I am really surprised we have not discussed this much here. I found several threads with some limited discussion but no dedicated thread.
I have got to start with the disclaimer that there is a 'right' boat for any given Sailor and intended use.
I have had a bias for more traditional designs. I like the old story about why so many Scandanavian designers drew similar boats...
"We build boats for thousands of years. The men would build their boats and go down to the sea. The boats that would venture forth and return. The men who lived to teach their sons to build boats all built boats that looked like this"
Of course those boats mostly looked a lot like Faith does. ;D
Full keel, maybe a cutaway forefoot. Good for holding a course, tracks well with little steering effort. Narrow beam with heavy lead ballast down low.. very stable right-side-up... not stable un-side-down. , Some overhang, reserve buoyancy fore and aft....
A nice wineglass shape with a fine entry that won't pound in a heavy sea, and increases stability as it heals.
An attached rudder, that sits in a heavy bronze shoe. No part of the rudder is lower then the keel, so groundings are much less of a problem unless you ground on a large pile of rocks...while sailing backwards.
Of course the design 'evolved' at least in part from the medium... wood. The design also lends it's self well to fiberglass, since the curves are very 'mold friendly' and all of the first production designs used the proven hull form to sell boats in this new material (that many were suspicious of).
There were some designers who wanted to get specific aspects of the traditional hull to work differently. Two areas that could be easily addressed in the new material were 'wetted surface' and the 'advance and transfer' of the keep hung rudder.
The same thing that improves 'tracking' or the boats ability to maintain a course also make it harder to make very tight turns around buoys. The cutaway forefoot helps, but the keep hung rudder works like a flap on an aircraft wing.. it makes drag which tries to slow one side of the boat to make the turn. This takes longer which means the boat travels farther after the rudder is turned (advance) before it starts to turn... it also saps speed. Making a rudder that is a plane in the water that can pivot independently of the keel allows for less drag and quicker turns. The rudder could also be made very narrow. The keel was also easier to make skinny with fiberglass supporting higher point loading a narrow iron keel could be bolted onto a hull that could resist lateral movement well, with a significant decrease in wetted area. (drag).
These 2 aspects of hull design rapidly gained favor, and the market started to shift.
Another significant market force was the decreased cost of fiberglass construction. The market opened up to segments that had not been able to afford hand built wooden yachts. This brought the 'family' into the picture and more interior space was quickly bumped to the builders design priorities.
Ok, I got into a lot of stuff here beyond what I intended.
Of course there is a lot that can be challenged in what I have written, but my intent was to discuss the general characteristics and some ideas about why they came to be.
An interesting look into this trend was to look at early Pearsons. The Triton is widely accepted as the first mass produced fiberglass sailboat. From the late 50's when it was first marketed it was a very successful design. No one can depute either the Triton's proven performance as a world cruiser, or the way it changed sailing history.
The market seemed to be asking for a slightly smaller version of the Triton so Pearson had Carl Alberg draw a smaller boat with the same formula.. and drew the Ariel (and Commander). They sold well through most of the 60's but the competition rapidly increased as several builders struggled to establish themselves in this new market.
By the time the 70's rolled around Pearson was having trouble getting Carl Alberg to deviate from his design parameters (or his license fee). They wanted (and the market demanded) a 30' interior in a 25' boat. The young family with little experience really liked the idea of a boat that could 'sleep 5' in the same LOA as a boat that could only 'sleep 4'... and their buying reflected this.
Most sailing was done on inland or coastal waters... so the 'blue water' features that had carried over from earlier drawings fell by the wayside. The bridgedeck on my Ariel is great for offshore... but an annoyance for a woman in a skirt stepping aboard at a boat show. It was eliminated in Pearson's successor to the Ariel.. the Pearson 26.
Here is the hull of a Triton;
(http://www.tritonclass.org/pix/linespt3.JPG)
An Ariel;
(http://sailboatdata.com/imagehelper.asp?FILE_id=1429)
and a (Bill Shaw drawn) Pearson 26;
(http://pages.sssnet.com/go2erie/pearson.gif)
Ok, I am tempted to go over the many differences, but lets focus on the hull (since that is the intent of this thread).
The Ariel has an 8'beam.. for a short distance nearly amidships. The P-26 is slightly longer but 8" wider... and carries the width much farther along it's length.
The most significant changes I want to point out are the fin keel, and the rudder design. These changes brought both an increase in speed (longer WWL, less wetted area) and lower advance & transfer (quicker turns, more agile near the buoys).
I have raced against a P-26.. they are faster (in light to moderate wind). They do not track as true as the Ariel, but are not difficult to maintain a course with.
I found a photograph of a P-26 Rudder.
