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PostPosted: July 25th, 2005, 8:57 pm 
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Location: Sunny Wasaga Beach
Kim Gass wrote:
Our leg length however never changes.

]


With the amount of leg pulling going on here I wouldn't take that as a given either! :)
Jwinters,
Maybe you could start a poll to guess Siren's weight! :) :wink:

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PostPosted: July 26th, 2005, 7:30 am 
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Posts: 442
Kim Gass wrote;

Quote:
Someone told me once when buying a kayak to get one that fit me well (mandatory) but made me a little uneasy when I tried to heel it or do a powerful stroke and actually paddle it for quite a while. That philosophy worked.


And very good advice it was - for you.


As for running a poll about Siren1's weight - surely you jest.

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 Post subject: Let the boats speak
PostPosted: July 26th, 2005, 8:32 am 
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Posts: 198
Location: Wilmington, Ma
Kim said "Let the boats speak"
Good advice.
Sireen said "OK, where do I go and test all these boats please? all at once?"

Don't test them all at once. Take some time. Try to spend some time in any that apeal to you. Boats don't talk fast. Look to dealers and builders for demo's and even better rentals. Post on this and other local boards asking if anybody will let you try their boat. (paddlers are like preachers and dope addicts, always looking for converts) If you are ever in the Boston area you're welcome to tryout my Osprey.

If you are lucky some of those boats will speak to you. If you are not lucky many boats will speak to you and you will end up with a collection.

Even if none of them say "take me home" you will then be able to speak to Mr. Winters or someone like him and say for instance, " I realy like the Osprey but I think I'd like it about three inches narrower and a touch longer. And maybe it could track a bit harder ( not turn quite so easily) . And a deck, yeah a deck like a kayak would be cool."
But that's Tommy's boat not Sireen's.

Have fun
Tommy


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 Post subject: objectives
PostPosted: July 27th, 2005, 5:25 am 
All too often paddlers can be so wrong in their 'objectives'.

Some want a 'fast' boat, while they have no intention to paddle that
hard. Others say they don't mind a slow boat, because they are not
in a hurry, but after a while they start complaining that getting
somewhere is such hard work...

Some prefer a maneuverable touring design, because they "can make
any canoe go straight", while a better tracking design would save
them a lot of energy in the long run?

All paddlers need stability, some less than others. Though with some
paddlers it sounds like instability is an advantageous design
feature...
Met a 'kayak' instructor once, who told me the best way to learn to
paddle well, was paddling an ICF racing kayak. Learned there is lot of
truth in that. But should all paddlers learn to paddle (well) in an
ICF racing canoe or kayak?

What do paddlers 'feel' when (test) paddling?
Long time ago, I participated in a touring canoe test for an outdoor
magazine. As it turned out, most remarks and complaints of the
paddlers were about seat height and comfort, interfering too much
with their opinion about the performance of the canoes involved.

What do I 'feel' when test paddling a canoe?
Depends on how tired I am too, as I have noticed:
for (touring) canoes it is probably wise to test paddle them when
you are tired from paddling hard for several hours?

"I know what I want,
but I just don't know how about getting it."

Dirk Barends


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 Post subject: oh my boat
PostPosted: July 27th, 2005, 7:42 am 
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Joined: October 16th, 2004, 11:11 am
Posts: 692
Location: Wakefield, Quebec
Dirk,
I want to get HIGH when I paddle my new boat,
I will want to feeeeel like I am Master of my UNIVERSE
(little that it is) :-?
each stroke I make will fuuuuuel my soul
that stolen one hour of l e i s u r e at dusk
on my river down the street.

Tommy?
of course you're right and you don't always get what you want
(ohhh, I feel a song comin' on . . .you get what you neeeeed)
I love Boston- when's Oyster season?
I'll meet you at the Union
:wink:

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 Post subject: Oh, that feeling
PostPosted: July 28th, 2005, 4:20 am 
Siren1 wrote:
>Dirk,
>I want to get HIGH when I paddle my new boat,
>I will want to feeeeel like I am Master of my UNIVERSE
>(little that it is)
>each stroke I make will fuuuuuel my soul
>that stolen one hour of l e i s u r e at dusk
>on my river down the street.

