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Re: Material: alu-tube rigidity
By:Yostwerks
Date: 11/15/2012, 11:06 am
In Response To: Material: alu-tube rigidity (CarstenT)

: Hi All
: After visiting the yostwerks pages on building a folding-kayak I
: decided to build my own. As it is, I'm usually not following the
: prescription on anything, and so too as to a transportable
: kayak.

That's your first mistake :)

: but today I got 4 of the 5m alu-keel
: up and hanging in strings attached to each end. This setup does
: not reflect how it will respond in water, but .. gee, it's SOFT.
: Awful soft. My instinct tells me that it's too soft to act as
: the central and only 'rigid' structure to 'hang' everything else
: up on.

That's your second mistake.

Since 6061 and 6063 aluminum tubing used in kayak building have a tensile strength of about 40,000 psi , I assume that by "soft" you mean flexing
along it's length, and most of the flex you encountered has to do with the insert connections between the 4 tubes. In actual usage, the aluminum
tubes are under stress, thereby negating the "softness" you describe. Add in a minimum of 6 full length stringers, tightly snap connected to
several HDPE cross sections, hard stem connections, and a tight skin, and you have the basis of the boat's unique strength / rigidity / durability.

Your "string" experiment has no basis in reality. What could 4 aluminum tubes sections suspended with strings possibly have to do with anything ?
A folding kayak's strength and rigidity is the sum of all it's parts, not a single tube hanging from strings.

Feathercraft, the leading manufacturer of high end aluminum stringer folding kayaks uses 3/4" thin wall tubing on most of it's folders, and on some they use
5/8" tubing. These boats have a legendary reputation for strength and durability. There's a reason why Feathercraft uses 3/4" thin wall tubing. Can you guess why ?

