Old Can of Worms, Deep keel vs Shallow/No Keel

[Einarr]

I do realize that the subject of deep keels verses shallow keels has been debated to death but I think that I may have a different perspective.

A little background

I am a very enthusiastic medieval re-enactor (SCA) and for the past 20 years or so I have researched Norse ship construction, both the long ship and knarr varities, as the Norse are my focal time period. In the process of this research, I have also looked at various cultural maritime designs spanning many mellinae.

One major fact has occured to me, deep keeled sailboats did not exist prior to their creation and advocation by Nate Herschoff. While this may be wrong, I have yet to come across one in my research. The deep keel was specifically created for racing, added righting moment to compensate for the additional sail area.

If you consider all of the maritime archeological evidence of vernacular ship/boat designs that span the last 10,000 years, there are no deep keels. While there are boats that have their keels deep in the water due to their weight and displacement, this is not a condition of their design.

The majority of the archeological evidence, that I have read, points to several common factors for all cultures and all time periods.

**Coastal and ocean going vessels were ballasted; inshore, lake and river boats were not.
**The midship section on ocean vessels had low to moderate deadrise while coastal and inshore vessels had no dead rise to moderate. By moderate dead rise I mean less than 15 degrees from the horizontal plane.
** The water line profile on ocean and coastal boats had a double ended profile while inshore vessels more often than not had a transom.

As with any common factors, there are exception so these points are not trueisms.

One major factor that is generally not taken into consideration is seamanship. Historically, sailors were raised around water and in general around the vessel type that they would sail for all of thier life. This experience is paramount.

To the point

It is my personal belief that nautical architects and designers are ignoring history. There is more than enough archeological and historical evidence that shallow draft boats are more than seaworthy. About 8,000 years of history says so.

The only problem with shallow draft boats being seaworth has not to do with the boat. It is ultimately the sailor that is not seaworthy.

I have heard and read, in many places, that the scow type hull (not racing scow) is not sea worthy. I dont think that the New Zealanders nor the Dutch would agree.

[Thorne]

I'm also an historical reenactor, but fail to see your point.

There is no official, formal, "find-it-in-the-manual" definition of seaworthy. Opinions, waters, and designs vary -- so trying to define the word is bootless. In some situations a dugout log canoe is the ultimate seaworthy vessel, in others nothing but a floating coffin, but you won't get far trying to insist on one over the other.

So you seem to be saying that deep, narrow, ballasted keels are new -- and maritime history agrees with you.

Experience in sailing primitive ships was one factor. Another was acceptance of massive loss of life, particularly for commercial sailing trips. Another was no requirement to meet tight, modern schedules.

Personally I find 16th and 17th C. European vessels the most interesting, with the Dutch paintings being a fantastic window into that time period...

[outofthenorm]

I don't entirely disagree with your main point - that shallow draft hulls can be "seaworthy". Generally, a lot of people believe that the make or break factor is ultimate stability and the ability to re-cover from knoockdown - ballasted deeper boats are better for that than shallower ones. But that's a "horses for courses" kind of debate, isn't it. You can find all sorts of examples to support either side. Slocum went around in Spray, a pretty terrible boat for the purpose, but came home unscathed because he was a consumate seaman. It might not work out so well for an unskilled first-time globe-trotter.

Something else to bear in mind is that many a vessel our forebearers would describe as perfectly seaworthy would be considered unsafe today - the first Pride of Baltimore is an example - mostly because we are now generally less willing to accept risk. If as many ships were lost in a year today as were lost in a month in 1850, the regulators and self-appointed protectors of mankind would have made going on the water illegal by now. Standards have definitely changed.

On your other point about deep keels - if you're referring to fin-like keels with exaggerated cutaways and separate rudders, you're probably right about the Herreshoff timeframe - but he wasn't alone. William Fife (1880s to WW2) is a good example and there are others. Sailors are notoriously conservative and you are correct that historically, they stuck with what they knew. Experimentation was a slow slow process but it was always going on. The naval cutters and packets of 1790-1820 were built for speed and are considered to be the pre-cursors of the clipper hull (David MacGregor wrote about that in "Fast Sailing Ships). They were built deliberately deep and narrow - no cutaways, but depth of keel was a required characteristic of so-called "sharp" or fast vessels.