Oh, that feeling... ;-)

Sounds a lot like what I experienced with my Mad River Pearl
when I started to get comfortable in it.
Very quick and responsive, and lightweight (12 kg / 26 lbs).
If only I could get a canoe like that again,
but with better (tracking) behavior in waves,
for use as a touring canoe.
Maybe a solo version of the Swift Merlin (a John Winters' design)
would be the answer?

My weight is 75 kg / 166 lbs
with about 0.05 HP -- I guess
My skill level is still dry...

Sorry Siren1,
got carried away a little.
Perhaps you should tell which designs you have paddled so far
that appealed most to you?

Dirk Barends


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 Post subject:
PostPosted: July 28th, 2005, 5:11 am 
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Posts: 442
I dredged out an old article of mine about glide because it was mentioned here as “important”. I have taken out most formulas and edited to make it shorter. Please excuse any typos.

To paddlers, “glide” is the distance a boat travels after you quit paddling or between strokes. It is believed that if the boat travels a longish distance or seems to hold its speed well then it has “good” glide and ergo must be a “fast” boat. On the other hand, an inefficient boat will slow down quickly and not coast so far. Sounds good but is it?

Among the world champions in the glide department are the fully loaded VLCC’s (short for Very Large Crude Carriers). Fully loaded at over 400,000 tons they can glide for miles. Jet skis, on the other hand don’t glide well at all and come to a rapid stop once we turn off the power. Neither of these boats are very good designs in canoe terms and yet the one is relatively slow and glides nicely and the other is relatively fast but glides poorly. The VLCC is designed for low speed travel and glides by virtue of its huge mass. The jet ski, despite its speed when planing, is poorly designed for low speed and stops like it has brakes. The same principles apply to canoes as to these extreme examples. Only the degree varies.

The resistance of a canoe is comprised of two major components, friction and wave making. Typically, at speeds above S/L 0.90 (the Speed/Length ratio is the speed of the boat in knots divided by the square root of the boat’s waterline length) the resistance comes primarily from wave making. Wave making increases roughly with the third or fourth power of speed (how fast depends on the design). So if you double your speed the wave making resistance can increase by a factor of eight or even sixteen. Below S/L ratio 0.60 most of the resistance comes from friction that increases with the square of speed. Fortunately, wave-making resistance is not significant below S/L 0.60.
How quickly a canoe slows down between strokes depends upon the resistance at the time the power is removed, how rapidly that resistance changes with changes in speed and the mass. A boat with low resistance in the low speed range will “glide” “better” than one with high resistance in the low speed range and vice versa and a boat with high mass will hold its speed better than a boat with low mass.

Some canoes low resistance a low speeds while others have lower resistance at higher speeds (relatively speaking). Major factors in this difference are wetted surface and prismatic coefficient (volume of the boat divided by the volume of a body having the same maximum cross section area and same length. For a constant displacement, a longer boat has higher wetted surface and consequently higher frictional resistance. The prismatic coefficient differs considerably between boats and some are more efficient at high speeds while others are more efficient at lower speeds. None is more efficient at all speeds.

As if that is not enough, another speed-robbing factor is the angle of yaw or the angle the boat makes with the intended course. All boats yaw a little but some more than others. Yaw can add as much as 5% to the resistance over that of a boat traveling straight ahead. Obviously, a yawing boat will seem slow while a straight traveling boat will seem fast. Similarly, two big paddlers will coast a lot farther than two lightweights in the same boat.

So "glide" does not provide a useful measure of performance unless you have a lot of other information not always available to the paddler and once you have that information you have no need to concern yourself with "glide" since you already know what the boat will do.

