Sept. 21th - 29th, 2002
Last couple of weeks have been busy with the continuing bathroom tile project and so I
didn't get as much Jumbo building in as I might desire. But the bathroom looks good so far and my sweetheart is happy, so I'm happy.
Dealing with four layers of 3/8" plywood that are 24' long is a bit of a challenge. But I'm hard headed and don't give up very easily. So the method of sprayrail construction I finally decided on was to install all four pieces of plywood (perside) one at a time. First the widest layer went down on the hull. I put in one sheetrock screw at 
the rear and then again every three feet or so until I had the first layer in place. Then starting from rear I installed the second layer, but first removing the underneath sheetrock screws as I went along. The second layer and all subsequent layers were temporarily fastened like this with sheetrock screws until all layers were in place. Then I used shorter screws to hold the layers together and removed the whole curved bit from the hull.
After removing the sprayrail from the hull I gave both the hull and the inside layer of the spray rail a liberal coating or two of unthickened epoxy. And after that had cured to the point where it was sticky, I put another coat on each surface of epoxy thickened with cabosil and minifibers. I screwed the whole thing into place on the hull and let it cure for about four hours.
After the first glued up layer (All four layers of sprayrail were still screwed together) had cured, I removed the top three layers of unglued plywood. I then coated the outside of the first
layer and the inside of the second layer with epoxy and screwed all to the hull. I kept repeating this for all layers and both sides of the hull until I had complete glued and screwed (now with stainless screws) sprayrails.
After the spray rails had cured for a day I started working on leveling out the edges with a low angle block plane, a Surform and sandpaper.
Then after dusting off all the saw dust and crud I liberally coated the sprayrails with unthickened epoxy. This means that one, two or even three coats might be required until the plywood stops sucking up the epoxy. Here and there I found voids that should needed a soaking and fill of thickened (in this case, microballoons & cabosil) epoxy. Also filled a few low spots with thickened epoxy. Then the 
sprayrails get two coats of graphite filled epoxy. The first coat ended up running quite a bit. Reason is that as the epoxy heats up during it's cure, it also thins quite a bit. So the second coat of graphite filled epoxy also gets a bit of cabosil to thicken it. I'm getting weary of scraping epoxy drool.