- Norm

[rbgarr]

To the point

It is my personal belief that nautical architects and designers are ignoring history. There is more than enough archeological and historical evidence that shallow draft boats are more than seaworthy.

Is your assumption that designers are generally dead set against shallow draft? I doubt it. For the most part they will design what buyers commission.

[Einarr]

Is your assumption that designers are generally dead set against shallow draft? I doubt it. For the most part they will design what buyers commission.

I think that people have been so innundate with 'reasons' to have a deep keel boat that they actually have not clue.

If you can find three 'authorities' to back up and valadate something, consumers have the typical Povlovian response of acceptence with out thought.

Now I know that the sailors and boat builders are a different breed, so please done be offended.

How many boat owners know calculus and hydrodynamics? The majority take somesones word for it.

It seems to me that the deep keel developed from the 'need' for speed, in the late 1800's and early 1900's. People have been taught for a hundred years that that is the only 'right' way to design and build a boat.

I have heard it said that those whom travel on a time schedule by boat should take a plane. In the modern age, the 'need for sped' is better suited for in other ways. So why not resort to time and tradition in the designs of baoats?

[Canoeyawl]

In making this historical assumption about “shallow draft” you must consider that until very recently ships and all vessels were commercial ventures and consequently loaded to the gills so to speak. An arbitrary water line on a set of plans or half model did not mean a thing. They were loaded down until in danger of sinking at the dock. This increase in displacement can help sailing qualities but only up to a point and then she is “gone missing” without a trace or a reason.
Shallow draft was simply losing money unless there was a valid reason like harbor work or speed in warfare.

[Einarr]

This increase in displacement can help sailing qualities but only up to a point and then she is “gone missing” without a trace or a reason.

I would venture a guess that a majority of the 'missing at sea' were because of this factor.

[RodB]

This brings to mind a conversation with Robert Perry, the notable designer of many cruising boats today such as the Valiant 40, Passports et al, Tayana 37, 48, 52, Baba 30, 35, 40, Nordic 40, and 44... Cheoy Lee 35,44, 48, 42LRMS, etc... etc... when asked about a shallow draft design... The gist of his comments was, designing shallow was like cutting off the balls of the boat...))))

Then, I also consider all the great anecdotal sailing accomplishments of Commodore Munroe with his beloved Presto (with a 50% ballast to displacemnt ratio...centerboard design) and his arguments for safety at sea with a hull that would not "trip" on its deep keel in survival conditions.

Modern designers are definitely afraid of the "Presto" concept.. I have found with personal research... and most feel the safety factor is only acceptable with a deep draft design... except for Reuel Parker.

This is always an interesting subject.

RodB

[Einarr]

Personally I think that the designers are over looking the viking knarr style. (I'm biased here)

The vikings used the same style cargo ship (knarr) for more than 450 years with little or no modifications because they worked.

It is a documented fact that they were used in open ocean as well as on rivers.

The closest modern equivelent that I can think of off of the top of my head is the Colin Archer designs. Which he based off of the north sea rescue boats, which in turn are descendants of the knarrs and byrdingr that plyed the waters of europe during the middle ages.

There was/is a design difference between the knarr and the long ship but most of it is due to a higher freeboard.

It seems to be a common myth that viking boats were mostly of small sizes, under 40 feet. This is not true. The longboats ranged in sizes from 30' to well over 100' in length, documented by archeological evidence.

Knarrs came in a variety of sizes as well. From the 20 on up, with the largest one so far being discovered at 88' in length with a beam of 20' and a cargo capacity estimated at over 60 tons.

When the 'Viking', (Gokstad replica) was sailed from Norway to the US in the late 1890's for the World's Fair. It was clocked doing more than 25 knots in the mid atlantic, during a storm, for several days running by the Captain. Even if he was in error by a factor of 25%. That is still better than most modern boats.

Even the fat bodies heavy knarr held good speed. The Icelandinc sagas record, in several places, the time required to travel from Norway to Iceland. Based upon the records, heavily loaded knarrs averaged between 5 and 10 knots. Pretty respectable for a 56' LOA, 30 ton boat.

Were I to win the lottery (Hey I can hope), I would take the best of the old and combine it with the best of the new. More specifically, using modern material and methods with a proven age old design.

A 60' loa, 18' beam, full keeled, full decked, 3' draft knarr constructed by strip planking covered with glass, lateen or cutter rigged instead of a square sail.

