Recently, I had installed the seacock base plates - made from laminating three layers of red oak, and then bonding to the hull with West System's 403 Micro Fibers. Here is the base plate installed for the starboard cockpit scupper seacock. For more on the seacocks and background leading to the installations, see my previous post in "Plumbing" entitled 'Attaching Seacock Backing Plates', May 28, 2010.
Next, I found the center mark for the base plate, and drilled for the through hull fitting itself, using a Rigid hole saw bit for my DeWalt corded drill.
Next step was to align the seacock flange over the base plate and mark for the 1/4" machine screws that will secure the seacock to the base plate. For this step I temporarily screwed the through hull into the flange - after removing the flange from the seacock - lined up the flange on the base plate to a satisfactory location, and carefully marked for the 1/4" machine screw holes to be drilled. After drilling the first 1/4" hole, I climbed out of the boat and threaded an old 1/4" bolt up through the base plate and flange, and tightened it down with a washer and nut. I repeated this step for the second of three holes to be drilled. The reason for placing the temporary 1/4" bolt was to keep the flange in proper alignment as the other holes are drilled. The task was made all the more difficult being alone on the job...in and out of the boat a half-dozen times, whew!
After I had the through hull and 1/4" machine screw holes drilled for each of the two cockpit scupper seacocks, I mixed up some 'neat' epoxy to wet out the base plates sufficiently. Since I chose to use red oak for the seacock base plate material, I wanted to make sure that no water could get to the wood, which would cause eventual failure. I sanded the original 403 micro fiber fillets, and generally prepared the surfaces for epoxy. I wetted the entire base plate and surround surfaces, as well as the interior of the through hull I had just drilled. I then climbed out and wetted the exterior hull surfaces around the through hull installation, and after preparing those surfaces for epoxy work. Finally, I formed a smoothing fillet of a mixture of 407 and 406 colloidal silica, which after I sand and paint will present a nicely faired surface.
Here is a picture of the exterior through hull and 1/4" machine screw holes - notice the counter sink on the three machine screw holes. I will be installing 1/4" x 3" silicone bronze machine screws for this under the water line installation. The components will be bedded in either 3M 4200 or Sikaflex 291 (undecided), and screw head counter sinks faired with 410 microlight fairing filler.
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