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From: 735769 <735769_at_ican.net>
subject: Re: [Paddlewise] RE:: Boat Strength and Weight
Date: Thu, 12 Oct 2000 08:48:01 -0400
Nick wrote;

>
> The reason I ask is I am working with a grad student who is looking
> to do some testing on this subject. We are currently discussing the
> conditions to investigate. He wants to find out how strong the
> materials need to be, to be "strong enough".
>

A challenging project, Nick. Just getting past the "strong enough" part
would challenge Solomon. (Nick already knows this and I mention it only to
suggest that he has probably already given this a lot of thought).

For example, any boat that survives to die of old age would qualify as
"strong enough" but we might consider any boat that fails "not strong
enough".

At a local outfitters they have two canoes. One has served for over five
years in their rental fleet. They estimate that their average rental canoe
gets over 100 days of use every year by all types of paddlers, for better or
worse. They now have it for sale and it will make someone a very nice,
inexpensive canoe for many more years of use. The other boat will get sent
to the dump after only a few weeks of use. The boats are identical in model
and construction.

Strong enough or too weak?

People explored Canada in birchbark and wood canoes long before we had SAR
but today anyone not using a poly, aluminum or Royalex canoe runs the risk
of getting labeled as "stupid" or "irresponsible" or worse.

Maybe we need a study of whether paddlers are strong enough mentally to stay
out of trouble. If they pass they can use any damned thing they like. The
rest have to stay home and watch extreme sport on TV. :-)

Cheers,

John Winters


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From: Nick Schade <schade_at_guillemot-kayaks.com>
subject: Re: [Paddlewise] RE:: Boat Strength and Weight
Date: Thu, 12 Oct 2000 10:11:40 -0400
At 8:48 AM -0400 10/12/00, 735769 wrote:
>Nick wrote;
>
>>
>>  The reason I ask is I am working with a grad student who is looking
>>  to do some testing on this subject. We are currently discussing the
>>  conditions to investigate. He wants to find out how strong the
>>  materials need to be, to be "strong enough".
>>
>
>A challenging project, Nick. Just getting past the "strong enough" part
>would challenge Solomon. (Nick already knows this and I mention it only to
>suggest that he has probably already given this a lot of thought).

Yes, it is a tough nut. The typical method in boat design is 
scantling rules which are based on past experience. A boat builder 
builds a boat for years using a certain amount of material and a 
certain method and gets reports back on how the boats holds up over 
the years and where there are problems. If something fails a lot the 
builder beefs it up, if it never breaks, he might slim it down a bit. 
If he decides to change materials or method he tries to make the new 
system as strong as the old system.

Unfortunately, this system does not strike everyone as scientific 
enough. The grad student (Sam Mcfadden) wants to put some strain 
gages on a boat and go paddling. I think we might learn something 
interesting. Will he learn how strong is "strong enough". At best, 
only what is strong enough for the conditions he paddled in. But that 
might be interesting. He will also see where the stresses are in the 
boat. And we might be able to draw conclusion about other conditions 
by extension.

One of the reasons I would like to hear stories of broken boats, how 
they broke and how they were built is to get more data for the less 
"scientific" method of actual experience. Some of the best science 
started with anecdotal information.

Nick
-- 


Nick Schade
Guillemot Kayaks
824 Thompson St, Suite I
Glastonbury, CT 06033
(860) 659-8847

Schade_at_guillemot-kayaks.com
http://www.guillemot-kayaks.com/

>>>>"It's not just Art, It's a Craft!"<<<<
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From: Larry Bliven <foxhill_at_shore.intercom.net>
subject: Re: [Paddlewise] RE:: Boat Strength and Weight
Date: Thu, 12 Oct 2000 12:13:29 -0400
Nick wrote:
>The grad student (Sam Mcfadden) wants to put some strain
> gages on a boat and go paddling. I


WoW, your students name made me go check names at NOAA Pacific Marine Lab
because
Michael James McPhaden
http://www.pmel.noaa.gov/toga-tao/mmcv.html
is known as the *Mother* of El Nino in the US.

i found out that it seems Sam ain't related to Mike.


> think we might learn something
> interesting. Will he learn how strong is "strong enough". At best,
> only what is strong enough for the conditions he paddled in. But that
> might be interesting. He will also see where the stresses are in the
> boat. And we might be able to draw conclusion about other conditions
> by extension.
>

sounds like a fun project, let us know how it develops.

bye bye bliven

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From: Wes Boyd <boydwe_at_dmci.net>
subject: [Paddlewise] PFD conviction
Date: Thu, 12 Oct 2000 12:54:24
There might be those interested in the story of a guy convicted for taking
the PFD from a drowning 7 year old girl:

http://dailynews.yahoo.com/h/nm/20001012/od/lifejacket_dc_1.html


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From: Bob Denton <BDenton_at_aquagulf.com>
subject: RE: [Paddlewise] PFD conviction
Date: Thu, 12 Oct 2000 12:57:55 -0400
The 7 year old wasn't drowning UNTIL he took the PFD!

-

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From: Michael Daly <michaeldaly_at_home.com>
subject: Re: [Paddlewise] RE:: Boat Strength and Weight
Date: Thu, 12 Oct 2000 20:48:16 -0400
From: "Nick Schade" <schade_at_guillemot-kayaks.com>

> Unfortunately, this system does not strike everyone as scientific 
> enough. The grad student (Sam Mcfadden) wants to put some strain 
> gages on a boat and go paddling. I think we might learn something 
> interesting. Will he learn how strong is "strong enough". At best, 
> only what is strong enough for the conditions he paddled in. But that 
> might be interesting. He will also see where the stresses are in the 
> boat. And we might be able to draw conclusion about other conditions 
> by extension.

When in university, studying structural engineering, I thought a lot 
about optimizing to the hilt.  Then I learned that the structure in 
a building represents about 20% of the total cost.  Saving 10% on
the structure saves 2% on the building - less than the margin for
cost overruns due to...  Plus you expose yourself to extra lawsuits
for adding risk.  I gave up the idea.

Optimizing a kayak is nothing compared to the several hundred pounds 
a fully loaded touring kayak weighs. Racers, of course, have other 
objectives.

It's also interesting that some say "this kayak is weak - it flexes
too much!" while others say "My skin-on-frame is flexible - that's 
why it's strong!"

Mike.

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