From: Todd Schlemmer <toddsch@microsoft.com>
To: "'Bill Blohm'" <bblohm@boi.hp.com>
Subject: RE: FW: Laminated ribs, etc..
Date: Fri, 30 May 1997 12:35:49 -0700
I don't question the wisdom of building with wood (so far, I've only
build wood-frame kayaks, and wooden boats), only building a boat in wood
by a method created for entirely different materials. I would never
say it can't be done, but I am a conservative boatbuilder.
I don't think the ribs are as big a concern as the unsupported (2+ feet
in Dyson's design) longitudinals between them. The ribs will form a
reletively sturdy arch, but the span of longitudinal between ribs could
flex catastrophically. You could laminate the longitudinals, even
incorporating some neat stuff like multiple plys of carbon fiber, but
then you spend more time and money.
<snip:>
> An idea I wanna try some time is using marine ply for framing with
> aluminum tubing for longitudinals (wait a minute - that's a Folbot!)
Haven't seen one, so what's the plywood ribs look like? My guess
would be that they're more like bulkheads with small holes cut
out in the middle to cut down on weight?
<end snip>
That's exactly what they look like. Except the new ones have some kind
of reinforced molded plastic ribs/bulkheads - and they're fastened with
screws to the longitudinals.
I hope it works.
> -----Original Message-----
> From: Bill Blohm [SMTP:bblohm@boi.hp.com]
> Sent: Friday, May 30, 1997 11:45 AM
> To: Todd Schlemmer
> Cc: 'baidarka@lists.intelenet.net'
> Subject: Re: FW: Laminated ribs, etc..
>
> > If you try to duplicate the construction of Dyson's aluminum
> baidarkas
> > in WOOD, I predict dire results.
>
> I dunno about the dire results. :-) Others have built them with
> wooden frames, or so I've gathered from this list. None, though,
> have mentioned laminating them. Besides, the original Aleut designs
> were made of wood and animal skins.
>
> > Aluminum has mechanical properties that lend itself to widely spaced
> > framed constuction. Your laminated longitudinals will need to
> duplicate
> > the rigidity of the aluminum tubing, with a huge weight (and size?)
> > penalty. Many ribs are necessary for wood longitudinals. You then
> > control the lines of the boat by providing adequately support.
> Exotic
> > lamination schemes for longitudinals / framing is no substitute for
> the
> > aluminum tubing called for by the construction methods. A better
> idea
> > would be to use the lines of Dyson's design (with permission - see
> > previous thread), with traditional construction and framing.
>
> This is exactly what I am wondering about. I *think* that while
> the ribs might lack stiffness in a stand-alone situation before
> assembling, I can't help but wonder if the entire assemblage
> with the longitudals in place might be quite stiff enough. Recall
> also that laminations are typically stronger than an equivalent
> piece of wood. I may well be wrong, but I believe others have
> built a Dyson with the same rib and longitudal placement as that
> called for in the plans, only using wood (solid). From what I
> recall of the e-mails referring to this, I think the sizes weren't
> that much greater than the Al framing sizes. The weight was a
> somewhat greater, but not detrimental. I'll have to see if I
> can find that e-mail in my files and re-read it.
>
> > An idea I wanna try some time is using marine ply for framing with
> > aluminum tubing for longitudinals (wait a minute - that's a Folbot!)
>
> Haven't seen one, so what's the plywood ribs look like? My guess
> would be that they're more like bulkheads with small holes cut
> out in the middle to cut down on weight?
>
> Bill B.