sometimes, the biggest improvement in weatherliness can be made by changing skippers! Now, what was the question again? Fresh BReezes- Doug King |
What makes a boat weatherly?
"DSK" wrote in message
... Usually it refers to a sailing vessel's ability to make good speed to windward, ie maintaining above average (or at least, better than the vessel being compared) VMG. In some senses, it can be taken to mean being able to make good to windward under adverse conditons. So, does that mean that a catamaran that has a good VMG is more weatherly than a monohull that points higher? Does "under adverse conditions" mean, for instance, a chop, which a cat might handle well, or does it imply the issue of tacking quickly, which may be needed to work off a lee shore? I'm not debating; I'm bringing this up because I've been asked if my cat would be considered "weatherly," and my answer is "in some ways, yes; in other ways, no." Having enjoyed the adrenaline rush of raising anchor and clawing off a nasty lee shore at 3 in the morning, I'm glad my cat has twin diesels. |
What makes a boat weatherly?
Jeff Morris wrote:
So, does that mean that a catamaran that has a good VMG is more weatherly than a monohull that points higher? Of course not, don't be silly ;) Actually, I'd give some consideration that the higher pointing boat would be the more weatherly, but actual VMG should probably be the deciding factor. Does "under adverse conditions" mean, for instance, a chop, which a cat might handle well, or does it imply the issue of tacking quickly, which may be needed to work off a lee shore? Again this is just my HO but 'weatherliness' doesn't include tacking. I'm not debating; I'm bringing this up because I've been asked if my cat would be considered "weatherly," and my answer is "in some ways, yes; in other ways, no." That's a good answer. Having enjoyed the adrenaline rush of raising anchor and clawing off a nasty lee shore at 3 in the morning, I'm glad my cat has twin diesels. Whatever works. I've not only motored out from lee shores, I've done it in reverse. Mind you, I'm not claiming that had Joshua Slocum been in my shoes he'd have done the same thing.... FB DSK |
What makes a boat weatherly?
(N1EE) asked:
What makes a boat weatherly? What is the best keel type, hull form, and rig type? What can you do to improve weatherliness on an existing boat? Back your answer with an explanation. Generically speaking, assuming we're talking about existing production boats and not esoteric drawing-board possibilites, I'd answer: Dictionary def: Ability to sail close to the wind with little drift to leeward. Deep fin. Low wetted surface; low CsubP. Masthead sloop. Depends on the boat; but... Always helps to: change to fresh sails; use appropriate sails for conditions; trim properly. If it has a full keel, high D/L ratio, low aspect ratio, multiple masts, or similar, ya just hafta sell it and buy something else. Physics. |
What makes a boat weatherly?
"Bobsprit" wrote in message ... What makes a boat weatherly? What is the best keel type, hull form, and rig type? Bart, I think more people here would take part in your sailing queries if you'd frame them within a hypothetical sailing story. Bob, all your sailing stories are hypothetical - and they aren't very interesting. Regards Donal -- |
What makes a boat weatherly?
Frank Maier) wrote:
....snip... Self-followup. I posted before seeing Doug's comments. Ignore mine and just read his. |
What makes a boat weatherly?
Bart,
James question should be answered. It was a good question. Define WEATHERLY? That is very important to be clear on what is meant by Weatherly. Doug's answer explains a boats ability to go to "weather" Jeff indicated VMG. They are only part of a good weatherly Boat. In the last Am Cup Race, the KIWI"s had a boat that could go to wind at a great angle. The POS needed full pumps and a man with a bucket to get rid of the stern wave. Any cruiser, worth his "Salt" would give away a little VMG for a dry boat that will get up wind reasonable in a dry, comfortable fashion. When beating into the wind for a couple of days, VMG isn't as important as a dry boat that doesn't pound your teeth out. A boat that will trim out at a decent heel (About 15 to 20 deg) that doesn't pull your arm out of your shoulder socket with windward helm. A boat that will let you fry an egg in the galley that is nearly round while climbing on the wind near or on a 45 deg heading into the wind. Some of us Ole Timers would call a boat that tacks thru 100 deg that has the other point a very, very satisfactory "Weatherly Vessel" A boat that can be trimmed with back stay tension, cunningham and maybe barbar hauled sheet (If necessary) a weatherly rig. No jacks or sail changes. That would be a Weatherly rig A Hull shaped so that it wouldn't round up in a 25 Deg heel and carry a neutral helm. A helm that would add enough reserved buoyancy in a heel to keep the hull close to under the sail to maintain a heading If it had all these characteristics and sailed like a witch would be perfect! Would you like to see the pictures of "Peunma" again? Ole Thom |
What makes a boat weatherly?
