How heavy is too heavy II ?
I was posting this in the thread “HOW HEAVY IS TOO HEAVY” but the thread has just vanished, so I am opening a II thread with the same name to continue the discussion (hope she come back).
I find this thread very interesting. It goes in the direction of the kind of boat I am interested, I mean ocean going, easy (solo crewed), comfortable, safe, fast and reliable. Of course we are talking of boat compromises and in particular of the role mass has on those compromises.
I was having in another thread an interesting discussion with Phil that is exactly about this subject, so I will bring it to this discussion. I would like to have your opinions.
We were discussing the new Swan 46 that very surprisingly turned to be a medium displacement boat, opposing the trend of all the other boats in the line, that are fast cruiser racers.
Why a high-tec. advanced design company would do that kind of boat, a heavy boat, an old design boat for some?
But first let me sum up what was said in the other thread that is relevant to this discussion .
I have said in another thread:
....And about sailing, there are many differences in the kind of sailing (traveling). There are the ones that want to go as fast as possible with a full crew, others want good speed but a boat that can be easily solo sailed, others want maximum comfort in a seaway others an optimized safety, for the size of the boat. There are a lot of compromises to be made (in hull shape and rig), originating completely different boats, depending on the assumed different priorities.
The only disagreement (possibly) with you has to do with this statement:"..."others appreciate the craftsmanship of fine joinery and designs that give a nod to tradition but acknowledge contemporary developments in keel/hull form and aerodynamics, albeit with little regard to weight reduction."
It seems to me that you think that weight (mass), besides the one needed to give the boat stability) is always a bad factor in a sail boat.
Although I agree that mass is always a bad factor in a racer or even in a cruiser-racer, it is not (in my opinion) in a pure cruising boat with priorities aimed to have an easy motion, maximum safety and lots of autonomy.
And I am not the only one thinking that way. Take as an example the new Swan 46. Swan are well known by their high-tec, luxurious cruiser racers (but also winning ocean racers), but recently they went to the old cruising roots and made a purely cruising boat, the 46.
The boat displaces 39 000 lbs. Compare it with the displacement of the Swan 45, a cruiser racer that comes in two versions : in the more racing version, 19 150 lbs and in the "cruiser" version, 23 920 lbs. The extra weight of the 46 doesn’t find its motive on a question of money ( kind of thinking – lighter, more expensive) because those guys don''t look at costs, just quality (both boats cost over $700 000, being the 45 the "cheapest".
It is obvious that the Nautor Company technicians believe that mass has an important role to play in a purely cruising boat and they surely know what they are doing, having lots of experience with racing and cruising boats.
Phil replied in the other thread:
...” Ballast weight should be maximized as deeply as possible while all other displacement contributors should be minimized to the extent it is possible within the design parameters....
The intuitive argument has often been made that increased displacement produces better motion comfort. Some also feel that it’s necessary for robust construction. Both of these claims are false.
I do not believe that Swan intentionally built the 46 to be heavier, only that they were appealing to customers with different priorities. Luxury equipment and solid wood joinery are not light and the people who are drawn to this yacht place a higher priority upon these things than sailing performance, simple as that. They did not make the boat heavier to improve motion or strength.
As it has been stated here before, if you are willing to pay for greater displacement, which is another way of saying “a bigger boat”, and you wish to maximize motion comfort, buy a longer waterline length instead. You will get more interior space and greater speed as a free bonus! ... My guess is that either of the Swan 45s will be much faster, more comfortable and easier to sail too...”
Phil, I don’t agree.
The Swan 45 interior is absolutely lavishly and of course also made of solid wood and you can believe it, nobody gives $700 000 for a boat of this kind if it is not a “very special” and luxurious boat.
I think they made the boat heavier to make it rock solid , and to give a boat a slightly curved hull (not flat). Both things will improve motion and contribute to give the boat an easy controllable handling.
I don’t think you are completely right when you say : “.....” Ballast weight should be maximized as deeply as possible while all other displacement contributors should be minimized to the extent it is possible within the design parameters....”
It is well known that a dismasted sail boat is much more easily capsized ,but the same boat with the mast (weight of the mast) has a higher center of gravity.