(http://www.drmarine.com/prodimages/p26rd.gif)
For me, the choice of hull is important. I am very pleased with the boat I have.
WHat about you? What features do you see that you like (or dislike) in a given hull?
Funny, but that (the Ariel) could so easily be the drawing of my Bristol Corsair. Mine's only a bit smaller, but lacking the inboard, makes up for the little bit of loss. I just 'knew' somehow that the full keel design was what I wanted... nothing else interested me (even though I could have gotten a better deal on a couple of other boats).
I love the form, and the design of a keelboat. Now, how well I do with one in the water remains to be seen... so far, I'm just an Internet sailor, but I'm sure that by June I will have enough hands-on and sandpaper on hull experience to know this boat inside and out.
Really glad this thread got started - hadn't even considered the implications for the origins of the hull form. Neat stuff to ponder. I'll do some digging and see what I come up with.
Quote from: tomwatt on January 03, 2010, 10:39:27 PM
....Really glad this thread got started - hadn't even considered the implications for the origins of the hull form. Neat stuff to ponder. I'll do some digging and see what I come up with.
That is really nice to hear Tom. Thanks.
My Ariel has an outboard also, most of those sold came with the 'outboard in a well'. I think I recall reading that something like 10% of the Ariels and Commanders were sold with the inboard (Atomic 4).
I have limited sailing experience, I sail mostly dinghies with center boards but have sailed some Ensigns and on a Hunter 34' . For my "big" boat I have pretty much limited my search to full keel boats 30' or less. With the Cape dory 27 and the Columbia 29 MkII (S&S designed) being some of my top choices. But lately another boat caught my eye, the Yankee 30 (again S&S designed), it is a modified keel with a Partial Skeg protected rudder. With this I have been wondering how this affects the boats "off shore" qualities.
The Columbia 29 MkII
(http://www.columbia-yachts.com/c29-dia2.jpg)
The Yankee 30 MkI
(http://yankee30.org/Y30sl-1.gif)
Craig- That line drawing of the Triton could be almost a photocopy of the drawing for the Rhodes Meridian 25. Ours is of course the version with the OB in a well.
Tehani has onlyy a 7 ft beam to th Ariel's 8 ft, but is otherwise a very close match.
I've long contended that Rhodes, Alberg and others of that era learned their craft designing wooden boats, thus the flowing lines so a Plank could be easily hung. Which also allowed an easy flow of water contributing to the more seakindly motion. Of course we DO give up some interior space because of that, but that's a trade off we can live with.
I know Laura is definitly in love with the boat- grin.
I'll offer a slightly different take on the topic and say that in my opinion, one of the biggest drawbacks of the move toward 'fin' type keels has been the reduction (in the minds of 'modern' sailors) of heaving-to as a survival tactic.
Years ago, when fin-keelers first appeared, folks had trouble getting them hove-to using the 'traditional' technique and thus was born the 'myth' that they cannot heave-to. In turn, heaving-to was lost (among modern sailors who have essentially learned to sail with this belief firmly entrenched) as a 'final' or 'go-to' technique.
So, lying ahull and running off under bare poles has replaced heaving-to in the popular mindset. Heaving-to has been relegated to a 'convenience' technique when conditions are not-so-terribly bad. "No Sail Up" has replaced "Sail The Boat" in the minds of many modern-boat sailors.
There are ways to get fin keelers to heave-to, but the technique is different from the traditional "back the jib, lash down the helm."
What it boils down to for this discussion is that as boat design 'evolved' (a matter of perspective, I guess), sailing competence has, perhaps, devolved. Perhaps this devolution, to the extent that it exists, is also linked to the prevalence of the 'casual' sailor that the modern designs (with larger interior volume and bigger cockpits) attract.
My more-or-less fin keel semi-balanced rudder boat heaves to nicely. We sat off Great Guana Cay hove-to for a couple of hours a few days ago waiting for light before running the Man of War cut.
Practice is good. *grin*
The Bristol 24 (Sail Star Corsair) was designed by Paul Coble in the mid 60's
It's funny how similar the hull shape is to the Ariel and many of the other 60's boats. One of the differences of the corsair to many of the other similar boats, is the ballast ratio. The corsair has more than a 50% ballast to displacement ratio. My 76 Bristol 24 still heels quickly, but I find I can carry a 155 genoa and full main in some pretty good wind and still have good steering and not bury the rail too bad.
I also like the keel with attached rudder. Everything is so solid and strong. I ran aground a few times coming down the Tenn-Tom to the gulf. There was no damage whatsoever, and I was able to get off without help. I also didn't worry about snaging pots and such.
...Yet more support for;
Quote from: s/v Faith on January 03, 2010, 08:34:11 PM
the old story about why so many Scandinavian designers drew similar boats...
