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PostPosted: December 9th, 2007, 11:17 am 
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Thanks for the update, GB.

Very interesting techniques you've developed. From the sound of things, the layup you are using will probably get you into a weight range that I thought was not possible. The choice of NWC coupled with a thinner glass/resin skin should shave a few critical pounds off.

I'm not quite on board with all the tumblehome carried so low down the hull. Seems that that will make it a bit less seaworthy and give it less final stability. Maybe it's just the photo. Anyway, the test will be in the paddling. Right now, it looks like you're on your way to owning one of the lightest wooden pack canoes in the Northeast. Hope to get a nice peek at it when you start to ply the ADK waters come spring. :wink:

BTW, that rotating strongback is the cat's ass. The legs make a nice counterbalanced system. Have to modify my design so I can do the same. How rigid is the box itself? I'm a bit worried about incorporating sag and twist into the hull. Maybe not so critical on a 10' hull but I'm concerned when I step up in size with my 14' Wildfire.

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PostPosted: December 9th, 2007, 3:43 pm 
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I'm not quite on board with all the tumblehome carried so low down the hull. Seems that that will make it a bit less seaworthy and give it less final stability.


True. I had two reasons for doing it that way, knowing that it would reduce final stability. The reason for tumblehome in the first place is to give the paddler better access to the water. Not much is gained, however, if the paddler can get his paddle over the gunwale but then can't hold it very vertical. (See Charlie Wilson's posts on adkforum.com for the advisability of keeping a paddle vertical.) I therefore kept the tangent to the midship section as vertical as I could, consistent with what I hoped would be both adequate stability and access to the water. As you point out, "the test will be in the paddling" or, to corrupt an old saying, the proof of the paddling is in the swimming.

The rotating strongback as shown is not the way I would build it again. In this case, making it rotate was an afterthought. True, the legs do counterbalance the canoe but they also get in the way, particularly with the cross braces I felt obliged to add. As originally built, the strongback was three sided--open on the bottom. The top and sides are 3/4" plywood, joined lengthwise with scabs glued and screwed on the inner sides, and assembled with several 2x6 "bulkheads", two of which became the legs. When I added the rotating feature I also added additional 2x6 pieces to close the bottom of the strongback to resist twisting. So braced, it does not twist or sag, but I suspect that there are better ways to get the job done. It would be handy if a reader with more background in mechanics would offer advice on resisting twist. I wonder, for example, if a triangular cross-section would be better.

The problem I mentioned in my post has been resolved. As it turned out, the shaft that broke did so because the lag screw on the inner end missed the pilot hole and entered the shaft only about a fourth of the diameter from the outer surface. The surprise is not that it broke but that it didn't break while turning in the lag screw in the first place. Next time around I'll design a strongback that rotates from the beginning.

One other tip that I didn't mention before: The secret to smoothing satin weave 'glass is to start at the middle of the "keel" and stroke only in the bias direction of the fabric, working out in an ever-increasing circle.

b

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 Post subject: Update-2
PostPosted: January 22nd, 2008, 2:49 pm 
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Hull complete, gunwales and breast-hooks complete, final sanding and a light spray of auto-enamel inside and out still to go. Weight at present, 16 lbs. 6 oz. (weighed on a thirty-year-old kitchen scale with a max. cap. of 25 lbs.)

While it hasn't been tested on water yet, from a building point of view I'm happy with the design of the gunwales that I used. As mentioned earlier, I incorporated a 1" tow of graphite fibers under the glass at the sheer. Next, I installed cedar spacer blocks, epoxying them to the inside at the sheer. I then put clear plastic packaging tape over the inside surface of the blocks, sleeved a 3/16" x 3/4" strip of cedar with both edges beaded with fiberglass sleeving, wet it out, and clamped it in place on the spacer blocks. That meant bending it in crook, bow, and twist. Removed after cure, there was zero spring-back. I then sanded it smooth and epoxied it in place to the spacers at the same time I installed the breast hooks. They're quite light and quite strong but could be even lighter. The only fiberglass sleeving I could find has a fabric weight of 11 oz. per square yard. Carbon fiber sleeving is available in half that weight with corresponding weight savings in the resin to wet it out. Now that I know that the procedures work well, I may jump for carbon sleeving the next time around.