If I agree that a boat should not have a high positioned weight it is known that a distribution of the weight all around (below the waterline) contributes to an easy motion (that’s why steel boats have an easier motion, compared with similar GRP boats of the same weight). A deep keel with a bulb certainly contributes for a lot of initial stability but not for an easy motion, quite the opposite.
About buying a bigger boat. Regarding motion I found that you are partially right (bigger boats have a better motion). The boat, if it is a cruiser- racer (light, shallow hull, big sails, deep small fin with a bulb) will continue to have a difficult, sharp and nervous character. After all it is made to be crewed with a lot of people and to be a quick boat, not only in speed but in all of its reactions.
Also the bigger the boat, the bigger the sails (you could say that because the boats have the same weight, the sails would be the same size, but that is just not true. The bigger cruiser racer will have always sails a lot bigger than the smaller cruiser boat with the same weight) and that will make the boat more difficult to sail alone.
There’s another three dissuasive important factors in a bigger boat:
1- costs , not really the boat but the marinas and maintenance prices are a lot different between a high displacement 39ft and a light weight 48ft.
2- other problem, at least in Europe, is that in many Marinas, no matter what you pay, you just don’t have places for boats of that size, and I don’t mean one or two, I say a lot of them, specially the nice old ones, in typical fisherman towns.
3-And finally, even if you can find a place, most of the marinas around here are not made for big boats so you just have a lot of trouble to put the boat in and out and forget about doing everything alone (I suppose most of us can do it alone with our boats), it is just not possible, even with a bow thruster (you have to push the other boats to fit in).
Of course, there is a fourth reason that I haven’t even considered. If the boat is heavier that means that probably it is stronger. I believe modern light boats will not have any strength problem unless they hit the ground or hit something in the water, and if it should happen to me, I would rather be in a heavy displacement, preferably in a steel one.
About your guess between the Swan 46 and 45 : “My guess is that either of the Swan 45s will be much faster, more comfortable and easier to sail too...”
I think that you have guessed wrongly.
In the February 2005 issue of “Yachting World” there is a comparative test between a Swan 46 and a Arcona 460. It is an interesting test because the Arcona (Swedish boat) is a cruiser racer that is very near in type and performance to the Swan 45. Both have narrow fins with a bulb about 8ft draft. the Swan is even more radical with a little bit more sail to the same displacement.
The guy that tested both boats in similar sea conditions (17 to 20 knots of wind) defines the boats like that:
“The Swan 46 is no speed machine, but there wasn’t a hint of slamming, just a very gentle, pleasant motion”.
“The Arcona is good fun to helm, an absolute pleasure, giving precise feedback.”
And in the conclusion.
about the Swan:
...”Nautor solidity and thoughtful cruising design are definitively back. She’s rock solid built with careful attention to detail and fantastic looks, and as a boat to take confidently round the world, she’s perfect.”
About the Arcona:
“The Arcona is a different beast all together, and beast is the operative word. With a powerful rig and lightweight construction, she has performance to shame many higher profile race cruisers.
She would be a fantastic boat to own, for cruising and racing...but she might be a bit more of a handful for the average family to cover thousands of miles on.”
About speed, from the test I will say that there is about 1knot (max 1,5) between the average speed of the two boats in the same wind condition.
For racing it is a huge difference, for cruising it will mean that you make it to the Azores in 13 days instead of 12.
It is not this difference in speed that is going to take you away of trouble if you find bad weather coming towards you.
For that you will need this:
Isn’t she a beauty? With one of those I believe you will make it in half the time. Only with one of those things it is true that you will need half the stuff (water, diesel, food) that you need with the other two.
Perhaps I am not too old to have one of those, or maybe I am still crazy after all these years, who knows?
About the Trimax. The boat with 3knots of wind will do 4 knots.
Magic, isn’t it?
How heavy is too heavy II ?
Just a quick thought, I have been passively following the "How heavy..." thread.
The comments you are making about the Swans, the 45 and the 46 are COMPLETELY different boats, the 45 with appx 20,000lb displ. with 9,000lb ballast vs the 46 with appx 31,000lb displ and a wide variety of ballast and keel configs.