[Woxbox]

Einarr, I agree with all of your observations, but disagree in the conclusion that modern designers are somehow mistaken in what they are doing. As soon as sailboats began to be used for a new purpose -- racing and recreation -- they evolved rapidly to suit the demand.

Bolger has commented often on how racing rules have distorted hull shapes and rigs -- and stoutly refuses to go along with the trend. So he draws more sail carried lower down, and longer, shallower keels on most of his boats -- going against the trend of high-aspect ratio rigs balanced by deep fin keels. Racing rules that put limits on sail area and waterline length drive a lot of the look of "modern" boats. The desire for speed does most of the rest.

And yes, the old boats are better than many suspect. Here's me and my crew enjoying a day out in Little Key, ship's boat to the Kalmar Nyckel. Not fast, but she's carrying 8 of us here and moving well enough with a little 75-square-foot spritsail.

She's modeled after an early 17th-Century shallop, and wouldn't win any modern race. But I've suggested that if we had a race where you had to row or sail across a river, pick up a live pig and a barrel of beer, and then bring the both back again, no 18-foot boat would be better suited. That race we should win.

[wtarzia]

[quote=Woxbox;1851687]She's modeled after an early 17th-Century shallop, and wouldn't win any modern race. But I've suggested that if we had a race where you had to row or sail across a river, pick up a live pig and a barrel of beer, and then bring the both back again, no 18-foot boat would be better suited. That race we should win.

--- Lovely in a practical kind of way! I fell in love with the shallop when I first saw the replica at the Wooden Boat show in Newport a couple of years ago. And if you have a crew to row, you negate the misery of trying to sail to windward. ;-) Do you use a leeboard on it? Does it go to windward at all? -- Wade

[Charles Burgess]

To the point

It is my personal belief that nautical architects and designers are ignoring history. There is more than enough archeological and historical evidence that shallow draft boats are more than seaworthy.

Is your assumption that designers are generally dead set against shallow draft? I doubt it. For the most part they will design what buyers commission.

For the most part they will design what buyers commission. - Very true - for better or worse.

[Dave Hadfield]

Then there's the consideration of what do you do when you get to port. These days, with crowded waterways, deep draft is a real liability. Anchorages tend to fill up early in the parts where you need enough water to float 5 or 6 ft. If you draw 3 ft, you never have to worry -- you can wiggle into the corners, even (in our case) with a 46 footer.

Dave

[Meadowlarker]

This is a very worthwhile thread, one of the very best I think.

I have an article by Henry Howard, who wrote, "The Yacht 'Alice' ",and had many years experience as a deep draft yachtsman before he switched to the 4' draft Alice for 20 years. It is titled, "Shallow Draft is Best for Deep Sea Cruising", and is in 2 parts totalling 14 pages. It was published in the British magazine, "Yachting Monthly" in 1930.
I have it scanned into a jpg format but have no time to post it here right now,,, Is there anyone I could email it to that would be willing to post it here or transcribe it onto the forum?? It is full of revelations by a most experienced sailor and many would enjoy to read it no doubt.
Any takers??
I have another article also by H. Howard titled, "Keels or Centerboards", from the Sept. 1926, "Yachting" magazine that speaks of the first storm encountered by the Alice's sister ship, Carib II, and it goes into some depth on the design of both of those 'good little ships'. Also in jpg form if anyone would like to post or transcribe it here?

[Paul Pless]

Meadowlarker, you can email it to me. I'll post it.

paulcplessner@hotmail.com

[Daniel Noyes]

Interesting discussion guys!
I think there are two answers to the question,
one is technical, hanging a large amount of weight down deep either on a thin keel of harder still on a fin is a technical challenge.

the other reason I suspect has to do with how boats are raced, previous to yacht racing top speed was important, heavily laden ships on the open sea raced-chased the objective was to stay out of cannon range of your pursuer, a boat being chased would go as fast as possible, this ment bearing off the wind and setting as much sail as possible...so up wind ability was less important than in a yacht race.