I also used sleeved cedar, 3/4" x 3/4" with 1/4" radiused edges, for thwarts.

I was hoping for 15 lbs. complete and said I would be disappointed if it went over 18 lbs. I'm now confident I'll be under 18 lbs. I can also say with confidence that 15 lbs complete is an achievable goal. The main reason I'm not on target to achieving it with this boat is that I blew the interior 'glassing and stem fillets. Factors in blowing it: 1: I'm impatient by nature. 2: It has been over twenty years since I 'glassed a canoe. 3: My resin was 20+ year old WEST 105 which had thickened somewhat with age. With more experience and thinner resin I'd guess that the weight added by the interior glass and resin would be a third of what I wound up with.

After re-reading the discussioin above on strip thickness, and thinking over my experiences with this boat, I've concluded that, at least for me, strips sawn to 3/16" thick is the minimum. That is especially true for a design with tight curves in the sections. Where such curves get down to a radius in the neighborhood of 4", strips are only 1/8" thick after sanding out the facets anyway. The successor to the current boat, now in design stages, will hold section radii to a minimum of 5".

As usual, comments and suggestions are more than welcome.

b.

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PostPosted: January 22nd, 2008, 4:50 pm 
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Graybeard

Comments : Well Done :clap: :clap: :clap: :clap:

Suggestions : None.

Queries :

Radii of 5 inches Minimum... I take it that you find the 4 inch too troublesome...
that is, that increasing the minimum to 5 would make a better result more
easily achievable?

I'd just like to say that I truly appreciate the fact that you have allowed us to
share in your process... and, to allow us to participate in the thought process
along the way.

Initially I was in favour of the 1/8 strips (planed/sanded from premachined
3/16 cove and bead)... but, your methodologies are so well thought-out and
meticulously effected, that when you say "3/16 and reduce somewhat by
finish sanding"... well, you will not find any argument from me.

One of my own huge personal regrets has been my lifelong reluctance to
take benefit of various computer-aided-design technologies... I've always
been a hand draftsman, and while my drawings are efficient and effective,
I see that I have limited my potentials... put a ceiling, perhaps, on the
maximum level of attainment of my imaginings. What I am trying to say here,
is that I was especially impressed with your patience at the design stage,
by a Man whom describes himself as "inherently impatient".

I agree with you... were you to repeat the process, I reckon you hit 15 or lower.

I cant wait to see the pics.

Thank you

Sundown


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PostPosted: January 22nd, 2008, 6:55 pm 
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Sundown wrote:
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Radii of 5 inches Minimum... I take it that you find the 4 inch too troublesome... that is, that increasing the minimum to 5 would make a better result more easily achievable?


Basically, yes.

I have enormous respect for Charlie Wilson of Placid Boats who knows far more about canoes and paddling than I could ever have learned even if I had started as early in life as he did. So when he blew my mind with the comment that the right paddle is more important than the right canoe (or something to that effect) I reflected on it. It put the whole topic of the shape of the canoe into a different perspective.

I began to buy into the notion that designing and building your own is not a decision based solely on parsimony, it's driven by the same motives as canoeing in the first place; enjoyment. So why should I incorporate some feature that may have some marginal hydrodynamic advantage if the cost is frustration during the building process? It made no sense.

I also reflected that throughout history the design of boats has been a compromise between what might work well as a boat and what is readily buildable. The history making designs of Rushton for George Sears were heavily constrained by Rushton's lapstrake construction. Whether Rushton would have liked to incorporate severe tumblehome to make paddling easier is a moot question--his construction method didn't allow it.

