1969 Chris Craft Roamer 46 Refit: New Exhaust Risers III

I’m finally back from the funeral trip abroad. Jet lag is slowly getting better, and as the fog has been clearing it’s become apparent that the Roamer will not splash in 2016. I could rush to get it done and have it ready to bring around to my home port a month later than I planned. But I’ve learned that rushing generally doesn’t work out well, and I’d need to splash around a month past the time the yard starts packing boats in tight for the winter. The downside to leaving it in the yard for another winter is that I’ll keep having to waste several hours per day driving to the yard and back every weekend. On the upside, it’s a lot closer to my Boatamalan painter, so as I install more mahogany panels in the interior it’ll be easier for him to come out and spray the ICA clear coat. It’s not ideal, but it is what it is.

In other news, I got the dry side of the starboard exhaust riser cut and tacked together. It was a bit more challenging to work out the angles than the port side riser.

Starboard riser will have to make a loop

Starboard riser will have to make a loop

It would be super easy to just make a straight shot out of the turbo and point it down to the muffler inlet. But the easy road would end up potentially destroying the engine if the muffler was ever to fill with water, since gravity would cause the water to flow into the turbo and engine long before it went over the hump and out the side of the hull. To make the exhaust system inherently safe, I’ll need to have a loop coming off the turbo and going as high as possible before turning and pointing back toward the muffler opening.

X marks the spillover spot

X marks the spillover spot

In the pic above, there’s a 1″ x 1″ x 30″ mahogany cleat clamped to the muffler inlet, which tells me the direction the riser needs to point in at the showerhead outlet. I’ve also tied a red and white collapsible mop handle to the bottom of the U-bend that connects the muffler outlet to the exhaust port through the side of the hull. The mop handle indicates the spillover point. As long as the final turn of the dry section of tubing is above that point, even if the muffler fills with water completely, gravity will naturally force the water to drain out the exhaust rather than backing up into the turbo and engine.

Somewhere around here will be inherently safe

Somewhere around here will be inherently safe

In the pic above, you can see the red mop handle clearly ~2″ or so below the bottom of the dry section exhaust tubing. That puts it well above the spillover point and also leaves sufficient room for the Inferno Wrap insulation I’ll use to keep the exhaust heat in the riser.

Trimming the tubing to fit the turbo flange

Trimming the tubing to fit the turbo flange

135° + 90° mandrel bend is a bit too much

135° showerhead tubing + 90° turn is a bit too loopy

Final fitting before tacking

Final fitting before tacking

Unbolt the whole thing and line up the Sharpie marks

Unbolt the whole thing and line up the Sharpie marks

Let the tacking begin!

Let the tacking begin!

Tacked all around

Tacked all around

Re-attach the riser, final fit, and mark the showerhead section

Re-attach the riser, final fit, and mark the showerhead section

Remove the riser, line up the Sharpie marks, and tack all around

Remove the riser, line up the Sharpie marks, and tack all around

Tacking complete!

Tacking complete!

Loopy riser

Loopy riser

Well above the spillover point

Well above the spillover point

That wraps up Phase 1 of my riser build. They’re tacked together, with the showerhead ends pointing toward the muffler inlets. I’m still waiting for my argon diffuser to arrive, which I need to finish the welding. I’ve already got a couple of lengths of 6″ stainless tubing that I’ll use for the showerhead itself, but I also need to finish the CAD drawings for the showerhead end plates. Then I need to find somebody with a CNC cutting machine who can cut the ends per the CAD drawings.  All in due time.

Next up on our 1969 Chris Craft Roamer 46 Refit: New Coolant Hoses, Clamps, and Coolant Test

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5 comments on “1969 Chris Craft Roamer 46 Refit: New Exhaust Risers III

  1. tdoriot@aol.com says:

    While I haven’t chimed in, in a few months, I read every post and look forward to the next update. Again, thanks for taking the time to share the adventure with all of us. As somebody who can do just about anything with wood or metal, your ingenuity and resourcefulness, coupled with craftsmanship is truly impressive. You achieve results with portable equipment that can be drug into the field that rivals shop stationary equipment. The truly stunning part is that in essence you are building a 50′ yacht from scratch. The product you end up will make a sister Chris look like a Hyundai parked next to a Bentley ! Your decision to not dump the thing in the drink prematurely is most likely a good one. It would be ashamed to see something disastrous happen due to an over looked detail. It will be an amazing boat when it’s done. The bitch is that you have set a tone that you have to match up thru upholstery etc. Keep up the amazing work. Tracy

  2. William B. Kelleher says:

    Not sure how far you are from Cape Cod, but there is a Machine shop there that has a CNC machine.
    Turnwrightmachineworks.com

    Hope this helps

    Bill Kelleher

    • 1969roamer46 says:

      Thanks Bill!
      I’m in the Mid-Atlantic region, so I plan on just sending the CAD drawings to a waterjet metal fab shop…there are lots on the internet. I just have to figure out which one.
      Cheers,
      Q

  3. Kent says:

    Look’n Good Cap’n..
    I worked on a Boat one time and whoever put the Manifolds and Risers on didn’t put Spacers in– Water backed up and Ruined the Engines.. Morons Are Everywhere– As I’m sure you know..

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