Also in regard to the technical stuff ancient construction methods making long passages sailing close to the wind for weeks at a time would have torn the boats apart.. modern advances such as wire rope rigging and multi layer planked hulls help hold modern (1850 and later) wooden boats together.
Dan
http://dansdories.googlepages.com

[esingleman]

Blame it on the geeks like Herreshoff that's okay, because it's true. Guys that want to push the limits lead to new advancements. Hell he even came up with the first racing catameran, now there is shallow draft for you. Deep keels afforded having less balast to create a righting moment (because the lead was lower), meaning less overall weight of the boat, and therefore faster. Somewhere alongthe way the geeks found out that waterline length limited boat speed so they maximized that dimension. Later someone found out that you get more aerodynamic lift from the front end of a wing than the rear, and high aspect ratio sails were invented. All these things lead to more speed.

So if you don't need a lot of speed then you have more options. There are so many considerations and so many compromises to be made when selecting a boat design. Tha's what makes it ineteresting and challanging when deciding what boat to make or own. And what makes your boat special.

[ahp]

There are several things to consider. The Vikings required a shallow draft vessel. In the case of the Knarr, there were times when they need to to be beached to unloaded. The Dragon ships were raiding up estuaries that were shallow, uncharted, and unmarked. finally how their technology build a deep fin keel, even it they could use it.

[wtarzia]

Two points:

(1) Define shallow vs. deep keel. Some Polynesian sailing voyaging canoes were 4 feet deep amidships with a length of around 25 feet (the rounded "deep-V" hull profile permitted some windward work); the proportions might seem deepish.

(2) Ask, how many ships were lost at sea/how many ships took too long to get to their destination and wore out the crew and put them at risk, etc., relative to the voyaging tradition. Sure, you can sail a variety of boats across the sea, but the issue is, how statistically reliable? If you sail 1000 deep keel and 1000 shallow keel boats across the ocean, what are the results and implications? I am not for/against these designs, but I am saying that we need an engieering tradeoff analysis to really bring the discussion to where it needs to go.

OK, three or four points ;-)

(3) In-shore ships need to work inshore -- around rocks, flats, and beaches. Shallow draft is a requirement. The trade-off is in windward ability ultimate stability. The larger Viking ships were really war-canoes that needed to ground out, make it up rivers, and even be able to be portaged (over logs of course) to some extent. Shallow draft required, but the trade off is, windward work, ultimate stability, etc.

(4) The ocean-going knarr is shallow draftish but also deeper than the larger Viking war conoes, so again, define shallow draft. -- Wade

[Einarr]

Ok.
I am defining shallow draft in this manner.

Any ballasted boat with an unladen displacement that creates the condition wherein the draft of the vessel is equal to or less than the freeboard of the vessel.

[Thorne]

Why? Why ballasted -- aren't you leaving out most historical ships and boats? What about leeboards -- do they count?

Many fishing boats have/had very low freeboard to allow pulling nets and fish over the sides, but cargo vessels would be fairly different. So a ballasted fishing boat would have to be shallower than the same boat design built to carry cargo to meet your specs...

As I said earlier, trying to clearly define terms used historically and generally can be bootless -- they are too fuzzy in actual use to be nailed down in a scholastic manner.

[Einarr]

I agree that things are too fuzzy to specify fully.
Historically, ocean going vessels used ballast when there was no cargo weight in the ship. Specifically speaking of the knarr, they used rocks for ballast when the ship was not loaded for cargo.

Why? Why ballasted -- aren't you leaving out most historical ships and boats? What about leeboards -- do they count?

Many fishing boats have/had very low freeboard to allow pulling nets and fish over the sides, but cargo vessels would be fairly different. So a ballasted fishing boat would have to be shallower than the same boat design built to carry cargo to meet your specs...

As I said earlier, trying to clearly define terms used historically and generally can be bootless -- they are too fuzzy in actual use to be nailed down in a scholastic manner.

[Peter Belenky]

Einarr, you don't seem to realize what a historical discontinuity there was between Norse ships and Colin Archer. In the nineteenth century, the typical fishing boats of the Norwegian coast were like this Nordland fembøring or five-oared boat. They were virtually unchanged from Viking days: largely open, internally stone ballasted, with low freeboard and long, shallow keels. It was because of the terrible loss of life in these fisheries that Colin Archer was asked to design a lifeboat.




The first rescue boat, or "Redningsskøyta," was built in 1893 and had many of the characterictics of modern cruising yachts. It was fully decked, had outside iron ballast on a deep keel, high freeboard, and a securely stayed, divided fore-and-aft rig.



There are many dimensions of seaworthiness, and both deep and shallow boats have gone offshore (and been lost). If the ballast can't shift and the hull can't flood and everything is well-fastened, either can stand wave action and recover. The boat with deep ballast can stand up to its rig better, however.