"We build boats for thousands of years. The men would build their boats and go down to the sea. The boats that would venture forth and return. The men who lived to teach their sons to build boats all built boats that looked like this"
One unusual, or at least less common, characteristic of the Yankee 30 is the prop location, extending from the keel rather than in an aperture immediately in front of the rudder (probably accomplished through a V-drive gearbox). Having the prop so far from the rudder will decrease close-quarters low-speed maneuverability (like when docking), as you can't "kick" the stern one way or another as easily...
Compare this underbody to one of my favorite hulls, the Contessa 32. Prop right in front of well-protected, skeg hung rudder will give good maneuverability. I also like the fairly low aspect fin - long enough for good directional stability but with much less wetted surface (drag) than the traditional full keel. Yes, it's a bit of a compromise, but in this case it seems to get the best of both worlds.
This might be heresy, but even though I've owned 4 of Carl Alberg's very traditional full keel designs, I think a Contessa 32 might be one of the boats I'd take around the big blue ball...
(http://i225.photobucket.com/albums/dd256/CaptSail/CO32.gif)
Nautical Survival of the Fittest...
I think I may have mentioned this before, but a few years ago, Ocean Navigator had an article on boat aesthetics vs seaworthiness in the design. The authors thesis:
Our "eye" for beauty in a boat has developed based on what boats we SAW, collectively over decades (or longer). Boats that lasted, ie that were seaworthy enough to 'survive' got seen more...so commonness was related to seaworthy, safe design.
Long overhangs fore and aft, a fine entry, rounded forefoot and other design characteristics developed into 'beautiful lines' from the premise that, subconsciously at least, "hey, there's a SAFE boat...a real SEA boat."
I think it's an interesting idea. It's not to say other design parameters are less seaworthy, but maybe they have not been around long enough to be 'proven' to our eye at an instinctive level.
Quote from: okawbow on January 04, 2010, 07:36:20 PM
.... I also didn't worry about snagging pots and such.
Yes, that is a nice added bonus. The crab pots are not nearly the problem, nor is it as likely for a boat to 'trip over her anchor' with the tide change. ;)
Quote from: Captain Smollett on January 04, 2010, 08:12:20 PM
Nautical Survival of the Fittest...
...Boats that lasted, ie that were seaworthy enough to 'survive' got seen more...so commonness was related to seaworthy, safe design.
Only scary thing about this is that nowadays boat designs seem to survive or flourish not based on seaworthiness but on marketability...
Quote from: Bill NH on January 04, 2010, 08:10:49 PM
One unusual, or at least less common, characteristic of the Yankee 30 is the prop location, extending from the keel rather than in an aperture immediately in front of the rudder (probably accomplished through a V-drive gearbox). Having the prop so far from the rudder will decrease close-quarters low-speed maneuverability (like when docking), as you can't "kick" the stern one way or another as easily...
This is one drawback of the outboard well boats such as the Ariel. Maneuverability under power can be challenging. One learns all kinds of dockside tricks to get in and out.
Quote from: Bill NH on January 04, 2010, 08:22:26 PM
Quote from: Captain Smollett on January 04, 2010, 08:12:20 PM
Nautical Survival of the Fittest...
...Boats that lasted, ie that were seaworthy enough to 'survive' got seen more...so commonness was related to seaworthy, safe design.
Only scary thing about this is that nowadays boat designs seem to survive or flourish not based on seaworthiness but on marketability...
Exactly what I was saying in the first couple posts on this thread.
I do not think this is insignificant to the SailFar Sailor. Many discussions take place over what is a 'suitable boat' for an intended voyage. I believe that the 'intended purpose' it is an important consideration. Not to say that a boat must be purpose built for bluewater if you are going off shore, but to look at the boat as a system... and consider what the limitations are. Some limitations can be addressed through modifications, others are dificult if not impossible to overcome.
Hull form is one of the things about a boat that is very difficult to change. If one is going to accept some of the weaknesses it it good to at least know about them.
If you have a wide beam (for a given length) you ARE going to pound in a seaway. There is NO way around it... you will have to reduce sail, or change course.
If you have a weak / unprotected rudder then you ARE going to have a liability that could cause problems at the very worst possible time. Most hulls / rudders will work fine underway... but a steering casualty when transiting an inlet can cost you the boat... there is NO way around it. The practice of good and prudent seamanship can reduce the risk, but never eliminate it.
The devil's advocate would say that a boat that points higher is better able to claw away from a lee shore and less likely to ground... and they would be right in some circumstances.
The bottom line is that every cruiser must know themselves, and and their limits... and those of their ship equally well.
Quote from: Tim on January 04, 2010, 08:44:13 PM
This is one drawback of the outboard well boats such as the Ariel. Maneuverability under power can be challenging. One learns all kinds of dockside tricks to get in and out.