So when I decided to follow his pack boat lead but to do it as a modern strip--built canoe I did what he couldn't do, incorporate severe tumblehome. Too severe as it turned out. It posed problems while stripping and then while sanding both the inside and the outside, and then a third time when 'glassing the inside. So the next will have a minimum radius of 5", an arbitrary choice but significantly larger than the current build. I don't make recommendations for others but I'm happy to share what I decide and why I decide it. Certainly somebody intending to sink five figures into a female mould for production will make decisions based more on marketability. Buyers of those canoes may well have better hydrodynamics than mine but they won't have the pleasure of building that I have.

Quote:
One of my own huge personal regrets has been my lifelong reluctance to take benefit of various computer-aided-design technologies... I've always been a hand draftsman, and while my drawings are efficient and effective, I see that I have limited my potentials.


I'm not convinced that the lack of software for designing hulls limits anyone's potential. I first got interested in the challenges of hull design in the sixties and learned the design process from Chapelle's Yacht Designing and Planning. Then for ten years or so I entertained myself designing live-aboard sailboats for the Pacific. When I came back to it thirty-plus years later to try my hand at canoes I looked into hull design software. What I found was that it took such a different approach that everything I had learned about the process was useless. But I had given away all my splines and ducks and planimeter. So I compromised. I used my find old '95 vintage CAD program to design directly with waterlines, stations, diagonals, buttocks, etc. in the way I was comfortable with--the way I enjoyed the process. I don't see myself as obsolete, just less hurried than the next generation.

b

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PostPosted: January 23rd, 2008, 6:33 pm 
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Graybeard wrote:

Quote:
So when he blew my mind with the comment that the right paddle is more important than the right canoe (or something to that effect) I reflected on it. It put the whole topic of the shape of the canoe into a different perspective


Charlie was being speaking for effect if he said that.

There are far greater differences between boats than between paddles. If you want to prove this to yourself try paddling a bathtub, or, better yet, a coracle and then compare it to one of Charlie's boats. This is easily proven by even the most casual analysis of boats and paddles. Charlie just likes to be outrageous sometimes. You should take him with a grain of salt.

One can build a boat with good or bad hydrodynamic principles. The fact that one enjoyed the experience and loves his boat doesn't make the boat a fine example of boat building or design. It just means the builder likes what he did.

It is odd that people are so negative about design software. It is just a tool. It does not change the design characteristic s or objectives, it just makes it easier and allows the kind of analysis that leads to improved boats - not just boats some one likes. Some of us learn how to use the tools and put them to ood use. Just beacuse you cannot understand the benefits of a first class plane does not mean you should not embrace its possibilities.

The difference in possibilities is important to everyone but the person building his own boat who, like the mother who loves her offspring regardless of his/her physical or intellectual differences, loves his boat. I have paddled dozens of these boats that people brought by my home in Ontario just tickled to death with them and wanting me to flatter them. I did. Who cares if they built a waterpig. They liked it and it did not hurt me to lie about it. Although one went into business building a boat he thought was great and I damned with faint praise and lost a lot of money. Maybe I should have been brutally honest.

Just don't confuse mother hood with common sense.

That said, I hope Graybeard enjoys his boat. I have built or designed thousands of boats and thought each one was special even though the passage of time has often revealed otherwise.

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PostPosted: January 23rd, 2008, 6:49 pm 
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jwinters...

interesting perspective...

thanks...

Sundown...


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PostPosted: January 23rd, 2008, 8:45 pm 
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jwinters wrote:
Quote:
Charlie was being speaking for effect if he said that.

There are far greater differences between boats than between paddles. If you want to prove this to yourself try paddling a bathtub, or, better yet, a coracle and then compare it to one of Charlie's boats. This is easily proven by even the most casual analysis of boats and paddles. Charlie just likes to be outrageous sometimes. You should take him with a grain of salt.


I have no doubt at all that Charlie was speaking for effect. I've chatted with him a few times and quickly concluded that much of what he says is for effect--for good effect. An outrageous statement is a pretty good device for making a valid point. In this case it did. It got me thinking about the importance of the many factors in having a good paddling experience--in this case specifically that the paddle may have more importance than it is usually given credit for, which is not to say that nothing else has importance but that the paddle does have importance.