[Einarr]

There is not that much discontinuity between the old Norse and Colin archer designs.

This is a picture of the Saga Siglar, a 56' knarr.

<img src="http://www.vaartips.nl/images/knarr.jpg">

This is the Talja, a 30' viksbaten or bydingr, a bay boat

http://www.talja.se/fvb2006/images/ritning.gif

Colin Archer took the best of the knarr and decked it over to create his ketch design.

I understand the need for a better ocean fishing boat, the bay boat was not designed for open ocean, nor large capacity. Loss of life was caused by incorrect use of a boat design. Happens today as well.

[outofthenorm]

There is not that much discontinuity between the old Norse and Colin archer designs.

http://www.talja.se/fvb2006/images/ritning.gif

Colin Archer took the best of the knarr and decked it over to create his ketch design.

I don't think so.

This is the one you posted:



This is a typical Colin Archer hull form.

[Einarr]

The Talja was an example of the fishing boats that you mentioned.
Click on the other link for a compairative look at the knarr

[Einarr]

I personally would not consider the Archer ketch as a deep keeled boat, full keeled, yes.

It seems to me that the draft of the hull is not much more than the height of the freeboard if you discount the keel.

[outofthenorm]

I personally would not consider the Archer ketch as a deep keeled boat, full keeled, yes.

It seems to me that the draft of the hull is not much more than the height of the freeboard if you discount the keel.

Huh? Height of freeboard is usually measured at it's lowest point, not the highest. And sorry, you can't discount the keel. On the CA hull I posted, draft is pretty well double the freeboard.

[Einarr]

It seems that the Archer Ketch hull resembles the Kalmar Cog. This cog is a transitional phase boat from the viking period to the late middle ages.

[outofthenorm]

Same point. I'd hazzard a guess that underwater the Tajla and the Knarr are very similar - and they are both radically different from the CA hull form. The CA form (as was said above) was designed around a deep draft model - the goal was to lower the centre of gravity and enable it to survive almost anything. Notice the minimal sheer, minimal overhangs, beam carried far fwd and aft, and markedly deep draft. He put the ballast down low because he was after exactly the same things as Herreshoff (righting moment) - except his solution is optimized for strength and safety rather than for speed alone.

- Norm

[outofthenorm]

Only superficially. The cog depends on its form and its load of either ballast or cargo for stability. It's midship section is basically round with low deadrise. The archer hull - any archer hull - has a much deeper wineglass midship section - steep deadrise and a form that depends on the heavy deep fixed ballast keel for stability. The cog likely has higher initial stability than the CA, but a lower maximum safe angle of heel. They're both double-ended, with a stern mounted rudder and they both carry their beam well out to the ends, but philosophically, they are very very different.

[Einarr]

If I remember correctly the Archer ketch was designed specifically with fast rescue in mind. Thus the steeper deadrise.

But back to the original discussion.

Regardless of the conditions, operated correctly by an experienced person that knows their boat, both deep keel and shallow keeled vessels are equally seaworthy.
I, personally, think that shallow keeled vessels are a better all around if you dont have the need to get anywhere fast. (Although there are some flatties that will scoot).

A shallowed keel vessel can go anywhere that a deep keeled one can. But the reverse is not true.

Granted there are trade offs, speed being the primary one. But then again I have always been told that if you have to get somewhere fast by boat, take a plane.

I just think that nautical designers are stuck in a rut and influenced too much buy racing rules. Cruising boats and racing boats are like apples and oranges. You cant compair the two nor should you try and cross the two. The infamous racing cruiser/ crusing racer is either too cramped or not fast enough, It has been shorted on both ends of the stick.

The only sucessful hybrid that comes to mind are the polynesian double canoes and their descendants (i.e catamarans, by the way Herschoff did not invent the racing cat. Ever been in a polynesian proa? It is like putting a saddle on a rocket.) Granted there are probably others.

There is archeological evidence of a couple of boats with semi-deep keels, nothing compaired with the modern age, but 2 to 3 time the average during the medieval period. Makes you wonder why they did not stick with it?

Postualte -- they were not conducive to use in shallow water.

I can think of sevearl styles of boat that were shallow water, flat or low dead rise that have lasted for centuries and used in both the open ocean and inland waters. The knarr, the dhow, the junk. All three having very large capacity in shallow waters.