Actually Tim, with practice the ability to 'vector thrust' with a properly sized outboard can make the outboard in a well a real advantage when docking. I know some folks on the Ariel site advocate leaving it centered, but I have had great success in close quarter steering with the motor. It is like having a stern thruster once you get really used to using it.
(not to say I can not mess up a docking, but more to suggest that the design affords me help that I appreciate.). ;)
Quote from: Auspicious on January 04, 2010, 03:56:29 PM
Practice is good. *grin*
Couple of thoughts.
I love the "practice is good" quote. The time to figure out how to get your boat to 'heave-to' properly is not when ya need to most. My flicka hove-to best with just the main. A backwinded jib and it fell off too far. This may be because the flicka has a traditional full keel with no cutaway forefoot.
One thing I found about the Ariel was it felt....well..."bouyant". It has low freeboard yet would seemingly bob like a cork in waves.Times I thought it would bury the bow it surprised me.I assume it was the reserve bouyancy with the longer overhangs.
I like the feel of a full keel boat....except at the dock ;D Backing out is always an adventure. Gun it and hope for the best seems to work.
Judy and I had a jammed rudder in the Keys once with a crab pot line on a fin keel boat.. Diving under a boat with wave action is no fun.
I too like the Contessa 32..they are relatively fast as well. Being a 'small boat guy' if money was no object I think a Dana 24 would be my ultimate pick. A 8000lb 24fter with full keel/,attached rudder/cutter rig has to be a great lil ship..
My only experience is with a fin keel that was on my Cal-29 Bill Lapworth design. Excellent boat that sailed very well and could turn quickly and tracked well enough. Great light air boat and strongly built.
When I`m in the buying market again in around 2 years I will most likely go with some sort on fin keel with light displacement. I`m seriously considering going engineless and ease of handling will be pretty important.
Quote from: Chattcatdaddy on January 04, 2010, 09:51:14 PM
with light displacement.
Don't underestimate the value of heavy displacement for her size in 'engineless' handling.
We once ran out of gas coming into the marina and drifted all the way into the slip. I've been on 'light' boats that would have not made it that far via inertia alone.
;D ;D
Good point! Something I will have to consider when I`m closer to a buying date.
I see the Paul Coble/Bristol Corsair info got posted ahead of me, so I won't go into that except to add that he seemed to have gone off into naval architecture for the Navy after this one foray into sailboats. Myself having succumbed to the lure of defense funding a time or two in my life, I cannot criticize. Destroyers pay better than sailboats anyday.
While I loved the quote about the Scandinavians building boats and seeing them come back, I seem to recall (cannot source this, as it stems from an old college lecture I almost slept through) the Viking craft being built in two modes - the dragon ship whose form we see in museums, etc. that was a flexible ship that is supposed to have given and sprung with the waves, and another craft, a much stodgier merchant/cargo/trading ship that I don't know of any surviving examples of... but might tie into the quote since this was a workhorse shipform for the Vikings.
Quote from: Bill NH on January 04, 2010, 08:10:49 PM
One unusual, or at least less common, characteristic of the Yankee 30 is the prop location, extending from the keel rather than in an aperture immediately in front of the rudder (probably accomplished through a V-drive gearbox). Having the prop so far from the rudder will decrease close-quarters low-speed maneuverability (like when docking), as you can't "kick" the stern one way or another as easily...
Compare this underbody to one of my favorite hulls, the Contessa 32. Prop right in front of well-protected, skeg hung rudder will give good maneuverability. I also like the fairly low aspect fin - long enough for good directional stability but with much less wetted surface (drag) than the traditional full keel. Yes, it's a bit of a compromise, but in this case it seems to get the best of both worlds.
This might be heresy, but even though I've owned 4 of Carl Alberg's very traditional full keel designs, I think a Contessa 32 might be one of the boats I'd take around the big blue ball...
Exactly! you sight two of the aspects that I dislike about the Yankee 30, the rudder isn't fully protected by a skeg and the prop position.
Quote from: s/v Faith on January 04, 2010, 08:45:05 PM
The devil's advocate would say that a boat that points higher is better able to claw away from a lee shore and less likely to ground... and they would be right in some circumstances.
The bottom line is that every cruiser must know themselves, and and their limits... and those of their ship equally well.
This is always a difficult point, especially with a newer sailor buying their first boat.
Greetings,
This is my first post on this forum. I've owned my Cape Dory 22 for a little over two years now and I'm still as enamored with her as the first time I sailed her. She is a bit on the small side. She wants to be a Cape Dory 27 when she grows up.