I''ve spent quite a few thousand miles on the older circa 1975 Swans, 44, 47, 48''s and they were wonderful boats with great motion. We nicknamed them "Flying Furniture" for their stunning woodwork below. They really needed nasty conditions to make them shine against their "Lesser" rivals. Stiff wind, steep chop, and they just powered though it all. Not much in the light stuff, however. I would take one of the older Swan 44 MK I boats ANYWHERE in the world with confidence and comfort. (Although they were a bit stuffy in the tropics)
The modern Swan 45 is a "Take no prisoners" race boat, and it shows. It is lighter, and the joinery below is nowhere near as lavish as in the older boats. They are screamers in just about all conditions. But overkill for a family cruiser. Have not been on the new 46, but it looks to be a tamer, more sedately cruiser in the mold of the older boats, yet with even more emphasis on the cruising comforts.
I think you can design a boat to just about any type of motion and performance. All you need is the money.
How about the Reichle-Pugh boats? Nelson-Merek? They make boats that have great motion, and excellent hull forms, easily handled rigs.
And there is my all time favorite cruising boat designer, Robert Perry. While there were some build issues with some of the Valiants back in the 90''s they seem to have them all solved. The Valiant 42 is a boat that would hit almost all of my "Must Have''s" when it comes to a swift cruiser.
You don''t need a ton of weight for good motion comfort. A well designed hull, proper weight distribution, a well thought out interior, easily handled rig. Good contruction techniques. And you would have something that would suit you.
The problem I see with many boats today, they either try to be all things to all people, or so single purposed that they alienate 90 of the buying public.
I had a few moments with Robert Perry at Annapolis last fall, told him that when I win the lottery, I''ll have him design me a 45 footer and get Hinckley to build it. That way I would get the boat that was perfect FOR ME.
How heavy is too heavy II ?
The old thread you seek was under Gear and Maintenance, for whatever reason.
I, too, enjoy such debates, but the dispersion of issues here has become tiring. A more targeted analysis is far better than a shot gun approach, but there are too many issues to deal with here. The original topic under discussion was about defining “quality yachts”, but there is no evidence of that in the quotes that have been taken out of context. This only reaffirms my original contention that boat discussions become rather meaningless without acknowledging the unique prejudices of the participants. I see now that, given our individual biases, it is doubtful we will see eye to eye.
Nevertheless, the basic subject, as I understand it, has evolved into a discussion of the benefits of mass in an ocean going cruiser. Paulo is evangelistic about the benefits and I know better than try to dissuade the faithful. Still, I might ask, how one defines the upper limit of massive benefits, based on these arguments. Is more always better? Why not? (One point at a time, if you please.)
If one finds comfort in the slower rocking motion of boats with heavier displacement / waterline length ratios, then by all means, these are the boats for you. -Phil
How heavy is too heavy II ?
If you''re a Perry fan, Silmaril, then Icon may be the boat for you. But a Valiant she ain''t. Check it out: http://www.elliottbayyachtsales.com/65_robert_perry_marten_yachts_pictures.htm
How heavy is too heavy II ?
Different horses for different courses. Yes Icon is a nice boat, but WAY too big. My ideal is closer to the 40 - 45 range. 65 is not realistic for a short handed (2 person) world cruiser. I''d refuse to use automated sail handling equipment, just one more costly thing to break down when you need it and to maintain. Nope, if I was going for a circumnavigation, I would use a variation of the Valiant 42.
But seeing that I am still in the coastal cruising/daysailing/racing mode, if I had some money lying around, I would go for the R/P designed Seaquest 36.
Since I DON''T have any money lying around, my Heritage One Ton will have to do for now. She has a comfortable motion (for me) intelligent design and construction(for her day) and moves along very smartly on all points of sail (as long as I keep a close weather eye out, and rig accordingly)
37'' long and 13,000 disp with 6,500 ballast on a 6''5" long chord fin, deep balanced rudder. She has "Big boat" motion in that her movements are not violently quick, and her shape does not foster excessive pounding. She tracks wonderfully, when trimmed well on a close reach, you can let go of the helm and adjust your course by sail trim. She will bite you, as all older IOR designs will, if you push her too hard running in a stif breeze and a following sea.
