Plywood Sheathing the Sides

Applying epoxy to the stem
 for the 3/4" filler strip

 A few last minute details....

Here we (my father and I ) begin sheathing the sides.  The only wildcard is the question of just how flexible the 1/2" marine ply is?  It hasn't kept me awake at night, sweating profusely and asking for divine intervention; however, we have wondered if  a nasty shock is in store for me when we was ready to push the plywood in two directions, having wished we had opted for one of the more flexible plywoods. 
There was a few last minute preperations to make...
We had originally intended to inlay the chines into the stem. Basically, cut a notch for them to fit into.  When we laid then up to the stem we realized that if we did this we would leave very little of the stem for fasteners. This may have even created a weak point.  Instead we fastened them to the outside of the stem.  We then cut filler strips, epoxied them in place and screwed them in position.  The result is, we now have one, uninterrupted plane to land the plywood on and was ready to clamp, mark, cut, glue and fasten.


Epoxy fillet and filler piece added.

We also had to deepen the 1" x 3" chine notch as it created an unfair bulge at Station #20 or the one right ahead of the transom.  It wasn't a big deal.  We just backed out the screws and used a Bosch flush cut saw to accurately deepen the notch about 1/2".  We did the same to the other side, then adjusted the edge of the frame that gets sheathed to match the now deeper chine.  Not bad, just a few minutes with a planer.


Clamp, mark, cut, glue and fasten...

Marking bottom edge of ply using the chine

So, as the title states, this is basically the sequence of steps in sheathing the hull.
Picking  the "A" face of the AB ply (not easy so far, they look the same) we prepared ourselves by positioning C-clamps close by and lifted the ply into position.
 
Step 1 - Clamp:
Starting at the stem, we clamped the ply at the upper and lower chine, starting from the back, and then clamped the upper edge of the ply leaving the hard twist at the bottom of the stem.  ***I'm building this hull upside down so we are using relative terminology to help everyone stay oriented.*** At the bottom of the stem, we used a bar clamp, screwing and pushing the ply in position till tight.  So far, so good.  No cracking noises.

Step 2 - Mark:
This part needs little explanation and you actually see me doing this in the photo to the left.  We used the outside edges of the chines to mark the shape of the plywood panel cut which meant some crawling around the strongback to make sure we have marked all edges.  We also went ahead and marked the chines at the plywood edges so that we had some idea of when we were close to proper position when it came time to fasten the cut panel. We also used this edge mark as a center mark for the butt blocks that will fasten panel to panel.

Step 3 - Cut:

Saw cutting on table. Depth set just below plywood.

Follow the line.  We used a circular saw since it was faster, the curves were gradual and we could set it to just cut through the ply and my panel could stay on the cut table without a lot of drama (falling pieces, saws binding, bleeding shins and contortionist positions trying to hold an 8' long cut together). Believe me, if you are going to cut much ply, take the time and a few bucks and make a proper table to cut on. It may even save a finger.

Step 4 - Glue:

We have covered the basics before.  We guess the real take away is to make the glue a little thicker than you may think.  We used a notched bondo squeegee to apply the glue.  We used some sheet metal notchers to make the teeth but you can do it with a razor knife.  It needs to be spread fast and we followed the squeegee with the plate held under it catching as much as we could that dripped off.  We generally mixed around 12 oz. per plywood panel.  We used a 5oz. dixie cup as a scoop and used about 1 1/2 cups of silica and 1/2 a cup (dixie) of milled fiber; came out somewhere between the consistancy of mayo and peanut butter.  Move briskly if its warm or buy slow hardener.

Step 5 - Fasten:

A repeat of step one with the potential of getting really nasty with epoxy so wear your protection.  We covered the chines and frame edges with the goo so its everywhere to touch but went well having the lines to go back to.  We did lightly clamp the pieces and adjust with a block and mallet before cranking down.  We used a combination of 2" and 1-1/2" 316 SS Screws.  No problems there and kept abot a 6" or so spacing pattern.  It seems extremely solid.




Two sheets glued in. Note the butt block at the edge of the plywood.
6" wide and two rows of 1" screws to hold it. Work from the top and bottom
toward the middle to pull it together slowly. Helper is admiring his work. Little does he know
that he has epoxy in his hair while putting on his glasses.




 





Another view.

 

 



Opposite Side Done