Category: True 5200 Bottom – Install Bottom Planks

As is typical of all Chris-Craft utilities and runabouts, this 1938 19’ Chris-Craft Custom Runabout, Flyin’ By’s hull is comprised of a series of heavy frames to which the bottom is fastened. A series of battens run athwart between the frames, thereby adding substantial stiffness to the bottom.

Simply put installing battens is a thankless, two-person challenge. Here are the steps for installing one batten at a time, followed by filling the countersinks, fairing the bottom, sealing, priming and applying bottom paint. The process is described for one batten, one that will be repeated for all of them:

Installing the Battens.

• From the inside, drill two pilot holes towards the ends of the batten. • Using a straightedge and pencil, scribe a line between the pair of holes.
• Drill holes along the line, about 1.5 inches apart using a countersink pilot drill.
• Dry fit the batten and, while the guy underneath presses it in place, drill two holes from the outside in through two of the countersinks.
• Sink screws through those two holes. We use #6 x 1 or x 1-1/4, depending on the thickness of the inner plywood skin plus the exterior planks.
• Stand the remaining screws through the remaining holes and drive them home.
• Release all of those screws for now.
• Butter the batten’s bottom face about 1/8” thick with 3M 5200 – mahogany.
• Hand it to the guy beneath the boat, who presses it in place.
• Starting with the two end screws, and remembering to stand screws in all of the holes, drive all of them in place. (Standing the screws in the holes first ensures that fountains – volcanoes? – of 5200 do not squirt though the other screw holes as you work along the batten.)
• Repeat for all battens on both bottom faces. Flyin’ By has twenty of them per face.

Filling Countersinks and Fairing the Bottom.

Filling countersinks and fairing the bottom is next. We use 3M Premium Marine Filler, available from Jamestown and elsewhere, to fill and fair the countersinks.

Three applications are required. We sand using 80 grit and one of our Festool random orbit sanders after the first coat, just to knock down ridges and what I call overspread.

Once the last application has cured – about 4 – 6 hours – we sand the entire bottom fair using 80 grit on our pneumatic longboard sanders. Declivities may show themselves at this stage, which requires interrupting the sanding as Premium Filler is applied to them. Sealing, Priming and Bottom Paint.

Once the bottom is fair, apply three coats of Smith’s Clear Penetrating Epoxy Sealer. Danenberg recommends applying the second coat immediately after the first, so we apply the CPES to one entire face and then return to where we began and apply a second coat.

I know there are other penetrating sealers available, and we’ve tested most of them. Let me just say that we use Smith’s CPES, which is available at good prices from Star Distributing in West Mystic, CT: http://www.star-distributing.com/smit….)

Our go-to primer is Interlux InterProtect 2000E Two-Part Barrier Coat Epoxy Primer because it works

From Jamestown:

Interlux’s Micro-Plate formula creates an effective barrier against water permeation. 2000E may be used above and below the waterline as a universal primer for all surfaces. It is also an excellent primer for all metals and can be used as part of a no sand system.

From Interlux:

• Two-part epoxy water barrier with Micro-Plates
• Up to two weeks is allowed between coats of 2000E
• Now available in two colors, Gray and White
• Fast drying, easy application
• Sag resistance to insure the elimination of sags and runs during application

Technically, InterProtect Micro-Plates provide millions of overlapping microscopic plates that create a barrier similar to shingles on a roof. These overlapping Micro-Plates eliminate any direct path for water migration and also improve the sag resistance of the epoxy making application easier.

We will have a gallon each of gray and white 2000E on hand for Flyin’ By’s bottom and chine plank – boot stripe included. Once we’ve applied five thin coats, we will have created an impenetrable barrier against water permeation.

Since Flyin’ By will be dry sailed by her new owners, we will apply three coats of Pettit Old Salem Copper Bronze Hard Racing Enamel, at which point she will sport a True 5200 Bottom.

Finally, she was in show ready condition, with over 20 coats of varnish having been applied and buffed when the moment to flip her arrives. No matter how careful any of us is, and no matter how many pads we placed strategically, Flyin’ By is heavy, and her hull shape presents long sweeping curves. And with three of us working around, under and even atop her, bumps and bangs are all but inevitable.

That said her varnish is scuffed in several places, so we will sand the entire hull flat anew and apply three or so coats of Interlux Perfection Plus Two-Part Varnish to her, and let it clear before she returns to storage.

Installing the bottom planks can be tedious and is fraught with all manner of challenges.

First and foremost, unless the planks are dry-fit so that the seams between them are of uniform width, you will all but certainly experience and “Oh X$#%^!” moment when try to install the final, chine, plank.

I cannot tell you how many bottoms we’ve encountered that sport the telltale “skinny plank” along the chine. Failing to fit first, mark the edge of each plank heavily and then obey the lines usually translates into a super wide seam, sometime over an inch, and a plank that does not fit at the stem.

Once again we drop screws part way into all of a plank’s holes before setting it in place, and screw each of them in only part way thereafter. Once all the screws are down far enough that the shanks are in the plank’s holes, begin driving them home. (We work from the middle out, but given how narrow the planks are, you can also work from either, or both ends towards the middle.)

When you clean excess 5200 – that which squeezes out – work towards to ancillary goals. Keep the countersinks free of the 5200 so that the 3M Premium Marine Filler can make a purchase on wood, not on slipper adhesive. And, be sure that all seams are filled fair with 5200.

Clean with Interlux Brushing Liquid 333, and then wipe everything down with acetone, which will accelerate the curing process.

Finally, be patient. I do not care what Interlux says, 5200 can have a mind of its own around curing.

Sometimes waiting 2 – 3 days are fine, but we wait longer, at least a week, before we go at the bottom with sandpaper.

You will be helped with being patient as the countersink filling and bottom fairing process is might time consuming when done correctly. Remember, whether it is 3M Premium Marine Filler or some other fairing compound of your choosing, it shrinks as it cures. You want every countersink filled fair to the plank surface. Apply it twice and then sand everything as smooth as you can with 80 grit – no finer, before applying it a third time and sanding again.

Even though the planks were dosed with three coats of CPES before installation, you have likely sanded into the sealed layers, so applying three more coats is not overkill.

We prime all bottoms with five, not three or four – coats of Interlux 2000E Barrier Coat Primer before applying Pettit Hard Racing Copper Bronze Bottom Paint – three coats.