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What makes a boat weatherly?
DSK wrote in message
amazingly well. If the chop increases and flow in both air and water gets turbulent, they loose their efficiency and lower aspect rigs, and keels that are stubbier & swept back are the best. Also in chop, lighter boats can be stopped by a wave. The light weight water ballasted Mini-Transat boats use ballast, not just for increasing righting moment but to maintain inertia--the added mass keeps them moving. I agree a broader keel would be less likely to stall in turbulent conditions. Why is it better for such keels to be swept back? Bart Senior |
What makes a boat weatherly?
"Jeff Morris" wrote
http://www.americascupcharters.com/2us17.htm These are some of the most beautiful boats sailing. I used to watch these yachts "pretend to race" every day when I worked in Newport. I have a general policy of not paying for "rides" otherwise I'd try one of these. Still I highly recommend them. It's a great idea for a date. |
What makes a boat weatherly?
Why a Mast head Rig?
He is probably a lot like me. That is what I'm use to. A mast head balances better while cruising. That's my opinion and it is just my opinion, for what its worth. I've sailed on 3/4 rigs, and have to admit, the ability of watching that rig automatically flatten the main in a puff does make me green with envy. No helm correction needed during or after. Nice! I've often wondered how it would preform on Main alone? My boat sails just fine. No excessive weather helm. I know some fractional rigs won't. I know my rig and am at ease with it Ole Thom |
What makes a boat weatherly?
DSK wrote
What makes a boat 'weatherly?' Firstly, an effective rig... most importantly one that can be shaped and sheeted inboard for maintaining drive at an angle close to the wind. One big improvement that can be made in many production boats is to put on a proper jib/genoa sheet track to bring the sheet lead inboard. Sheeting to the toerail ain't gonna get it (in most boats). Using a second jib sheet to place the jib clue where you want it is an option--like a barber hauler only pulling inboard. This only works if the shrouds don't get in the way! Usually, the jib tracks are located as far inboard as the shrouds will allow, and barberhaulers are used to pull the jib clue outboard when sailing more off the wind. So it all depends on what you are using for a head sail. A small jib with it's clue forward of the shrouds could be controlled more accurately using this method, with jib sheet chafing at the shrouds. Bart Senior |
What makes a boat weatherly?
"N1EE" wrote in message om... I think the most import issue regarding having a weatherly boat is the ability to claw off a lee shore--that is survivability. So you brought up a very good point Thom! Points to you. If you are freezing cold, wet, seasick, and hungry, the upwind performance of the boat will not matter much. I've been wondering about the definition of "weatherly" since this question was posed [ one point Bart]. A couple of years ago, I was on a friend's 42' Bavaria. It was February, and we were beating into an F5 under sail and 50 hp engine. I was very aware of the fact that we were slamming much less than Setanta would have been, under the same circumstances. The main difference was the extra waterline length. The extra weight was also noticable. So, to answer your original question, I would say that waterline length is the most important factor. Regards Donal -- |
What makes a boat weatherly?
N1EE wrote:
Also in chop, lighter boats can be stopped by a wave. True. And while it is possible to foot off and regain some VMG, usually you can't regain all of it. The light weight water ballasted Mini-Transat boats use ballast, not just for increasing righting moment but to maintain inertia--the added mass keeps them moving. They also shift the center of mass forward, put the bow down. I agree a broader keel would be less likely to stall in turbulent conditions. Why is it better for such keels to be swept back? I don't really know how it works, but swept back foils are more resistant to stalling. Anther keel shape you might notice some time is that many fin keels are tapered in profile to the bottom edge, but they are not tapered in section. The chord gets shorter and the camber gets fatter. This does two things, it reduce turbulence off the bottom edge and makes the lower secton harder to stall, and gets more ballast down low. BTW I thought Frank's answer was good. Much shorter and to the point than my rambling posts. Fresh Breezes- Doug King |
What makes a boat weatherly?
"N1EE" wrote ...