I sail mainly on Lake Sinclair in Georgia, and have made it to the BEER Cruise for the last several years. Hope to do more coastal cruising.
Cheers,
Warren Hughes
Welcome to Sail-Far Warren
Thanks Tim.
CD22 looks like a pretty capable pocket cruiser. Gonna put that on my list of models to keep a watch out for when I get around to actively shopping.
Quote from: Captain Smollett on January 04, 2010, 08:12:20 PMOur "eye" for beauty in a boat has developed based on what boats we SAW, collectively over decades (or longer). Boats that lasted, ie that were seaworthy enough to 'survive' got seen more...so commonness was related to seaworthy, safe design.
Long overhangs fore and aft, a fine entry, rounded forefoot and other design characteristics developed into 'beautiful lines' from the premise that, subconsciously at least, "hey, there's a SAFE boat...a real SEA boat."
I think it's an interesting idea. It's not to say other design parameters are less seaworthy, but maybe they have not been around long enough to be 'proven' to our eye at an instinctive level.
This made me reflect that the wide-stern boats of a more modern design come from 'race boat heritage'. Look at the downwind sleds typical of the big races
(Open 50's & 60's and the like) - its the same design, carried to an extreme in the case of a racer. Similar to automotive tech, race-course thinking then "leaks" into the consumer end of things...
I'm not sure that the question "Is that good?" can be asked about this; seems to me that there is plenty enough of gray area that that question is moot. But I think that the 'purpose-built design' aspect of those kinds of hull forms need to be taken into account. Long distance, shorthanded cruising by *recreational* sailors is different than the endurance feats performed by long distance, shorthanded *racers*.
The 'old' 'classic' hull shapes, I think lend themselves to a certain amount of 'easier' sailing - less taxing, less of an endurance feat to keep them making the miles, and in conditions when things goes tits-up, they act and react to sea state and weather in a manner which is less taxing on those aboard, and that due to the older style hull shape, rig and general design.
Just some thoughts, pretty incomplete, but perhaps enough to contribute, well, something... ;) Good discussion!
Saw a copy of SMALL CRAFT ADVISOR today that had a South Coast 21 on the cover. I immediately said, "That looks like an Alberg designed boat."
When I flipped open to the article, I saw the hull out of the water and saw fin keel and exposed rudder. Then I said, "uh, now I don't think it's a Alberg boat."
Sure enough, Alberg designed the South Coast 21, and from the waterline up, you can really tell. It looks quite a bit like a Cape Dory Typhoon (what I thought this one was at first blush). His original design had the typical Alberg keel, but the fellow that commissioned the design wanted something 'sportier.' Alberg refused for a while but ultimately gave in ... the article said that he really did not trust the fin keel design (it was still new at the time).
Interesting story...
From the South Coast Owners Association Site:
(http://southcoastus.tripod.com/SC21/sc21.jpg)
Great-looking boat, Haidan. I'll bet that doghouse is great in the Pacific Northwest!
Can you tell us more about the design and who built her? Is she custom, or were a number built?
In another thread I posted a link to a guy who plans to take his Albin Vega around cape Horn and I find this especially interesting because of recent years debate in Sweden about the suitability of the Vega for bluewater sailing. The debate mainly concerns the fact that the Vega, despite a number of Atlantic crossings and even the odd circumnavigation, does not have the classic Scandinavian design but was one of the earliest popular cruisers to get its stability from hullshape (wide, flat) rather than a deep, heavy keel. Those who are critical say it is unsafe and unsuitable while those who approve say "well it seems to work, doesn't it?"
In one of his articles (august 2008) http://thesimplesailor.com/articles.html (http://thesimplesailor.com/articles.html) Roger Taylor claims that his twin keel Corribee is less prone to capsize because the shallow draft doesn't "trip" the boat when forced by a large wave, instead the boat slides sidewas. I wonder if this may be why the Vega works better in rough conditions then it "should".
What do you think?
That is very likely. That is the reason many multihulls do very well in storm conditions, and why you're supposed to retract the boards prior to a storm, unless you're trying to claw off a lee shore.
Avid 'small boat guy-author" Larry Brown found the same. In what were storm conditions for his lil 15...it handled 'cork like' with the board up and did not display the same 'being thrown around' behaviour it did with the board down
I never thought of the Vega's 3'10" design draft (actually a good even 4' in the water) as shallow draft. With its long, low-aspect fin keel it has quite a bit of lateral surface area. I would doubt that the same affect as a cat or tri pulling up the board(s) is coming into play.
Frankly, I was not impressed with the strength and construction of the Vega I owned. Compared to my Cape Dory almost everything was lighter, thinner, flexed more and was less well-supported and definitely did not inspire confidence on my part. The Vega was engineered to cut materials where the designer thought they could be safely cut - that's why a Vega 27 weighs in at about 5700 lbs where a Cape Dory 27 would be more like 7000. I would not put a Vega at the top of my offshore list despite its reputation.
