Re: Question?

[Rick Lucertini <empiricus@sprint.ca>]

> [snip]

> Here's
> >what I was thinking, design a wood hull and then encase the wood
> (inside
> >and out) with several layers of fibreglass.

> I can just feel the tension building as I type this, but I believe that
> wood and fiberglass would work just fine as long as you design for its
> limitations and keep SAFETY the #1 priority. Remember that the first sub
> "the Turtle" was made of wood.

> OK, lets have it.
>
> Scott Shakespeare

Hi, All - Scott's got a point.  Every material's got its window of usability - wood and f/g included.
To wit: there was a wooden sub built out of rings of thick ply, the thickness determining, in effect,
a station or section of the boat.  The rings were laminated to each other along the longitudinal axis,
forming the shape of the hull.  It was a one atm. boat.

The thickness of the hull, and therefore, the pressure resistance, was derived simply by cutting the
plywood rings with an ID (inside diameter) of one diameter, say 4 ft., and the OD (outside diameter)
of 4 1/2 ft.  The difference, the thickness of the hull, is 6 inches.  This is an excellent low-tech,
low-skill way of getting a pressure hull without resorting to fancy welding or what have you. Again,
as we all point out, safety is the main issue.  Fortunately, as in DIY house builders, boat builders
tend to err much more on the conservative side.  Probably out of sheer paranoia - healthy in this
case.

The beauty of this method is that hull thickness and shape can be varied using very simple carpentry
skills and tools.  Paranoid?  Hey, just cut your sheet ply with wider doughnuts!

Another thought: the sections can be joined not only with epoxy, but, by through bolting with ready
rod, as well.  Compressing the sections along the longitudinal axis would, I imagine, strengthen the
hull enormously.

Again, a simple technique to incorporate.  Seal the thing with epoxy and fibreglass to keep water away
from the edges of the ply and Bob's your uncle.

>From an aesthetic standpoint, think of the graceful, organic and, hence, hydrodynamic, curves you can
build in using this technique.

Another practical note: whenever there are through hull fittings, hulls have to built up to avoid
stress points at the fitting.  Think of how simple it would be to merely cut the extra thickness on
your band saw.

                                           |
                                  '        |         '
                     '                   ..|...                  '
            '                '             |              '                '
       '         '                         |                         '           '
SECTION "x" , looking aft
    '     '                             C/L                              '        '
  '     '                                  |                                   '       '
 '     '                                   |                                     '       '
'     '                                    |                                      '       '
      [<---------------------  4'0" ----------------------->[ 6" ]<---
[<-------------------------  5'0" ref.------------------------>]
                                           |
                                           |
                                           |


Hey, I think I've talked myself into using this building method!
---------------------------------

Rick Lucertini
in Vancouver, Canada
empiricus@sprint.ca

"To a rational being it is the same thing to act according to nature and according to reason."

    Marcus Aurelius Antoninus, 121 - 180 a.d.