She loads nicely for cruising, taking on about 2,000 lbs of well placed gear with ease. I don''t need RV style amenities when I cruise, more on the mode of "camping with sails" so I have not burdoned her with excess amenities. Trying to overload an old race boat and convert them to cruising is just a bad idea. Even worse is taking a boat''s keel, lopping off "a few feet" and adding a bulb or fins to make it shoal draft is near lunacy.
I enjoy her speed, and the "Vintage Racer" appeal she maintains, not to mention the occasional bullit on the race course.
How heavy is too heavy II ?
A descriptive form of shorthand that often helps is to apply automotive analogies to boat preferences. Vehicle identities are so well understood, in American culture at least, that it can facilitate boat comparisons.
Speaking of motion characteristics, for example, we all recognize the differences between a cushy Caddie and a tightly sprung Porche and the diverse individuals that drive them. Sailboats have similar differences, but for some reason we lump them all together when discussing their beneficial qualities, without acknowledging the fundamentally different personalities they possess. Who would ever compare a 911 to a Fleetwood? Yet many would prefer one over the other to cross the country aboard.
I have compared sport utility vehicles to motor homes before, by way of explaining different styles of cruising. An even further departure from the traditional concept may be found in an old TV show. How many recall and are willing to admit it, Route 66 and the adventures of Buz and Tod traveling the highway in their classic ’60 Corvette. It would have been far more practical to have taken a station wagon, but then how many would still remember. I admired their sporty traveling light aesthetic as they moved from town to burg achieving both chivalry and mischief, with an occasional race or chase thrown in. And I think that a sailboat can be made to do the same, especially with the technical improvements we have seen.
The world is a smaller and more developed place than ever before. We can only very rarely go beyond the reach of communications and the information safety that provides. Provisions can be replenished most everywhere and our sailboats can get there quicker and be used for broader purposes than ever before. I would not climb mountains with burdensome gear and I seek to tread equally as lightly across the sea. -Phil
How heavy is too heavy II ?
Silmaril, I believe older boats, even old racing boats, are normally "less radical" than most of modern boats and have a smoother sea movement.
They have a less flat hull and have more ballast, depending less on form stability.
I own a modern 36 footer ( length overall 37.4 ft) that is not even a racer, (only a fast cruiser) and it displaces only 10,361 lbs for a ballast of 2,954lbs. This displacement in a flat hull and 721 sq feet of sail makes a fast easy planning boat, but also (I believe) a less comfortable boat than yours in what regards sea motion.
Of course, this light displacement, which is what I want for the use that I give to the boat (costal, with some short ocean passages, like Madeira and Canary Islands), makes this boat not an ideal boat for Oceangoing, I mean go anywhere boat, even if it is U.E. classified as a class A boat (oceangoing).
You can have a 36ft much better suited for ocean travel, but it would be a lot heavier and a lot slower.
I am looking for the right type of boat to go anywhere as fast as possible, safely and with some comfort . I will only need it in 5 years or so, when I will have more time to travel.
I don''t want a slow boat, so I agree with you that the right size is between 40 and 45 (to handle the boat alone) and I don''t want a difficult boat to handle because I am not going younger and I want to sail and travel till an old age.
The balance will be between size, weight and price, knowing that a smaller boat will have to be proportionally heavier and a bigger boat will have a more costly maintenance, higher marina prices, and it will be a lot more difficult to handle in small marinas.
Everything considered (including price) I will look for a boat between 38 and 43 ft.
I know what I don''t want, but I still don''t know what will be the better choice.
I want a modern boat that makes full use of technology and design advances.
Lots of different choices out there.
The Vailant 42 is a great boat (and very expensive, too expensive to me anyway) but I think that there are other boats that offer the same qualities with a better price and performance.
How heavy is too heavy II ?
Phil, you don''t know me and you are very wrong about what I like.
Going for the automotive example, I have a Toyota Mr2. It weights 2094lbs, with a motor with around 160 hp. It will have around 200, when I add a TTE turbo.
