1969 Chris Craft Roamer 46 Refit: Fairing the Cabin Top (cont.)

It’s been a very busy two weeks. The weather gods suck…windiest winter ever, and what’s the deal with two snow storms in March, including one just before the Cherry Blossom Festival???

Oh, also, if anybody thinks up how to produce 20cfm of air at 90psi with only 120VAC on a 20 amp breaker in the boatyard that services 16 power pedestals, drop me a line. ūüėČ

The fairing work continues on the cabin top, though you wouldn’t know it by looking at the end-of-the-day pix. We’re also taking a different approach to the cabin top-to-deck joint than Chris Craft did.

Back at the Chris Craft factory in 1969, 1″ x 4″ mahogany boards were bolted to the deck structure all the way around the opening that will become the salon and galley. The FRP cabin top was then craned onto the deck, with the bottom edge fitting tightly to the mahogany on the inside.¬† Screws spaced 8″ apart secure the bottom edge of the cabin top to the mahogany. Large radius quarter-round mahogany was then screwed in place over the seam, with bedding compound to keep things dry.

It was a good approach except for a couple of problems that arise over decades of use: The coating on the wood fails eventually, so there’s a maintenance premium without as associated payoff. The bedding compound eventually gives up, usually in just a spot or two. This allows small amounts of water to leak in and go unnoticed, rotting out whatever mahogany it comes into contact with without a telltale drip to alert the owner.

So our approach has been to cover cabin top-to-deck joint seam with 1708 biaxial fiberglass, which we’ll cover with very nice, water-shedding fillets.

Circa 2008: quarter-round mahogany covering the cabin top-to-deck-joint seam.

This shot is from when we first got the boat, and shows the port side deck looking aft at the transition from aluminum decks to teak. The quarter round is broken from where the teak deck buckled, but you get an idea of how it worked. Also, note the paint has mostly fallen off the wood. It doesn’t matter how you do it, paint will not stick to exterior wood and stay there like it will to fiberglass or metal.

I think there’s a better, more modern way.

Circa 2013: heavy 1708 bi-axial FRP covering the cabin-top-to-deck joint seam where once there was wood.

As when we fiberglassed the cabin top, bowseat and dashboard, we use US Composites 635 epoxy for the FRP layup (with just a touch of cabosil to improve adhesion between the ‘glass and aluminum) and then hot coat it while it’s still tacky with fairing compound made of 635 epoxy, 3M microbubbles, and cabosil.

Though the deck was sandblasted in 2008, we ground it back a bit and also stripped the gelcoat from the cabin top before applying the FRP.

Same thing on the bow, where there was evidence of two old leaks at each corner that no doubt contributed to some of the rotten bulkheads we found when we first started the project.

Oh, my achin’ shoulders! Fairing work also continues.

It’s amazing how much fairing compound you put on compared to what remains in the end. The windshield base that had been previously repaired is now much stronger and straighter than it was before.

Fair lines from the bow seat to the helm.

We’re blocking the filler to sharp lines at the edges, which made low spots and wiggles very apparent. Before priming, we’ll sand the sharp edges down to a nice radius.

That’s a whole weekend worth of sanding and fiberglassing, but she just doesn’t look much different than when we started. We really are heading into the painting home-stretch, though.

Next up on our 1969 Chris Craft Roamer 46 Refit: The Helm Station Side Door Openings.

Advertisements

4 comments on “1969 Chris Craft Roamer 46 Refit: Fairing the Cabin Top (cont.)

  1. CVS37 Cary says:

    Eric is right: this is inspirational and I am inspired. Need to do this same quarter-round replacement on a 37′ aluminum Roamer (1966, express, 427’s ). I agree that the quarter round has to go, but I can’t tell from the pictures whether you have glassed over a different molding (could it be a 1/2″ X 3/4″ door stop type or similar that you milled yourself to match the window?) or just built up a shape with the glassing mixture you used…. sure would like to know as my knowledge of glassing is way far behind what you are doing. Again, your workmanship is spectacular. I plan to follow the same techniques you have set out as to the glassing as well. I have followed your postings on the YF forum (especially the unimetal rudder logs, I have that problem too) and DoomPatrol kindly informed us that this now continues in blog form and I thank you for all of this infomation so ably delivered over many years now. – Cary

    • 1969roamer46 says:

      Thanks, Cary! It’s always nice to see comments…let’s me know people are actually reading this thing! lol

      I removed the quarter-round entirely, then used 36 grit on a grinder to take the cabintop back to FRP and also to roughen up the aluminum deck for about 1.5″ from the seam all the way around. With the entire seam area roughened up, I wetted out 1708 bi-axial fiberglass cut into long 3″ strips (they make 1708 tape, too, that’s already the right width, but I had plenty of scraps laying around). While waiting for the cloth to saturate, I applied just a bit of epoxy resin thickened just a touch with cabosil to the joint area–the cabosil vastly improves the bond strength over straight epoxy, especially on aluminum. I then applied the fiberglass tape over the seam all the way around and rolled out the bubbles. Then I made another trip around with the epoxy-based fairing compound I use (resin+hardener+cabosil+micro-balloons) and covered the still-tacky fiberglass with some filler. After it cured, we sanded the filler smooth and mixed up more of the epoxy filler, then applied it with a fillet blade so it’s nice and pretty.

      If you only use filler without the strong FRP layer securing the seam, I believe it’s only a matter of time before the seam cracks and you’re back to square one.

  2. 1969roamer46 says:

    Thanks, E!
    There’s always that toss-up between going with the original approach that worked for probably a decade or more vs trying out a modern approach. When it comes to leaks…I’m a fan of the newfangled way. ūüėČ

  3. So thatz why I kant find the leaks which have destroyed the mahogany bulkheads. Well, now at least I know where to look (search & destroy). Great (great) work again – you are an inspiration and able guide for all us Roamer owners.
    Cheers!
    -Eric

Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s