I think the most import issue regarding having a weatherly boat is the ability to claw off a lee shore--that is survivability. Agreed, it is a very important ability especially in a cruiser that goes into out of the way anchorages. So you brought up a very good point Thom! Points to you. If you are freezing cold, wet, seasick, and hungry, the upwind performance of the boat will not matter much. I dunno... seems to me that being cold, wet, seasick, hungry, and getting bashed into rocks on a lee shore would be worse. Donal wrote: I've been wondering about the definition of "weatherly" since this question was posed [ one point Bart]. A couple of years ago, I was on a friend's 42' Bavaria. It was February, and we were beating into an F5 under sail and 50 hp engine. I was very aware of the fact that we were slamming much less than Setanta would have been, under the same circumstances. The main difference was the extra waterline length. The extra weight was also noticable. So, to answer your original question, I would say that waterline length is the most important factor. Bigger is better, but it ain't evrything. The old square riggers were much longer on the waterline than any modern sailboats, and they were not weatherly at all by comparison. Look up the term 'embayed' and think if this has happened to you or anyone you know sailing a modern small boat. Fresh Breezes- Doug King |
What makes a boat weatherly?
"DSK" wrote in message ... snip Bigger is better, but it ain't evrything. The old square riggers were much longer on the waterline than any modern sailboats, and they were not weatherly at all by comparison. Valid point! I now see the "windward" aspect of *weatherly* a little more clearly. Regards Donal -- |
What makes a boat weatherly?
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What makes a boat weatherly?
Frank Maier wrote: Ole Thom pretty much answered for me. I've raced and cruised on both masthead and fractional rigs. I guess I answered "masthead", assuming as my default a full crew of experienced sailors who'd manually deal with changing conditions on a constant basis. Then you don't need the fractional rig to "automatically depower" for you. Conventional wisdom has it that mast head rigs will point higher, and I think that's true in ideal pointing conditions. But I think the frac rig is more versatile. If we're down to the level of the "real" world, then theoretical factors become less important than human factors, like Ole Thom's comfort level with his boat as it is. If I were buying for myself tomorrow, I'd get a Freedom 38, which is not gonna be as "weatherly" as either a masthead or fractional Bermudan rig; but it meets a whole lot of other pragmatic criteria. heh heh the old Fredom 40 cat-ketch is one of my dream boats. They don't point so high either, but it's a marvelous cruising rig. Sturdy and very easy to handle. It's also a very good point that knowing how to get the optimum out of the rig you have is more important than pining away for some theoretical ideal. There are too many sailors who study teensy detailed ways of scrooching some small improvement out of their boat, when their basic sailing methods are notably below optimal. I remember acting as 'guest skipper' on a very nice European designed and built racer-cruiser, a boat that should have had good performance but usually did very poorly in casual races. The usual skipper stood at my elbow and appeared to be very interested in how I drove the boat and had the sails trimmed. He usally cranked everything in hard and made the boat heel 'way over, when I skippered we did much better. The next day, I was sailing on another boat and he went back to doing the same old thing.... and was complaining about it the rest of the season. Thom's keel mod is a good idea IMHO because he does not sail in the conditions the boat was designed for, so it benefitted from increased keel area. For most sailors, I don't think such a modification would be a good idea. Fresh Breezes- Doug King |
What makes a boat weatherly?
DSK wrote: To improve the weatherliness of any boat, start first with the rig. The mast should be straight & vertically centered... you'd be amazed at how many sailors, even racers, are breezing around with crooked and/or slanted masts. Doug, I am surprised at this comment and I'll disagree with it for a number of reasons: Bending the mast aft can flatten the main. A flatter main is better at high wind strengths -and apparent wind is highest when going upwind. Flattening the main also helps keep the slot open to increase the efficiency of the foresail. The latter is the most important sail for weatherliness. So by bending the mast aft, forestay tension is increased to reduce forestay sag that reduces efficiency. Finally, straightening the mast is not a good idea if the main sail is old and out of shape (where the bend helps keep the draft forward) or even not originally cut to a straight mast! Finally, as an extra bonus, adding some mast bend can help prevent mast inversion in severe conditions which can lead to a catastrophic collapse (but I wouldn't expect you to know about that problem). while most should know that the rake of the mast affects C of E and the degree of weather helm, I'll guess that many do knot know that by giving the boat some weather helm she climbs to windward better as the rudder adds lift. So, the bottom line is that it may be quite inappropriate to straighten the mast to make the boat weatherly. Cheers |
What makes a boat weatherly?
DSK wrote: Jeff Morris wrote: So, does that mean that a catamaran that has a good VMG is more weatherly than a monohull that points higher? Of course not, don't be silly ;) Actually, I'd give some consideration that the higher pointing boat would be the more weatherly, but actual VMG should probably be the deciding factor. No, your first guess was right : the most weatherly boat is the boat that goes closest to the wind. As long as the DMG is to windward you can escape a lee. A high VMG might be made by a very shallow angle to the wind. Think about being caught in a lee bay... When you add in losses for tacking the faster VMG might not get out... Cheers |
What makes a boat weatherly?