I have a special suspension set up with TTE springs (TTE are the ones that make the F1 Toyota), special konnies and the chassis is completely upgraded by a specialized German performance tuner.
I like it light and fast.
Weight in a sailboat only counts because it is a part of the stability equation.
For calculating the maximum rightening moment of a boat you have to multiply the max. GZ (rightening lever) by the meters of the waterlength, and then by the total displacement of the boat.
So, as you use to say, bigger is better, but in what concerns me, ideal size is around 40ft (maintenance, marina prices, handling the boat in tight marinas), and for this size, if you want a go anywhere boat, you have to make some compromises in weight, to have a good safety margin.
What is the weight of that compromise? The minimum to guarantee the safety stability for the use the boat is intended to, and of course that is also a personal choice, you can try to cross oceans in a Hobbie cat.
How heavy is too heavy II ?
You keep focusing on the weight aspect of the Righting Moment (RM) without looking at the generally negative changes in the righting arm (GZ) that is implicit with changes in weight. It is way too simplistic to assume that more weight is a good thing for stability.
Focusing simply on weight ignores that relationship between adding weight and the GZ of a boat. Generally speaking when you add weight to a boat the Vertical Center of Bouyancy (VCB) moves lower which reduces the RM of the boat by reducing the GZ. This can be mitigated a little but it comes at the price of a wider waterline beam which results in a quicker motion.
Also you do not seem to be focusing on the vertical location or typical sources of that additional weight. If the weight is added in a manner that maintains the same relationship between the Vertical center of Gravity (VCG) and the VCB so that the GZ remains constant, the ratio of ballast to displacement, as well as, the draft of the boat would need to increase. This would be the case because the vertical center of gravity would need to be lowered by the same amount that the vertical center of buoyancy was being lowered.
What generally happens in cruising boats is that the weight increases disproportinately to the increase in ballast and draft (in fact mosy cruising boats usually have less daft than higher performance boats.) And most of that weight increase occurs well above the VCB in heavier interior appointments, heavier deck hardware and heftier rigs to deal with the higher stresses that come from added weight, increased storage above the CB, larger engines and tankage and so on, all of which generally raise the VCG.
The Swan 46 to Swan 45 comparison is a good one. In the case of the Swan 45 (in contrast to the 46) all of the interior case work and components are very light, veneered cored material so as to reduce weight and the rig is proportioned to be comparatively light so as to reduce weight aloft. Deck hardware is proportioned to the lighter loads. Storage above the waterline is comparatively minimal. Freeboard is compartively low. All of the weight saved by these measures were placed in the bulb located very deeply at the bottom of the keel so in comparason the 45 has a much lower VCG and with its lighter weight a higher VCB. In other words you would expect the Swan 45 to have a similar or larger area under its righting curve. With its lower VCG and its better dampening relative to momentum, you would also expect it to have a more comfortable motion on five of the six degrees of motion, with heave being the exception.
When you look at the average cruising boat the VCG is generally at or slightly above the VCB in the static position. Small changes in the vertical height of either the VCG, or the VCB, or both can dramatically change the GZ so that owering the VCB even as little as several inches (50mm) can often result in a doubling or tripling of the GZ and consequently the RM. It is hard to get that kind of increase in the RM by increasing weight because of the attendant consequences to the VCB mentioned above.
The other side of this is the overturning moment, which also generallty decreases proportionate to weight so that the lighter boat will also have a significantly lower overturning moment than the heavier boat and therefore typically requires proportionately less RM.
One ofter point here, modern high performance boats have an amazingly comfortable motion compared to older performance boats of the IOR and CCA eras dispite being considerably lighter in weight. One of the advances of the early IMS was a careful study of motion. Early on in the IMS era it was determined that the kinds of motion that are uncomfortable for crew, is also really bad for performance. Quick or large amounts of motion tend to disrupt hydrodynamic and aerodynamic flows and so slow the boat and increase leeway. Designers quickly discovered that improved motion was an un-handicapped element within the rule that could add a lot to performance and so modeled boats to minimize both the amount of motion and the acceleration/ deacceleration during impact with waves, and during rotational motion. This has resulted in race boats that offer an amazingly comfortable motion as compared to earlier performance boats. There was nothing worse than slamming to windward in short chop in an IOR era boat despite their substanially greater weight.