My own experiences, skill level, and goals are such that many fine points are lost on me. If a particular design has a clear but modestly lower resistance while at the same time making me feel a bit uneasy then my enjoyment is less, not more. Similarly, for some but by no means all, there is a satisfaction in using a canoe that you designed and built yourself, even if it's less than perfect and less than a canoe that you could have bought. I'll go for that satisfaction even while applauding the paddler who takes the greatest satisfaction in buying and owning the boat he or she deems best for his or her purposes.

Quote:
It is odd that people are so negative about design software. It is just a tool. It does not change the design characteristic s or objectives, it just makes it easier and allows the kind of analysis that leads to improved boats - not just boats some one likes. Some of us learn how to use the tools and put them to ood use. Just beacuse you cannot understand the benefits of a first class plane does not mean you should not embrace its possibilities.


If my comments about hull design software came across as being negative about such software, I apologize: that was not my intent. I have no doubt whatsoever that had I begun with such software instead of beginning to mess around with hull design before such software was available, then I would have embraced it and thought of the "old way" as absurdly labor intensive. The point I was trying to make was that I preferred to use the basic approach that I was familiar with rather than learn a quite different approach just to modify an existing design. My comment in response to sundown was that the tool one uses does not necessarily limit one's potential. The great age of clipper ships did not stop being a great age when hull design software became available. The design of those hulls no doubt took far more man-hours, and may well have been even more productive with such software, but the achievement was nevertheless a great achievement.

Quote:
That said, I hope Graybeard enjoys his boat. I have built or designed thousands of boats and thought each one was special even though the passage of time has often revealed otherwise.


I suspect that I will enjoy my boat. I am even more certain that I will be critical of it and go back to the design stage in an effort to improve it, and that I will enjoy the process even if the redesign is worse than the original.

Now I have a question for those far more experienced than I am. Why is it that the best designers produce an excellent hull shape and then experienced paddlers advise paddling the boat just a wee bit stern-heavy? Surely trimming the boat other than parallel to the design waterline changes the underwater shape, no longer the shape that the designer intended. Is one or the other "wrong"?

b

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PostPosted: January 24th, 2008, 8:22 am 
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Graybeard wrote:
Now I have a question for those far more experienced than I am. Why is it that the best designers produce an excellent hull shape and then experienced paddlers advise paddling the boat just a wee bit stern-heavy? Surely trimming the boat other than parallel to the design waterline changes the underwater shape, no longer the shape that the designer intended. Is one or the other "wrong"?


Far more experienced? .....Oh, you must mean me! :roll: :lol:

I'll give you my take on it anyway.

There is no such thing as a design waterline except on a drawing board. Unless you are sitting in a pool and not moving the actual waterline in constantly changing. Even the act of rowing or paddling a boat causes the bow to rise and drop. Trim is a dynamic thing in real life.

A great example of this is the St. Lawrence River Skiff. Rigged for sail, it has no rudder. Directional control is obtained merely by the sailor moving fore and aft. Add to this the necessary heel used in sailing and the varying weights of individual sailors, and it is clear that the waterline is pretty arbitrary.

A well designed boat will behave well within a certain set of limits regarding trim, carrying capacity and degree of heel. In the end, users decide how and when these limits are approached. Wind, waves, load and direction of water flow all influence where the waterline is at any moment and the better paddlers make adjustments based on what actually works in the varying conditions encountered.

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PostPosted: January 24th, 2008, 4:05 pm 
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BK:

What you say is true, and understood by both designers and knowledgeable, experienced paddlers. But it doesn't explain why the design is presented to the public either by the designer or the builder as having certain characteristics when experienced paddlers trim the boat in a manner that changes those characteristics. The simplest and most readily visualized characteristic is rocker. A boat may be specified as having an inch of rocker both fore and aft even when experienced paddlers routinely load the boat so the rocker is an inch and a half fore and a half inch aft. Similarly the shape of waterlines changes, the angle of entry may change, the curve of areas changes, etc.