DSK wrote:
....snip... BTW I thought Frank's answer was good. Much shorter and to the point than my rambling posts. Thanks, Doug; but my comments were too brusque. You actually took the time and effort to explain some details, when by contrast I just said something like "trim appropriately." Probably not very valuable advice to someone who's a bit hazy on the "best" way to trim his/her boat. Sounds like we're basically talking about the same concepts; so maybe in either case it's a starting point for discussion/argument, like the thread about cats vs. monohulls and pointing vs. VMG which developed from your comments. That was good stuff. These are the kind of threads which make this ng valuable to participants. (Well, *this* participant, anyway.) I hadda laugh when Bobsprit jumped in and offered his advice on how to pose a question for discussion. Yeah, right. Like anything he's ever posted has generated and actual discussion. It's always just looooong threads of "my dick's the biggest" vs. "no, my dick's bigger" and "you're gay" vs. "no, you're gay." I'm happy to have an honest disagreement with someone. I have friends who favor "classic cruisers" with full keels, high D/L ratios, etc.; and we often have long "discussions" over a bottle of wine (or two) about what constitutes the "best" sailboat. We sometimes get a bit loud; but somehow it never degenerates into that silly ad hominem crap. Anyway, I'll just say that this was a good thread. I've enjoyed it and look forward to others like it. I don't participate often; but I read most threads here. |
What makes a boat weatherly?
MC wrote:
Doug, I am surprised at this comment and I'll disagree with it for a number of reasons: Bending the mast aft can flatten the main. That isn't what I was talking about. And the sail has to be cut to take the mast bend into account, or it doesn't work. So, the bottom line is that it may be quite inappropriate to straighten the mast to make the boat weatherly. Considering that you don't know that 20 doesn't equal 15, and from what you have said about your racing results, you have a lot more to learn than to teach. DSK |
What makes a boat weatherly?
MC wrote:
DSK wrote: while most should know that the rake of the mast affects C of E and the degree of weather helm, I'll guess that many do knot know that by giving the boat some weather helm she climbs to windward better as the rudder adds lift. I believe this to be true for full keels, but how does it work with a fin keel? Cheers Marty |
What makes a boat weatherly?
Same effect. It adds lift.
Cheers MC Martin Baxter wrote: MC wrote: DSK wrote: while most should know that the rake of the mast affects C of E and the degree of weather helm, I'll guess that many do knot know that by giving the boat some weather helm she climbs to windward better as the rudder adds lift. I believe this to be true for full keels, but how does it work with a fin keel? Cheers Marty |
What makes a boat weatherly?
DSK wrote: MC wrote: Doug, I am surprised at this comment and I'll disagree with it for a number of reasons: Bending the mast aft can flatten the main. That isn't what I was talking about. And the sail has to be cut to take the mast bend into account, or it doesn't work. So, you don't understand why bending a mast can flatten the main? Try visiting a sail trimming site such as North -they explain it well and it is really basic stuff. So, the bottom line is that it may be quite inappropriate to straighten the mast to make the boat weatherly. Considering that you don't know that 20 doesn't equal 15, and from what you have said about your racing results, you have a lot more to learn than to teach. Aww, don't pout so. Why do you continue with this nonsense. Look up the boat I named and you'll find it's not 24' nor 20' long. These are your fabrications getting in the way of truth again. Sorry, you lose again. Cheers |
What makes a boat weatherly?
Donal wrote: It was February, and we were beating into an F5 under sail and 50 hp engine. Why the engine? F5 should be good sailing conditions for that boat? Cheers MC |
What makes a boat weatherly?
"MC" wrote in message ... Donal wrote: It was February, and we were beating into an F5 under sail and 50 hp engine. Why the engine? F5 should be good sailing conditions for that boat? Hmmm! The boat was a centre cockpit Barvaria 42. The wind was a very cold easterly(4-6C). The owner had his wife aboard. She was diagnosed with bronchitis a week later, and it took her a couple of months to recover. The wind was almost dead on the nose, and the decision to motor made sense at the time. In Setanta, I would have sailed further off the wind. I might also have had the engine on (depending on time and tide constraints). Setanta would definitely have slammed a lot more. Regards Donal -- |
What makes a boat weatherly?