I honestly believe that many of the incredible exploits that sailors have made in Vegas should be credited to the skill and guts (and good fortune) of the sailors, and could have been made by these same sailors in a variety of boats. The fact that Vegas can be found in abundance and cheaply all over the world may also have contributed to them making notable voyages, as there are literally thousands of them out there sailing!
Frank,
Did he have any canvas up or was he under bare poles? I have a swing keel and always trying to figure out what is best position up, down, part way down for different conditions.
I would prefer a boat like Tehani but I have what I have.
Bill
As the Vega has only 35% of its displacement in the keel and the slightly shallower draft gives even less of a righting momentum, this is the main argument against its "seaworthiness". The flimsy hull and need for reinforcements also speak against it. As you say, it's recent rise in popularity as a bluewater cruiser is almost completely due to the fact that in Sweden, were most of the 3500 ever built still remain, they go for around 7000$! This means that although it is lacking in many areas it makes the worlds oceans accessible to any 19 year old school dropout. The recent Atlantic crossings and a circumnavigation have been done by people in their early twenties with little or no sailing experience at all which is why the boat seems to have some kind of "hidden" seaworthiness. It is not my first choice either but compared to staying home it might be.
A bit off topic but here's a link to the latest(?) circumnavigation. http://www.runtjorden.com/eng_projekt.php (http://www.runtjorden.com/eng_projekt.php)
Check out "Economy". Around the world for 13500$ a head! How is that for go simple, go small, go now"?
Both of those Vega circumnavigator sites are cool. :)
Grog fer ya, SeaHusky!
You know, I think of my boat as "small" and I often forget that it's got quite a bit of room compared to some. Of course hanging out on Sailnet with the 50-footers will do that I guess. I consider myself blessed with a nice hull.
(NOTE: The following post was made in response to a post that has since been deleted. Without the earlier post, the reply seems completely out of context).
Computer modeling, whether it's the weather, structural engineering, aeronautical engineering, fluid dynamics or whatever, is only as good as the person doing the modeling using the computer as a TOOL.
Therein lies much of the problem that many "lay" people don't appreciate. There are a TON of people using computers tools that DO NOT understand the models or how to apply them. So, they run a model, the computer spits out a number or a pretty picture and blammo...the number or picture gets reported/use/quoted/debunked.
I'll give a little case history from just a couple of weeks ago. I was contacted by a client to do some modeling of something that is VERY dangerous and could have life-ending consequences for both my client and INNOCENT bystanders.
In my reply, I cautioned the client that ANY results we get from our models MUST be thoroughly and carefully tested with real-world, hands-on engineering tests. The modeling results can guide the process, but it's NOT a 'model this, and go into production' type solution. The potential costs are too high.
He absolutely agreed and was already thinking on that page. I like to work with professionals that understand this sort of thing, and only felt compelled to mention it because all too often, the prospective client does NOT appreciate this.
Would you 'ask' a circular saw to build a house? No, of course not. Nor should one entrust the results of a computer model, which are nothing but numerical calculations, to provide a solution to a contextual problem. The computer is only calculating numbers based on the equations it is programmed to use and only using the base data it is given.
Back to the topic at hand....the ONLY conclusion that can/should be drawn by ANY scientist or engineer using modeling is "this model says that cannot be done." He SHOULD understand that the model could be limited (on purpose) or flawed. The discussion should then go into "why might this model suggest that" and the thinking, problem solving HUMAN BEING should evaluate the results.
So, yes, there are many cases where a model says something cannot happen (or happens differently than reality). That's often not the fault of the model itself or theory upon which it is based. Rather, it is either (a) the fault of the USER applying a model in an incorrect context or (b) there is something unknown that the model is not taking into account.
Further, that's how models are improved...just like any other science, it is the FAILURES that teach you more than the successes.
Just some near-random thoughts from a dude who does the following professionally:
Quantum Chemistry Modeling
Molecular Dynamics Modeling
Computational Fluid Dynamics
Reactive Flow (Detonation) Modeling
Quote from: SeaHusky on February 03, 2010, 05:22:06 AMhttp://thesimplesailor.com/articles.html (http://thesimplesailor.com/articles.html)
Thank you for this link. Roger Taylor also has some interesting youtube videos. I really like the concept of his boat, he stays in the cabin all of the time and rarely is in the cockpit when at sea. The boat is set up to be sailed from inside the cabin.