While I am on a tirade.

The current design trend and my opinion on it. Designers are designing sailing houses, not sailboats. Simply to get money out of the pocket of the retiring babyboomers. If they dont design it like a house then most ladies will not have anything to do with it, making it less likey for a babyboomer couple to buy one. Why not buy a houseboat instead? It will get used just about as much. Probably more.

Now I am not one of the crowd that advocates going without but there has to be a balance somewhere between what is necessary and what is too far off on the luxury end. I know that this is a personal choice but spending $200k or more on a sailing house that depreciates in value when you could spend a like amount (??possible) on a beach front condo that grows in value and has all of the same luxuries or better ones in most cases.

I dont know it for a fact, but I have been told that most boat owners use their boats for a total time of less than 3 weeks a year. (??)

I think that these factor also influience the designs of boats.

[Canoeyawl]

Being Seaworthy in the context of Colin Archer rescue boats (and any other boat in my opinion) means having the power to go to weather in terrible conditions.
This ability to sail off of a deadly lee shore (maybe while towing another vessel off) will define “safe”
Many or dare I say most boats can not do it, they don’t have a prayer without an engine.
This power to carry sail to weather will simply not happen with shoal draft, the vessel will blown to leeward.

[Einarr]

Unless of course it is rocks, it would be easier to beach a shallow draft boat.

[sv Lorelei]

Unless of course it is rocks, it would be easier to beach a shallow draft boat.

The idea of seaworthiness isn't requisite to how easy it is to get your boat on land, it's keeping it off land and in a (presumably) safe and controllable condition.

The idea of ballast is to provide resistance to the tipping moment of the wind on the rig and to a lesser degree the waves, and modern hull forms have evolved largely to try and make the most of that. It's a direction boat designs took in search of maximizing the characteristics of stability and speed.

Simple physics dictates that the further away from the fulcrum point you exert and quantified effort the more effect it'll have a fixed distance on the other side of the fulcrum. Yacht designers didn't invent this. It isn't right or wrong. It just is.


"Traditional" designs followed a significantly different brief. Often it was requisite that a design was required to be stored on land and launched off the beach. This lets out comparatively deep hulls and comparatively heavy ones so the successful designer would need to maximize other qualities to compensate. So instead of building a boat that could right itself with it's own weight, one had to take more of a design it so that it's less likely to tip over in the first place.

Thus simple, low aspect rigs and hull forms that would plane or at the very least bob efficiently without having the mass or proclivity to be run off by the waves or to broach in a swell. Again not a perfect design brief considering the first set of requisites.

There are boats that have been designed in both branches of this evolution that have just plain sucked. There are boats that have been designed in both branches of this evolution that just plain excel. I happen to own one of each. I also know the track record of the Hanseatic merchants and I'll tell you what. At some point "out there" you're going to find that when a breaking sea gets large enough all bets are off, and that moment comes (generally) sooner for a shallow draft boat than it does for a more burdensome design.

In general I'll take a storm in my deep keeled boat and let you head out in my shallow draft double ender. If we meet on the other side of the storm and you haven't painted the bulkheads green, then I'll shake your hand. But if it comes on to blow again before we turn for home, I'll still take the more burdensome boat back.

Regarding the latest market driven gin palaces. Yes. Indeed many of them sail like poop (and I don't mean the deck) and are designs generated by marketing departments in response to surveys that have less accuracy than most exit polls. And in truth to call many of them deep draft is wrong. (I want it to be really big inside, and not too much draft, and motor and sail really well doesn't make for a very sensible design brief once one starts doing the math.) The trend for quite some time has been toward planing type hulls... and in some respects more closely resemble the boats you're espousing than what the average blue water cruiser would consider ideal or even adequate.

Boats need to be designed for the purpose they mean to fulfill. Each time you go out on the water, you're taking some kind of risk. How you assess that, and what tools you take to cope with it, have as much bearing on whether you will make your passage successfully, as do luck and skill.

YMMV

[Canoeyawl]

If you are able to pick a soft spot to crash you are a luckier sailor than most. But that is not the definition of seaworthy now is it?
In Norway they are few and far between.
The California beaches are all sand and just lovely, but if you are thinking about landing on one in a blow the chances are very good that you will die.