(I need to finish my sandwich and get back to work.)
How heavy is too heavy II ?
I am discussing here only the importance of weight in ocean going boats.
On boats used only in coastal navigation I agree with you, for the same strength and stiffness, for me, the lighter the better and new materials and new technologies can make a light boat as strong as a heavy one, except perhaps in what regards collision. A coastal boat doesn''t need the same degree of safety stability, because if the weather goes really bad, you should not be at sea, and have plenty of time to make it to a port.
Of course, I don''t get seasick and I like the fun of going fast more than I care for comfort, otherwise I would disagree, because modern, light and fast boats rely a lot on form stability and have comparatively small ballasts (in many cases less than 30%) and heavier boats (ocean going ones) have a stability more dependent on ballast having a bigger %, some times approaching the 50%.
That means that the cruiser-racers tend to follow the movement of the wave (perpendicular to the wave hall) and the heavier ballasted cruisers tend to remain horizontal, regarding the wave hall. The implications of this are clear in motion comfort even if they don''t degrade (quite the opposite) the speed of the boat.
About the GZ (rightening arm) what you say is that a cruiser-racer has a better maximum GZ (and I agree, but also a bigger negative maximum GZ) and that a light cruiser racer, like the Swan 45, will have the same area (positive) or bigger, under the rightening moment curve. That area is the measure of the total amount of energy needed to capsize the boat; in other words, that it will require the same force to capsize both boats.
I think you are confusing things.
Let’s examine the stability data of the two boats and have a look at those curves:
Well, I agree that the area under the GZ (rightening arm) curve it is about the same for the two boats, marginally better for the Swan 45.
This is not normal, it only happens because the S45 has a very exceptional 150º AVS , when a typical cruiser-racer normally will have an AVS between 115 and 125. I have to say that the GZ curve of the S46 is also exceptional (and that almost makes things even), having an unusually good max. rightening arm (for a pure cruising boat) of 0.85 (S45 has 0.95).
what normally happens is that the extra area that is gained in the higher and more vertical initial part of the GZ curve of a cruiser racer is lost in the descending part of the GZ curve, that is more vertical in the first case and softer (going to a higher AVS) for an ocean cruiser, thus obtaining more area that way. In the end, for well designed boats, the area under the GZ tends to be similar.
Of course, as the areas under the Rightening Arm curve are similar, the areas under the rightening moment curve (that you obtain multiplying in each point the value of GZ by the meters of the water length and then by the displacement of the boat) are very different and a lot bigger on the Swan 46, because the boat has a much bigger displacement.
I could give you exact numbers but I just don''t have the time right now (I would have to import those curves to my computer), but, taking into account the marginally bigger GZ righting arm of the S45 I would say with reasonable accuracy that the positive area under the rightening moment curve of the Swan 46 is about 53% bigger than the positive area of the Swan 45.
That means that the energy necessary to capsize the Swan 46 is more than 50% bigger than the energy necessary to capsize the Swan 45.
If , in this case it is not very important, according to my personal safety standards (the energy necessary to capsize the S45 is already a lot) , the same reasoning applies to smaller boats, and there, the importance of mass as means of generating more stability, has a lot of importance. The boat will be smaller (as the force necessary to capsize it) but the waves and the sea will be the same.
I believe that Swans are some of the best boats around and not only in luxury, but in design. Those two, as Silmaril has pointed out, are just two excellent boats for different kinds of sailing.
And even if I would believe that the S46 has a much more comfortable sea motion (I do not have any doubt that the Swan designers know exactly what they are doing), I would prefer the S45. But that’s my personal taste (very fast, sporty and safe) , and that is right now, ask me 10 years from now and it is possible that I will prefer the S46 (reasonably fast, super comfortable and super safe).
|All times are GMT -4. The time now is 11:22 PM.|
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2016, vBulletin Solutions, Inc.
User Alert System provided by Advanced User Tagging v3.1.0 (Pro) - vBulletin Mods & Addons Copyright © 2016 DragonByte Technologies Ltd.
(c) Marine.com LLC 2000-2012