I too like Roger Taylor's "unconventional" thinking and agree on some more than other. The idea of hardly ever leaving the cabin would for me take a lot of the fun away but then I haven't spent as many years getting cold and wet as Mr Taylor. I do very much like his idea of making his boat unsinkable but I think filling half the cabin with foam to achieve positive buoyancy when swamped only works on small boats with a special purpose. A more realistic approach is James Baldwins idea http://atomvoyages.com/projects/UnsinkableBoat.htm (http://atomvoyages.com/projects/UnsinkableBoat.htm) to make every storagelocker and compartment of his boat into a watertight compartment which will contain a leak or hullbreach to a small part of the hull adding maybe hours of repairtime before sinking. I find this so logical that I am astonished that it is not common practice to do this with at least the V-berth.
Have any of you done something similar?
By the way, thanks for the grog! :)
Nicely said... grog to ya for it. :)
Quote from: Captain Smollett on February 04, 2010, 05:04:15 PM
Computer modeling, whether it's the weather, structural engineering, aeronautical engineering, fluid dynamics or whatever, is only as good as the person doing the modeling using the computer as a TOOL.
Therein lies much of the problem that many "lay" people don't appreciate. There are a TON of people using computers tools that DO NOT understand the models or how to apply them. So, they run a model, the computer spits out a number or a pretty picture and blammo...the number or picture gets reported/use/quoted/debunked.
I'll give a little case history from just a couple of weeks ago. I was contacted by a client to do some modeling of something that is VERY dangerous and could have life-ending consequences for both my client and INNOCENT bystanders.
In my reply, I cautioned the client that ANY results we get from our models MUST be thoroughly and carefully tested with real-world, hands-on engineering tests. The modeling results can guide the process, but it's NOT a 'model this, and go into production' type solution. The potential costs are too high.
He absolutely agreed and was already thinking on that page. I like to work with professionals that understand this sort of thing, and only felt compelled to mention it because all too often, the prospective client does NOT appreciate this.
Would you 'ask' a circular saw to build a house? No, of course not. Nor should one entrust the results of a computer model, which are nothing but numerical calculations, to provide a solution to a contextual problem. The computer is only calculating numbers based on the equations it is programmed to use and only using the base data it is given.
Back to the topic at hand....the ONLY conclusion that can/should be drawn by ANY scientist or engineer using modeling is "this model says that cannot be done." He SHOULD understand that the model could be limited (on purpose) or flawed. The discussion should then go into "why might this model suggest that" and the thinking, problem solving HUMAN BEING should evaluate the results.
So, yes, there are many cases where a model says something cannot happen (or happens differently than reality). That's often not the fault of the model itself or theory upon which it is based. Rather, it is either (a) the fault of the USER applying a model in an incorrect context or (b) there is something unknown that the model is not taking into account.
Further, that's how models are improved...just like any other science, it is the FAILURES that teach you more than the successes.
Just some near-random thoughts from a dude who does the following professionally:
Quantum Chemistry Modeling
Molecular Dynamics Modeling
Computational Fluid Dynamics
Reactive Flow (Detonation) Modeling
Sometimes, the hull form is such an integral part of the boat's safety and the shape plays into stability in ways we often forget. Too many times, we associate the stability of the boat coming from ballast, keel shape or some combination.
What about when a ballasted boat loose her keel completely? Can the boat remain upright? This happened to an Alberg 30 (lightning and age damaged keel bolts failed).
Quote
... the boat rolled completely from one side to other every ten
seconds. There was no longer anything counter-balancing the force of the mast. It felt
like rounding the Horn on a windjammer. It was a startling demonstration of Carl
Alberg?s genius. For her lines, her beautiful lines would capture and hold her right
there at the edge of the roll, and come back despite the fact that she was so badly
crippled.
(emphasis added)
I would be VERY interested to read about 'keel failure stability' of modern (post CCA era) designs.
I got the new ports I installed in our previous boat from a Catalina 30, that lost it's keel off Matagorda Island. The boat washed ashore and other than parts salvage, was a total loss. They burned the hull and deck, since there was no way to get any kind of tow vehicles or trailers down that 12 miles of virgin beach.
I happen to have the masthead fitting, if anyone is interested.
It seems we are not the only ones that "debate" the merits of hull design in various seas.
I found this gem of a post in a fishing forum, of all places. The general discussion had veered to taking an open canoe out Bogue Inlet (which had nothing to do with the OP's question, but thread creep was kicking in). Someone replied with what appeared as a snarky comment regarding what kind of "boat is needed" to run the inlet. The comment also seemed to suggest only double bladed paddles had merit.
