Re: doubling ply bottoms

For the bottom of my AS29 (two layers 1/2' ply) I didn't use screws at all
. Only bolts through the chinelogs as designed. I applied pressure using
some scantlings as braces between shop roof and ply sheet. A brace or two
under the bottom was needed too in some places. Some wedges were usefull.
Drilling some pilot holes (to let out air and epoxy to make sure you have
no bubbles) is definitely a good idea.
I did the whole planking job singelhanded, but I would strongly advise
against it! 45° bevels on two sides of the ply sheets (to have some kinda
mini scarf) did help with alignement. You can put(plug?) the next sheet
under the edge of the last one. Use slow hardener ...

Leo

tom,
Even with the 1/2" thickness and a layer of cloth my bottom is
still flexing. That is why I am adding the side battens on the
bottom. It did stiffen up when I attached the keel batten.
I used drywall screws every 4" staggered through out and started
at the middle and worked my way out to the sides only 1 panel a day.
It came out ok but added a lot of extra work. Filling and sanding
all
of those screw holes was very tedious, boring work.

Good luck,
David Jost

--- Inbolger@egroups.com, "Tom Etherington" <tetherin@j...> wrote:
> I made my bottom of one layer 1/4 inch and one layewr 3/8 inch. I
> used the drywall screw method to clamp the layers together. I used
> one screw about every foot of bottom, plus screws about 4 inches
> apart along the edges of each sheet to make a tight joint. I know
> there is at least one spot where the sheets did not meet perfectly
> and so I have an air pocket, but it should never get wet. Later I
> may cut into it and fill it up with epoxy.
>
> The bottom doesn't flex when I walk on it with the boat upside down.
>
>
> --- Inbolger@egroups.com, "Derek Waters" <dgw@d...> wrote:
> > Hi Group
> >
> > How have members clamped and glued double skinned ply bottoms?

I made my bottom of one layer 1/4 inch and one layewr 3/8 inch. I
used the drywall screw method to clamp the layers together. I used
one screw about every foot of bottom, plus screws about 4 inches
apart along the edges of each sheet to make a tight joint. I know
there is at least one spot where the sheets did not meet perfectly
and so I have an air pocket, but it should never get wet. Later I
may cut into it and fill it up with epoxy.

The bottom doesn't flex when I walk on it with the boat upside down.

--- Inbolger@egroups.com, "Derek Waters" <dgw@d...> wrote:
> Hi Group
>
> How have members clamped and glued double skinned ply bottoms?

I just finished the bottom of my Micro using 1/4" doubled marine ply.
I used sheetrock screws and epoxy. Starting at the center and only
doing one section at a time. There are no visible voids between the
two layers.
If I were to do this again (I am not!) I would use a single layer
of ply the correct thickness to begin with. Patience, time, and a
little water in the correct location will help it bend quite a bit
prior to fastening if the bend is too extreme for the extra
thickness.
How thick are we talking here?

David Jost " celebrating the installation of the keel batten and
skids"

>
> How have members clamped and glued double skinned ply bottoms? At

present I'm leaning towards using the drywall screw clamping method
for the first layer, and vacuum bagging on a second layer - a process
with which I have zero experience.

>
> I'd love to hear success (and failure) stories, alternative

methods,
etc. Somewhere (on the group?) I read about someone using strip balsa
to ensure the epoxy didn't get squeezed out entirely....

>
> Derek

Hi -

Just go get one of those notched trowels that you us when putting
down
the glue for a tile floor, dump a big glup of epoxy on the ply,
spread
it with the trowel, set the second layer of ply on the first, start
nailing on one edge with bronze ring nails. do it on a day when you
are really po'd about something and it feels great to drive all of
those nails. works great. feels great. cheap. easy. don't even
worry about getting the edges lined up - just hit them with a
straight or round-over bit on a router.

Mike

--- Inbolger@egroups.com, "Derek Waters" <dgw@d...> wrote:
> Hi Group
>
> How have members clamped and glued double skinned ply bottoms? At
present I'm leaning towards using the drywall screw clamping method
for the first layer, and vacuum bagging on a second layer - a process
with which I have zero experience.
>
> I'd love to hear success (and failure) stories, alternative
methods,
etc. Somewhere (on the group?) I read about someone using strip balsa
to ensure the epoxy didn't get squeezed out entirely...