Canterbury J General Discussion - Page 71 - RC Groups
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Sep 06, 2017, 01:38 AM
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Maybe ... I might be wrong and someone needs to do the math / geometry ... but consider the following attempt to explain ...

Think of the king plank (ctr line) and related deck planking as an oval / ellipse ... where the minor narrow points of oval / ellipse are aligned with the bow / stern of the yacht.

BUT ACTUALLY ... the king plank is NOT ALIGNED ON THE CTR LINE of the oval / ellipse ... instead the king plank ctr line is OFFSET & PARALLEL ... like a chord line ... making the Starboard / Port deck planks as mirror image about this offset chord line.

At the same time ... each deck plank intersecting the king plank has the SAME WIDTH ... and ... as these equal width deck planks - starting from outer deck perimeter and planking toward king plank ctr line ...

Thus, the intersection of constant equal width planks converge at the intersection with the king plank ... end up having SLIGHTLY DIFFERNT ANGLE ... because to fit within the BOUNDARY RESTRICTED by king plank and outer perimeter of deck WITH CONSTANT EQUAL WIDTH DECK PLANKS ... results in these SLIGHT ANGLE CHANGES AT THE KING PLANK INTERSECTION (ends) in order to fit within the defined boaundaries of the king plank and outer perimeter deck outline.

NOTE: Maybe the existing assumption is misleading everyone astray - like where I also started ... That EQUAL WIDTH DECK PLANKS should intersect king plank with SAME ANGLE due to constant equal width deck planks ... kind of like - thinking of the deck planks as concentric equal width circles intersecting ctr line of circle (i.e. Diameter) ... BUT LIKE I NOTED and described above - the deck planks ARE NOT CONCENTRIC CIRCLES ABOUT CTR LINE ... INSTEAD - the equal width deck planks intersect a CHORD LINE THAT IS OFFSET & PARALLEL to the CIRCLE CTR LINE (i.e. Diameter)

See for yourself by simple drawing ...
circle with ctr line diameter line 12 / 6 o'clock - with equally spaced concentric circles ... THEN add a "Chord line" offset and parallel to a diameter ctr line ... you will see the intersection of the equal concentric circles WITH THE CHORD LINE ... each have a SLIGHTLY DIFFERENT ANGLE of interaction with the Chord Line that you do NOT SEE with the diameter ctr line ... the intersection angle with the chord line becomes more shallow when you do the same BUT USING AN OVAL / ELLIPSE

maybe this explains things ... BUT ... I could be completely wrong ???
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Sep 06, 2017, 07:35 AM
Modeler/ Historian
Stephen Vick's Avatar
Yes. What he said.... LOL! Math is not my strong suit, my degree is in history, and historically it goes something like that....
Sep 06, 2017, 12:57 PM
Registered User
All I gotta say is I typed that out on my phone last night while sitting in the ER on an IV being pumped full of drugs. I thought it was a pretty good explanation, considering!
Sep 07, 2017, 06:47 AM
Registered User
Wow! That made my head hurt. But I think you're on the right track. Here's some of my thought on it.

The planks are indeed parallel to each other. The thing that changes everything is the fact that the planks are curved and the King is straight. Because at some point, near the middle of the deck, the planks AND the King have a point where they are ALL parallel to each other. And the angle of intersection has been effectively reduced to zero. For an instant so to speak.

This angle changes because the angle of the outermost plank, relative to the King, changes as it goes around the edge of the hull. The trick is explaining it!

And I aced Geometry......................................some 49 years ago.
Sep 07, 2017, 10:41 AM
Modeler/ Historian
Stephen Vick's Avatar
My experience has been that: if I properly taper the planks, line them up tight, and ensure both sides were even, that the nibbling would come out about right. As I said, math/geometry is not my strong suit, but, I do have a practiced eye.
Sep 10, 2017, 11:26 AM
Modeler/ Historian
Stephen Vick's Avatar
I will be planking my wishbone schooner soon. I will follow the same technique I used on my CJ. This will be my second time using this method, we'll see if I've improved! Following the Schooner re-fit, I plan a second CJ. Anyway, for any interested, I have a build log running on the schooner, and I will thoroughly document the planking.
Sep 10, 2017, 12:37 PM
Registered User
Hey Stephen

Will you post LINK here where your build blog is located ... since did not see build blog under your forum bio page ??

Interested to follow along (when I have time to view the progress and reference in future)
Sep 10, 2017, 08:29 PM
Modeler/ Historian
Stephen Vick's Avatar

Here's the build log link....not a blog. I don't blog.
Sep 11, 2017, 12:52 AM
Registered User
Me either ... thanks for the link ...
Will be watching and keeping up with good ideas for future reference ...

Good luck
Nov 05, 2017, 11:14 PM
Modeler/ Historian
Stephen Vick's Avatar
I swapped my Dacron sails for Mylar as an experiment. Thanks again Rod Carr for his amazing turn around time. I like the look and performed flawlessly.
Nov 05, 2017, 11:27 PM
Kevin Gault
poltergeist's Avatar
Looking good Stephen. Very racy!!!

Nov 06, 2017, 08:42 AM
Modeler/ Historian
Stephen Vick's Avatar
Thanks Kevin, I was sailing with a fellow modeler, who had a beautiful live steam launch.... He wants to build a CJ!
Nov 06, 2017, 08:44 AM
Registered User
Ed Crowell's Avatar
Those are nice sails and it looks like you have them adjusted correctly.

Nice looking "CJ"
Nov 06, 2017, 08:55 AM
Modeler/ Historian
Stephen Vick's Avatar
Thanks Ed, I've had a lot of practice lately, going to the river almost every weekend. Perhaps, if Carl builds a CJ, we can have some side by side tuning.
Nov 07, 2017, 10:59 PM
Modeler/ Historian
Stephen Vick's Avatar
There is another CJ coming to San Angelo TX! Hoo Yah!

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