Table of Offsets Chestnut Prospector

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Rehd Brown
Posts: 148
Joined: Sat Sep 08, 2007 8:23 pm
Location: Fresno, California

Table of Offsets Chestnut Prospector

Post by Rehd Brown » Sat Nov 05, 2016 1:11 am

Hi Brian or Jim or ..?
I am curious about some of the numbers in the Prospectors offsets.
Table B.. at east station, the last number down has another number followed by "and Up". The numbers, whether lower or higher than the station # matches the sheer line from Table A. I'm not sure what the "and Up" designates. In some cases, it's higher than the station # but in others, it's lower than the station #.
Any clarification would be appreciated.


Rehd

Rehd Brown
Posts: 148
Joined: Sat Sep 08, 2007 8:23 pm
Location: Fresno, California

Re: Table of Offsets Chestnut Prospector

Post by Rehd Brown » Sat Nov 05, 2016 1:14 am

Sorry, that should read "Table B.. at EACH station"

Rehd

Stephen
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Joined: Fri Apr 18, 2014 12:36 am
Location: Eastern Ontario

Re: Table of Offsets Chestnut Prospector

Post by Stephen » Sat Nov 05, 2016 6:07 am

Are these offsets from the newest edition of Canoecraft? I have the 1983 edition and the 2000 edition and I'm not seeing the numbers you're referring to. Something in the back of my brain says this was done in later editions between '83 and 2000.

Anyway, I found a really old Glen Smith post that may or may not answer your question. viewtopic.php?f=1&t=1610

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Cruiser
Posts: 609
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Location: Bowmanville, Ontario

Re: Table of Offsets Chestnut Prospector

Post by Cruiser » Sat Nov 05, 2016 8:58 am

I think Stephen has posted the answer ( we are lucky to have him mine the site for answers). Just in case you want more info, I actually lofted and did the molds, from the Canoe Craft tables, for the Freedom 17 I just completed.

I posted a complete description of what I learned here:

viewtopic.php?f=9&t=4658

There may be something of use there as well.


Brian

Rehd Brown
Posts: 148
Joined: Sat Sep 08, 2007 8:23 pm
Location: Fresno, California

Re: Table of Offsets Chestnut Prospector

Post by Rehd Brown » Sat Nov 05, 2016 12:07 pm

Stephen & Brian

This copy of Canoecraft is 1997 vintage.
Chart B - Station 0, at 16" from baseline, the distance out reads 16 3/4" (14 7/8" up) and Station 7 - at 24" from baseline, the distance out reads 2 3/8" (22 5/8" up)
The 14 7/8" & 22 5/8" figures match the sheer line numbers taken from Chart A at those stations.
I'm not sure what that indicates and what the 'up' means.

I have not checked those possible answers you have given me, so I'll do that now and Thanks for your responses.


Rehd

Stephen
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Joined: Fri Apr 18, 2014 12:36 am
Location: Eastern Ontario

Re: Table of Offsets Chestnut Prospector

Post by Stephen » Sat Nov 05, 2016 10:59 pm

Brian's link is a welcome explanation of a topic a lot of people seem to struggle with, however, since what you have is a reprint of the original edition, a lot of the terminology will be unfamiliar. Brian is working from a post-2000 edition.

In the original edition, Ted invented his own modified table of offsets which did not follow standard boat-building nomenclature. Beginning in 2000, he changed to the standard method. Chart A became Table of Heights and Chart B became Table of Half-Breadths. The numbers in the table were written differently and the baseline was moved from below the keel to above the canoe.

BTW I am embarrassed that it's taken me a couple of years to figure out why you post using red and brown text :)

Rehd Brown
Posts: 148
Joined: Sat Sep 08, 2007 8:23 pm
Location: Fresno, California

Re: Table of Offsets Chestnut Prospector

Post by Rehd Brown » Sat Nov 05, 2016 11:48 pm

I always simplified it even further. One chart has the form crossing the horizontal lines and the other has the form crossing the vertical lines. When there are long areas where the form doesn't touch one set, you just don't get enough information to get a fair curve. I also noticed that Brians description calls for the +/- to indicate 1/8". Whereas my book indicates 1/32" for the +/-. :thinking

You are the first that's ever mentioned my colorful name. Don't know that anyone ever really thought about it, but certainly nobody mentioned it. :applause


Rehd :cool

Stephen
Posts: 61
Joined: Fri Apr 18, 2014 12:36 am
Location: Eastern Ontario

Re: Table of Offsets Chestnut Prospector

Post by Stephen » Sun Nov 06, 2016 12:38 am

I also noticed that Brians description calls for the +/- to indicate 1/8". Whereas my book indicates 1/32" for the +/-.
This is another thing that changed in 2000. Before then, +/- did indeed mean 1/32". Since then + has meant 1/16" (- is no longer used at all)

phmiller
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Joined: Mon Sep 12, 2011 2:41 am

Re: Table of Offsets Chestnut Prospector

Post by phmiller » Sun Feb 12, 2017 10:58 pm

You guys are lucky that inches and their fractions are still standard in North America. Quite a few years ago I wrestled with these unfamiliar measurements. In New Zealand where I live metrics have been standard for a long time. My sons couldn't believe why I would struggle with an old ruler to work out the tables of off sets. These days I convert straight to metrics ! Patrick.

Rehd Brown
Posts: 148
Joined: Sat Sep 08, 2007 8:23 pm
Location: Fresno, California

Re: Table of Offsets Chestnut Prospector

Post by Rehd Brown » Mon Feb 13, 2017 2:24 am

On that same note, my father once built a home-built aircraft called "Piel Emeroud" or something of that nature. French Canadian design, I believe. All Metrics... He used to figit and fuss with calculators and things trying to figure it out. Took a lot of Aspirin in those days..!! :laughing
After playing with it a while, I believe he came to appreciate it. :thinking
More and more we are converting to metrics, mostly because of all the cars, tools and so on being imported from other countries. To be a mechanic or just any type of repair person, you absolutely HAVE to own two complete sets of tools. Many American cars now have parts using both systems. Now that's a real pain in the butt.!! Lots of people resist it, but, some time in the near future I believe we will be using the metric system exclusively here as well.

Rehd

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