How to Install the Inner Plywood Skin in a True 5200 Bottom – 1938 19′ Chris Craft Custom Runabout

Actually installing Flyin’ By’s True 5200 bottom begins today.

After cutting and fitting all of them, we applied three full coats of Smith’s Clear Penetrating Epoxy Sealer (CPES) to both surfaces and the edges of the 4 mm Aquatek meranti marine plywood panels.

Once the CPES was cured, three coats of Sandusky Chris-Craft Mahogany Bilge Paint were applied to the inner (bilge) side of each sheet.

We are installing those panels bedded in 1/8-inch-thick layer of Mahogany 3M5200 and secured with #6 x ¾” Frearson (Reed & Prince) silicon bronze screws.

This install is a multiple-step process

  • Lay each panel down dry – without any 5200 – and scribe lines running through the center of each frame.
  • Pre-drill, complete with countersink, all of the hole we will drive the screws through.
  • Apply a solid, 1/8”-thick layer of 5200 along each frame and the landings along the keel, chine and transom (in the cast of the aft-most panels).

The layers spread on the landings are a generous 1/8”, especially along the seams between the panel edges and the landings. Doing so produces amble squeeze-out, which, when cleaned with Interlux Brushing Liquid 333, leaves a complete seal.

As Danenberg admonishes, scrimp on 5200 and you end up with a shortcut bottom that will not last. We will apply in excess of one hundred tubes of 5200, which works out to about five tubes per foot LOA, for Flyin’ By’s True 5200 bottom.

  • Use a plastic spreader to essentially “frost” the beads of 5200 into a uniform layer.
  • Lay the panel in place and begin inserting screws.
  • Do not drive and of the screws home until all of them are driven about halfway down. Why? We know by bitter experience that driving the screws home from any edge or other starting place ensures creating fountains of 5200 up and out of the empty pilot holes that lie ahead of you. Inserting all of the screws halfway ensures zero fountains and a much more pleasant experience.
  • Drive all the screws home.
  • Clean all of the squeeze-out inside and out with Interlux Brushing Liquid 333.
  • Wipe all seams and any visible 5200 down with Acetone, which accelerates curing.

Once all the panels are installed and we’ve allowed the 5200 to cure for several days, it will be time to install the mahogany bottom planks. (Remember, all of them received three full coats of CPES – both faces, the edges and the butts – after releasing and cleaning them.)

Then it is time to fill the countersinks with 3M Premium Marine Filler and fair the bottom to be absolutely fair from stem to stern and chines to keel.

Next comes three more coats of CPES before we apply five coats of Interlux 2000E Barrier Coat Primer, and then three coats of hard racing bronze bottom paint.

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