1973 47 Commander Exhaust connections from muffler replacements

Hello.  Just had a conversation with a fellow Commander owner and he strongly recommended  that I replace the couplers and clamps between the exhaust pipe and the mufflers.  

Well, how do I get access to those places -  I'm thinking that they are outboard of the fuel tanks.  Can anyone give me some advice as to how to proceed?

Thanks in advance for any assistance

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Thanks  -- On my boat, the mufflers are in the aft cabin outboard of the fuel tanks.  I've ordered a strong magnet to see if the exhaust tubes have metal in them.  


David Hiser said:

Dennis, that is 6" exhaust hose with wire. It went from the muffler under the sink in the bathroom to the aft exhaust tube.

Dennis,

I think you will have a hard time telling if your hose has steel re enforcing wire in it as the wire does not have much mass and tends to be significantly less magnetic then a normal steel alloy. I think your best method will be to take a small screw driver or a small pick to the ends of the hose and try to feel for where the wire is sticking out at the ends.

Thanks, but the ends are covered  -- I'll have to do that out of the water so I can expose the ends.

I'm not following why you need to know if there is metal wire reinforcing in your exhaust hose?  It definitely should be, and your replacement hose should be.

I see what you mean about the hose over hose, looks like that was to adapt a smaller pipe to larger hose.  I'm not sure how else it would be done.  But it looks like a section of the original hose, and one of the hose clamps, were left in place for that.

You asked about failure mode.  The hoses decay over time and split open, or slide off.  Your clamps are probably not really holding anything by now, if you try turning a few you will have them fall apart on you.  This includes your shaft log hoses and clamps, your bilge pumps will not keep up if one of those fail.  Raw water hoses and clamps, fuel lines and clamps, bilge pump hoses and clamps, are all things that can cause your boat to sink if they fail.

I want to verify if there is metal in the hoses.    The thinking is that if they are original, there would be.  If they were all changed out when the boat was repowered in the late 80s, they may or may not be.  The exhaust tubes may be made out of another type of material if the originals were replaced during the rebuild.  It looks to me, based on everyone's opinion that I need to go from stem to stern replacing hoses and clamps -- That can be done with the boat in the water.  The exhaust hoses have to be done on-shore.  That's a fall project.

For clarity:  Exhaust hose:  The black hoses connecting the muffler to the forward and aft exhaust tube.  Could also be called a "Sleeve," or a "Coupler."

Exhaust tube:  Rigid structure made from high temp fiberglass, wire hose, or other high temp material.  So on my boat: Motor coupled with reinforced hose to complex angle steel exhaust pipe.  The output of that pipe is coupled to the forward exhaust tube.  The aft side of this tube is coupled to the input to the muffler.  The output of the muffler is coupled to the aft exhaust tube -- That's the one that looks like it has a coupler over a sleeve.  The aft exhaust tube exits the boat. 

I've ordered the 6 inch T clamps for exhausts,  and I will order the 1/1/2 inch T Clamps -- How many did you order?  

Havin' fun now!!!!

Dennis



Scott Miller said:

I'm not following why you need to know if there is metal wire reinforcing in your exhaust hose?  It definitely should be, and your replacement hose should be.

I see what you mean about the hose over hose, looks like that was to adapt a smaller pipe to larger hose.  I'm not sure how else it would be done.  But it looks like a section of the original hose, and one of the hose clamps, were left in place for that.

You asked about failure mode.  The hoses decay over time and split open, or slide off.  Your clamps are probably not really holding anything by now, if you try turning a few you will have them fall apart on you.  This includes your shaft log hoses and clamps, your bilge pumps will not keep up if one of those fail.  Raw water hoses and clamps, fuel lines and clamps, bilge pump hoses and clamps, are all things that can cause your boat to sink if they fail.

I agree that all of those failure points need to be addressed.  And the exhausts can be a boat sinker under the right conditions.  But if failure of a stuffing box hose will sink the boat, you have nowhere near enough pump capacity.  Chris Craft was particularly bad about not installing sufficient pump capacity from the factory, so larger pumps should be added if they haven't already been. 

