Wayne,

Sounds like your really enjoying the project. I am enjoying reading about it.
Rather that drilling holes and injecting liquid nails would it be a better idea to lay your PVC with the groove/slot up lay the liquid nails in through the groove so it's laying on the inside of the PVC opposite the slot, now push the plywood into the slot into the liquid nails and against the i/s of the PVC. That way you get full coverage with the liquid nails and don't have to drill holes that may weaken the PVC. Plus you use just enough liquid nails to get full contact with your plywood which would save weight.
If I missed something and this is not a feasible idea I apologize.

Ken

: Howdy!

: 'Tis a glorious boat building day in TX, and your faithful correspondant took
: most of the day off to hack away at the PVC folder.

: Here's the update: 1. Gunwales are in place. I was going to make them c-beams
: w/PVC and plywood, but these proved unsatisfactory - too much flex
: vertically as well as horizontally. After a couple of dead ends, I hit
: upon using a table saw to run a gap lengthwise down a peice of PVC. I had
: to double up the blades to get the correct width of the groove (dado
: blades were $100 at home despot!). PVC mated easily with the plywood and
: presto, Chester! I had gunwales. I put notches in the plywood to hold hose
: clamps and the gunwales are secured. When I put vertical pressure, there's
: not much give at all. I plan to drill holes in the PVC and inject liquid
: nails (waterproof kind) into both sides of the pipes to create a bead that
: will hold the plywood in place.

: So far so good. I'm pleased with how well the hose clamps hold, and with the
: vertical rigidity of the gunwales.

: Some questions: 1. I need to secure the keel and gunwales at the bow and
: stern. So far nothing elegant comes to mind. Ideas?

: 2. I'm uncertain about my keel strength. The I-beam is really impressive, and
: I built a short "demo" of an I-beam that has little height. I'm
: wondering if I can make an I-beam that uses plywood that is only about
: 1.75" wide. The PVC would "swallow" it up, but it would add
: some strength to the PVC.

: 3. I wonder about making such a squat I-beam and using it for my keel.

: 4. There seems to be too much wiggle side to side right now. I'm not sure if
: this will be solved by completing the keel/stem connections or if I need
: to be concerned about the boat's proclivity to shimmy side to side. I
: wonder if I need to try my squat I-beam keel concept, but put it sideways
: and possibly resolve my shimmy problem. One possible advantage of this is
: it wouldn't make the boat deeper as it would if I put the I-beam vertical.

: I think it was McCartney who sang, "I'm getting closer - my
: salamander."

: ad salamanderium,
: Wayne