1969 Chris Craft Roamer 46 Refit: Exhaust

With the paint work above the rub rail done, I’ve been working on the exhaust system. Late ’60s Chris Craft Roamer Riviera 46s like mine have metal tubes for exhaust that’s welded in from the engine room bulkhead out through the transom. They all rot out eventually. Mine had pretty severe pitting and I know of one boat that nearly sank when it’s steel exhaust pipes rotted through. Granted, these boats are more than 40 years old, so maybe it’s not surprising that the exhaust would need to be replaced. But since we seriously got into this refit when the paperwork SNAFU was resolved in 2012, I’ve been thinking a lot about the exhaust and how it might be done better.

Initially, when I repowered with the wrong engines back in 2008, I made caps for each end of the original exhaust pipes and had 15 feet of 3.5″ schedule 80 6061 aluminum pipe welded inside. Since I decided in 2012 to install Cummins 6CTAs instead as my propulsion choice, the brand new exhaust that I put in back in 2008 had to come out. I decided to get rid of the pipe out the transom entirely and route the exhaust out the sides of the engine room instead.

Centek fiberglass exhaust system components

On the up-side, fiberglass exhaust should last a lot longer than aluminum pipes, especially with the corrosive nature of diesel exhaust. On the down-side, it’s fiberglass. I finally got over the itchy-scratchies from fiberglassing the cabin top and making the the aft enclosure window frames, I’m not looking forward to working with ‘glass again.

Marking the hole for the new exhaust

Marking the hole for the new exhaust

It’s challenging lining everything up for the cut. Just when I thought I had it, I’d look at the top of the 45* Centek elbow and see that it was pointed in the wrong direction. That stubby piece of the 3.5 inch exhaust pipe sticking out into the space didn’t help either.

Cummins power and the exhaust bits

Cut off the brand new exhaust pipe.

Cut off the brand new exhaust pipe.

The great thing about aluminum is that you can cut it with carbide woodworking tools. My beater Skill saw with an old carbide blade made quick work of removing most of the old exhaust pipe. I’ll leave the stub as a chase to go through the bulkhead.

Next, I drilled pilot holes…

Cut with a jigsaw

…and cut with a jigsaw

I had to go outside the boat to finish the cuts at the top and the bottom.



Make sure the hole is big enough for the exhaust part to fit through

Make sure the hole is big enough for the exhaust part to fit through

Fitted and clamped in place

Fitted and clamped in place

Taping the outside

Taping the outside

The blue tape is like thick shrink tape and resin doesn’t stick to it.

Fully taped and waxed...ready for fiberglass

Fully taped and waxed…ready for fiberglass

4 layers of 1810 fiberglass hot coated with homemade fairing compound

4 layers of 1810 fiberglass hot-coated with homemade fairing compound

Since this was the first time I’d done this sort of thing, I spent a lot of time thinking through each move before doing it. So what should have taken a few hours took a whole day. No worries…now that I know how to do it, the other side should be much quicker.

Next up on our 1969 Chris Craft Roamer 46 Refit: Dismantling the Deck-level Scaffolding.


3 comments on “1969 Chris Craft Roamer 46 Refit: Exhaust

  1. Got it – better choice: more dough for electronics, eh?

  2. Not sure I understand the tape being under the fiberglass. Went with SS pipes/grommets myself. Then attached exhaust to them inside hull.

    • 1969roamer46 says:

      The tape protects the faired (but not painted) hull surface from release wax contamination so I can remove the parts. These will be removable flanges, sealed with 4200.

      I considered SS outlets, but they would have to be custom made. $1200 for a pair vs $200 for FRP. I didn’t think the shiny metal was worth an extra grand.

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