Scott Miller said:

You asked about failure mode.  The hoses decay over time and split open, or slide off.  Your clamps are probably not really holding anything by now, if you try turning a few you will have them fall apart on you.  This includes your shaft log hoses and clamps, your bilge pumps will not keep up if one of those fail.  Raw water hoses and clamps, fuel lines and clamps, bilge pump hoses and clamps, are all things that can cause your boat to sink if they fail.

Yeah, I have 4 pumps going to five -- 

Rob Slifkin said:

I agree that all of those failure points need to be addressed.  And the exhausts can be a boat sinker under the right conditions.  But if failure of a stuffing box hose will sink the boat, you have nowhere near enough pump capacity.  Chris Craft was particularly bad about not installing sufficient pump capacity from the factory, so larger pumps should be added if they haven't already been. 

Scott Miller said:

You asked about failure mode.  The hoses decay over time and split open, or slide off.  Your clamps are probably not really holding anything by now, if you try turning a few you will have them fall apart on you.  This includes your shaft log hoses and clamps, your bilge pumps will not keep up if one of those fail.  Raw water hoses and clamps, fuel lines and clamps, bilge pump hoses and clamps, are all things that can cause your boat to sink if they fail.

I agree.  My original stock Jabsco pump isn't nearly the capacity to handle any substantial leak, it is more for rain water or spray.  I'm not sure how many higher capacity pumps would be needed to handle a shaft log hose failure.  Maybe on a plane, the water would be sucked out?  Seems unlikely, as flow in through the packing is needed when underway.  I keep a wax toilet ring in my toolbox for bigger leaks.  I keep the boat out of the water when I'm not on it, so that helps.



Rob Slifkin said:

I agree that all of those failure points need to be addressed.  And the exhausts can be a boat sinker under the right conditions.  But if failure of a stuffing box hose will sink the boat, you have nowhere near enough pump capacity.  Chris Craft was particularly bad about not installing sufficient pump capacity from the factory, so larger pumps should be added if they haven't already been. 

Scott Miller said:

You asked about failure mode.  The hoses decay over time and split open, or slide off.  Your clamps are probably not really holding anything by now, if you try turning a few you will have them fall apart on you.  This includes your shaft log hoses and clamps, your bilge pumps will not keep up if one of those fail.  Raw water hoses and clamps, fuel lines and clamps, bilge pump hoses and clamps, are all things that can cause your boat to sink if they fail.

My approach is generally to assess the size and depth below water line of shaft logs, thru hulls, rudder logs, etc. and look at one of the flooding charts available online to determine how much water would come in via a complete failure.  Then size pumps (figuring real world output is around 60% of actual) to keep up with the failure of the worst case fitting. 

On my 381 Catalina, I've got a small pump in each of the 3 compartments (good for 5 - 6 gallons / minute).  Then a much larger pump (good for 35+ gallons / minute) mounted higher in the engine room bilge.  I'm working on plans to add a mid-size pump below that with a high water alarm, as well as a secondary pump with high water alarm in the aft bilge.  None of the 3 compartments are truly watertight, so that should be enough to take care of any single failure, certainly for long enough that I can find and mitigate the problem. 

This thread does have me trying to figure out how to get to the short rubber hose couplers connecting the fiberglass exhaust tubes to the thru hulls at the transom.  There's only about a 1/4" gap of exposed hose on the inside at the joint, but it's still a concern and I know the hoses are original. 

Scott Miller said:

I agree.  My original stock Jabsco pump isn't nearly the capacity to handle any substantial leak, it is more for rain water or spray.  I'm not sure how many higher capacity pumps would be needed to handle a shaft log hose failure.  Maybe on a plane, the water would be sucked out?  Seems unlikely, as flow in through the packing is needed when underway.  I keep a wax toilet ring in my toolbox for bigger leaks.  I keep the boat out of the water when I'm not on it, so that helps.

I believe Dennis called the hoses "couplers", that sounds more appropriate and what I would call them on industrial machinery.  All my hoses were just short pieces connecting components that were fairly close together.  Fiberglass tubes connected the iron collectors behind my engines, to the mufflers in the back.  I would definitely replace any long exhaust hoses with fiberglass tubes if possible, they are available in McMaster Carr and other sources.

My iron collectors weren't the most precise castings, I ended up grinding the ends smooth to get a better seal.