[mmd]

Might I be so bold as to suggest that, in order to carry this conversation past the dead-end activity of posting pictures and repeating, "Yes, I'm right and you're wrong!", that a study of a text on basic hull stability (Barnaby is a good author) and maybe a reading of Marchaj's text, Seaworthiness: The Forgotten Factor would go a long way to defining the argument that you so wish to make? Physics is so much more exact than opinon... <wink>

[Einarr]

Using physics a log will roll over easier than a plank the same wide and length.

Fortunately the log will just as easily roll back over while the plank is happy upside down and needs assistance.

Since I do not think that it is possible that a ship large enough could be built NOT to be pitchpolled, rolled or knocked down on the ocean it is a moot point.

[mmd]

Seriously, Einarr (Mike); If you want to present an argument to firmly cap your premise, use your passion for research of ancient boat types to build a convincing argument based on the science of boat design. A quick study with a bit of math understanding can learn the basics of determining static stability and lines measurement in a few months of study.

Research into the shapes of ancient boats (there’s not much information but I have read references to some) would provide you with the fodder for determining the stability characteristics of old vessel types. Similar analysis of a representative group of modern hull forms would then give you sufficient hard data to perform a useful and pragmatic comparison. The results would be fascinating.

This is the kind of scholarly work that interested amateurs excel at. Working naval architects are too busy trying to make a living to have the luxury of the time to do low- (or no-) paying pure research. I’d bet that if you did this work and had it reviewed by a professional naval architect for errors or omissions, our hosts would be interested in publishing the data and results.

I’d be interested in reading it.

[sv Lorelei]

Okay, so you're talking about power boats now.....? Because your last statement selective eliminates the concepts of ballast or the effect of rigging.

Suggestion. If actually educating yourself by reading a few books is too much of an insult to your gut feelings, try sailing a few different types of boats offshore before you decide that the last couple hundred years of naval architecture have been a lunge down a blind alley.

By your latest evaluation, the best boat for you would be a fifteen hundred foot long surf board. Good luck with that.

Physics doesn't let you pick and choose your characteristics.

[Peter Belenky]

Not to beat a dead fish, but research into principles of boat design has also had its false starts. Colin Archer was an adherent of John Scott Russell's wave line theory. For those who are interested, here are some plans of his lifeboats:





Two things to notice are the great beam and the flush deck. The first ensures buoyancy in extreme conditions but also slowness. The latter gives strength but limits space. Designers like William Atkin who adapted the type for yacht use and smaller size introduced finer ends and cabin trunks:

[Tom Hunter]

Einarr,

You should look closely at MMD's proposal, if you follow up on it you will get your Laurel. (for those not in the SCA, it is an arts and sciences award)

I'm reading your posts, and there are a lot of topics all rolling around like loose cargo. Yes, we all know that the plastic palaces are designed as living rooms, not boats.

You need to read up on designers before making blanket statements about them. Some are strong advocates of shallow draft, others are not. There is a great diversity out there.

All the world thinks Colin Archer designed deep draft keels. That is a semantic debate, but it is nice to have a common lexicon.

Seaworthy means at sea, suggesting a boat be saved by beaching is not a discussion of its capabilities at sea, its a discussion about its ability to make safe harbor. You are welcome to change the subject mid argument if you like, but I doubt it will improve the audiences opinion of your original assertion.

Spend more time around boats, the arguements are very nuanced. It makes the topic fascinating, because just when you think you have it figured out you learn something new. It gets even better when you start sailing them. Welcome aboard.

[Woxbox]

Here's an old ship that rolled over and didn't come back on her first voyage. The Wasa, (aka Vasa) of course. Boats were only marginally seaworthy back in the 17th century and before, for all that we know about them, and didn't get much better until the science of it all was figured out. First came fitting as many cannon on top or as much cargo inside as possible. After that, there was some concern about keeping the boat upright. The Wasa was modified on the king's orders. Who's to argue? But she never made it out of Stockholm harbor.

It's hard to argue that people who didn't know the physics involved produced better boats. They built to known proportions and weren't quick to experiment. Once the science was developed, the evolution of boat design took off.

[SaltyD from BC]

I can't see any way that the Vikings or other early boat builders could build a boat with a deep keel so I don't think it was a matter of perference, but one of necessity.