Tom

Messages In This Thread

Material: alu-tube rigidity
CarstenT -- 11/14/2012, 3:26 pm
Re: Material: alu-tube rigidity
Marc Upchurch -- 11/14/2012, 6:55 pm
Re: Material: alu-tube rigidity
ancient kayaker -- 11/15/2012, 12:06 am
Re: Material: alu-tube rigidity
Bill Hamm -- 11/15/2012, 2:03 am
Re: Material: alu-tube rigidity
Brian Nystrom -- 11/15/2012, 7:18 am
Re: Material: alu-tube rigidity
Bill Hamm -- 11/16/2012, 10:22 am
Re: Material: alu-tube rigidity
Brian Nystrom -- 11/16/2012, 12:31 pm
Re: Material: alu-tube rigidity
CarstenT -- 11/16/2012, 5:32 pm
Re: Material: alu-tube rigidity
Marc Upchurch -- 11/16/2012, 9:22 pm
Re: Material: alu-tube rigidity
Bill Hamm -- 11/17/2012, 1:39 pm
Re: Material: alu-tube rigidity
Marc Upchurch -- 11/17/2012, 3:53 pm
Re: Material: alu-tube rigidity
Bill Hamm -- 11/18/2012, 12:35 am
Re: Material: alu-tube rigidity
Marc Upchurch -- 11/18/2012, 9:40 am
Re: Material: alu-tube rigidity
Bill Hamm -- 11/19/2012, 1:16 am
Re: Material: alu-tube rigidity
Mike Savage -- 11/17/2012, 3:54 pm
Re: Material: alu-tube rigidity
Marc Upchurch -- 11/17/2012, 7:07 pm
Re: Material: alu-tube rigidity
Bill Hamm -- 11/18/2012, 12:38 am
Re: Material: alu-tube rigidity
Mike Savage -- 11/18/2012, 12:42 pm
Re: Material: alu-tube rigidity
Yostwerks -- 11/15/2012, 11:06 am
Re: Material: alu-tube rigidity
CarstenT -- 11/15/2012, 12:22 pm
Re: Material: alu-tube rigidity
Yostwerks -- 11/15/2012, 1:42 pm
Re: Material: alu-tube rigidity *PIC*
Yostwerks -- 11/15/2012, 2:02 pm
Re: Material: alu-tube rigidity
CarstenT -- 11/15/2012, 3:04 pm
Re: Material: alu-tube rigidity
Bill Hamm -- 11/16/2012, 10:26 am
Re: Material: alu-tube rigidity
Jeff Buyer -- 11/15/2012, 11:11 am
Re: Material: alu-tube rigidity
CarstenT -- 11/15/2012, 12:51 pm
Re: Material: alu-tube rigidity
Bill Hamm -- 11/16/2012, 10:32 am
Re: Material: alu-tube rigidity
CarstenT -- 11/16/2012, 5:53 pm
Re: Material: alu-tube rigidity
Bill Hamm -- 11/17/2012, 1:42 pm
Re: Material: alu-tube rigidity
Bill Hamm -- 11/16/2012, 10:29 am
Re: Material: alu-tube rigidity
Jeff Buyer -- 11/16/2012, 11:21 am
Re: Material: alu-tube rigidity
Bill Hamm -- 11/17/2012, 1:44 pm
Re: Material: alu-tube rigidity
Jeff Buyer -- 11/17/2012, 3:53 pm
Re: Material: alu-tube rigidity
Bill Hamm -- 11/18/2012, 1:45 am
Re: Material: alu-tube rigidity
Jeff Buyer -- 11/18/2012, 1:56 pm
Re: Material: alu-tube rigidity
Bill Hamm -- 11/19/2012, 1:19 am
Re: Material: alu-tube rigidity
CarstenT -- 11/16/2012, 6:53 pm
Re: Material: alu-tube rigidity
Marc Upchurch -- 11/16/2012, 9:29 pm
Re: Material: alu-tube rigidity
CarstenT -- 11/17/2012, 5:30 am
Re: Material: alu-tube rigidity
Yostwerks -- 11/17/2012, 10:40 am
Re: Material: alu-tube rigidity
Bill Hamm -- 11/17/2012, 1:47 pm
Re: Material: alu-tube rigidity
Jeff Buyer -- 11/17/2012, 4:07 pm
Re: Material: alu-tube rigidity
CarstenT -- 11/17/2012, 4:34 pm
Re: Material: alu-tube rigidity
Jeff Buyer -- 11/17/2012, 5:40 pm
Re: Material: alu-tube rigidity
Bill Hamm -- 11/18/2012, 1:50 am
Re: Material: alu-tube rigidity
Jeff Buyer -- 11/18/2012, 2:10 pm
Re: Material: alu-tube rigidity
Bill Hamm -- 11/19/2012, 1:22 am
Re: Material: alu-tube rigidity
Bill Hamm -- 11/18/2012, 1:51 am
Re: Material: alu-tube rigidity
Jeff Buyer -- 11/18/2012, 2:07 pm
Re: Material: alu-tube rigidity
Bill Hamm -- 11/19/2012, 1:25 am
Re: Material: alu-tube rigidity *PIC*
Yostwerks -- 11/19/2012, 10:14 am
Re: Material: alu-tube rigidity
CarstenT -- 11/18/2012, 4:31 am
Electrolysis
CarstenT -- 6/2/2013, 6:39 am
Re: Electrolysis
Jeff Buyer -- 6/2/2013, 7:39 am
Re: Electrolysis
CarstenT -- 6/2/2013, 9:46 am
Re: Electrolysis
Tom Cooper -- 6/2/2013, 10:35 am
Re: Electrolysis
CarstenT -- 6/2/2013, 12:57 pm
Clogged up hinges. Solution
CarstenT -- 6/26/2013, 4:43 am
Re: Material: alu-tube rigidity
JohnAbercrombie -- 11/18/2012, 3:03 pm
Re: Material: alu-tube rigidity
Bill Hamm -- 11/19/2012, 1:33 am
Re: Material: alu-tube rigidity
Yostwerks -- 11/19/2012, 9:48 am
Re: Material: alu-tube rigidity
CarstenT -- 10/17/2014, 5:31 am
Re: Material: alu-tube rigidity
Bill Hamm -- 10/17/2014, 9:56 am
Re: Material: alu-tube rigidity
CarstenT -- 10/18/2014, 6:00 am