Rob Slifkin said:

My approach is generally to assess the size and depth below water line of shaft logs, thru hulls, rudder logs, etc. and look at one of the flooding charts available online to determine how much water would come in via a complete failure.  Then size pumps (figuring real world output is around 60% of actual) to keep up with the failure of the worst case fitting. 

On my 381 Catalina, I've got a small pump in each of the 3 compartments (good for 5 - 6 gallons / minute).  Then a much larger pump (good for 35+ gallons / minute) mounted higher in the engine room bilge.  I'm working on plans to add a mid-size pump below that with a high water alarm, as well as a secondary pump with high water alarm in the aft bilge.  None of the 3 compartments are truly watertight, so that should be enough to take care of any single failure, certainly for long enough that I can find and mitigate the problem. 

This thread does have me trying to figure out how to get to the short rubber hose couplers connecting the fiberglass exhaust tubes to the thru hulls at the transom.  There's only about a 1/4" gap of exposed hose on the inside at the joint, but it's still a concern and I know the hoses are original. 

Scott Miller said:

I agree.  My original stock Jabsco pump isn't nearly the capacity to handle any substantial leak, it is more for rain water or spray.  I'm not sure how many higher capacity pumps would be needed to handle a shaft log hose failure.  Maybe on a plane, the water would be sucked out?  Seems unlikely, as flow in through the packing is needed when underway.  I keep a wax toilet ring in my toolbox for bigger leaks.  I keep the boat out of the water when I'm not on it, so that helps.

On the complex curve structure that coupled to output of the motor to the forward exhaust tube I got leaks from pin holes in the metal.  Then I got more because I poked at the area with a screw driver (That's how a wood boater chased dry rot) -- Bad idea since it was like I was trying to drain Lake St. Clair.  Anyway, I bought a 4 inch wide water activated fiberglass tape and covered the area to where I knew I was above the waterline.  This stuff is good with the exhaust heat, and pressure -- Way above the operating temperature and pressure of the exhaust gas and water.  So my thought was to cover the "couplers" with a fiberglass "sheath" if I had a problem, and move on.  As long as I made the "sheath" with enough material, I would have made a new "coupler" that would never deteriorate --  The industrial magnet was just delivered so now I start sleuthing in order to figure out what's installed on my boat.  Hopefully the exhaust tubes are fiberglass, and all I'm really dealing with are the "couplers."



Scott Miller said:

I believe Dennis called the hoses "couplers", that sounds more appropriate and what I would call them on industrial machinery.  All my hoses were just short pieces connecting components that were fairly close together.  Fiberglass tubes connected the iron collectors behind my engines, to the mufflers in the back.  I would definitely replace any long exhaust hoses with fiberglass tubes if possible, they are available in McMaster Carr and other sources.

My iron collectors weren't the most precise castings, I ended up grinding the ends smooth to get a better seal.



Rob Slifkin said:

My approach is generally to assess the size and depth below water line of shaft logs, thru hulls, rudder logs, etc. and look at one of the flooding charts available online to determine how much water would come in via a complete failure.  Then size pumps (figuring real world output is around 60% of actual) to keep up with the failure of the worst case fitting. 

On my 381 Catalina, I've got a small pump in each of the 3 compartments (good for 5 - 6 gallons / minute).  Then a much larger pump (good for 35+ gallons / minute) mounted higher in the engine room bilge.  I'm working on plans to add a mid-size pump below that with a high water alarm, as well as a secondary pump with high water alarm in the aft bilge.  None of the 3 compartments are truly watertight, so that should be enough to take care of any single failure, certainly for long enough that I can find and mitigate the problem. 

This thread does have me trying to figure out how to get to the short rubber hose couplers connecting the fiberglass exhaust tubes to the thru hulls at the transom.  There's only about a 1/4" gap of exposed hose on the inside at the joint, but it's still a concern and I know the hoses are original. 

Scott Miller said:

I agree.  My original stock Jabsco pump isn't nearly the capacity to handle any substantial leak, it is more for rain water or spray.  I'm not sure how many higher capacity pumps would be needed to handle a shaft log hose failure.  Maybe on a plane, the water would be sucked out?  Seems unlikely, as flow in through the packing is needed when underway.  I keep a wax toilet ring in my toolbox for bigger leaks.  I keep the boat out of the water when I'm not on it, so that helps.

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