Of course, we have the common problem of perception. Red boats, apparently, always glide better than other colours. :D

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John Winters


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 Post subject: boat design
PostPosted: July 28th, 2005, 1:29 pm 
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Joined: May 13th, 2004, 4:23 pm
Posts: 75
Insightful and helpful information, John. Thanks so much! (But I already knew that red canoes run faster).


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 Post subject: more on bubbles
PostPosted: July 28th, 2005, 3:33 pm 
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Joined: July 16th, 2004, 2:17 pm
Posts: 496
Location: Pelican Rapids, MN
alscool's link on another thread

http://cgi.ebay.ca/ws/eBayISAPI.dll?Vie ... 27859&rd=1

talked about an installed 'bow bubbler' on an icebreaker to reduce ice friction, soooo, maybe that request for Viking bubbles under the boat are doable, and practical.

Good thinkin Siren :clap:

pake

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 Post subject: mah boat
PostPosted: July 28th, 2005, 6:03 pm 
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Posts: 692
Location: Wakefield, Quebec
Pake wrote:
Quote:
Good thinkin Siren

Thank you Minnesota
s'all instinct Baby
i n s t i n c t.

Good Paper Mr. Winters,
very eruditely technical
A+
buuuu-ut,
does that mean I can or can't use the term
g l i i i i i i d e to describe
the after burner of my stroke?

(insert) Architecture Corner:
A window is not a window in erudite-academic-elitist Architectural terms
A window is really: Negative s p a c e :o

Let's not get too hung up* on the correct nomenclature of 'to glide' or 'to be yaw',
please lecture us about the performance enhancement/stabilizing effects
of an outrigger on the canoe . . .
and then about the pointey part (keel) where you need it
and the flat part where your butt shifts to when you want to
p i v o t the boat around in a jiffy :D

8)

*we are in the conceptual . . maybe inventing something n-e-w 'imagineering'
stage, and to get the ideas out, we have to let go, think outside the physics
remember the humble beginnings of all these boats
Man needed fish . . .to eat
what do we borrow and bring forward(remember)
take further . . . go beyond
(back to the old patch-kit on the Discovery :-? , this is not amusing)

JUMP INTO THE MILLENNIUM!

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 Post subject:
PostPosted: July 28th, 2005, 10:04 pm 
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Joined: April 14th, 2004, 4:26 pm
Posts: 1895
Location: Toronto
WHAT?????? :-?


Do you talk like this in real life too?


The damn internet is negative space... negative time too
Ok, I got it.....

You want a canoe that does not take alot of effort, to achieve difficult manouvers.

You want a ride that
- looks nice
-paddles without a great deal of effort
- turns without alot of effort
- goes straight without alot of effort.

You don't need a fancy canoe, you need fancy canoe lessons.

I am not the best paddler in the world, or this message bored, and I paddle a beat up royalex prospector. However, I feel all the fantastically poetic things you describe when I paddle. In fact now that I think about it, when I was 11 and paddling grummans at summer camp I felt the same thing. The point is, feelings are a state of mind, so they wont come from the boat they will come from within. If you want to paddle without alot of effort, then you will need alot of effort to learn to paddle effortlessly. kind of a paradox, but thats life.... Look at any pro athlete, it always looks easy... but you can bet that it wasnt easy to learn how to make it look that way.


OK, so If you want a custom canoe to feed your ego, Johnny here is the man to do it. If you want euphoria and great skill set, buy a canoe off the shelf and spend the money on lessons and free time on the river. If you want to keep everyone entertained than keep posting impossible requests, they are fun to read. Cheers..



End of rant, Peace 8)

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 Post subject:
PostPosted: July 28th, 2005, 10:55 pm 
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Posts: 841
Location: Bay Village, Ohio
Dan. wrote:
WHAT?????? :-?

You want a ride that
- looks nice
-paddles without a great deal of effort
- turns without alot of effort
- goes straight without alot of effort.



Sounds like you need an old Grumman with a newly buffed hull. The second and third points might not apply, but they do go straight, and they have sort of an Airstream camper-trailer aesthetic appeal.