The saw had not been invented yet. They split logs lengthwise in wedges comming up with a plank thin on one end (heartwood) and thicker on the other (sapwood). Then the faired the wedge shaped pieces up with an axe or an adze. With this technology I can't see it being very feasable to build up deadwood for a keel.

Secondly they didn't have iron fasteners yet, they used tree nails. Again making it pretty hard to reliabley attach a full keel.

Thirdly even if they could build a full keel boat how would they launch it? Not a big deal to skid a shallow draft boat from just above high tide into the water. But I can't quite picture a big old hand hewn cradle to hold up a full keel boat being realistic as far as skidding the whole works into enough water to float the thing.

[Einarr]

The saw had not been invented yet. They split logs lengthwise in wedges comming up with a plank thin on one end (heartwood) and thicker on the other (sapwood). Then the faired the wedge shaped pieces up with an axe or an adze. With this technology I can't see it being very feasable to build up deadwood for a keel.

Here is a link for the Mastermyr chest and carpentry tools that are carbon dated from 1000AD +/- 50 years. There are two saws in the tool kit.

http://www.netlabs.net/~osan/Mastermyr/ImageLib.html

Here is a link for wood working during the viking age, including tool.

http://www.vikinganswerlady.com/wood.shtml


Secondly they didn't have iron fasteners yet, they used tree nails. Again making it pretty hard to reliabley attach a full keel.

Yes they used tree nails (trenagl) but the also used iron rivets and nails (jarnnagl). Here is a link on Norse ship construction.

http://home.online.no/~joeolavl/viki...ipbuilding.htm

Thirdly even if they could build a full keel boat how would they launch it?

There are two finds that have additions made to the keel. The additional pieces were of the same width of the keel and of the same depth. (looking for the links) Therefore extending the keel to twice its usual depth. Granted this is not the same as a full 6' keel. But it is not normal for the viking age and if I remember correctly they were fairly early in period, around the 600-700's.

As far as I know there are only two examples of this. One theory is that it was to add resistance to sideways drift and the other theory is that is was a repair job because the keel was cracked. no evidence to support or discount either as far as I know.

Not a big deal to skid a shallow draft boat from just above high tide into the water. But I can't quite picture a big old hand hewn cradle to hold up a full keel boat being realistic as far as skidding the whole works into enough water to float the thing.

The same way everything else got built and moved prior to the modern age, by hand and levers. If you have enough manpower you can move anything, look at the pyrmids.

I dont know for fact but I surmise that the large ships stayed in the water once launched. But i do know that even the large ones were built on land, how did the get them in the water? by manpower.

[SaltyD from BC]

That will be a saw in your link all right. Do you know its size? Just a small cutt off saw? In reading that I've done making planks with a whip saw didn't happen until the industrial revolution type of time line...

[SaltyD from BC]

From one of your very interesting links above. This is how I understood the plank making process of early Vikings, split with an axe, then hewn.

[Einarr]

You are correct that is how they split the planking. But the also used adz to cut and shape other items. It would be simple to make a keel addon with an adz, and have it spiked or treenailed to the keel.

Woodworking has not changed all that much in a 1000 years, they had joinery that was almost exactly the same back then including dovetails and joints that you will only see now in an Amish built barn.

[py]

Guns aint dangerous either, its just the fools that use them.

I guess real seaworthiness, in addition to being able to make way off a lee shore, is about inherent safety, regardless of the skill, and perhaps physical condition, of the crew.

The right skipper could be quite safe in a little, fast, over canvassed, flat bottomed racing skiff, way out at sea. Doesn't make the craft seaworthy.

[heimlaga]

According to the book "Fem vikingeskipe fra Roskilde fjord" there were NO toolmarks left by a saw on any of the five shipwrecks found. I have read other books too and it seems like the experts consider the viking age saw a rather inefficient tool used for fine furnituremaking and carvings and such but not for shipbuilding.
In my area house carpenters tried to avoid the use of saws as late as the 18th century. The saw was a too valuable and inefficient tool to use when it could be avoided.

That extra piece under the keel sounds like what we call "drag" in my dialect. The drag protected the keel from being worn out when the boat was beached. It was usually made from half the trunk of a spruce tree and was shifted out as it wore out. A viking ship was launched and beached just lika a 19th century fishing boat so it would be logical to assume that they protected the keel in the same manner.
I think the english term is false keel.

Iron fastenings were used for boatbuilding during the viking age and even before.

I am nether historican nor shipbuilder.