JW rightly emphasizes how important the careful analysis of hulls is to the development of new hulls. Yet isn't that misleading if the analysis is based on the designed lwl and the feedback from paddlers is based on performance when trimmed by the stern?

Perhaps the answer to my question is right out there in front of us. Perhaps the growing number of asymmetrical designs is simply a reflection of designers observing that their boats function best at a trim other than they intended. It raises the possibility that an "all new asymmetrical design" might be nothing other than a successful old design with a neat pin-stripe indicating a lwl when loaded a bit aft. :-?

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PostPosted: January 24th, 2008, 5:26 pm 
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Graybeard wrote:
Yet isn't that misleading if the analysis is based on the designed lwl and the feedback from paddlers is based on performance when trimmed .... Perhaps the growing number of asymmetrical designs is simply a reflection of designers observing that their boats function best at a trim other than they intended. It raises the possibility that an "all new asymmetrical design" might be nothing other than a successful old design...?


Greybeard

I posed this query here somewhere before, and I have tried unsuccessfully to
find it, and I always wondered if my query was posed in such a fashion so as
to be fully understood... enabling an answer.

No question... at least I reckon you wont get any (much :wink: )argument...
that a "boat" is most efficient when designed to the precise specs which
most precisely suit the methodology of both Trimming and Heeling and Paddling.

The question I had asked was whether or not anyone had ever thought of
designing (or had designed) a "boat" which was specifically intended to be
most efficient in the Solo-Paddler Heeled Position.

Why (i Wonder) do we all choose to Heel our Non-Intended-to-be-Heeled Hulls
rather than design/acquire a longitudinally/latitudinally pre-designed Heeled
Hull Configuration... and, lets now say, pre-trimmed according to specific weight trim (since I know Graybeard is meticulous enough to not vary his
intended planned cargo weight).

Regards

Sundown


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PostPosted: January 24th, 2008, 7:43 pm 
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Sundown wrote:
Quote:
The question I had asked was whether or not anyone had ever thought of designing (or had designed) a "boat" which was specifically intended to be most efficient in the Solo-Paddler Heeled Position.


Hmmmmm. That could be a pretty tall order.

But then maybe it has been. I don't do that style so I don't have any idea what aspects of it would cry out the loudest for hull shape modification. But just from reading the forums I gather that some boats do better in the heeled position than others. Is it known for sure that the designer didn't have the heeled position in mind when laying down the lines? There are so many things that the designer has to keep in mind that maybe the better adapted designs are as close as can be hoped for. Or maybe somebody really went all out to design for the heeled position and nobody else recognized it as a canoe. :doh: :doh:

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PostPosted: January 24th, 2008, 7:56 pm 
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Graybeard wrote:
Sundown wrote:
Quote:
The question I had asked was whether or not anyone had ever thought of designing (or had designed) a "boat" which was specifically intended to be most efficient in the Solo-Paddler Heeled Position.


Hmmmmm. That could be a pretty tall order.

But then maybe it has been. I don't do that style so I don't have any idea what aspects of it would cry out the loudest for hull shape modification. But just from reading the forums I gather that some boats do better in the heeled position than others. Is it known for sure that the designer didn't have the heeled position in mind when laying down the lines? There are so many things that the designer has to keep in mind that maybe the better adapted designs are as close as can be hoped for. Or maybe somebody really went all out to design for the heeled position and nobody else recognized it as a canoe. :doh: :doh:


As a Professor of Hydronamics, I see that you comprehend the possibilities.

That's enough for a Northern Lad.

Regards

Sundown


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PostPosted: January 24th, 2008, 8:09 pm 
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Sundown wrote:

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As a Professor of Hydronamics.....


NOW he tells us!!! :o :o

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PostPosted: January 24th, 2008, 8:24 pm 
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Graybeard wrote:
Sundown wrote:

Quote:
As a Professor of Hydronamics.....


NOW he tells us!!! :o :o


Non,Non, Mon Ami... c'est vous, pas moi, certainmente !!!

Ma Faux

Bonsoir

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