Steve


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 Post subject:
PostPosted: July 28th, 2005, 11:04 pm 
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Location: Vancouver, British Columbia Canada
Maybe what's interesting about this topic is how it very nicely shows how an artist/architect would approach designing a canoe. Not many of us into our various headspaces could do such a competent and entertaining job of that.

My own "inarticulated" approach to gear is that I want about 90% of what would be "perfect" for me, and getting out and using it is more important than the other 10% any day. As it turns out, people swoon over our canoe.

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 Post subject:
PostPosted: July 29th, 2005, 6:20 am 
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pake wrote:

Quote:
talked about an installed 'bow bubbler' on an icebreaker to reduce ice friction, soooo, maybe that request for Viking bubbles under the boat are doable, and practical.


Note the important point that the bubbles are supposed to reduce friction between the boat and ice. Ice, of course, is not a fluid.

Why won't bubbles work on boats?

Friction retards the flow of water across the hull’s surface but not in the same fashion as friction between solids. Instead of water sliding across the hull surface, one layer of molecules attaches to the hull and successive layers of molecules slide across each other until, at some distance from the hull, the boat’s passage no longer has an effect. Friction between molecules drains away energy from the moving boat not friction between the hull surface and water molecules.

We call the region in which the friction loses occurs the boundary layer. Its thickness, and accordingly the drag, depends upon the surface finish, length, and the velocity. The boundary layer starts out relatively thin with laminar flow (flow in uniform layers traveling more or less parallel to each other). In this state the energy loss is relatively low. In theory laminar flow can exist over the full hull length but not in practice. Constantly changing pressures due to wave action and boat motions create turbulence under all but the most carefully controlled conditions and the boundary layer normally becomes turbulent within the first two or three feet . The transition point between laminar and turbulent flow moves back and forth depending upon conditions but generally moves forward with increased velocity.

Builders have often tried to capitalize on the buying public’s ignorance. One manufacturer tweaked public credulity by claiming that fine whiskers on its polyethylene kayaks reduced resistance – a claim they could not support. The claim also conveniently ignored that the whiskers may have resulted from an improperly made porous mould. Another claimed that the shape of its bow maintained laminar flow longer than others but could provide no proof nor could they explain why other boats with the same configuration could not make the same claim. In this way does advertising make a silk purse of a sow’s ear.

We must also look askance at claims for friction reducing treatments and coatings. Independent testing has shown that some coatings actually increased resistance by allowing bubbles to adhere to the surface which made it rougher. One method that does work utilizes a soft pliable rubber skin that mimics the skin of dolphins. By damping pressure changes this skin prolongs laminar flow. Unfortunately the outrageous cost, weight and lack of durability make it impractical. Another method uses long-chain polymers that reduce the local water viscosity. Unfortunately they dissolve quickly and require constant replenishment. Given the amount required, the increased weight of polymers carried more than offsets any benefits. That and the environmental aspect of leaving a trail of synthetics in the water exclude long chain polymers from serious consideration. A more recent development called structuring utilizes microscopic grooves to reduce the total area in contact with the flow in the boundary layer. Unfortunately the grooves must align precisely with the flow and have precise depths making structuring impractical were the flow varies in direction and velocity over a wide range.

Bubbles can actually increase friction where they adhere to the surface forcing the water to flow around them like little barnacles.

As most wil recall S used the Viking ships as an example of boats that used this principle. Regrettably the clinker construction of Viking shps actually increased resistance in two way - first by increasing the wetted surface and second by introducing edges out of alignment with the flow increasing form resistance. Bubbles also get trapped along the plank joints which aggravates the problem.

If you wll recall S did not like long fish with bad teeth. Bet she wouldn't like a big ugly, smelly Viking with bad teeth either. :D

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 Post subject:
PostPosted: July 29th, 2005, 6:32 am 
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Posts: 36
Not to hijack the thread, but doesn't the Navy use some sort of orange-peel type finish on their subs? I think it's to achieve an effect like a golf ball with all the dimples?


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