Close, but not quite the case. The rudder can not provide any
significant lift on its own. Any rudder angle adds drag and any rudder angle effects heal. Rudder to correct weather helm increases healing monemt. What is really happening is that the weather helm introduces an attack angle for the keel. What you actually want to do is set the boat up to balance with a heading that is a little higher than desired course. When the rudder brings the track back to course, you are left with the foil (keel)at a small attack angle. This works on all hulls, but is most apparent on fin keel boats. Matt Colie -www.yachtek.com Martin Baxter wrote: MC wrote: DSK wrote: while most should know that the rake of the mast affects C of E and the degree of weather helm, I'll guess that many do knot know that by giving the boat some weather helm she climbs to windward better as the rudder adds lift. I believe this to be true for full keels, but how does it work with a fin keel? Cheers Marty |
What makes a boat weatherly?
No, I'm afraid you are wrong. The turning moment which causes the boat
to heel has a component to windward. If the rudder is neutral it adds no lift of couse and is simply feathered in the water flow. Perhaps you might like to consider the rudder as a wing: the angle of attack to the water flow causes lift (and drag)? Cheers Matt Colie wrote: Close, but not quite the case. The rudder can not provide any significant lift on its own. Any rudder angle adds drag and any rudder angle effects heal. Rudder to correct weather helm increases healing monemt. What is really happening is that the weather helm introduces an attack angle for the keel. What you actually want to do is set the boat up to balance with a heading that is a little higher than desired course. When the rudder brings the track back to course, you are left with the foil (keel)at a small attack angle. This works on all hulls, but is most apparent on fin keel boats. Matt Colie -www.yachtek.com Martin Baxter wrote: MC wrote: DSK wrote: while most should know that the rake of the mast affects C of E and the degree of weather helm, I'll guess that many do knot know that by giving the boat some weather helm she climbs to windward better as the rudder adds lift. I believe this to be true for full keels, but how does it work with a fin keel? Cheers Marty |
What makes a boat weatherly?
Strangly,
That is not at quite what the towing tank data work here says. For a conventional vessle sailing in moderate conditions with a slight weather helm (Ra 3). Yes, the rudder has a lift component to weather and it is most typically below the center of bouyancy. If the rudder provided significant hydrodynamic lift and the keel did not: then the foil section for the keel would have no advangage and vessles otherwise equal varying only in draft would be substantially equal performers. I can demonstrate that this is not the case. Also: the only attack angle control for the keel would be the slip angle (leeway) and this is negative, so there would be no value in trying to use boat speed to reduce the slip angle. Matt Colie (see prior sigs) MC wrote: No, I'm afraid you are wrong. The turning moment which causes the boat to heel has a component to windward. If the rudder is neutral it adds no lift of couse and is simply feathered in the water flow. Perhaps you might like to consider the rudder as a wing: the angle of attack to the water flow causes lift (and drag)? Cheers Matt Colie wrote: Close, but not quite the case. The rudder can not provide any significant lift on its own. Any rudder angle adds drag and any rudder angle effects heal. Rudder to correct weather helm increases healing monemt. What is really happening is that the weather helm introduces an attack angle for the keel. What you actually want to do is set the boat up to balance with a heading that is a little higher than desired course. When the rudder brings the track back to course, you are left with the foil (keel)at a small attack angle. This works on all hulls, but is most apparent on fin keel boats. Matt Colie -www.yachtek.com Martin Baxter wrote: MC wrote: DSK wrote: while most should know that the rake of the mast affects C of E and the degree of weather helm, I'll guess that many do knot know that by giving the boat some weather helm she climbs to windward better as the rudder adds lift. I believe this to be true for full keels, but how does it work with a fin keel? Cheers Marty |
What makes a boat weatherly?
MC wrote:
So, you don't understand why bending a mast can flatten the main? No I understand it quite well. But it's pretty obvious that you understand very little (in fact, nothing) about how to set up the basic tuning of a mast. DSK |
What makes a boat weatherly?
DSK wrote: MC wrote: So, you don't understand why bending a mast can flatten the main? No I understand it quite well. But it's pretty obvious that you understand very little (in fact, nothing) about how to set up the basic tuning of a mast. Ignoring your usual childish ad hominem, I wonder why did you say that straightening the mast makes a boat more weatherly? Cheers |
What makes a boat weatherly?