This is a reply to that comment:
Quote
A large area of the Bering Sea was paddled by single paddle boats. We've all seen the crab fishery shows on television...........just about the worst climate on the planet to paddle in. Remember.........the aboriginal paddlers were not paddling for sport, but to make a living. No radio, no EPIRB, no SAR helicopter to pick them out of the water, and no wetsuits/drysuits to prevent hypothermia. Everything they did, every nuance of boat construction, served a purpose. They used sea mammal air bladders for floatation during recovery techniques, if they came out of their boat. The literature remaining today suggests the original kayakers made few wet exits, due to boat design.
{my emphasis}
I love it! ;D
Small OPEN boats, Longish Distances on ROUGH SEAS.
(I'll stick to my Alberg-30 for such conditions, though... ;) )
Quote from: Captain Smollett on April 06, 2012, 12:18:46 AM
I love it! ;D
Small OPEN boats, Longish Distances on ROUGH SEAS.
(I'll stick to my Alberg-30 for such conditions, though... ;) )
I remember some of the discussion surrounding the "re-introduction" of the Aleutian kayak design... so different than a Greenland kayak... even the Aleuts had stopped using them, until someone built one based on a museum specimen. Apparently everyone decided the weird bow and stern forms were just some kind of native superstition, without realizing how fast and agile the shapes made them. There's an old video from PBS out on the Internet showing the launch... featuring an Olympic kayaker.
Although it's arguable that Aleut
baidarkas (kayaks) are open boats, since they are decked and have hatches. Hull form, and especially those graceful overhang areas, come into play in little boats too... the Aleutian kayak's weird bow form apparently does away with the need for long overhanging bow in a Greenland kayak by splitting the waves and driving through them.
Here's a link to an Aleutian kayak designer/builder:
http://www.wolfgangbrinck.com/boats/baidarka/thealeutiankayak/introduction/index.html
Quote from: tomwatt on April 06, 2012, 06:03:02 AM
I remember some of the discussion surrounding the "re-introduction" of the Aleutian kayak design... so different than a Greenland kayak... even the Aleuts had stopped using them, until someone built one based on a museum specimen. Apparently everyone decided the weird bow and stern forms were just some kind of native superstition, without realizing how fast and agile the shapes made them. There's an old video from PBS out on the Internet showing the launch... featuring an Olympic kayaker.
Although it's arguable that Aleut baidarkas (kayaks) are open boats, since they are decked and have hatches. Hull form, and especially those graceful overhang areas, come into play in little boats too... the Aleutian kayak's weird bow form apparently does away with the need for long overhanging bow in a Greenland kayak by splitting the waves and driving through them.
Here's a link to an Aleutian kayak designer/builder:
http://www.wolfgangbrinck.com/boats/baidarka/thealeutiankayak/introduction/index.html
Thank-you, Tom, for that very cool, informative post.
I must cry "Mea Culpa" on the open boat comment.
Not being familiar with the specific boats to which the poster referred, I apparently conflated this boat with one(s) mentioned in later paragraphs where it is very clear he was talking about open boats. In addition to rolling/righting techniques, he was even talking about bailing with a paddle blade (which clearly cannot be effectively be done with a decked boat).
On the topic, I have a "How-To" canoe book we bought almost 20 years ago in which the author spends a good deal of effort in early chapters laying into the 'myths' of what can be done with an open canoe (provided buoyancy is provided). This book was also my first introduction to the idea decked canoes (not kayaks).
Anyway, I just find the parallels interesting now that I think about them. Hull form and design play a larger role than some folks care to admit. I recently was engaged in a conversation with a colleague who explicitly said "An Alberg 30 will be just as bouncy and uncomfortable as {boat x}," where boat x was a flat bottomed, plumb stemmed tub.
This poster on the fishing forum, like us here and the author of my canoe book, seemed to be fighting the current of "conventional wisdom" in boat design.
Thanks again...,I'm going to see if I can track down that PBS video...
I have owned quite a few boats over the years; An Ensenada 20 with a swing keel, a Pearson 26, an Albin Vega, an Olympian 34, and now an Allied 30. I prefer a full keel with a tiller-steered transom hung rudder.
Quote from: Captain Smollett on April 06, 2012, 08:03:47 AM
Thanks again...,I'm going to see if I can track down that PBS video...
Here it is: Rebuilding the Baidarkas (http://www.pbs.org/saf/previous/watchonline203.htm)
Wow. Thanks again. This is good stuff.
Just got in from work... yes, I first thought the Greenland kayak design was "pretty" and the Aleut design was weird... but the more I see them (as well as having watched the PBS video over and over again), there is something very wonderful about that little boat.
And yes, a good kayaker (not including self in that category) can not only roll, but cover great distances over open water (deck mounted compass helps) in even rough seas. I have a few kayaking acquaintances who go fairly far out in the Gulf of Maine... I someday hope to have a decent mount for my kayak aboard my boat, so I can do a little fishing from the kayak.
8)