Editor Note: This was part of a classified that has been deleted.
Mark Patrick Hillman wrote:
I have a year 1972 47' Chris-Craft Commander located in Point Edward, Ontario at this moment, which I am doing a few repairs and updates on. Questions: Were your cast iron exhaust flapper assemblies in good condition still ??? Do you know where to obtain new cast iron exhaust flapper assemblies or alternatives or what did you do with your situation here ??? (On ALL classic boat's, the exhaust systems are a potentially dangerous"sink the boat situation", as on the YouTube video Chris-Craft 45' Commander boat "Inspiration") Also, I had to add additional support blocking to my huge and extremely heavy cast iron exhaust mufflers because, originally, this is an area which was under supported with only two (2) pieces of 3/4" plywood vertically installed and laminated, which is ridiculously under supported for the heavy weight AND if these fall or shift it will sink the motor yacht. Thank you, in advance, Warren.
Warren Whitmore answered:
Regarding the cast iron flapper/check valve assemblies and cast iron mufflers, my 47 never had them. My boat shipped from the factory with Vernatone fiberglass mufflers, a bit hard to see in the photo below but they are oval in cross section, and quite long - close to 4' if I recall correctly
I believe the check valves were not needed on my boat due to the design height of the original dry risers off the turbos on the Cummins VT8370Ms (see example of the starboard dry portion of the riser wrapped in white insulation in photo below).
I did not do dry risers on the Caterpillar 3208TAs. I went with Vetus waterlift mufflers immediately aft of the engines instead to get the height and protect the turbos from water backing up. By keeping the original Vernatones downstream the boat has a very quiet exhaust note from idle through 2800rpm WOT, though I suspect the majority of the silencing is being done by the waterlift mufflers. Photos below are of the starboard exhaust between turbo and aft engineroom bulkhead.
I think the best course of action regarding the cast iron check valve assemblies is to replace them with new fiberglass units from Centek, refer to photos and attached data sheet below.
Char - thanks for moving this back over to the forum general discussion.
Michael - I was concerned about the exhaust hoses on my 47 but thankfully they checked out just fine. My boat was almost exclusively fresh water and then spent a decade in storage waiting for a repower, which I think explains the good condition of the hoses.