Matt Colie wrote: Strangly, That is not at quite what the towing tank data work here says. For a conventional vessle sailing in moderate conditions with a slight weather helm (Ra 3). Yes, the rudder has a lift component to weather and it is most typically below the center of bouyancy. So now we agree. If the rudder provided significant hydrodynamic lift and the keel did not: then the foil section for the keel would have no advangage and vessles otherwise equal varying only in draft would be substantially equal performers. I think you've evaded the point. Of course the keel provides most of the lift but the rudder dfoes add some -right? Remember even a small gain wins races to windward! Cheers MC I can demonstrate that this is not the case. Also: the only attack angle control for the keel would be the slip angle (leeway) and this is negative, so there would be no value in trying to use boat speed to reduce the slip angle. Matt Colie (see prior sigs) MC wrote: No, I'm afraid you are wrong. The turning moment which causes the boat to heel has a component to windward. If the rudder is neutral it adds no lift of couse and is simply feathered in the water flow. Perhaps you might like to consider the rudder as a wing: the angle of attack to the water flow causes lift (and drag)? Cheers Matt Colie wrote: Close, but not quite the case. The rudder can not provide any significant lift on its own. Any rudder angle adds drag and any rudder angle effects heal. Rudder to correct weather helm increases healing monemt. What is really happening is that the weather helm introduces an attack angle for the keel. What you actually want to do is set the boat up to balance with a heading that is a little higher than desired course. When the rudder brings the track back to course, you are left with the foil (keel)at a small attack angle. This works on all hulls, but is most apparent on fin keel boats. Matt Colie -www.yachtek.com Martin Baxter wrote: MC wrote: DSK wrote: while most should know that the rake of the mast affects C of E and the degree of weather helm, I'll guess that many do knot know that by giving the boat some weather helm she climbs to windward better as the rudder adds lift. I believe this to be true for full keels, but how does it work with a fin keel? Cheers Marty |
What makes a boat weatherly?
Doug you are talking about a mast
being straight side to side, and of course you are correct that many people don't get this right. For one thing is a pain and take a lot of time tweaking the shrouds. MC is talking about mast bend as used for sail shaping--another subject entirely. Bart Senior DSK wrote MC wrote: Doug, I am surprised at this comment and I'll disagree with it for a number of reasons: Bending the mast aft can flatten the main. That isn't what I was talking about. And the sail has to be cut to take the mast bend into account, or it doesn't work. So, the bottom line is that it may be quite inappropriate to straighten the mast to make the boat weatherly. Considering that you don't know that 20 doesn't equal 15, and from what you have said about your racing results, you have a lot more to learn than to teach. DSK |
What makes a boat weatherly?
DSK wrote
Frank Maier wrote: Ole Thom pretty much answered for me. I've raced and cruised on both masthead and fractional rigs. I guess I answered "masthead", assuming as my default a full crew of experienced sailors who'd manually deal with changing conditions on a constant basis. Then you don't need the fractional rig to "automatically depower" for you. Conventional wisdom has it that mast head rigs will point higher, and I think that's true in ideal pointing conditions. But I think the frac rig is more versatile. Masthead rigs can also carry a bigger spinnaker and go faster downwind. heh heh the old Fredom 40 cat-ketch is one of my dream boats. They don't point so high either, but it's a marvelous cruising rig. Sturdy and very easy to handle. I want to try one of those. They look like fun. It's also a very good point that knowing how to get the optimum out of the rig you have is more important than pining away for some theoretical ideal. There are too many sailors who study teensy detailed ways of scrooching some small improvement out of their boat, when their basic sailing methods are notably below optimal. I remember acting as 'guest skipper' on a very nice European designed and built racer-cruiser, a boat that should have had good performance but usually did very poorly in casual races. The usual skipper stood at my elbow and appeared to be very interested in how I drove the boat and had the sails trimmed. He usally cranked everything in hard and made the boat heel 'way over, when I skippered we did much better. The next day, I was sailing on another boat and he went back to doing the same old thing.... and was complaining about it the rest of the season. Lots of sailors jump into big boats and think they know to sail them. The fact is they will never get good, if the boat is forgiving. Small boats make the sailor. If you learn on a dinghy, and screw up, you end up in the water. When you are wet, and cold, is it very obvious which way the wind is coming from. I am still amazed at the number of people, who can't tell where the wind is coming from! I tell me students if they screw that up, I'm dumping a bucket of water on their heads to help them learn. Threats seem to help. Thom's keel mod is a good idea IMHO because he does not sail in the conditions the boat was designed for, so it benefitted from increased keel area. For most sailors, I don't think such a modification would be a good idea. I'm not familiar with what Thom did, so I'll take your word for it. Bart Senior |
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